Journal of the
Vol. 70 Spring
2007
Copyright © 2007 by the
Published by the
The
The
Address Editorial Correspondence to: Editor,
Abstracts are listed alphabetically by
the last name of the first author listed.
THE BRANCHING INSTABILITY OF DENDRITES
Stephanie L. Anderson and
Rodney J. Kubesh (Advisor)
Department of
Earth and Atmospheric Sciences
Dendrites are complex structures created as ice
crystals grow. Commonly grown around -15°C, these crystals are time-dependent
interactions between atmospheric temperature, humidity, and pressure. During
growth, all ice crystals’ shapes are controlled by the rate of vapor diffusion.
This diffusion-limited growth, a function of pressure, determines whether a
crystal develops a “branched” (long, intricate arms) or “faceted” (platelike)
appearance. While extremes exist, most dendrites are a delicate balance between
faceting and branching.
Diffusion-limited growth begins when water vapor is
drawn toward the crystal. Diminutive corners of plates protrude farther than
the rest of the crystal; water vapor reaches these edges first. These tips
continue to collect more water vapor, emerging away from the crystal. The
crystal continues to develop, by branching or faceting, on its journey to
earth.
Our study aims at finding how diffusion-limited
growth, at various pressures below standard sea level pressure, affects
branching instability. Using a water bottle; hot water; dry ice; sponge; and
thin fishing line; a supersaturated, subfreezing atmosphere was simulated for
crystal growth. Temperature, supersaturation, and pressure were held constant.
A COMPARISON OF
GENERALIZED PAIN IN THE EMERGENCY ROOM BETWEEN SELF-REPORTED ALCOHOL USERS AND
ABSTAINERS
Grace
Arnold1, Vittorio Addona2 (Advisor), Devavani Chatterjea1
(Advisor), and Jim Miner3
1Department of Biology
2Department of Mathematics and Computer
Science
3Emergency Department,
Pain is one of the
most common symptoms patients present with in the Emergency Department (ED). To
determine if self-reported alcohol use influenced the level of generalized pain
patients presented, we prospectively screened all patients (N= 7856) presenting to the ED during a
randomized distribution of 8-hour shifts totaling 772 hours between June and
August 2006. We screened patients for alcohol use, pain, trauma, illicit drug
use, domestic violence, and homelessness. Patients were excluded from the study
if they were younger than 18 years old, non-English speaking, mute or deaf, or
had altered mental status and therefore could not give consent.
Overall, 1910
patients (24%) were enrolled. Of these patients, 1159 (61%) reported using
alcohol. Amongst users, 741 (64%) reported experiencing pain, with an average
numeric rating scale (NRS) score of 6.42. Non-users reported an average
pain of 7.69 (N=686). Those who
reported never drinking (N=686)
presented with significantly more pain than those who drank occasionally or
rarely (N=787, NRS Score = 6.54, p
< .001) or those who never drank frequently or every day (N= 197, NRS Score = 5.93, p
<.001). These results held when ethnicity, education, occupation and
drug use were taken into account.
Based on our data, we
conclude that patients reporting alcohol use in the ED present with
significantly less pain than those who report never drinking. This suggests
that those who drink more frequently may come to the ED for complaints other
than pain.
DIEL VERTICAL MIGRATION
UNDER THE ICE: AN EXAMINATION OF ZOOPLANKTON COMMUNITIES IN A NORTHERN
TEMPERATE
Janet
R. Aubin, Benjamin D. Dickinson, Elizabeth W. Goldsmith, Anna M. Shamey, and
Jerald J. Dosch (Advisor)
Department of Biology
Zooplankton
exhibit daily movement patterns known as diel vertical migration (DVM). DVM in strat-ified lakes is characterized by
heterotrophic organisms’ exploiting the inverse relationship between light
intensity and depth to avoid predators and to forage for food. While DVM
patterns have been studied extensively, few investigations have been conducted
during periods of ice-cover. Winter DVM merits investigation for its
significance to aquatic ecology and fisheries management. Temperate lake
ecosystems change significantly under the ice, experiencing limited nutrient
availability and inverse temperature stratify-cation compared with summer
conditions. Light conditions also shift drastically, limited by both ice cover
and decreased photoperiod, suggesting that DVM patterns could exhibit seasonal
variance.
Our study investigated DVM
in an ice-covered lake to determine if winter patterns differ from those found
in previous summertime studies. We sampled zooplankton and abiotic variables
below the ice in January 2007 at the
INTERMOLECULAR INTERACTIONS IN BENZY-LIDENEANILINE
Barjeta Balidemaj and William
H. Ojala (Advisor)
Department of
Chemistry
We are examining, using single-crystal X-ray
diffraction, the crystal structures of pairs of benzylideneanilines that we
describe as “bridge-flipped” isomers of each other, isomers that differ only in
the orientation of the -CH=N- bridge between the phenyl rings. Pairs of these isomers that assume similar
molecular packing arrangements in the crystalline state might form solid
solutions with properties that could be readily adjusted by co-crystallizing
desired proportions of these isomers.
Solid-state intermolecular interactions common to both isomers might
encourage this isostructuralism. We have
determined the crystal structures of two halogen-nitrile benzylideneanilines,
4-fluorobenzylidene-2-cyanoaniline and 2-cyanobenzy-lidene-4-fluoroaniline, to
determine whether inter-molecular Lewis acid-Lewis base contacts between
halogen atoms and nitrile groups on these molecules might encourage the isomers
to pack similarly. We find in this case
that they do not. In accord with the
weak Lewis acidity of fluorine, no fluorine-nitrile contacts are found, and the
isomers assume unique packing arrangements.
COMPLEXATION OF CERIUM(III) NITRATE IN
SOLUTIONS CONTAINING ALCOHOLS OF VARYING CHAIN LENGTHS
J. Sigrid
Barklund, Jean-Jacques Gaumet, Gary Gresham (Advisor), and
An issue of significant concern is the amount of
radioactive waste generated by nuclear reactors. Different extraction agents
are being developed to pull specific species from solutions containing
radioactive waste so that at least some of the waste can be purified and
recycled. To develop an effective extraction agent, the complexation behavior
of the species in question must be studied. Cerium is often used as a model for
uranium in the early stages of research.
Our study examined the complexes formed when cerium
nitrate was dissolved in solutions containing alcohols with 1-4 carbons.
Electrospray mass spectrometry was used to determine the composition, relative
bond strengths and some structural data for these cerium complexes.
PHARMACOLOGICAL EFFECTS OF THE AQUEOUS EXTRACT OF BLUE
COHOSH (Caulophyllum thalictroides)
ON ISOLATED Mus musculus UTERI
Jennifer N. Berger and Teresa
F. DeGolier (Advisor)
Department of
Biological Sciences
The roots and rhizomes of blue cohosh (Caulophyllum
thalictroides), traditionally used as an aid for childbirth, contain
several active alkaloids and saponins, which act directly on uterine smooth
muscle resulting in an oxytocic response. The historical use of this herbal
supplement has been well documented, but there are few clinical studies
addressing its efficacy and potential side effects.
Our research investigated the physiological and
pharmacological responses of blue cohosh on isolated strips of murine uterine
tissue. Uterine horns from mice (Mus
musculus) were suspended in a smooth muscle bath and exposed to the aqueous
extract of blue cohosh (0.037-23.8 mg). All tissues showed an increase in the
strength of contractile force and these forces were significantly greater with
higher doses (P=.0001). The stages of estrous were determined by vaginal smears
and dose-dependency was consistent in all stages of estrous observed (diestrus,
estrus, metestrus). Blocking experiments showed that uterine tissues given a
control dose of blue cohosh, followed by the nicotinic receptor antagonist
curare, resulted in a 70% decrease in contractile response following a second
application of blue cohosh. This is consistent with the proposed mechanism for
blue cohosh.
IMMUNOLOCALIZATION OF ACTIN IN
TRANSGENIC AND WILDTYPE MURINE MYOCARDIUM
Meghan Bohland, Gabriel
Johnson, and Marilyn C. Hart (Advisor)
Department of
Biological Sciences
MN
In myocardium, actin and myosin filaments are
organized into repeating units of sarcomeres, the basic unit of muscle
contraction. Actin Capping Protien (CP) binds to the barbed ends of the actin
filament at the Z-line, directing and maintaining the proper organization of
the thin filament in the sarcomere. CP is a heterodimer composed of an alpha (a) and a beta (b) subunit. Muscle cells contain two b subunit isoforms, b1 and b2. The b1 isoform is present at the Z line; the b2 isoform is found elsewhere including cell-cell junctions. In previous
studies, transgenic mice were generated that replaced the b1 isoform with the b2 isoform using the
cardiac-specific promoter, the a-myosin heavy chain (a-MyHC). The promoter is turned on at birth in the ventricles with
increased expression as a function of murine age.
We hypothesized that a decrease in b1 expression will lead to a disorganized myofibrillar structure and
that the disorganization will become increasingly severe as a function of
murine age. We examined the myocardium of transgenic mice ranging in age from 3
months to 12 months. Murine hearts were extracted and frozen sections prepared
using a cryomicrotome. The tissue sections were fixed, quenched with
ethanolamine, permeabilized with methanol, and washed in PBS. The sections were
probed with mouse anti-actin primary antibody and anti-mouse IgG rhodamine
conjugated secondary antibody. Immuno-fluorescence studies revealed an
increased disorganization of myocardium as a function of murine age, supporting
our hypothesis.
NOVEL RESPONSES OF THE CLOCK GENE frequency IN ENTRAINING AND CONSTANT LIGHT STUDIES OF THE
FILAMENTOUS MOLD Neurospora
Brian J. Bourne and Van D.
Gooch (Advisor)
Biology
Discipline
Circadian rhythms are daily biological cycles
occurring in a range of organisms from bacteria to humans. These cycles persist
when all external clocking cues are removed and thus demonstrate an underlying
capacity for cellular timekeeping. In constant conditions, the circadian clock
does not exhibit an exact 24-hour cycle. However, circadian rhythms may be
entrained by a periodic light-dark cycle, as, in nature, when the sun
synchronizes the clock to a 24-hour period. Neurospora
crassa, a eukaryotic model organism, has long been a tool for genetic and
circadian rhythm studies. Classically, the Neurospora
clock has been studied by observing a daily cycle of spore formation. Since
spore formation itself is influenced by light, independent of the clock, few
studies of light effects have been reliably performed.
The frequency
(frq) gene of Neurospora has been
ascribed a central role in the clock and its light response. Using the firefly
luciferase gene, linked to the frq
promoter, high-resolution bioluminescent study of the circadian light response
is now possible. With this tool, using a 12 hr:12 hr light-dark cycle, we have
been able to produce an entrained frq
rhythm. One observation is that only a very low light intensity – as low as
moonlight levels – is needed to induce an entrained rhythm. In addition, we
have shown that there is a high-amplitude, angular rhythm under entraining
conditions when compared with the rhythm classically measured in constant dark.
Also, we found that rhythmic behavior appears to be absent in constant light
conditions.
THE EFFECT OF TEMPERATURE ON THE OPTOELECTRONIC
PROPERTIES OF POLYCRYSTALLINE Zn:Al
Kyle Braam and James Doyle
(Advisor)
Department of
Chemistry
Zinc oxide is a direct band gap semiconductor that has
many different applications in solar cells, thin film transistors, and LCDs.
The effects of temperature on the properties of RF magnetron sputtered aluminum
doped zinc oxide (ZnO:Al) films were investigated in this project. The films
were characterized by four point probe resistivity measurements, theta-two
theta x-ray diffraction, spectrophotometer analysis, and Hall effect
measurements. The mobility, carrier concen-tration, resistivity, and Tauc
energy gap all increased with increasing temperatures. The x-ray diffraction
scans indicate that the better properties at higher temperatures were due to
improved crystalline quality. The best resistivity obtained was r=1.55*10-3 W-cm at a substrate temperature of T=164ş C and further
improvement is expected at higher substrate temperatures.
SUBSTANCE P MODULATION OF ANTI-TUMOR RESPONSES:
ENHANCED TUMOR RESISTANCE BY ADOPTIVE TRANSFER OF SP-TREATED T CELLS
Lucas Brand, Amanda Kastelic,
and Jill Manske (Advisor),
Department of
Biology
Substance P (SP) is a neuropeptide that has been shown
to have immunoregulatory properties including effects on many of the mediators
involved in anti-tumor immunity. In previous studies we have shown that
treatment of mice with SP provides protection against tumor growth. This
protection requires both T cells and NK cells, and adoptive transfer of cells
from SP-treated animals can transfer tumor protection. These earlier studies
suggest a model in which SP treatment prior to tumor challenge primes immune
mediators to prevent or delay tumor establishment. In this study we examined
the role of T cells in tumor protection. To examine whether SP-primed T cells
could increase tumor resistance, purified T cells from SP-treated donor mice
were adoptively transferred into animals prior to tumor challenge. Mice
adoptively transferred with T cells from SP-treated donors developed
significantly fewer tumors than did control animals receiving T cells from
PBS-treated donors. These results suggest that SP mediates anti-tumor immunity,
at least in part, by effects on T cells, and that tumor protection provided by
these primed T cells can be transferred between individuals.
IT FITS!
MOLECULAR SHAPE BY CIRCULARLY POLARIZED LIGHT ABSORBTION PATTERNS
Sara J. Bush, Kristine L.
Carlson, Sarah Vollmer, and Kathryn A. Thomasson (Advisor)
Department of
Chemistry
Molecular shape is critical for understanding
biochemical properties of peptides and proteins. One way to examine molecular shape is through
characteristic circularly polarized light absorbtion patterns (aka CD spectra). Preferred molecular shapes were explored for
cyclo(Gly-Pro-L-Pro)2 as a model for cis-peptide bonds in tightly wound
systems. Fifteen computer models of the
system were explored under various conditions, including a variety of solvents,
to examine how the molecular shape may change in different environments. Three different methods of calculating the
preferred molecular shape were used (CVFF, CFF91, and AMBER force fields). The calculated structures were classified by
their characteristic protein turns. The
published observed ultraviolet CD spectrum of cGPP2 in acetonitrile was used to
determine the “goodness” of calculated CD spectra in that solvent. Structures that lead to “good” CD spectra
would be most likely to exist in real (not calculated) systems.
