Traits of Introduced and Native Grass Species in North Carolina that Influence Rates of Herbivory and Pathogen Acquisition

Sam Abercrombie

Research Advisor:  Dr. Charles Mitchell

Research Mentor: Dr. James Cronin

Introduced species can affect community structures by decreasing species diversity and altering dominance patterns. One mechanism by which introduced plant species may change their communities is by altering herbivore and pathogen dynamics. Because non-native species allocate little energy to defensive traits, such as leaf toughness, and instead maximize their growth rates and nutrient absorption, they may be more palatable to generalist herbivores. Increased contact rates with herbivores enhances the risk of acquiring herbivore-vectored diseases, and simultaneously subjects exposed and damaged tissue to fungal infection. I measured leaf toughness as well as herbivore and pathogen damage on four grass species grown in monoculture at Mason Farm. I found that non-native grass species tend to have less tough leaves, and more herbivore and pathogen damage than native species. These results suggest that non-native plant species may cause indirect competition in their new communities by establishing new patterns of herbivore and pathogen interaction.

Isolation of Gene(s) Responsible for Binding of Agrobacterium tumefaciens to Plant Host Cells

Brittany Baffer

Research Advisor: Dr. Ann Matthysse

Agrobacterium tumefaciens causes crown gall tumor formation in plants. Tumor formation results from transfer of DNA from the bacterium to host cells. The initial step in tumor formation involves attachment of bacteria to the plant. Without the ability to bind tightly, the frequency of transformation dramatically decreases. Previously isolated non-binding mutants of A. tumefaciens do not affect molecules directly involved in attachment. Thus, identification of molecules involved in binding has not been possible using bacterial mutants. The failure to isolate this class of mutants is thought to be a result of genetic redundancy. To identify genes whose mutant phenotype may be masked by genetic redundancy, I have cloned genes from A. tumefaciens into a non-binding strain of Escherichia coli and selected for clones containing DNA segments that enable E. coli to bind to alfalfa sprouts.

Developing a Novel in vivo Technique to Identify Unknown Substrates of the E3 Ligase Rsp5

Rick Baker

Research Advisor:  Dr. Brian Kuhlman
Biology Sponsor: Dr. Robert Duronio
Research Mentor: Carrie Purbeck

The process of ubiquitination is observed in hundreds of cellular processes and is regulated by a cascade of protein classes, E1, E2, and E3.  This cascade results in a substrate protein being labeled with ubiquitin, thus determining its cellular fate.  E3 Ligases are responsible for substrate recognition and labeling with ubiquitin.  The yeast E3, Rsp5, has been studied extensively, but many of its substrates remain unknown.  With this is mind, the primary goal of my research is to use protein design to develop a novel in vivo technique to identify unknown substrates of Rsp5.  This technique could hopefully be used in future research to identify unknown substrates of other E3 Ligases such as E6AP, a human E3 which plays a vital role in Angelman Syndrome.

The Effect of a Mutation in the PPARγ Gene on the Induction of Adiponectin by Thiazolidinedione Drugs

Essraa Bayoumi

Research Advisor: Dr. Terry Combs
Biology Sponsor: Dr. Albert Harris

 

Insulin is a hormone with a vital role in glucose metabolism. Type-2 Diabetes, a disease which is characterized by a decreased response to insulin, is often treated with Thiazolidinediones (TZDs). TZDs work by binding to a receptor (PPARγ) in the nucleus of adipose tissue cells which causes an increase of adiponectin, a hormone secreted exclusively by fat cells. In conjunction with the increase of adiponectin, glucose levels and insulin resistance are decreased. Presently, I am comparing wild-type mice to mice that have a defect in the PPARγ gene to study the role of PPARγ on the induction of adiponectin. Furthermore, I am looking at two different strains of mice to determine whether genetic differences play a role in the stimulation of adiponectin. Understanding the mechanism by which adiponectin levels are regulated will give more insight into the cause of Type-2 Diabetes and aid in the development of more effective treatment.