THE INFLUENCE OF OXIDATIVE STRESS ON IMMUNE RESPONSE
IN CHICKENS
Sara Bush, Kwaku Gyenai,
Xiaojing Guan, Tuoyu Geng, and Ed Smith (Advisor)
Virginia Tech
Summer Undergraduate Research Program
Virginia Tech,
Oxidative Stress (OS) occurs when an organism has
higher levels of oxidants than antioxidants. In this research, OS and Immune
Response (IR) are analyzed in chickens. We are evaluating OS and IR to
determine if a higher oxidative state would induce a higher or lower immune
response in the birds.
MOLECULAR ANALYSIS OF THE MM-50 TRANSCRIPTIONAL
SILENCER IN Drosophila melanogaster
Chris Chamberlain and Presley
Martin (Advisor)
Department of
Biology
The MM-50 transgenic line of Drosophila melanogaster contains a D.melanogaster Alcohol dehydrogenase (Adh) transgene inserted at
position 25C of chromosome 2. Previous
analysis has shown that expression of this Adh transgene is inhibited by a
silencing activity located in an 1180 b.p. region near the 51 end of
the inserted gene. The sequence of the
silencer region revealed the existence of two 20 b.p. homologies, which have
been shown to inhibit Adh expression by 50%.
The objective of this investigation was to determine
what other sequences whithin the silencing region are required to produce the
near-100% inhibition of expression observed when the whole region is
present. Seven unique fragments of the
silencer sequence were cloned using PCR and purified using standard
procedures. Two fragments contain the
first homology of the sequence, one fragment contains the second homology, and four
fragments contain neither of the homologies.
Each of the seven fragments were transformed into plasmids containing a
functional Adh gene, thus yielding seven complete plasmids each containing one
of the fragments and one copy of the Adh gene.
Each plasmid has been injected into Drosophila
embryos and the larvae assayed for the level of Adh gene expression. Results suggest that the silencing activity
is not localized to one of these seven segments, but is possibly the result of
the interaction of two or more segments within the 1180-b.p. region.
PRODUCTION AND CHARACTERIZATION OF OXIDATION-RESISTANT
VARIANTS OF HUMAN RIBONUCLEASE INHIBITOR
David Chrastek, Anna Krawisz,
and Kim Dickson (Advisor)
Department of
Biology
Ribonuclease inhibitor (RI) is a cytosolic protein
that inhibits the activity of pancreatic-type ribonucleases. RI is of interest
because it restricts the activity of certain ribonucleases that exhibit
anti-tumoral activity and are currently being investigated as
chemotherapeutics. Additionally, RI inhibits angiogenesis by blocking
angiogenin (ANG), a ribonuclease and potent inducer of neovascularization. This
function of RI may potentially be used to inhibit vascularization surrounding
tumors. Unfortun-ately, the oxidation-sensitivity of RI renders it difficult to
study in laboratory settings and may limit its efficacy as a pharmaceutical
agent for preventing angiogenesis.
Our research attempts to create a variant of RI that
resists oxidation, but retains its affinity for pancreatic ribonucleases. The
instability of RI in oxidative environments arises from its 32 reduced cysteine
residues, each of which must remain reduced for proper functioning of the
protein. Therefore, site-directed mutagenesis was used to replace the cysteine
residues with amino acids that are not oxidation-sensitive. The cysteines were
divided into six groups based on their locations in the primary and tertiary
structures of the protein and six RI variants, each containing a subset of the
positions mutated, were successfully created. After purification of the
variants, the oxidation-sensitivity will be assessed using peroxide assays, and
Ki values will be
determined for inhibition of bovine pancreatic ribonuclease. This will allow us
to evaluate the contributions of the cysteine residues to the stability of RI
and its affinity for ribonucleases.
RNA TARGETS OF ANGIOGENIN
Pavlina
Chuntova, Mark Jackson, and Kim Dickson (Advisor)
Department of
Biology
Angiogenin (ANG) is a member of the bovine pancreatic
ribonuclease superfamily of proteins, and it is the only one that stimulates
neovascularization. ANG is an extracellular protein that is in continuous
circulation in the blood, yet is effective only on endothelial cells that are
uniquely primed to bind to ANG. ANG-induced blood vessel growth is dependent on
two factors: ribonucleolytic activity and its nuclear localization signal (NLS).
The NLS ensures translocation to the nucleus upon surface receptor recognition
and subsequent endocytosis. The criticality of ribonucleolytic activity
solicits further investigation of the cellular mechanisms of ANG; specifically,
why ribonucleolytic activity is vital for angiogenesis and once inside a cell,
what target(s) are degraded by ANG.
We will use real-time RT-PCR to monitor the quantities
of putative ANG substrates including mRNA, miRNA, rRNA, and tRNA. The goals of
our study are therefore to develop reliable, reproducible assays for
quantifying miRNA expression as well as to identify possible targets of ANG,
which might give insight as to why ribonucleolytic activity is a requisite for
ANG activity.
LANGUAGE AND COMMUNICATION SKILLS IN INTERNATIONALLY
ADOPTED CHILDREN FROM EARLY ADVERSITY
Joni
J. Coleman1, Erika R. Hoyt2, Joann P. Benigno (Advisor)1,
Jennifer Windsor (Advisor)2, and Megan Gunnar (Advisor)1
1Institute of
Child Development
2Department of
Speech, Language, and Hearing Sciences
Internationally adopted (IA) children who were
institutionalized prior to adoption often arrive in their adopted countries
with physical, mental, and psychological delays or deficits. The purpose of
this project is to assess the language and communication skills of IA children
who lived in some type of institutional care prior to their adoption. We
hypothesized that children who were institutionalized for longer periods of
time would experience greater deficits in their language and communication
skills due to possible effects of early social deprivation. We also
hypothesized that the children’s standard scores on the language tests would
differ from parents’ reports of their children’s language abilities.
Thirty elementary-school-age children adopted from
Implications regarding the impact of length of
institutionalization on children’s language skills will be discussed. Further
analyses will examine the relations among the parents’ report on the CCC-2,
children’s standardized language scores, and their communication skills during
the parent-child conversations.
MORPHOLOGY OF RAT BRAIN ENDOTHELIAL CELLS
Adam C. Crego and Lester R.
Drewes (Advisor)
Department of
Biochemistry and Molecular Biology
The Blood-Brain Barrier (BBB) is composed of
endothelial cells which form the lining of brain capillaries that are composed
of tight intercellular junctions. The
BBB is responsible for a strict control of influx and eflux of substances via
the bloodstream to the brain.
In stroke these endothelial cells experience
conditions of hypoxia and hypoglycemia.
I hypothesize that under these conditions of physiological stress,
endothelial cells may undergo morphological changes. An in vitro BBB model using RBE4 cells, rat
brain endothelium derived cell line will be used to investigate this
hypothesis. RBE4 cultures, 90%
confluent, will be grown in 3 conditions: control (5% carbon dioxide, 20%
oxygen, 5.5 mmMolar glucose); hypoxic (oxygen reduced to 1%); hypoxic and
glucose deprived (oxygen reduced to 1%, glucose reduced to 0.5 mmMolar). After sixteen hours, live cultures will be
examined and photographed at 10X and 40X magnification using an inverted
microscope and a digital camera.
Additional cultures will be fixed, hematoxylin/eosin (H & E)
stained, and examined under higher magnification. Evaluation of these cultures should provide
evidence to morphological changes and cell densities.
STAYING GREEN DURING WINTER: SEASONAL CHANGES IN PHOTOSYNTHETIC PROTEINS
ASSOCIATED WITH LIGHT HARVESTING IN Pinus strobus AND Abies balsamea
Jordan Crow and Amy Verhoeven (Advisor)
Department of
Biology
Evergreen plants, during winter, are exposed to
combined stresses of low temperatures and high light. Low temperatures limit
carbon reduction without impacting light absorption, thus creating an imbalance
between light absorption and its utilization. Evergreens deal with this problem
by increasing the amount of light that is dissipated thermally within their
light-harvesting complexes (LHCs). There is strong evidence that the LHCs
change functionally from energy-harvesting to energy-dissipating centers during
winter.
The goal of our study was to determine if there are
physical changes in the composition of the light-harvesting complexes that
accompany these functional changes. We
examined seasonal changes in relative abundance of light-harvesting and
reaction-center proteins in the evergreens Pinus
strobus (growing in the sun) and Abies
balsamea (growing in sun and shade environments) in the seasonally cold
climate of
ANALYZING
HIGH-BOILING AROMATIC COMPOUNDS AND SOIL SAMPLES USING GC-ARSLID
Timothy J. Dickhudt and Tony Borgerding (Advisor)
Department of
Chemistry
The Aromatic Selective
Laser Ionization Detector (GC-ArSLID) is an innovative way of analyzing
aromatic compounds in that it is selective for only aromatics and no other
compounds. We worked on maximizing its efficiency by adding various heating
elements, which was essential for being able to view higher-boiling-temperature
compounds. This summer we have studied various soil samples as well as diesel
fuel to see what kind of aromatic compounds can be found in our
environment.
Low-boiling compounds such as toluene, xylene, cumene,
various phenols, and halogenated benzene rings have been analyzed in
concentrations as low as 1.6 x 10-6
M. Higher boiling compounds such as
naphthalene, anthracene, benzanthracene, anthrone, fluorene, and acenaphthene
have been analyzed in concentrations as low as 8.5 x 10-5 M. Extracts of soil, soot, and cigar
smoke samples have been analyzed as well, indicating the presence of many
aromatic compounds. Although we have not successfully identified any compounds
in the samples, we have been able to identify how many rings compounds within
these samples have based on the retention time.
FLUID PROPERTIES IN THE FORMATION OF HIGH-GRADE IRON
Elizabeth A. Drommerhausen
and Steven Losh (Advisor)
Department of
Chemistry and Geology
MN
The
READABILITY LEVELS OF COLLEGE CHEM-ISTRY TEXTBOOKS
FROM INTRODUCTORY CHEMISTRY TO PHYSICAL CHEMISTRY
Elizabeth
A. Drommerhausen and Jeffrey R. Pribyl
(Advisor)
Department of Chemistry and Geology
MN
The perception of
many students is that their chemistry textbooks are difficult to read. Textbooks often present too many concepts at
once and contain numerous vocabulary words in a unit. The reading level, also known as the
readability level, is an important factor to be considered during textbook
selection. My work demonstrates that
chemistry textbooks typically are written at a reading level above college
students’ abilities. Numerous college
chemistry textbooks used throughout an undergraduate chemistry program (from
Introductory Chemistry to Physical Chemistry) were analyzed for their readability
level using several standard readability formulas and graphs. Results of this work show that organic and
biochemistry textbooks are the most difficult to read due to the extensive use
of chemical nomenclature. Readability
levels of textbooks in the various chemical disciplines will be discussed.
EFFECTS OF
PHOTOPERIOD ON THE CIRCADIAN MECHANISM IN Synechococcus
elongatus PCC 7942
Joseph
W. Dubis and Jayna L. Ditty (Advisor)
Department of Biology
Cyanobacteria are unicellular, photosynthetic microorganisms that
utilize a circadian clock to efficiently regulate their cellular activities.
The mechanism of the circadian clock in the cyanobacterium Synechococcus elongatus PCC 7942 has been
studied intensively. However, what has received little attention in this
field, thus far, has been how the circadian clock communicates with the
environment. In particular, very little is known about how the circadian
clock in cyanobacteria responds to photoperiod, or the duration of light versus
the duration of darkness within a 24-hour day. Photoperiods have been shown to
have considerable impacts on circadian clocks in other model systems.
Therefore, this project investigated the effect of varied photoperiods on the
circadian rhythm of wild-type S. elongatus. Wild-type S. elongatus cultures were
entrained to the photoperiods of 12 hours of light and 12 hours of dark
(12L:12D) and 18L:6D for seven days and then allowed to free-run in constant
light. Results showed that increasing the duration of light (18L:6D)
within a photoperiod has little effect on the free-running period.
However, the varied photoperiods result in a phase angle difference of
approximately 4 hours. In determining how the phase angle difference
manifested itself, sets of wild-type S. elongatus were analyzed while
being entrained to 18L:6D and 12L:12D photoperiods. It appears that they
exhibit biphasic rhythms as they entrain themselves to the environmental
light:dark cycles, primarily the lights off cue. This data has been used
as a baseline in further experiments underway to determine the relationship
between photoperiod and individual circadian clock input genes such as cikA and ldpA.
POLYMERIZATION OF ε-CAPROLACTONE BY
ALUMINUM-ALKOXIDE COMPLEXES: A STUDY OF THE RELATIVE IMPORTANCE OF THE
COORDINATION VS. INSERTION STEPS
Benjamin M. Durheim1,
Christopher P. Schaller1 (Advisor), William B. Tolman2
(Advisor), and Marc A. Hillmyer2 (Advisor)
1Department of
Chemistry, College of St. Benedict/St. John’s Univ., St. Joseph, MN
2Department of Chemistry,
The use of metal-alkoxide complexes as catalysts for
the ring-opening polymerization of cyclic esters has been well documented,
especially for cyclic esters like caprolactone (CL) and lactide (LA). It has
been postulated that the polymerization of ε-caprolactone (εCL)
proceeds by a coordination-insertion mechanism, wherein the metal-alkoxide
complex coordinates with the εCL, and then the ring is opened, forming a
new alkoxide.
Our project aimed at determining the relative
importance of the coordination and insertion steps (an augmentation of a
previously started project), so a greater degree of control could be exercised
over the polymerization. Michaelis-Menten as well as reaction progress kinetics
studies were performed on three aluminum-based catalysts with ligands
containing –OMe, -tBu, and –NO2 functional groups. Though the other
compounds yielded inconclusive results, the reaction progress kinetics
suggested that saturation was reached with the –NO2 compound (so
that Vmax and Km may be found).
IDENTIFYING LIPIDS OF THE RED BEET TONOPLAST MEMBRANE
Rachel Dyer, Anne Walter
(Advisor), and Douglass Beusmann (Advisor)
Departments of Biology and Chemistry
The tonoplast membrane of the red beet regulates the
passage of molecules and ions between the cytosol and the vacuole, which
involves regulation of pH and potential energy gradients. Phytoalexins are
secondary compounds produced by plants in response to infection by foreign
agents. Dihydrowyrone (DHW) is a phytoalexin that causes the collapse of the H+
gradient across the tonoplast membrane. The vacuolar H+-ATPase
embedded in the tonoplast membrane is not responsible for this gradient
collapse.
The goal of this research was to identify chemical
components of the tonoplast that might, with DHW, be responsible for the
collapse of the H+ gradient. I adapted an isolation protocol based
on keeping the vacuole intact in hypertonic sorbitol and differential
centrifugation. I identified the membrane by its signature enzyme ATPase using
a 12% acrylamide gel for SDS-PAGE and determined a preliminary molecular weight
profile of 110, 52, 19 and 9 kDa for the tonoplast (52-55 kDa g-subunit, 16-19 kDa d-subunit). A vacuolar-specific ATPase assay revealed
that the new isolation protocol obtained tonoplast samples free of non-specific
phosphatase and mito-chondrial ATPase. I extracted the tonoplast lipids by the
Bligh-Dyer method and determined a lipid/protein ratio of 20:1. Using
two-dimensional thin layer chromatography and electrospray ionization-mass
spectrometry, I identified DMPC as a significant component of the tonoplast
lipids. Mass spectrometry also revealed that other lipids might be present in
lower concentrations. Therefore, further optimization of protocols to identify
lipids by ESI-MS is needed, as well as improved protection of lipids during the
isolation procedure. Future research also allows for further proof of tonoplast
membrane purity and characterization of tonoplast proteins by SDS-PAGE and
ESI-MS.
FORENSIC LIPSTICK ANALYSIS USING CHEMICAL
FINGERPRINTING VIA GAS CHROMATOGRAPHY
Ann Engebretson and Dan Besemann (Advisor)
Department of
Chemistry
Various lipstick samples were extracted with acetone,
with the extracts subsequently analyzed via gas chromatography with flame
ionization detection (GC/FID). By identifying unique patterns in the
chromatogram of each lipstick sample, a searchable database of known samples of
lipsticks can be compiled. Chromatograms of unknown lipstick samples, such as
those collected from a crime scene, can be compared with this database,
potentially providing investigators with another piece of evidence in a
forensic case.
DYNAMICS OF POTASSIUM CHANNELS IN THE ACTION POTENTIAL
Sean Ewen1,
Mikhail Shvartsman1 (Advisor), and Dwight Nelson2
(Advisor)
1Department of
Mathematics
2Department of
Biology
The nervous system of a vertebrate animal transmits
information with incredible speed. Signals must travel rapidly through a
complicated network of specialized cells called neurons. Many neurons have
cable-like membranes, called axons, that transmit information via the action
potential, which re-amplifies the signal. The axon carries electrical charges
across the membrane aided by sodium and potassium ions entering and leaving the
axon through specialized channels. The action potential consists of active
changes in membrane voltage caused by the movement of sodium and potassium ions
through activated channels in the membrane.
I will focus on interpreting the behavior of potassium
channels by evaluating applicable parts of the Hodgkin-Huxley model. In addition, I will introduce the possibility of modeling
potassium channel dynamics with wave-specific equations. This presentation will
be of interest to those who wish to gain insights into signal transmission in
the nervous system and mathematical modeling of biological processes.
Language
and Theory of Mind in School-Age Post-Institutionalized Internationally Adopted
Children
Clare E. Faulhaber, Megan R.
Gunnar (Advisor), and Joann P. Benigno (Advisor)
As rates of internationally adopted (IA),
post-institutionalized (PI) children increase in the
Several tests were used to evaluate children’s
language ability and yield a core language (overall language ability), a
receptive, and an expressive language score.
In order to assess Theory of Mind understanding (e.g., white lies,
irony, and sarcasm) Happé’s “strange situation stories” were used. Preliminary analyses on 17
post-institutionalized children revealed that time spent in the institution
negatively related to children’s language scores. Future analyses will compare
the language skills of children adopted early (before 14 months) versus later
(after 14 months) relative to the birth children as well as the relations
between language and theory of mind across the groups.
CASE STUDIES FROM LOCAL MESOSCALE
METEOROLOGICAL DATA NETWORK
Amanda Felber,
Heather Lehmkuhl, and Rodney Kubesh (Advisor)
Department
of Earth and Atmospheric Sciences
Research was conducted to determine if a
wintertime heat island existed over
TRADE LIBERALIZATION AND DEVELOP-MENT: WELFARE
IMPLICATIONS OF OUTWARD-ORIENTATION IN THE WEST AFRICAN ECONOMIC AND MONETARY
Cody Fischer and Charles
Rambeck (Advisor)
Department of
Economics
St. John’s
University, Collegeville, MN
This paper examines
the empirical relationship between trade liberalization and welfare within the
West African Economic and Monetary Union (WAEMU). In addition to using a
traditional measure of economic welfare, GDP per capita, I employ broader measures
of welfare derived from Catholic social teaching. I use a panel data series
fixed effects regression to verify that outward-oriented policies—as measured
by Wacziarg and Welch (2003)—lead to trade growth. Next, I apply the same
technique to test the dynamic impact of trade growth on aggregate economic
activity for these small agricultural West African economies. I then interpret my results within the
context of historical events for each country. My assessment of the efficacy of
outward orientation as a mechanism for enhancing human welfare is based on
diverse quantitative measures suggested by the principles of Catholic social
teaching.
RESETTING OF THE CIRCADIAN BIOLOGICAL CLOCK USING
LIGHT IN THE MOLD Neurospora crassa
WITH A FIREFLY LUCIFERASE REPORTER GENE
Julie A. Fox and Van D. Gooch
(Advisor)
Department of
Biology
Intrinsic daily oscillations, known as circadian rhythms, are an integral part
of most organisms. It is known that
these clocks need to be reset by the rising and setting sun. Under constant environmental conditions
the filamentous fungus Neurospora crassa expresses a clearly defined
rhythm of spore formation with a period length of about 21.5 hours, and the
phase of this clock is known to be resettable by light. The genetic mechanism
of the Neurospora circadian clock is
fairly well understood and the frq
gene is known to be a major component.
To more closely understand how the frq gene actually works, the frq promoter was recently placed in
front of a codon modified firefly luciferase reporter gene. Now we can directly
see the molecular mechanism of the circadian clock using bioluminescence. In
this study this new construct is used to examine the effects of light in
resetting the circadian biological clock using different growth media and
conditions. It is interesting that under certain conditions I find that a
one-hour light pulse easily resets the biological clock while under other
conditions it does not. Most interestingly I find some very strange behavior at
intermediate conditions. It is hoped that these results will yield important
information about how light affects the resetting of circadian clock
mechanisms.
RESEARCH INTO ARRESTING DETERIOR-ATION IN
ARCHAEOLOGICAL BRONZES
Giovanna Fregni, Gretchen
Anderson (Advisor), and John Soderberg (Advisor)
Department of
Anthropology
Bronze disease is one of the greatest hazards to
bronze artifacts and is caused by the combination of chlorides (which are
intrinsic to the metals alloyed to create bronze) and oxygen. When the
artifacts are not curated properly the copper chlorides convert to hydrochloric
acid, which causes the artifact to disintegrate. The disease first appears as
small patches of green-colored corrosion, which, if left unattended, spreads
over the artifact and causes pits to form in the artifact’s surface. This
corrosive process eventually causes the artifact to fragment. Depending on the
size, an artifact can be destroyed within a few years.
In spite of the prevalence of bronze disease, there
are few methods for arresting its development. Factors such as the impurities
inherent in the alloy and the original techniques used to create the artifact
all play major roles in how deterioration develops and how it might be treated.
At present further research is being done in the field
of museum studies. For example, it is unknown what level of relative humidity
causes reactions to create hydrochloric acid and how changes in the composition
of artifacts are affected by it.
Currently researchers in the field of museums
conservation studies are searching for options in the control of artifact
deterioration and for an understanding of the correlation between the physics
and chemistry involved in the condition. My research asks how the current state
of research on bronze disease and metal deterioration in archaeological bronzes
is affected by knowledge of ancient metal mining and refining techniques, and
how this knowledge contributes to research designed to mitigate deterioration.
USE OF FLUORESCENT DYES FOR DETERMINATION OF LOG USE
OF Peromyscus spp., Myodes gapperi, AND Zapus hudsonius IN ITASCA STATE PARK, MN
Peter V. Gailans, Jennifer
O’Neill, and Joseph C. Whittaker (Advisor)
Department of
Ecology, Evolution, and Behavior
Path selection of small mammals has been studied with
the use of fluorescent dye to study behavior and habitat selection, and to
estimate home range. This study examines log use by three
Previous research suggests that log use decreases risk
of predation, and this study might indicate that jumping mice may be less
susceptible to predation by decreasing the frequency of log use on the forest
floor. Alternatively, jumping mice may be inherently less vulnerable to
predation than are other species of mice, perhaps because of their mode of
locomotion.
INTERACTIONS OF ANGIOGENIN WITH PROTEINS IN THE
NUCLEAR VS. CYTOPLASMIC FRACTIONS OF HELA CELLS
Alexis Gerber, Elizabeth
Zorn, and Kimberly Dickson (Advisor)
Department of
Biology
Angiogenin (ANG), a
protein belonging to the bovine pancreatic ribonuclease superfamily, displays
angiogenic activity in addition to the ribonucleolytic activity
characteristic of ribonucleases. It is unique among the pancreatic
ribonucleases in that it possesses a nucleolar localizing signal, and stimulates
neovascu-larization. In order to exert its angiogenic effect, ANG, which
is a secreted protein found in the blood, must be translocated to the nucleus
upon endocytosis. Although a cell surface receptor appears to be involved in
the endocytosis of angiogenin, the details of endocytosis and nuclear
localization are currently unknown.
The goal of the current
project is to elucidate some of the proteins with which ANG interacts to
determine its mechanism of action. We will utilize immunoprecipitation to isolate
ANG-protein complexes, comparing proteins from the nuclear fraction of cell
lysates with those found in the cytoplasmic fraction. Since it has been shown
that ANG must be translocated into the nucleus for angiogenic activity to
occur, we do not expect to find cytoplasmic proteins that play a significant
role in the angiogenic activity of angiogenin. We will, however, analyze
proteins in the cytoplasm that form complexes with ANG in an attempt to
differentiate and characterize relevent protein interactions. In order to
determine which proteins bind to ANG, we will analyze the complexes using
in-gel trypsin digest and mass spectroscopy. By isolating and identifying
cellular proteins that bind to ANG, we hope to begin to understand the ways in
which these proteins play a role in the mechanism of ANG-induced neovascu-larization.
URBAN GROWTH: IMPACT ON ROADSIDE OLD-FIELD BIRDS
Elizabeth
W. Goldsmith and Mark A. Davis (Advisor)
Department of
Biology
Birds have been used as biological indicators of
habitat quality in a variety of studies. The impacts of human disturbance on
habitat quality are varied according to the ecosystem of study and species of
interest. Roads in particular have been shown to negatively impact bird communities.
Roads fragment habitat and introduce a source of disturbance to bird
communities. The rapid expansion of the
Over two field seasons in 2005 and 2006, the impacts
of traffic density on old-field bird communities was investigated at the
MAPPING GENES AFFECTING SHELL COLOR AND SHAPE IN THE
PACIFIC OYSTER Crassostrea gigas
Philip Grupe1 and
Dennis Hedgecock2 (Advisor)
1St.
2Department of
Biological Sciences,
Variation in the color and shape of oyster shells is
widely believed to be environmentally determined. However, Brake et al. (2004 Aquaculture
229:89) recently provided evidence that shell and mantle edge color in the
Pacific oyster Crassostrea gigas are
heritable. We observed variation in shells of an F2 family of
Pacific oysters that appeared to be inherited, and we tested this hypothesis by
statistical analyses and genetic mapping. Measures of shell shape, size and
color were made from digital photographs of 179 oysters, using ImageJ software.
Principal component analyses were used to consolidate the measured traits, and
mapping was done on both principal components and some of the original individual
traits. Mapping was made possible by a previously compiled linkage map for this
same family of oysters, comprising 59 microsatellite DNA markers on 11 linkage
groups. Using an interval mapping method, we identified a quantitative trait
locus (QTL) for pigment saturation of the left valve on linkage group VIII,
between ucdCgi183 and ucdCgi184; genotypes at ucdCgi183 explain 32% of shell color
variance. Similarly, we identified two QTL for a pronounced left bend in some
anteriorly viewed valves (“hook hinge”) on linkage group III, in the adjacent
intervals of cmrCgi–ucdCgi198–imbCgi49; genotypes at ucdCgi198
explain 32% of hook hinge variance. Left hook hinge appears to be
recessive, while shell pigmentation is nearly additive.
Our observations suggest that genes, as well as
environment, play a role in determining the color and shape of oyster shells.
Markers associated with these QTL could be used to breed oysters with more
desirable shell characteristics.
INTENSIFIED MEROMIXIS AS A RESULT OF FRESHWATER RINSING
Sarah Haas, Matt Kaylor,
Simon Kinsler, and Virginia Card (Advisor)
Department of
Natural Sciences
RIMING OF ICE
Isaac
E. Hankes and Rodney Kubesh (Advisor)
Department of
Earth and Atmospheric Sciences
Living in the
A THEORETIC Cell
Cycle mechanism and computer simulation
Angie Hastings, Erin Hennen,
Tony Ostlund, Greg Simonson, Scott White, Arthur Guetter (Advisor), and Olaf
Runquist (Advisor)
Department of
Chemistry and Mathematics
We developed a computer cell cycle model based on
biochemical events of cell division. The model provides concentration/time
changes of 52 cell cycle components for slow-, rapid- and non-cycling cells.
These cells correspond to properties of stem, proliferating, and differentiated
cells as found in the human colonic crypt. The model is an array of 61 coupled
reactions governed by 48 rate constants and incorporates DNA licensing
(G1-phase), P-kinase initiated DNA replication (S-phase), geminin, cyclin,
maturation-promoting factor formation and function (G2-phase), and mitosis
(M-phase). Also included in the model are timing loops that “turn-on/turn-off”
catalyst systems at precise intervals. Rate equations describing the formation
and transformation for each of the 52 components were written and solved using
Mathematica 5.2 (numerical integration). Mathematica outputs provided a
probability/time profile for each system component. Iterative adjustments of
rate constants and component concentrations produced perpetual cell cycling with
G1/S/G2/M phase times coinciding with those of human colon crypt stem and
proliferating cells. Each cell cycle produced a new parent and daughter cell
with properties identical to those of the original parent cell. Probabilities
for daughter cell differentiation/death will be included in future work
Our research is significant because it demonstrates
how simplifying tenets of chemistry and mathematics can be applied to a
biological system, as well as providing a connection between biochemical
reactions and time events of cell division. It also presents a tool for
discovering requirements of normal and abnormal cell division, while at the
same time providing a template for models exploring stem cell involvement in
cancer genesis.