The Effect of Mitotic Spindle Tension on Histone Protein Turnover in Saccharomyces cerevisiae

Lisa Bond

Research Advisor: Dr. Elaine Yeh

During cell division, duplicated chromosomes are anchored to either side of the dividing cell by structural units called microtubules.  Histone proteins bind and coil these chromosomes into more compact structures.  Those histone proteins bound to the chromosomal regions attached to microtubules (pericentric regions) are exposed to the tensile forces of microtubule contractions.  This study used the budding yeast Saccharomyces cerevisiae to address the hypothesis that tension reduces the background rate of histone movement in a cell (turnover rate).  The turnover rate of pericentric histones was compared to that of histone proteins bound to tension-free chromosomal arms.  Furthermore, wild-type histone turnover was compared to turnover in tension-free cells.  For these experiments, the microscopic method of fluorescence recovery after photobleaching (FRAP) was used to determine the turnover rate of a histone subunit tagged with green fluorescent protein.  The results of this study illuminate the potential role of tension in cell death caused by histone malfunction.

Tactile Perception in Older Adults

Alice Broadhead

Research Advisor: Dr. Mark Tommerdahl
Biology Sponsor: Dr. Alan Weakley

 

Investigation of sensory perception in humans has been complicated by factors such limitations in spatial resolution of available brain imaging techniques. One way to bypass these difficulties is to have subjects report information regarding their perception of stimuli. I have taken this approach in studying the tactile perception in the elderly by means of a non-painful, non-invasive stimulator. The stimulator consists of two blunt probe tips attached to motors controlled by the use of computer software.  The software then records quantitative data regarding subjects’ reported perception of vibrations and taps administered by the stimulator.  Predictions from animal models as well as current understanding of human cortical processing will be used to interpret the data gathered. This research should contribute to a better understanding of cortical connectivity and plasticity in regions of the elderly brain pertinent to perception of tactile stimuli.

The Role of Palladin in Early Vertebrate Vasculogenesis

Jessica Carter

Research Advisor: Dr. Carol Otey
Biology Sponsor: Dr. Mark Peifer

 

The actin cytoskeleton is vital to cell physiology. Palladin is an actin-associated protein with a critical role in cell morphology and motility. To explore its role in embryonic development, a palladin-null mouse line was previously developed. This mutant displayed multiple defects, including failure of the neural tube to close anteriorly, a pronounced facial cleft, and embryonic lethality by day E13.  Still, the cause of lethality is unknown. I hypothesize that palladin is necessary for proper early embryonic vascular development in vertebrates. The association of palladin with actin-based structures in many types of cultured cells suggests that it may be required for the normal assembly of cell-cell junctions in the heart and blood vessels. To test this, I will perform whole-mount embryo staining of palladin-null mouse embryos.  In addition, I will knock down palladin expression in the zebrafish D. rerio to determine if palladin’s role is conserved in embryonic vasculogenesis.

The Role of Nitric Oxide in Catechol-O-methyltransferase-dependent Pain Sensitivity

Matt Conrad

Research Advisor: Dr. Andrea Neely
Biology Sponsor: Dr. Shawn Ahmed

 

Temporomandibular joint disorder (TMD) is a common persistent pain condition. Recently, our group demonstrated that TMD onset and heightened pain sensitivity are associated with genetic variants of catechol-O-methyltransferase (COMT) that exhibit low enzymatic activity. Depressed COMT activity results in elevated levels of catecholamines, which stimulate β₂/β₃-adrenergic receptors to produce pro-inflammatory cytokines.  These cytokines stimulate nitric oxide synthases to produce nitric oxide.  Nitric oxide likely drives persistent pain conditions by inactivating the COMT enzyme and/or causing oxidative stress reactions.   Thus, the purpose of the present study is to evaluate the role of nitric oxide in COMT-dependent pain sensitivity.  We will measure nitric oxide expression levels in rats receiving a COMT inhibitor alone or together with nitric oxide synthase inhibitors. We hypothesize that nitric oxide levels will be elevated in animals displaying increased COMT-dependent pain sensitivity and that blocking nitric oxide production will prevent the development of pain.