SYNTHESIS OF N-HYDROXYSUCCIN-AMIDYL ESTERS
OF FATTY ACID OMEGA-DISULFIDES
Patrick Hawk and
Thomas C. Marsh (Advisor)
Department
of
Chemistry
Molecular scaffolds composed of nucleic acid are of
great interest for development of nanometer scale devices. The common strategy
for attaching things such as nanoparticles (NPs) to these scaffold structures
involves reactions that occur, by necessity, in an aqueous
environment. Unfortunately, these conditions may also lead to instability
that ultimately causes the scaffold to fall apart. This fundamental problem
poses a significant drawback in the development of fabrication processes that
would otherwise take advantage of DNA’s ability to self-assemble. An
alternative approach that may preserve scaffold structure would be to decorate
a nucleic acid molecular scaffold with non-polar gold NPs at a water/organic
solvent interface. This strategy would retain the structure of the nucleic acid
scaffold during NP decoration. To accomplish this, non-polar tether molecules
were synthesized so that, when attached to a DNA scaffold, they will facilitate
binding of gold NPs suspended in an organic solvent upon self-assembly.
A series of omegamercapto-fatty acids was
used to synthesize non-polar disulfide tethers of varying lengths. Ultimately
these fatty acyl-disulfides will be coupled to an oligonucleotide and
incorporated into a molecular scaffold, known as a G-wire. The disulfide groups
of these G-wires act as non-polar tethers that can project into the non-polar
solvent, and they will bind to gold nanoparticles in the aqueous layer across
the polar/non-polar interface. These tethers will be tested for their
effectiveness in mediating interfacial gold NP decoration by UV/Vis
spectrophotometry and gel electorophoresis. It is expected that an optimal
non-polar tether length will be found for efficient G-wire self-assembly and
interfacial NP decoration.
UNDERSTANDING PHYTOPLANKTON PHYSIOLOGY: NUTRIENT
UTILIZATION, CYCLING, AND THE MARINE SYSTEM
Abigail Heithoff and Gina
Mancini-Samuelson (Advisor)
Department of
Chemistry
Phytoplankton are vitally important to the health of
the marine system, acting as primary producers and forming the basis of the
food web, where they are responsible for nutrient cycling throughout the marine
system. In addition to this role, they fix half of the world’s atmospheric
oxygen, and are vitally important to the carbon cycle.
Our project focuses on research done at Woods Hole
Oceanographic Institution related to nitrogen and phosphorus metabolism in
several species of phytoplankton. Also included is research about the
phytoplankton Emiliania huxleyi, whose
blooms have been implicated as contributing to atmospheric carbon dioxide. A
possible nitrate transporter was identified in Lingulodinium polyedra and new methods for studying the effects of
high atmospheric carbon dioxide on Emiliania
huxleyi were tested.
ANALYSIS OF DOMAIN BOUNDARY FLUCTU-ATIONS IN
TWO-DIMENSIONAL BIOPHYSICAL SYSTEMS
Alison M. Heussler, Tracy A.
Bibelnieks (Advisor), and Benjamin L. Stottrup (Advisor)
Departments
of Physics and Mathematics
Phase separation in lipid membranes is a subject of
intense interest in both biophysical and cell biology communities. Lipid
monolayers are an ideal model system for the study of many aspects of phase
separation in two dimensions. Previous work has been done on model systems
containing cholesterol to characterize the liquid-liquid phase transition as
well as the fluctuations of phase-separated domains. However, important
questions about thermodynamic equilibrium in monolayers remain.
Our research has taken advantage of accessible digital
image processing and Fourier and power spectrum analysis to re-examine the
canonical mixture of dihydrocholesterol and DMPC (phospholipid). Additionally,
these techniques are applied to lipid monolayers containing
25-hydroxycholesterol (25OH). 25OH is an oxysterol known to suppress
cholesterol synthesis. Monolayer systems containing 25OH exhibit the novel
lipid monolayer phase behavior of both upper and lower transition pressures.
Most excitingly, our studies of fluctuating domain boundaries have led to
further applications in live-cell imaging including monitoring GFP fluorescence
intensity with the lifetime of the cell.
THE EFFECTS OF SEROTONERGIC REAGENTS ON T CELL
PROLIFERATION
Melinda K. Hexum and Jodi
Goldberg (Advisor)
Department of Biology
Previous research has indicated that serotonin
(5-hydroxytryptamine, 5-HT) is a signal necessary for human T cell
proliferation. The role of 5-HT in T cell proliferation was investigated by
examining the impact of the 5-HT synthesis inhibitor p-chlorophenylalanine
(pCPA) on the proliferation of purified human peripheral blood T cells
activated by accessory cell independent (anti-CD3/CD28 beads) and accessory
cell-dependent (phytohemagglutinin, PHA) methods. T cell proliferation in
response to either method of activation was inhibited by pCPA, although T cells
activated by PHA and accessory cells were inhibited at significantly lower
doses than pure T cells activated by antibody beads. Methiothepin, a 5-HT receptor antagonist, was
also shown to inhibit T cell proliferation. Unlike pCPA, methiothepin inhibited
proliferation of T cells activated by accessory cell independent and dependent
methods at similar doses.
Attempts were made to reverse the inhibitory effects of
these serotonergic reagents by providing pCPA or methiothepin treated cells
with exogenous 5-HT, however 5-HT failed to restore proliferation at any
concentration tested. These data suggest that T cells are inhibited by both
pCPA and methiothepin, but that nonT cells may be more sensitive to pCPA’s
effects. It is yet to be determined if the
inhibitory effects of either reagent on T cell activation occur via a
serotonin-dependent pathway.
WHI-P131 INHIBITS THE MIXED LYMPHOCYTE REACTION (MLR)
Joe Hobbs, Emily
Messner, and Marina Cetkovic-Cvrlje (Advisor)
Department of Biological Sciences
It has been recently described
that WHI-P131, a specific inhibitor of the Janus tyrosine kinase (JAK) 3,
prevents autoimmune, T-cell-dependent diabetes in a mouse model (NOD mice) for
human autoimmune type 1 diabetes. However, the mechanism of P131 action has not
been described yet. The aim of this study was to determine the effects of P131 on T-cell proliferation induced by alloantigen using the
one-way mixed lymphocyte reaction (MLR). T-cells, obtained from the spleens of
BALB/c mice, were stimulated in vitro by allogeneic C57BL/6 T-cells (treated by
mitomycin C to prevent their proliferation to BALB/c’s alloantigens). Single
cell suspensions of BALB/c splenocytes were made, and 4x106 cells/mL
were plated in 96-well-plate. C57BL/6 splenocytes were added to the plate in
three different concentrations (4x106 - “high”, 1x106 -
“medium”, and 5x105 cells/mL - “low” concentration). The WHI-P131 was added in the concentration range of 0–25 mg/mL. The proliferation
of BALB/c splenocytes was measured after five days of culturing by WST-1 assay,
using plate reader at 480 nm. It is
found that WHI-P131 induced a dose-dependent inhibition of MLR induced by
either “high”, “medium” or “low” dose of stimulators. Moreover, even the lowest
dose of P131 (0.8 mg/mL) induced statistically significant inhibition of MLR
(P=0.001, Student t-test). These data
confirm that WHI-P131 acts on T-cell level, hence WHI-P131 affects
alloantigen-induced T-cell proliferation in vitro. Our further studies will be
focused on defining the exact population of T-cels affected by WHI-P131.
RED LIGHTS AND RED TAPE: ECONOMICS AND POLICY IN
SEXUAL MARKETS
Anna Hovde and Fahima Aziz
(Advisor)
Department of
Management and Economics
Prostitution has been called the world’s oldest
profession, making the market for prostitution services one of the most
enduring markets in human history. Despite the persistence of sexual markets,
no consensus has been reached on what policy approaches are appropriate or likely
to be effective in managing paid sex markets. This paper builds a comprehensive
represent-tation of the market for sexual services through analysis of survey
responses and transaction-level data, and through a comprehensive literature
review. Policy recommendations are provided based on an economic analysis of
prostitution policy options.
Temperature Variation of VOC
Extraction from Aqueous Samples using a Microdialysis Membrane
Matthew Humbert and Anthony
Borgerding (Advisor)
Department of
Chemistry
A probe using a microdialysis membrane is useful to
extract VOC from an aqueous solution into the gas phase. The probe is small and
extraction is fast. Steady state concentrations are achieved in less than 5
seconds. Because the extent of extraction is based on Henry’s Law, temperature
should have a large impact. We measured VOC signals for aqueous solution
temperatures from 0oC to 37oC. We found that these
signals increase with an increase in the temperature of the aqueous solution.
THE EFFECT OF Rap1 ON PROGRAMMED CELL DEATH
Sara Hyatt and Jennifer
Cruise (Advisor)
Department of
Biology
Previous research has shown that increasing the amount
of active Rap1 in MDCK (epithelial) cells causes a decrease in cell
proliferation. Previous techniques used to study the role of Rap1 in cell
proliferation have not demonstrated whether changes in cell number are purely
due to changes in the rate of proliferation and not in the rate of programmed
cell death (apoptosis).
For our study, MDCK cells were stably transfected with
an active Rap1 gene, a control plasmid, or a dominant-negative Rap1 gene. To
induce apoptosis, cells were starved for 0, 24, 48, 72, or 96 hours. Cells were
stained with Annexin V and propidium iodide and analyzed via flow cytometry in
order to quantify apoptosis in each population. Our preliminary data indicate
that decreasing the amount of active Rap1 within cells decreases the rate of
apoptosis in response to starvation conditions. Our data also suggest that
increasing the amount of active Rap1 within cells increases the rate of
apoptosis in response to starvation conditions, although these data are less
conclusive. Presently, it is unclear whether exposing cells to trypsin may be
influencing our results. We are experimenting with other techniques for
quantifying apoptosis that do not require the integrity of the cell membrane to
be maintained. We are also currently looking at the effects of Rap1 on anoikis
(induction of apoptosis by preventing cell adherence to a substratum).
Effects of Insulin-Like
Growth Factor-I Activation on Monocarboxylic Acid Transporter Expression in Rat
Brain Endothelial Cells
Kassandra Kaas and Lester R.
Drewes (Advisor)
Department of
Biochemistry and Molecular Biology
The blood-brain barrier (BBB) is a specialized system
composed of capillary endothelial cells that form a tight lining covering the
inner surface of the entire brain vasculature. It functions to protect the
brain from potentially harmful substances in the bloodstream, while also
supplying the brain with nutrients required for proper brain function. However,
the high selectivity of the BBB creates a challenge for diagnosing and treating
brain disorders and thus necessitates investigation of BBB receptors and
substrates alike. From previous studies it was established that the BBB
contains the insulin-like growth factor I receptor (IGF-IR). IGF-IR is a
transmembrane receptor activated by Insulin-Like Growth Factor-I (IGF-I), a
polypeptide protein hormone.
The objective of our study is to examine the effect of
IGF-IR stimulation on the expression of monocarboxylic acid transporters (MCTs)
in a rat brain-derived endothelial cell culture line (RBE4). RBE4 cells will be
incubated for periods of 4, 8, 16, and 24 hours with IGF-I (10 ng/ml).
Following stimulation of the IGF-IR, cells will be harvested, and proteins will
be collected from each sample and examined in order to quantify MCTs present.
To accomplish this, an immunoblot assay will be performed in order to analyze
the expression of MCT1 and MCT2 in cells with and without IGF-IR activation. An
increased level of MCT1 will suggest that IGF-IR signaling is coupled with MCT1
expression in the BBB. If MCT2 is not observed to increase following IGF-IR
activation, it may imply that distinct types of signals regulate MCT1 and MCT2.
CHANGES IN THE IRON/MANGANESE RATIO IN
Matthew Kaylor, Sarah Haas, Simon
Kinsler, and Virginia Card (Advisor)
Department of
Natural Sciences
RIM101 PROCESSING IN SNF7 SUPPRESSORS OF Candida
albicans
Matthew J. Kesler and Dana
Davis (Advisor)
Department of
Microbiology
The pathogenesis of Candida albicans is dependent on its ability to respond to changes
in environmental conditions. Rim101 is a transcription factor that responds to
changes in environmental pH. Rim101 is activated at neutral-alkaline pH by
proteolytic processing to remove an inhibitory C-terminal domain. Rim13, a
putative protease, Rim20, which binds to the cleaved domain of Rim101, and
Snf7, a scaffold for Rim13 and Rim20, are required for Rim101 processing and
thus activation. C. albicans strains
that lack SNF7 have severe phenotypes
on media that requires Rim101 processing, including the ability to grow on pH 9
or lithium-containing medium and the ability to form hyphae on tissue culture
medium. However, spontaneous suppressors of snf7-/- mutants arise in
which one or more of these phenotypes has been restored. We predicted that these
suppressors could be (1) premature stop codons in Rim101, (2) bypass of the
Rim101 pathway, or (3) Snf7-independent Rim101 processing.
To test these models, Western blot analysis of Rim101
was done for suppressors in which at least two of the phenotypes had been
rescued because restoration of more than one phenotype is less likely to be due
to bypass of the pathway. The Western blots ruled out models 1 and 2 and
suggest that Snf7-independent processing is the likely mechanism by which the
suppressors act. Since Rim13 and Rim20 act on Rim101 directly, we are currently
determining if mutations within these genes allow them to process Rim101
independently of Snf7.
EFFECTS OF MEROMIXIS ON THE SEDIMENT DIATOM ASSEMBLAGE
OF
Simon Kinsler, Sarah Haas,
Matthew Kaylor, and Virginia M. Card (Advisor)
Department of
Natural Sciences
Diatom transfer functions, which are used to
reconstruct past water chemistry by examining the diatoms present in a sediment
core sample, have become an important tool to assess human impact on lakes and
determine public policy in
Previous research has suggested that the onset of
meromixis changes the diatom composition throughout a lake as nutrients become
partitioned in the monomolimnion: but does meromixis in turn affect which
diatoms are preserved in the sediment? The drastically changing chemocline
level of Brownie provides an opportunity to examine the effects of meromixis on
diatom frustule preservation, and implications to diatom training sets will be
discussed.
DO STUDENT AND FACULTY
LEARNING STYLES DIFFER IN THE CHEMISTRY CLASSROOM?