Screen for Residues that Regulate Nucleotide Exchange in G Proteins

Jeff Duffy

Research Advisors: Dr. Alan Jones & Dr. Henrik Dohlman
Research Mentor: Dr. Jan Jones

 

Responding to the extracellular environment is fundamentally critical to all biological processes.  G protein coupled receptors (GPCRs) participate in this process by connecting extracellular cues to intracellular downstream effectors.  G proteins are one of the largest and most ubiquitous groups of membrane bound receptors and respond to a variety of signals including: drugs, light, odor, taste, hormones, and neurotransmitters. G protein signaling is activated when the receptor responds to a ligand and causes a conformational change in Gα allowing GDP to be released and replaced by the higher concentration of GTP.  The plant Arabidopsis thaliana G protein is unique and releases nucleotides spontaneously without receptor activation. In an effort to discover how the Arabidopsis Gα protein maintains fast nucleotide exchange without loss of stability I am employing a high throughput screen for mutations in the Arabidopsis Gα gene that correspond to residues that regulate nucleotide exchange in Gα proteins.

A Comparison of the Environmental Condition of Three Distinct Sites of Pokeberry Creek

Katherine Evans

Research Advisor: Dr. Seth Reice
Research Mentor: Christy Violin

 

By understanding the makeup of a biotic community within an environment that is constantly changing in the face of human and natural impact, it is possible to estimate the condition of the environment.  Benthic macroinvertebrates present in a stream are principle players in the decomposition of dead organic matter by breaking the material down through shredding and feeding activities.  The rate of decomposition of dead organic matter can reflect the amount of organisms present. After identifying these organisms, the biodiversity can then be analyzed to estimate the health of a stream.  I am studying three unique sites of Pokeberry Creek in Chatham County, NC.  The biodiversity of the stream is likely to have been affected by nearby construction and a severe drought.  By determining rates of leaf decomposition, I can estimate and compare the condition of the sites and make assessments about the impacts of construction and drought.

The Role of SOX9 in Cell Lineage Specification in the Mouse Small Intestine Epithelium

Eric Formeister

Research Advisor: Dr. Scott T. Magness
Biology Sponsor: Dr. Steve Rogers

 

The small intestine epithelium (SIE) has one of the fastest regeneration and growth rates of any tissue.  Though this suggests the existence of an intestinal stem cell (ISC), this cell has not yet been defined because of the lack of a specific ISC biomarker.  The Magness Laboratory has implicated the transcription factor SOX9 as a potential ISC biomarker.  We have demonstrated differential levels (high and low) and restricted expression of SOX9 in the putative location of the ISC.  High SOX9 expression identifies differentiated enteroendocrine cells in the SIE whereas low SOX9 expression marks proliferative stem/progenitor cells.  These data suggest that a threshold level of SOX9 is important in committing a stem/progenitor cell to an endocrine fate.  To test this hypothesis, I aim to over-express SOX9 in an ISC line and hope to fate-specify cells to an enteroendocrine lineage.  This research will provide further insight into the control of SIE proliferation, maintenance and repair in normal, diseased and cancerous states.