Hanna
L. Kolzow and Ashley Mahoney (Advisor)
Department of
Chemistry
The importance of student
learning styles in education has been thoroughly researched, and the research
has shown that students retain and understand information most effectively when
their learning style is utilized. Research has also agreed that the role of the
educator is to best meet the needs of the students by including a variety of
learning techniques. When student learning styles are considered in teaching,
greater motivation, deeper understanding, and clearer communication occurs in
the learners.
Recognizing the importance
of learning styles in education, the authors desired to examine student
learning styles in different student populations enrolled in chemistry courses.
This study compares the learning styles of chemistry faculty to nursing,
elementary education, science, and chemistry majors using the Felder-Soloman
Index of Learning Styles inventory. Initial results and conclusions based on
data analysis will be presented.
FUEL OF THE
FUTURE: BIODIESEL A NOVEL METHOD AND
CATALYST FOR BIODIESEL PRODUCTION
Brian Krohn1,
Arlin E. Gyberg1 (Advisor), Sue Hill1 (Advisor), Clayton
McNeff2 (Advisor), and Ben
Yan2 (Advisor)
1Department of Chemistry,
2SarTec
Corporation
Biodiesel or Fatty Acid Methyl Esters (FAME) is
derived from the transesterification of triglycerides found in plant oils and
animal fats. As a fuel it is environmentally friendly, biodegradable,
renewable, domestic, and can be used in existing diesel engines with little or
no modification to the engine. Biodiesel is energy efficient, yielding
93% more energy than what is invested in its production; petroleum fuel results
in a net loss of energy. Finally, biodiesel C02 emissions are
not from sequestered carbon sources. As a result, biodiesel does not
increase the C02 composition of the atmosphere, which is a leading
cause of global climate change.
The cost of biodiesel, however, limits its effectiveness as an alternative
fuel. The current use of NaOH as a catalyst requires the use of expensive
food grade triglycerides contributing up to 88% of the production cost.
Also, the current transesterification method is an inefficient batch
reaction. In order to make biodiesel a viable alternative fuel we have developed
an efficient high temperature, high pressure, flow reactor using zirconia or
titania metal oxide microspheres as the catalyst. The resilient and
highly catalytic micro-spheres allow for the use of waste feed stocks reducing
the cost of biodiesel and making it into a viable alternative fuel.
PRICE
STABILITY IN THE FRENCH ECONOMY UNDER THE EURO: A MARKET BASKET STUDY
Steven J. LaFave
Department of
Business Administration
In January 2002 the majority of countries in the European
Union converted to the use of the euro as their currency. In an earlier study,
a market basket of goods was priced in euros shortly after the conversion from
the French Franc to the euro in June 2003. This paper extends that earlier
research into the effect of this conversion on price stability in the French
economy. As in the earlier study, data were gathered in
AN ANALYSIS OF SILVER-SILVER CHLORIDE REFERENCE
ELECTRODE CONSTRUCTION METHODS
Christie Lund and Ken Rohly (Advisor)
Department of Chemistry
The goal of this research was to explore procedures
and parameters for the construction of silver-silver chloride reference
electrodes. Three methods were studied
and compared: the first involved dipping
a silver wire in molten silver chloride; the second involved sintering via high
temperatures; and the third involved using an electric current to anodize a
silver wire in silver chloride solution.
Electrodes made by dipping were tested for their stability in several
solutions. Sintered electrodes were
analyzed for reproducibility of the method.
Anodized electrodes of various diameters were tested for differences in
delamination. Thus, procedures and
parameters were determined which contribute to the best overall electrodes and
electrodes from the three methods were compared based on results indicating
their reproducibility and stability.
WHITE SUCKER SPAWNING IN REFERENCE TO AIR TEMPERATURE
Jody Lutterman, Jennifer
Plaster, Lisa Walter, and Virginia A. Card (Advisor)
Department of
Natural Sciences
White suckers (Catostomus
commersoni) begin migrating upstream to spawn when the lake, in which they
normally reside, reaches a specific temperature. There have been many reports generated by the
A SOLID-STATE SEARCH FOR HALOGEN-NITRILE CONTACTS IN A
SERIES OF “BRIDGE-FLIPPED” ISOMERIC BENZYLIDENEANILINES
Kendra M. Lystad and William
H. Ojala (Advisor)
Department of
Chemistry
We describe as “bridge-flipped isomers” those
molecules that differ in structure only in the orientation of a bridge of atoms
connecting two major portions of the molecule. This isomerism occurs among the
benzylidene-anilines: Ar-CH=N-Ar’ vs. Ar-N=CH-Ar’ (Ar = aryl). We are
interested in whether or not these isomeric pairs are isostructural, assuming
the same solid-state molecular packing arrangement. Co-crystallization of
isostructural isomers may yield solid solutions possessing properties that
could be modified systematically by varying the proportions of the
co-crystallized compounds. Isostructuralism between benzyl-ideneanilines
bearing both a nitrile group and a halogen atom might be encouraged by Lewis
base-Lewis acid CşN:---X contacts linking molecules into similar chains in their
respective crystals.
Using single-crystal X-ray diffraction, in previous
studies we determined the crystal structures of two pairs of bridge-flipped
benzylideneanilines from the ortho-cyano-para-halogen series, the fluoro and
chloro derivatives. We have now determined the crystal structures of the bromo
isomers and of one of the iodo isomers. None of the bridge-flipped isomeric
pairs in our collection are isostructural thus far. Significantly, in accord
with the relative weakness of fluoro, chloro, and bromo substituents as Lewis
acids, there are no close halogen-nitrile contacts in these structures;
however, the iodo-nitrile benzylideneaniline we have examined does possess
them. We are currently attempting to crystallize the remaining iodo-nitrile
isomer to determine whether or not a similar contact in this last
benzylideneaniline of the series would compel this compound to crystallize with
a packing arrangement identical to that of its isomer.
UV RADIATION TOXICITY AND
FLUORANTHENE-PHOTOINDUCED TOXICITY TO Daphnia
magna IN
Michael MacMillan Jr.1,
James T. Oris2 (Advisor), and Craig E. Williamson2
(Advisor)
1St.
2Department of
Zoology,
The direct UV toxicity and photoinduced toxicity of
fluoranthene to Daphnia magna was studied in single-treatment
evaluations in a laboratory system under simulated sunlight in water from three
SYSTEMS GENETICS:
ELUCIDATING NETWORKS THAT UNDERLIE HERITABLE VARIATION IN ADIPOSE
FUNCTION AND SUSCEPTIBILITY TO OBESITY
Ian-James Malm1 Chiaki Nakata2, and
Brynn H. Voy3 (Advisor)
3Biocsciences Division, Oak Ridge National Laboratory
Obesity and its
co-morbidities are rampant in Western society.
Excess adipose tissue not only physical-ly stresses the organism but
also disrupts homeostasis through release of adipokines, bioactive molecules
produced in adipose tissue. The
long-term goal is to determine the mechanisms by which heritable differences in
adipose function impact risk for obesity and its consequences. Systems genetics was employed by anchoring
phenotypic variation to naturally occurring genetic polymorphisms in two mouse
genetic reference populations (GRP): 1)
recombinant inbred BXD (C57BL/6J X DBA/2J) strains, and 2) a panel of eight
genetically diverse strains that serve as progenitors for the collaborative
cross (CC), an emerging GRP. Body and
fat pad weights, plasma hormone profiles and adipose expression of adipokine
genes were measured in males of twenty-four BXD strains and in both sexes of
the eight CC parental strains. Current
progress demonstrates: 1) adiposity is
highly correlated with expression of some adipokine genes (e.g., leptin, r2=
0.626; p=5.4E-6) but not others (eg., visfatin, r2=0.012, p=0.937); 2) a subset
of tightly intercorrelated adipokines are regulated independent of adiposity;
and 3) sexually dimorphic relationships exist among adipokines and adipose weight. Ongoing assay of adiposity in emerging
generations of CC mice confirms that this new GRP will provide physiological
diversity reflective of its genetic diversity and on par with that in a human
population, highlighting its power to dissect the molecular components of
complex traits. Collectively the results
suggest that factors in addition to adipose mass need to be considered when
predicting genetic risk for conditions co-morbid with obesity.
DESICCATION RESPONSE OF Geobacter sulfurreducens
Jason Malsam1,
Vishard Ragoonanan1, Daniel R. Bond2, and Alptekin Aksan1
(Advisor)
1Biostablilization Laboratory, Dept. of Mechanical
Engineering,
2Dept. of Microbiology, BioTechnology Institute,
An investigation of the electricity producing
bacteria, Geobacter sulfurreducens,
drying at different conditions was conducted. The bacteria were dried and
re-hydrated at different temperatures (5, 30 or 40°C). Different disaccharides
were added (sucrose or trehalose) to the drying medium (NBFA) to protect the
bacteria against the desiccation stresses. NBFA is the growth medium for G. sulfurreducens, which contains mainly
fumarate and acetate. The drying media used were NBFA or NBFA containing 6.75%
w/w of either sucrose or trehalose.
It was observed that G. sulfurreducens dried for 45 minutes at 5°C and re-hydrated at
5°C had the highest viability. The viability for the corresponding conditions
were as follows: for sucrose (66.07% ± 3.41), trehalose (92.57% ± 7.57) and
NBFA (93.06% ± 9.03). The bacteria dried and re-hydrated at 30 or 40°C
experienced a decrease in viability (sucrose 59.74% and 54.50%, NBFA 53.61% and
59.11%, respectively). Also, an investigation was conducted to determine how
the osmotic stress prior to desiccation affected viability. It was determined
that NBFA containing 6.75% w/w sucrose had approximately the same acute
viability as NBFA. Further analysis showed that higher concentrations of
sucrose in NBFA decreased acute viability as follows: 63.41% for 13.5% w/w
sucrose and 40.75% for 27% w/w sucrose.
These results show that G. sulfurreducens is susceptible to increased
osmotic shock even prior to desiccation. During desiccation, extracellular
sucrose or trehalose do not protect G.sulfurreducens, on the contrary, they
further decrease viability, possibly due to the additional osmotic stress.
THE EFFECTS OF SEROTONIN ON HUMAN T-CELL PROLIFERATION
Audrey Mayer, Melinda Hexum,
and Jodi Goldberg (Advisor)
Department of Biology
T cells are immune cells that divide rapidly, or
proliferate, when activated by the presence of foreign proteins. Previous
research has shown that the neurotransmitter serotonin is a necessary signal
for T-cell proliferation. However, these
studies employed heterogeneous populations of blood immune cells. In order to
determine the direct impact of serotonin on human T-cell proliferation, T cells
were first purified to >98% purity from whole blood. Additionally, previous
research has cultured cells in media that contains fetal calf serum (FCS),
which includes unregulated concentrations of exogenous serotonin.
Alternatively, Stemline Serum-Free media (Sigma) contains undetectable levels
of serotonin (as determined by ELISA).
In our study, T cells were cultured in either FCS or
Stemline Serum-Free media. T cells cultured in Stemline Serum-Free media
survived and proliferated, though not as strongly as those cultured with FCS.
It has not yet been determined if this is directly due to the absence of
serotonin in Stemline. Disorders such as depression and schizophrenia are
caused in part by abnormal serotonin concentrations. Additionally, therapies
for these disorders (selective serotonin reuptake inhibitors in particular)
alter serotonin metabolism. If serotonin affects T-cell proliferation, these
drugs may be causing unintended immune effects. Also, abnormal blood serotonin
levels have been observed in Autistic patients, as well as patients with
Alopecia Areata. Therefore, if serotonin does affect T-cell proliferation, it
may be a causal factor in these diseases.
INTRA- AND INTER-GENERATIONAL COLLEGE
ATTENDANCE PATTERNS
Jason
Q. McClintic, Arkady Shemyakin (Advisor), and Brenda Tiefenbruck (Advisor)
Department of
Mathematics
This presentation explores intra- and
inter-generational change in college attendance patterns. Data from the 1979 and 1997 National
Longitudinal Survey of Youth (NLSY) studies is used. In particular, three major tasks will be
undertaken: (1) identify predictors of college attendance for each cohort, (2)
build a logistic regression model of college attendance, and (3) compare and
contrast the models for the two generations as possible. This project builds on the previous literature
by examining differences between cohorts and by examining economic and
demographic variables.
AN EVALUATION OF THE EFFECTIVENESS OF INDIRECT METHODS
FOR STUDYING WHITE-TAILED DEER POPULATIONS AND MOVEMENTS ON THE NATURAL LANDS
OF
Kathryn
Meyers, John Giannini (Advisor), and Gene Bakko (Advisor)
Department of
Biology
This study examines the effectiveness of indirect
methods for studying the White-tailed deer (Odocoileus
virginianus) population at
CIRCADIAN RHYTHMS IN MAMMALS: THE EFFECTS
OF PHOTOPERIOD ON CLOCK GENE EXPRESSION IN VITRO
Carl Mickman, Jeremy J.
Stubblefield, Kiersten E. Norby, and Dwight Nelson (Advisor)
Department of
Biology
Period2 (per2), a gene expressed in the tissues of all
circadian animal species, has been implicated in several recent studies as a
"clock" gene, or a gene whose rhythmic expression influences and
possibly sustains an inherent circadian "pacemaker." This pacemaker
synchronizes and drives physiological rhythms everywhere in the body and is
suspected to be located in the Suprachiasmatic Nucleus (SCN) region of the
hypothalamus. Circadian rhythms in the body are sustained by regulating gene
expression in a complex feedback loop resulting ultimately in sleep/wake
cycles. Over the past several years, research has shown that specific
photoperiods, or variations in the duration of light in a 24-hour cycle, elicit
specific responses in mouse behavior. These responses include variation in
activity duration, circadian period, and phase response.
Using a newly developed procedure, we are now able to
detect changes in the cyclic expression of the clock gene product Per2 in the
SCN using brain tissue cultures of transgenic mice. Research with the use of
this procedure showed significant correlations between behavioral data and the
rhythmicity of Per2 expression in vitro for mice in different photoperiods.
TREE GROWTH PATTERNS AND SOIL NUTRIENT
VARIATION IN A MAPLE-BASSWOOD
Timothy S.
Mitchell, Allison W. Wagner, and Kathleen L. Shea (Advisor)
Department of
Biology
Growth patterns and survival of trees in restored
maple-basswood forest in southeastern
Our data suggest
that nutrient levels change slowly in agricultural soils. Tree growth patterns
of Fraxinus, Juglans, and Quercus fit a linear growth model,
while Acer and all trees combined
closely fit an exponential growth model. Variability in mean height increased
over time within species as some individuals became
much larger than others. Recent growth rates slowed in moderately
shade-tolerant species such as F.
INVESTIGATIONS INTO THE EFFECTS OF SPECIES DIVERSITY
ON INVASIVENESS OF REED CANARY GRASS (Phalaris arundinacea) IN UNDISTURBED WETLANDS IN THE CEDAR CREEK
NATURAL HISTORY AREA
Carly F. Miyamoto and Martha
M. Phillips (Advisor)
Department of Biology
Reed canary grass (RCG) is a well-known invasive
species in wetlands across
We hypothesized that existing species diversity acts to
help undisturbed communities resist invasion. To test this hypothesis, we
surveyed transects in wetlands at the CCNHA with and without RCG. Plots 1 x 1 m were placed every 5 m starting at the upland edge
of the RCG zone and ending in central plots without RCG. We made visual
estimates of percent over of all species, measured the change in elevation from
plot to plot, and collected soils samples for analysis of moisture content and
pH.
We found statistically significant differ-ences in the
average Shannon-Weiner diversity (H’) in the central wetland plots of sites
with and without RCG. These data support our hypothesis in that existing
species diversity has an impact on the invasive nature of RCG. We observed no
statistically significant differences pertaining to topography, soil pH, or
soil moisture, allowing us to rule out these variables as controlling
factors.
AMMONIA-OXIDIZING PROKARYOTES IN
Jensine Ohaju, Jason Kish,
and Randall E. Hicks
Department of
Biology
The archaeal amoA
gene, which codes for the enzyme ammonium monooxygenase, was amplified in
nucleic acids extracted from picoplankton collected in
DETECTING DOPAMINE EXOCYTOSIS WITH ELECTROCHEMISTRY
Han Na Park, Shencheng Ge,
Adam McFarland, and Christy Haynes (Advisor)
Department of
Chemistry
Retinitis pigmentosa is a retinal degenerative disease
that affects over 1 million people worldwide. Dopamine, a retinal
neurotransmitter, is responsible for various visual functions including retinal
light adaptation and retinal sensitivity. Recent studies suggest that abnormal
dopamine function plays a key role in overall retinal degeneration.
Our study exploits electrochemical detection of
dopamine from amacrine cells arborized in the inner plexiform layer to
investigate the role of dopamine in retinal degeneration. Samples are prepared
as dissociated cells, slices, or whole mount from a retina isolated from a
wild-type control mouse. A carbon-fiber electrode of approximately 7-µm
diameter is placed onto either an individual cell or approximately at the inner
plexiform layer to detect dopamine exocytosis. Upon stimulation, amperometric
measurements are recorded from samples holding the electrode at ±650 mV (vs. an
Ag/AgCl reference electrode). Fast-scan cyclic voltammograms are also recorded
with a triangular waveform scanning from -0.4 V to 1.0 V at a scan rate of
300V/s. Further research is required to improve reproducibility before applying
these techniques to study retinitis pigmentosa disease model samples.
INVESTIGATING GENETIC
CONTROL OF AUXIN METABOLISM IN Arabidopsis thaliana MUTANTS WITH ALTERED ADVENTITIOUS ROOTING VIA
HIGH-THROUGHPUT INDOLEALKANOIC ACID QUANTIFICATION
Ben
Pederson1, Lana Barkawi2, and Jerry Cohen2 (Advisor)
1Dept. of
Horticultural Science and Microbial and Plant Genomics Institute,
2Dept. of
Biology,
Auxins are a class of plant hormones, or
phytohormones, that mediate the coordination of a number of important growth
and behavioral processes in plants. Two important auxins are indole-3-acetic
acid (IAA) and indole-3-butyric acid (IBA). Interestingly, IBA can be converted
to IAA and IAA can serve as a precursor to IBA.
Our work aims to identify and characterize enzymes
involved in catalyzing the interconversion of IBA and IAA through the
quantification of these auxins within lines of Arabidopsis mutated in
genes that have been positively or negatively correlated with adventitious
rooting and/or endogenous auxin levels. Endogenous auxin levels are determined
by a high-throughput solid-phase extraction purification method and GC-SIM-MS
analysis that utilizes a novel IBA internal standard, 13C815N1-[Indole
Ring]-3-butyric acid. Specifically, this work focuses on the potential of the
auxin-conjugating enzymes GH3-3, AtGH3a, and GH3-6/DFL1 in the role of IBA / IAA
metabolism and adventitious rooting.
MATRIX-ASSISTED LASER DESORPTION / IONIZATION MASS
SPECTROMETRY ANALYSIS OF THE ADHERENCE OF PROTEIN TO A POLYMER-COMPOSITE
Charles Peterson, Ken Roily
(Advisor), and Megan Nagel (Advisor)
Department of
Chemistry
Matrix-assisted laser desorption / ionization (MALDI)
mass spectrometry is used to determine, both quantitatively and qualitatively,
protein-polymer composite binding interactions by the use of porcine albumin
and a variety of polymer-silicone composite disks. The presence of protein
adherence to the polymer-composite is qualified by MALDI analysis to reveal
whether or not samples are suitable for quantification. Following this
procedure, a quantification process involving a prepared calibration curve that
will determine protein concentrations versus mass/charge ratios determined by
MALDI is tested. Successful qualification and quantification of protein
adherence demonstrates that MALDI is a useful tool for the analysis of protein
binding to polymer-composite materials.
EFFECTS OF SNOW COVERAGE AND RUNOFF ON THE SPAWNING OF
WHITE SUCKER
Jennifer A. Plaster, Jody
Lutterman, Lisa Walters, and Virginia M. Card (Advisor)
Department of
Biology
Research has shown that the white sucker (Catostomus commersonii) spawns at
certain times according to the temperature of the water. When streams or rivers
that lead to the lake become ice-free in the spring, there are records of
people spotting this fish running upstream. Suckers migrate upstream to spawn
and then return to their normal habitat in the bottom of the lake. All the snow
that melts and runs into the stream may be colder than the main body of water
and sink to the bottom. This would allow the warmer water to be pushed upward.
The amount of snow per year could also have an effect on how early the suckers
spawn. We have researched this using
data collected from the newspapers on microfilms at the
CHARACTERIZATION OF PROTEINS THAT INTERACT WITH THE
ALPHA SUBUNIT OF ACTIN CAPPING PROTEIN
Ryan Raver, Joshua Kamrud,
and Marilyn Hart (Advisor)
Department of
Biological Sciences
MN
Actin plays a key role in cell structure, shape, size,
and motility. Actin is regulated by a variety of accessory proteins including
actin capping protein (CP). CP is a heterodimer composed of an alpha (α)
and beta (β) subunit. Lower organisms have one isoform of both the α
and β subunit. In contrast, in higher organisms, three α and three
β subunit isoforms have been identified. We hypothesize that the three
α isoforms have unique cellular and biochemical roles and therefore
interact with different cellular proteins.
In a previous study, a yeast two hybrid screen was
employed using a murine embryonic cDNA library as prey and either α1 or
α2 as bait to identify protein interactions between α1 and α2
and other structural or regulatory proteins. The α1 screen identified five
interacting clones and the α2 screen identified seven interacting clones.
Sequence analysis confirmed the identity of four of the α2 clones as
actin, myosin heavy chain 3, serine proteinase inhibitor, and a novel gene on Musculus chromosome 1.
The purpose of our research is to characterize the
remaining clones. We have isolated total DNA, including genomic and plasmid,
from yeast cells and confirmed the integrity of the DNA. The plasmid inserts
were amplified via the Polymerase Chain Reaction using vector specific primers
to determine insert size. PCR products were sequenced. Preliminary data will be
presented
IDENTIFICATION AND CHARACTERIZATION OF GLYCOSOME
BIOGENESIS GENES IN THE AFRICAN PARASITE Trypanosoma
brucei
Keri Robideaux, Emily Vogt,
and John Flaspohler (Advisor)
Department of Biology
Members of the genus Trypanosoma are vector-borne blood and tissue parasites of
vertebrate organisms, including humans. Trypanosoma brucei includes species of
human blood parasites that cause significant morbidity and mortality in many
regions of
This project is designed to further understanding of
glycosome biogenesis through identification and characterization of T. brucei genes and gene products
required for glycosome biogenesis. We report here the cloning of two T. brucei genes, TbPEX1 and TbPEX4, and
constructs designed to allow for characterization of their role and importance
(if any) in glycosome biogenesis. The two genes were isolated from the T. brucei genome using PCR based on
their homologies with previously identified peroxisomal biogenesis genes. We
have cloned both genes as fusions with the gene for green fluorescent protein
(GFP) and have also cloned portions of TbPEX1
and TbPEX4 into trypanosome
expression plasmid constructs designed to allow inducible expression of
interfering RNA (RNAi) when transfected into T. brucei cells. It is our hope that these experiments will provide
evidence as to whether the glycosome organelle may
prove to be an attractive potential target for anti-trypanosomiasis therapies.
QUALITATIVE ANALYSIS OF AN UNKNOWN
SOLUTION VIA SOLUTION MODELING AND INSTRUMENTAL ANALYSIS
Christopher B. Rognrud and Ken
Rohly (Advisor)
Department of Chemistry
Qualitative analysis of an unknown green solution
containing an aromatic Iodide compound and 3.4 M NaOH was analyzed via solution
modeling. Important for industry, this
green solution was modeled with sixteen different solutions containing varying
metals such as Mo, Mo+3, Mo+4, Mo+6, Cu+2,
Ni+2, Fe+2, and Cr+2 at varying pH. Each model
was analyzed via UV-visible spectroscopy, while the unknowns composition was
analyzed via atomic absorption furnace spectroscopy.
UNDERSTANDING THE PRECIPITATION OF NA2SO4 WITHIN A
STAINLESS STEAL PUMPING MECHANISM
Christopher B. Rognrud and Ken
Rohly (Advisor)
Department of Chemistry
A stainless steal pump immersed in a solution of NaCl,
H2SO4, and Na2S2O5 has
shown to produce a Na2SO4 precipitate. The solution, reacting with the surface of
stainless steal, forms this precipitate which can hinder the optimal operation
of a pumping mechanism. This is believed
to be induced through production of SO2 which can react with NaCl in
the solution to precipitate Na2SO4. The sulfate precipitate was analyzed via ESCA
and several qualitative analytical techniques.
THE EFFECTS OF LYSINE MUTATIONS ON Runx2
TRANCRIPTIONAL ACTIVITY
Julia Rood1 and
Jennifer J. Westendorf2
(Advisor)
1St.
2Department of
Orthopedic Surgery,
Runx2 is a transcription factor necessary for
osteoblast development and maturation and is associated with numerous protein
partners that regulate its activity. p300 is a known coactivator of Runx2
possessing histone acetyl transferase (HAT) activity. Because four critical
lysine residues in Runx2 are acetylated by p300, we hypothesized that mutation
of those residues would reduce Runx2-dependent transcription and convey p300
independence. We created parallel sets of Runx2 mutants containing either
lysine to alanine or lysine-to-arginine substitutions at residues 225, 230,
350, and 351. We transfected these DNA constructs into C2C12 cells in the
presence or absence of p300 and analyzed activation of p6OSE2-Luc using a dual
luciferase reporter assay. None of the lysine to alanine or lysine-to-arginine
mutations affected co-activation of Runx2 by p300. However, lysine-to-arginine
mutations significantly decreased Runx2-dependent transcripttion, whereas
lysine-to-alanine mutations had little or no effect.
Our findings suggest that acetylation of Runx2 lysine
residues may not be responsible for the activating effect of p300. A different
mechanism, such as recruitment of p300 by Runx2 to a promoter for histone
acetylation, may be the cause. Further study is needed to clarify the
interaction between p300 and Runx2 lysine residues.
ANALYSIS OF THE ANTIBACTERIAL ACTIVITY OF ENROFLOXACIN
AND TYLOSIN PHOTOPRODUCTS
Jenna Schroeder, K. Brook
Jacobson, and Kristine H. Wammer (Advisor)
Department of
Chemistry
Enrofloxacin and tylosin are two antibacterial
compounds used for agricultural applications.
Both have been found in natural waters at low concentrations. Both drugs are subject to photodegradation
when exposed to natural sunlight. While
attenuation by sunlight usually mitigates the environmental impacts of
antibacterial compounds, problems may arise if the photoproducts themselves
introduce additional antibacterial activity.
In separate experiments the antibacterial activities
of enrofloxacin and tylosin were compared with that of their photoproducts to
determine whether the products presented any additional antibacterial activity
against Escherichia coli DH5a.
Enrofloxacin’s photoproducts greatly inhibited bacterial growth while
tylosin’s main photoproduct (resulting from a photoisomerization) did not
inhibit bacterial growth at all. These
results indicate that photodegradation of tylosin will likely result in
elimination of its potential to affect environmental microbial communities
whereas assessment of enrofloxacin’s potential environmental impacts will
likely need to include analysis of its photo-products.
SURFACE MODIFICATIONS OF PLATINUM AND TITANIUM BY
SINTERING AND OTHER METHODS
Kelly Schwartzbauer and Kenneth Rohly (Advisor)
Department of Chemistry
Sintering is a technique used to fuse powder particles
together to create an object with increased surface area. Improved mechanical and electrical properties
and increased strength are often desired results. For example, powder injection molding
requires sintering to densify raw metal powder particles together in a
mold. The strength of bonding between
particles is determined by the length of time spent at the sintering
temperature. In this study, sintering
was employed to achieve a thin, porous coating on metal wire surfaces.
The sintering process requires binding powder to the
substrate surface prior to heating.
Obtaining a uniform coating on the wires proved challenging and the
method of powder and binder application was varied. The wires were also etched to roughen their
surfaces. Pressureless sintering on
etched platinum (Pt) and titanium (Ti) wires was performed in a high-vacuum
furnace to avoid oxide film formation on the wire surfaces at elevated
temperatures. Pt powder (28 micron) and
Ti powder (3 micron) were sintered onto Pt and Ti wires respectively with the
sintering temperature just below the melting point of each metal. Optical and scanning electron micro-scopy
(SEM) revealed that Ti sintered wires possessed a uniform, porous coating
whereas Pt wires showed areas of variable thickness. Subsequent texturing treatments resulted in
surface modifications that were compared between the two metals, as shown by
SEM images of the topography at various magnifications. This groundwork sintering research forms the
foundation for future experiments.