Characterization of Epidermal Growth Factor Receptor Independent Colorectal Tumors in the Apc^min Mouse Model

Richard Frye

Research Advisor: Dr. David Threadgill
Biology Sponsor: Dr. Kelly Hogan
Research Mentor: Ming Yu

 

The Epidermal Growth Factor Receptor (EGFR), responsible for growth and proliferation, has been implicated in colorectal cancer.  Drugs that target EGFR have been developed and, while exhibiting promising preclinical results, have been ineffective in large-scale clinical trials.  Previous data have shown that colorectal tumors still develop in conditional EGFR knockout models.  This suggests that these tumors exploit a pathway independent of EGFR activity.  If these EGFR-independent tumors are present in wild-type tumor populations (represented by the Adenomatous Polyposis Coli Multiple Intestinal Neoplasia (APC^min) model), characterization of the EGFR-independent pathway could provide new therapeutic targets.  Determining whether this subset exists in wild-type tumor populations is a first step toward developing more effective therapeutic strategies.  To investigate the genetic and molecular differences between EGFR-independent and APC^min tumor populations, genetic targets were assayed using quantitative PCR to investigate ligand distribution and molecular targets were assayed using immunohistochemistry to investigate apoptotic activity.

Presentation of Smith Antigen to B Cells by Dendritic Cells and Macrophages in Mus musculus

Chris Hilliard

Research Advisor: Dr. Barbara Vilen
Biology Sponsor: Dr. Gregory Copenhaver
Research Mentor: Diane Carnathan

 

The autoimmune disease systemic lupus erythematosus is characterized by the unregulated secretion of autoantibodies by immune cells.  Prior research indicates that chronic exposure to antigen, we believe Smith (Sm) antigen, is required to suppress this secretion. My research focuses on identifying the particular receptor on dendritic cells (DCs) or macrophages that is responsible for presenting Sm. I apply a fluorescent antibody specific for Sm to DCs derived from the bone marrow of mice with various receptor genes knocked out and then examine the DCs with confocal light microscopy. In doing so, I can determine if the receptor in the knock-out mouse is the receptor that binds to and presents Sm. The results of this research will help to describe the molecular basis for secretion dysregulation of immune cells in individuals with lupus..

Expression of the Xenopus Transcription Factor Tbx20 in Early Neurogenesis

Elizabeth Jarvis

Research Advisor: Dr. Frank Conlon
Research Mentor: Dr. Elizabeth Mandel

 

Vertebrate development involves a complex series of events that are highly regulated at the molecular and cellular levels, and determining the signal transduction pathways that regulate gene expression is essential to understanding proper development.  Tbx20, a member of the T-box transcription factor family, is expressed throughout development in several tissues and cell types where it functions as a regulator of embryonic patterning and organogenesis. Since Tbx20 is necessary for nervous system development, it is important to understand how Tbx20 expression is controlled in neuronal cells. My project investigates the regulation of Tbx20 expression in Xenopus, the African clawed frog. Using a transgenic approach, I have identified two DNA sequence elements that are sufficient to drive Tbx20 expression in the developing nervous system. My goal is to reveal the molecular pathways of Tbx20 expression in neural development, thereby gaining a better understanding of the role of Tbx20 in mechanisms of human development and disease.

Characterization of Sox4 as an Intestinal Stem Cell Marker

David Lorance

Research Advisor: Dr. Scott Magness
Biology Sponsor: Dr. Frank Conlon

 

Stem cells have been identified in many tissues, including the brain, bone marrow, liver and skin; however, stem cells have not been identified or defined in the intestine due to the lack of specific cell markers. Yet, the intestinal epithelium is a remarkably proliferative tissue, engaging in entire cell turnover every 3-5 days. This suggests the existence of a stem cell pool in the intestine. Recently, stem/progenitor cells in the retina have been marked by the SRY-related HMG-box (SOX) family of transcription factors. Further, preliminary experiments have localized expression of one of these transcription factors, Sox4, to a putative stem cell niche in the intestine. Thus, the protein Sox4 may mark stem/progenitor cell populations in the intestine. To test this, a dual Sox4 cyan fluorescent protein (CFP) reporter and Cre recombinase lineage marking transgenic mouse is being generated. This “knock-in” mouse model stands to identify and define Sox4-expressing cells.