EFFECTS OF DHT AND FLUTAMIDE ON PSA AND ZEB-1
EXPRESSION IN 22RV1 PROSTATE CANCER CELLS
Megan R. Schwartzbauer and
Bynthia M. Anose (Advisor)
Department of
Chemistry and Biochemistry
Prostate cancer (PCa) is the second most common type
of cancer and second leading cause of cancer deaths in American men. In 2007,
there will be 27,050 men in the
Our work studies the effects of dihydrotestosterone
(DHT), an androgen, and flutamide, an anti-androgen, on the expression of PSA
and ZEB-1 in 22Rv1 cells. Real-time polymerase chain reaction was used to
quantify the mRNA expression of PSA and ZEB-1 in response to various
concentrations and combinations of these compounds. DHT and flutamide are
hypothesized to have opposite effects on the two genes. Previous research,
however, has revealed that flutamide is able to show agonistic behavior.
Further investigation of flutamide behavior is necessary, as it is currently
used as a purely antagonistic treatment in androgen ablation PCa therapy.
EFFECTS ON PSA EXPRESSION IN 22Rv1 PROSTATE CANCER
CELLS BY DHT DERIVATIVES
Jamie K. Schwendinger and
Bynthia M. Anose (Advisor)
Department of Chemistry
Prostate cancer (PCa), while initially very responsive
to androgens, can be sent into remission by treatment with anti-androgens.
However, despite these treatments, the cancer often returns in its metastatic
form, and is no longer susceptible to androgen ablation. The likely cause of
this resurgence is that another gene or chemical involved in the androgen
pathway is responsible for stimulating cancerous growth. Currently, the most
potent stimulator of metastatic activity is dihydrotestosterone (DHT); this
steroid is therefore the one targeted for androgen ablation. However, many
derivatives of DHT exist that may also be implicated in androgenic stimulation:
examples are testosterone propionate and dehydroisoandrosterone, which have not
yet been studied extensively.
In our study, derivatives of DHT with potential for
androgenic capabilities to stimulate uncontrolled prostate cell growth are
being investigated for their effects on prostate cancer cells. DHT provides a
positive control in the experiment. 22Rv1 cells (a human prostatic cancer cell
line) are treated for 24 hours with 10-nM concentrations of testosterone,
testosterone proprionate, dehydroisoandroster-one, dihydrotestosterone, and
ethanol. After harvesting, the expression levels of prostate-specific antigen
(PSA) are quantified using Real Time-PCR. PSA is known to be very sensitive to
androgens, and thus provides an excellent control for testing possible
androgenic compounds. Expression of PSA for each drug treatment can then be compared
with the ethanol treatment (to provide a baseline) and the DHT treatment to
determine if the androgen derivatives contain agonist activity.
CRYSTALLOGRAPHIC MISORIENTATIONS, SUBGRAIN BOUNDARIES,
AND U ZONING IN MONAZITE GRAINS
Niccole Shipley and Annia
Fayon (Advisor)
Department of
Geology and Geophysics
Radiometric and thermochronologic dating of accessory
minerals such as zircon, monazite, and apatite is often used in building
geologic histories of an area. Several factors can affect the ages obtained by
these methods, making it necessary to understand the processes affecting age
measurements, including diffusion rates and annealing rates. Previous experiments have revealed
connections between zoning patterns and crystallographic misorientations in
zircons and garnets. The crystal-ographic misorientations have been shown to
affect diffusion rates in these minerals. Electron backscatter imaging revealed
U zoning patterns ranging from simple to complex in monazite sand grains taken
from placer deposits.
Electron backscatter diffraction analyses were
conducted on several monazite grains to determine crystallographic
orientations. These data were compared with quantitative and qualitative
electron-microprobe analyses of U concentrations for the selected grains.
Grains exhibiting concentric zoning were used as a standard for comparison.
Initial data indicate that complex zoning patterns coincide with
crystallographic misorientations in monazite grains. This indicates existence
of subgrain boundaries corresponding to zoning patterns in monazite. Such a
correlation will affect rates of diffusion and fission track annealing and must
therefore be considered when obtaining thermochronologic ages for monazite.
THE MISCIBILITY PHASE BEHAVIOR OF LIPID MONOLAYERS
CONTAINING 25-HYDROXYCHOLESTEROL
Benjamin J. Sonquist and
Benjamin L. Stottrup (Advisor)
Departments
of Biology and Physics
Langmuir film-balance and epi-fluorescence microscopy
techniques have been combined to study the biophysical properties of lipid
monolayers. These monolayer techniques provide several advantages
including a precise knowledge of monolayer composition, a wide range of
accessible molecular areas, and relative ease of preparation. Extensive
work on these model systems has investigated lipid-protein interactions, bulk
modulus, and phase behavior of biologically relevant compositions. A well characterized
system is the binary and tertiary mixtures of cholesterols and phospholipids.
These model systems are believed to mimic many important properties of a
membrane leaflet. However, despite considerable progress, important
questions remain. One interesting observation is the failure to detect a
discontinuity in a monolayer’s compressibility as it passes through a
liquid-liquid miscibility phase transition for an arbitrary cholesterol / phospholipid
system. Recently it was observed that mixed lipid monolayers of the sterol
25-hydroxycholesterol (25OH) and the phospholipid DPPC exhibit unique phase
behavior. 25OH is an oxysterol containing two spatially separated
hydrophilic hydroxyl groups. In the 25OH/phospholipid system the
liquid-liquid miscibility transition corresponds to a kink in the pressure-area
isotherms of the system as well as both upper and lower miscibility
transitions. We explore the influence of chain length and sterol structure on
this monolayer phase behavior.
THE EVOLUTION OF BREEDING SYSTEMS IN Tolpis
(ASTERACEAE) ON THE
Danielle Stoermer1,
Daniel Crawford2
(Advisor), and Mark Mort2
(Advisor)
1St.
2Department of Ecology and Evolutionary Biology,
Baker’s Rule states that island plants should be
self-compatible, because self-compatible, as opposed to self-incompatible, taxa
can establish a sexually reproducing population from one seed and long-distance
dispersal to a remote island is an unlikely event. However, this view has been
questioned because outcrossing taxa generate genetically diverse progeny that
are necessary for subsequent radiation into different habitats.
We examined the reproductive biology of different
species of Tolpis, a genus of
Asteraceae largely endemic to the
IDENTIFICATION OF THE BDC-6.9 T-CELL AUTOANTIGEN
THROUGH UTILIZATION OF THE FISAT TECHNIQUE
Kristina Stoermer1,
Jennifer Profozich2,
Sheila Schreiner2, Gina
Randa2, Martha Milton2, Hubert Tse2 (Advisor), and Jon
Piganelli2 (Advisor)
1St.
2University of
Type I Diabetes (T1D) is initiated by T-cell
recognition of pancreatic ß-cell antigens and is characterized by a leukocytic
infiltrate into the pancreatic islets, ß-cell destruction, and ultimately
hyperglycemia. It has been hypothesized
that a number of environmental triggers (viral infection, drugs, oxidative
stress, and chemical induction) leading to ß-cell stress or damage may cause
the onset of T1D by releasing self-antigens to the immune system, though a
common link between these triggers and disease onset has never been formally
proven. To investigate this hypothesis we used the non-obese diabetic (NOD)
mouse that spontaneously develops diabetes characterized by autoantibodies,
insulitis leading to ß-cell destruction, and subsequent hyperglycemia, thus
serving as an ideal mouse model for T1D.
Efforts to elucidate the progression of autoantigenic
recognition by T-cells may help to reveal the role of environmental triggers in
T1D. To expedite the identification of candidate autoantigens, we previously
utilized the pathogenic BDC-2.5 T-cell clone to reconstitute NOD.rag mice with a Functional Immune System
via Adoptive Transfer (FISAT). FISAT was
performed by transferring diabetogenic BDC-2.5 T-cell clones together with
purified B-cells from pre-diabetic NOD mice. Reconstituted mice were immunized
with a purified ß-cell membrane preparation (ßGAP) that is known to stimulate
BDC-2.5 T cells in vitro. Serum from
the FISAT mice detected a 70-kDa-protein identified as the endoplasmic
reticulum-associated Glucose Regulated Protein 78 (GRP78). As a continuation of
this work, NOD.scid and NOD.rag mice were reconstituted by FISAT
with purified NOD B-cells and another diabetogenic T-cell clone, BDC-6.9, in
hopes of identifying its autoantigen. These BDC-6.9 FISAT mice were immunized
with a ßGAP preparation, and the resulting serum was used to identify its
cognate autoantigen by immunoblot analysis. After adoptive transfer of B-cells
and BDC-6.9 T-cells into NOD.scid and
NOD.rag mice, no antibody was detected
by Western analysis until after ßGAP immunization. Two bands with a molecular weight of 55 kDa
and 33 kDa were notably detected; these candidate autoantigens are currently
being identified by MALDI ToF mass spectrometry analysis.
MEASURING HOW WE IMPACT THE WORLD THROUGH GAS
EMISSIONS
Ashley J. Stoffers, Richard
Harsdorf, and David R. Hanson (Advisor)
Department of Chemistry
There are many different trace gases (or vapors) in a
sample of atmospheric air. Many gases
are naturally occurring, but some are pollutants (man-made aka
anthropogenic). These latter gases are
present at trace levels but can be important for example in some aspects of
global warming and in air quality. A
mass spectrometer is an instrument that measures the mass of a compound. The instrument being developed can sample and
measure the trace gases in the atmosphere, both ‘natural’ and
anthropogenic. This is important for a
better understanding of natural and anthropogenic influences on the
atmosphere. We are designing and
building an instrument that will be deployed on a high altitude airplane. We
will test it thoroughly via calibrations and sampling of air around
IDENTIFICATION OF PROTEINS THAT INTERACT WITH ACTIN
CAPPING PROTEIN
Kevin Y. E. Strehler, Nathan
M. Martinez, and Marilyn C. Hart (Advisor)
Department of
Biological Sciences
MN
Actin, a component of all eukaryotic cells, plays an
important role in maintaining cell structure and contributes to cell motility.
Actin is regulated by a variety of accessory proteins including actin capping
protein (CP). CP attaches to the barbed end of actin filaments, regulating
length and stability. CP is composed of two subunits, an alpha (α) and a
beta (β) subunit. In vertebrates, three alpha isoforms (α1, α2,
α3) and three beta isoforms (β1, β2, β3) have been
identified. The β1 isoform is the predominant isoform of muscle, whereas
the β2 isoform is the predominant isoform of nonmuscle. Previous
transgenic studies indicate that β1 and β2 are functionally distinct
in murine myocardium and might interact with novel proteins.
We are using a yeast two hybrid genetic screen to
identify proteins that interact with β1 and β2. We have generated the
appropriate constructs and have confirmed their orientation and expression. We
have also amplified a mouse embryonic cDNA library. The screen is ongoing.
ENTRAINMENT PHOTOPERIOD MODULATES THE
MOUSE CIRCADIAN SYSTEM AND ITS RESPONSIVENESS TO LIGHT
Jeremy J. Stubblefield and
Dwight E. Nelson (Advisor)
Department of
Biology
In mammals, circadian
rhythms in behavior and physiology are driven by endogenous circadian
oscillators. These oscillators in turn are entrained by environmental
light-dark cycles. Seasonal modulations of behavior and physiology are also
thought to involve the circadian system through the effects of daylength or
photoperiod on circadian production of pineal
melatonin.
We are examining
photoperiod-induced changes in the circadian system in C57BL/6 mice―a strain commonly regarded as insensitive to
photoperiod because it lacks pineal melatonin. Mice were entrained to
photoperiods ranging from LD 4:20 to constant light (LD 24:0) and then released
into constant darkness (DD). Light pulses were delivered to each mouse in DD to
assess the photic responsiveness of the circadian system using phase shifts.
Free-running period and duration of activity were also measured. Mean delays following
4:20 and 6:18 (153+/-14; 171+/-8 min) were significantly smaller than following
16:8 (82+/-10 min; ANOVA, Tukey, P<0.05).
Photoperiod differences also induced significant changes in circadian
period and duration of activity. Because mice entrain to LD cycles through
daily phase shifts induced by light at various times of their circadian cycle,
we also examined the effect of photoperiod (8:16 and 16:8) on the phase
response curve (PRC). Phase delay and advance amplitude for the PRC was reduced
following LD 16:8 compared with LD 8:16 (P<0.05, Student’s t Test). Surprisingly, photoperiod has a very large influence on circadian
functions in “non-photoperiodic” C57BL/6 mice.
USING A CHEMICAL GENETICS APPROACH TO IDENTIFY
COMPONENTS OF THE AUXIN SIGNALING PATHWAY IN Arabidopsis thaliana
Can Sungur, Ronald Brisbois,
Rebecca Hoye, and Paul Overvoorde (Advisor)
Departments
of Biology and Chemistry
Auxin, typified by Indole-3-acetic acid, is a class of
plant hormones that is involved in such vital and diverse processes as cell
division, cell elongation, tissue differentiation, phototropism, gravitropism,
and root development. Chemical genetics provides a novel means by which to
investigate the auxin response pathway in Arabidopsis
thaliana. Combining high-throughput screening, chemical synthesis, and
genetic analysis, chemical genetics is a means by which to find small molecules
that are capable of binding to and inhibiting the function of a protein
involved in a process of interest. In terms of the auxin response pathway, a
previously conducted high-throughput screen of 10,000 small molecules yielded
four compounds (A, B, C, and D) that strongly inhibited auxin signaling.
Further tests determined the core moiety of Compound A, furylacrylic acid
(FAA), capable of inhibiting the auxin pathway.
Our research is aimed at identifying the cellular
targets of two inhibitors, FAA and Compound C, as well as to learn more about
their modes of inhibition. Assays with wild type seedlings indicate that both
FAA and Compound C inhibit root elongation. Furthermore, each of these
compounds attenuates the expression of an auxin-responsive reporter gene.
Specificity of the inhibitory compounds has been studied by testing the
compounds’ effects on other plant hormones such as abscisic acid and cytokinin.
Possible modes and locations of inhibition have been studied through
fluorescent localization of GUS reporter PIN1 constructs that mediate auxin
flow. The effects of the inhibitory compounds were also explored through
various GUS stains of different reporter lines of Arabidopsis, measurements of hypocotyl growth, and addition of the
inhibitory compounds specifically to the root-shoot junction. Western
pull-downs have uncovered the binding of Compound C to the TIR/F-box structure
without the addition of external auxin, though Compound C does appear to bind
to auxin receptors AFB2 and AFB3 with stronger affinity. Finally, fluorogenic
assays have been conducted in order to obtain quantitative data regarding the
effect of these compounds on the auxin-inducibility of an auxin-inducible
reporter gene.
FLUORESCENT PROBES FOR STUDYING RUBBER BIOSYNTHESIS
Trista
Talbot and Mark Distefano (Advisor)
Department of
Chemistry
This project involves the synthesis of THP-protected
geraniol amine, a known compound. This compound will then be used for the
attachment of a fluorescein molecule via an amide linkage. Deprotection and
diphosphorylation produces fluorescein-labeled geranyl diphosphate. The
synthesized fluorescein-labeled geranyl diphosphate will be used to investigate
their ability to serve as primers in the biosynthesis of rubber. The rubber
produced will be analyzed with fluorescence to measure the molecular weight and
polydispersity of the resulting rubber.
DIFFERENTIAL REGULATION OF CELLULAR SIGNALING PATHWAYS
THAT CONTROL CELLULAR MIGRATION IN HUMAN LUNG CANCER CELL LINES: THE EFFECTS OF
LYSOPHOSPHATIDIC ACID, UROKINASE-TYPE PLASMINOGEN ACTIVATOR, AND PHENYLEPHRINE
Jason Tan, Jenny Canine,
Craig Kutz, Dani Rastedt, Blake Heinz, Jennifer Taves, Joseph Provost
(Advisor), and Mark Wallert (Advisor)
Departments
of Chemistry and Biosciences
MN
Lung cancer is the leading cause of cancer deaths in
the
Thus we screened cellular responses to
lysophosphatidic acid (LPA), urokinase plasminogen activator (uPA) and
phenylephrine (PE) in the human lung cancer cell lines, H460, H358, H69AR, and
A549.
DOES WHI-P131, AN INHIBITOR OF JANUS
TYROSINE KINASE (JAK) 3, AFFECT MITOGEN-INDUCED T-CELL PROLIFERATION?
Fei Chin Tsan,
Gargi Dayama, and Marina Cetkovic-Cvrlje (Advisor)
Department of
Biological Sciences
T-cells express a signal transduction protein molecule
called JAK3. Recent studies have shown that a potent inhibitor of JAK3 called
WHI-P131 prevents the development of autoimmune T-cell-mediated diabetes in
mice. However, it remains unclear whether P131 directly acts on T-cells.
Therefore, the aim of this study was to determine the effects of P131 on T-cell
function in vitro by using mitogen-induced T-cell proliferation assays. First, the optimal conditions for
quantification of T-cell proliferation were established. T-cells proliferation
is commonly quantified by incorporation of
isotope [3H] thymidine in T-cells. As this assay cannot be performed
at SCSU, the cell proliferation was quantified using the commercially available
WST-1 assay. Two types of the T-cell mitogen – concanavalin A (ConA) and
phytohemagglutinin (PHA) were tested in three different concentrations in order
to find the optimal cell proliferation detectible by WST-1 assay. Splenocytes were isolated from BALB/c mice
and cultured in 96-well-plate with addition of different concentrations (0, 2,
5, and 10 µg/mL) of ConA or PHA for three days. Then WST-1 was added, and the
absorbance was measured by a plate reader at 480 nm. ConA in concentration of
2µg/ml induced statistically significant (P=0.002, Student t-test)
proliferation compared to control, untreated cells. The P131 was added in a
concentration range of 0 - 25 µg/mL to determine whether ConA-induced
proliferation of T-cells can be inhibited.
The addition of P131 induced a dose-dependent suppression of
ConA-induced splenocyte proliferation. These data show that P131 can directly
affect T-cell function determined by mitogen-induced proliferation.
In situ SELF-ASSEMBLY OF G-DNA MOLECULAR
SCAFFOLDS NUCLEATED BY A POLYMERIC TEMPLATE
Matthew
Turner and T. C. Marsh (Advisor)
Department of
Chemistry
Research on the structure and function of guanine-rich
nucleic acids has shown that multiple guanine repeats in a sequence enable
these biopolymers to adopt a quadruple helical structure generally known as
G-DNA. In previous work, the DNA oligomer GGGGTTGGGG (Tet1.5) was used to
create a self-assembling linear supramolecular G-DNA termed a G-wire. This
molecular scaffold is able to direct the positioning of gold nanoparticles on a
mica substrate. However, the linear scaffolds were previously deposited from
bulk solvent and were randomly dispersed on the mica substrate.
To achieve better localization and dictate initial
orientation of G-wire self-assembly, in-situ self-assembly using a
polymeric template was performed. Specifically, the polymer poly-5-norbornene-2-carboxylic acid
(D.P. 4400) with the oligonucleotide NH2-GGGGTTGGGG coupled at a ratio of 1
oligonucleotide to 10 carboxylic acid groups was synthesized to serve as a
rigid polymeric template for the self-assembly of G-wires. Atomic Force
Microscopy was used to characterize copolymer-templated self-assembly of
G-wires on a mica substrate.
EFFECT OF INCREASED ANGIOGENESIS ON MUSCULAR DYSTROPHY
MODEL MICE
Mayank
Verma and Atsushi Asakura (Advisor)
Department of
Neurology
Duchanne Muscular Dystrophy (DMD) is a genetic
disorder in which the absence of the protein dystrophin causes muscle fibers to
be more susceptible to damage and die easily. Several rounds of
degeneration/regeneration results in a progressive deterioration of the muscles
and causes the muscle fibers to be replaced by connective tissue. Recent work
has reported the functional role of dystrophin in vascular smooth muscle. Damage to blood vessels may be a reason for further deterioration in DMD
afflicted muscle.
The goal of this project is to test whether increased
angiogenesis has any effect on muscular dystrophy model mice (mdx). For this purpose, we created
double mutant (mdx5cv:Flt1+/-) mice. Flt1is
a surface protein that is a receptor for Vascular Endothelial Growth Factor
(VEGF). Our data demonstrate that the double mutant mdx:Flt1+/-
mice have significantly higher blood vessel density then the control mdx:Flt1+/+. Both genotypes were tested for fibrosis,
calcification, and membrane permeability. Interestingly, mdx:Flt1+/-
mice displayed less fibrosis, less calcification, and decreased membrane
permeability in the skeletal muscle compared with mdx:Flt1+/+.
These data suggest that increased blood vessel density may have a positive
effect on the muscle pathology and function in mdx mice and possibly for DMD patients. Eventually we would like to
induce angiogenesis in the mdx5cv by administration of VEGF
or shRNA for Flt1 gene knockdown (KD)
to test whether increased angiogenesis can improve muscle phenotype for
clinical application.
EFFECTS OF LOCAL AND LANDSCAPE FEATURES ON
THE COMMUNITY STRUCTURE OF WETLAND BIRDS
Christa von
Behren and Mark Davis (Advisor)
Department of
Biology
Wetlands provide important habitat for many types of
animals, especially for birds. They are
also some of the fastest disappearing habitats in
The purpose of this study was to analyze the effects
of several wetland features on wetland bird assemblages and nest predation
rates at several spatial scales. Bird
surveys, vegetation surveys, and measurements of nest predation were conducted
in wetlands at the Cedar Creek Natural History Area in
OPTIMIZATION OF SURFACE GEOMETRY TO ENHANCE THE
SUPERHYDROPHOBIC EFFECT
Jeremy P. Wade and Nicholas
E. Schlotter (Advisor)
Department of Chemistry
This project focuses on determining hydro-phobicity as
a function of surface roughness on both the micron and nanometer scales by
producing combinations of both roughness scales in order to establish the
optimum roughness regime for superhydrophobic surfaces (contact angle >
150°). The micro- and nanometer scales that are being investigated were
originally based on the lotus leaf, a naturally occurring superhydrophobic
surface, which uses a combination of these two roughness scales to achieve a
superhydrophobic, self-cleaning surface. Additional studies in the literature
and our own work point to the need for roughness on both scales to achieve
maximum superhydrophobic behavior. We are creating patterns on the micron scale
using spin-coated photoresist and contact exposure lithography. The nanometer
scale roughness (5-500 nm) is formed using fluorescent tagged silica
nanoparticles. These silica nanoparticles are made and sized via a base
catalyzed sol-gel reaction and then deposited on the substrate. Finally, the
patterns are made chemically hydrophobic by reacting with octadecyltrich-lorosilane
(OTS) to form a bound layer of packed hydrocarbon tails.
Surfaces have been covered with patterns
formed of posts, square in cross-section (from the top), which are
made using lithography. The posts have a height of 10-15 µm and the
spaces between the posts are the same size as the post's widths, between 10-50
µm, in steps of 5 µm. The authors have observed contact angles between water
and the lithographically patterned surfaces of up to 145° as a function of post
width and spacing.
We have created nanoparticles between ≈ 5-500 nm
resulting in contact angle as large as 160° on a flat surface.
EFFECTS OF CLIMATIC
WARMING ON THE DURATION OF ICE COVER OF
Lisa M. Walter, Jennifer
Plaster, Jody Lutterman, and Virginia M. Card (Advisor)
Department of
Natural Sciences
Ice cover is perhaps the most sensitive indication of
a warming climate and climate variability (Magnuson et al 2001). By examining the trends in ice cover duration
of
AN ANALYSIS OF TROPICAL CYCLONE
RECURVATURE IN THE
Donya Weibeler
and Anthony Hansen (Advisor)
Department of
Earth and Atmospheric Sciences
An observational analysis of tropical
cyclone recurvature in the
EXPRESSION OF SEMAPHORINS AND SEMAPHORIN RECEPTORS IN
MOUSE THYMUS
Kai Wilhelm1,
Matthew Rosenbaum1, Udochukwu Obodo1, Grace Linder1,
Katelynne Gardner Toren1, Nathaniel Crider1, David J.
Matthes2, and Devavani Chatterjea1 (Advisor)
1Dept. of Biology,
2Dept. of Biological Sciences,
Immature immune T cell precursors arise from
hematopoietic stem cells in the bone marrow, migrate through the circulatory
system, and selectively enter the specialized microenvironment of the thymus
gland at the cortico-medullary boundary.
The double negative (CD4-CD8-) thymocytes undergo positive selection and
migrate upwards through the thymic cortex and then back to the medulla also
starting to express both surface CD4 and CD8.
In the thymic medulla, after negative selection, emerge as mature CD4 or
CD8 T cells that re-enter the circulation.
Though the stepwise development of T cell subsets in the thymus has been
exquisitely characterized in terms of location within the thymus and surface
phenotype of the thymocytes, the specific guidance
cues that orchestrate this developmental migration are only beginning to be
characterized.
Semaphorins, originally discovered as neuronal
guidance cues, have been characterized as a family of thirty proteins twenty of
which are found in mice or humans. Semaphorins mediate axonal guidance in the
nervous system and mainly use two families of receptors: plexins and
neuropilins. Sema4A, Sema4D, Sema4F, and
Sema7A are also expressed in the immune system; Sema4A and Sema4D use
non-neuropilin/plexin receptors, Tim2 and CD72 respectively. Semaphorins modulate activation of dendritic
cells, monocytes, T cells and B cells. Our preliminary evidence for in situ sema expression in the thymus
suggests that semaphorins may modulate intrathymic T cell migration. We isolated
total RNA from thymuses of 6 week old ND4 and BALB/C
mice, and used reverse-transcriptase (RT) -PCR to assay expression of Sema 4A, 4D, 4F, 7A, neuropilin1 and plexin β1genes
in whole thymus and in isolated hematopoietic and epithelial subsets derived by
magnetic cell separation based on CD45 surface expression.
VISUALIZATION OF THE MICROVASCULATURE
STRUCTURE OF THE RAT SCIATIC NERVE
Michael W.
Witthaus, Adam W. Sudbeck, and Michael Bentley (Advisor)
Department of
Biological Sciences
MN
The vascular supply to the peripheral nerves is
important for axon maintenance and survival.
Little information is known about the architecture of the microvasculature
and capillary beds of peripheral nerves.
The microvasculature architecture of sciatic nerves from male adult
Wistar Kyoto rats were visualized by scanning electron microscopy. To visualize the vessels, a
polyurethane-based casting resin was infused into the aorta. The sciatic nerves were dissected after the
resin completely polymerized. The nerves
were placed in a potassium chloride solution.
The resulting casts were critical point dried, sputter coated with gold
palladium and analyzed via scanning electron microscopy. The arterial supply and venous drainage were
visible, running parallel to the sciatic nerve.
Capillary networks longitudinally extended between the arranged
arterioles and venuoles. The arrangement
may have relevance in experimental neuropathic conditions such as diabetes
mellitus.
GAS CHROMATOGRAPHY DETERMINATION OF
BENZENE AND ETHANOL IN GASOLINE
Malinmuon
Xayaphet, Arlin
Department of
Chemistry
Benzene, also
known as benzol, is an organic chemical compound with the formula C6H6.
It is a colorless and flammable
liquid with a sweet smell and a relatively
high melting point. Benzene, a component of products derived from coal and
petroleum, is found in gasoline and other fuels, and is also an aromatic
hydrocarbon that is produced by the burning of natural products. Benzene is
used in the manufacture of gasoline, detergents, pesticides, and other chemicals.
Research has shown
that benzene is a carcinogen (cancer-causing). Short-term exposure of an
individual to high levels of benzene can cause drowsiness, dizziness,
unconsciousness, and death, while long-term exposure may cause leukemia because
it affects bone marrow and blood production.
According to the Department of Justice’s
benzene-in-gasoline regulations published July 1st, 2000, it is
prohibited that any gasoline contain benzene at a concentration that exceeds
1.5% by batch volume, meaning total supply. There is a move in congress to
reduce the batch level to 1.0%, which could be expensive and raise gasoline
prices even higher.
This
research project was done using Gas Chromatography to determine benzene levels
(as well as ethanol levels) in local gasoline stations’ gasoline. Historically gasoline has had up to 3 or 4% benzene
although usually much smaller. Benzene is naturally present in gasoline
but is also produced in the catalytic reforming process Recent
regulations have limited benzene to a batch 1.5% level and is moving toward a
1.0% batch level by law becoming effective soon.. The national government
is now moving towards a 0.60% batch level but no legislation has been
passed. With about +/- .3% leeway
(to be more accurately determined when all data is analyzed) our results so far
pretty much are around the 1.5% level with a few small results and one at 2.4%
which might be an anomaly. We're checking. The ethanol level
jumped from 10% in October to around 20% ethanol for "winter" gasoline.
Soon