Conditions Affecting α-Synuclein Aggregation and its Implications in Parkinson’s Disease

Evan Lutz

Research Advisor: Dr. Gary Pielak
Biology Sponsor: Dr. Jason Reed
Research Mentor: Rebecca Ruf

 

Affecting over a million people in the United States, Parkinson’s disease is a degenerative disorder that impairs motor skills and speech.  Parkinson’s disease is characterized by the presence of Lewy bodies, which contain large amounts of the protein α-synuclein, in dopamine producing neurons of the midbrain.  Much of this sequestered protein is in fibrils, a non-covalent aggregate of monomer α-synuclein.  I am currently studying the ability of mechanical agitation to cause fibril degradation as well as the ability of oxidizing agents to stabilize aggregates by forming covalent cross-links at exposed tyrosine residues.  My research aims to determine intracellular conditions that could affect the progression and stability of α-synuclein and will potentially shed light on the structure and conformation of α-synuclein during its aggregation pathway.  These results could potentially lead to a better understanding of the change in intracellular conditions during the progression of Parkinson's disease.

Gene Order Polymorphisms in Yeast

Biff Mann

Research Advisor: Dr. Jason Lieb

 

DNA polymorphisms across populations are well-documented, as are the molecular events of point mutations and changes in gene copy number.  However, the transposition of genes from one chromosomal location to another is poorly understood.  The scope of this project is to analyze gene expression patterns across transposed regions of the yeast genome.  We combined two microarray-based techniques to develop a high-throughput method of identifying and locating transpositions in yeast.  The experiments were performed on genomic DNA resulting from a cross between two strains of yeast: one very similar to the sequenced strain, the other known to have many transpositions in its genome.  Additionally, I am conducting other experiments on gene expression in the nematode C. elegans.

Using Existing Alleles of the Canoe Protein to Begin a Structure-Function Study in Drosophila melangaster

Doug Meardon

Research Advisor: Dr. Mark Peifer
Research Mentor: Jessica Sawyer

 

During embryonic development, morphological changes like organ development require strong cell-to-cell adhesion.  For mechanical strength, cells adhere at cellular junctions connected to the cytoskeleton; one such type is the adherens junction (AJ).  Recently, the Echnoid-Canoe protein complex has been proposed as a secondary system of adhesion at AJs.  Canoe is the intercellular protein, which is proposed to interact with actin, a cytoskeletal molecule.  Using seven mutant alleles of canoe, I am looking at Canoe’s role in embryonic development in Drosophila melanogaster (fruit fly).  After I have characterized the morphological defects of the alleles, I want to determine the molecular basis of the phenotypic differences between the alleles through sequencing and western blots. While Canoe has been shown to be important during development in Drosophila, the human homolog of Canoe, Afadin (Af-6), has been implicated in acute leukemia.  By relating its structure to its function, I hope to further elucidate Canoe’s role during development.

The Role of Bub1 Loss in Transformation

Jordan Morreall

Research Advisor: Dr. Terry Van Dyke
Biology Sponsor: Dr. Bob Duronio
Research Mentor: Mark Schliekelman

 

One of the most common developments during tumorigenesis is aneuploidy.  Aneuploidy is abnormal chromosome number, which can arise from the failure of the spindle checkpoint.  The spindle checkpoint arrests mitosis at metaphase if the chromosomes are not aligned properly at the metaphase plate.  One gene involved in activating the spindle checkpoint is Bub1, of which an inducible mutation has been generated.  Using this mutation, this work investigates the degree to which Bub1 loss affects the rate of oncogenic transformation in vitro. Transformation assays were conducted on wild-type, Bub1-heterozygous, and Bub1-homozygous mouse embryonic fibroblast (MEF) cultures.  These assays used lipid transfection systems, and continue now with retroviral transfection.  The conclusive results of these assays will improve the understanding of Bub1’s significance in tumorigenesis.  More broadly, the results will show how such oncogenes can promote uncontrolled growth, and depending on the number of functional alleles at work, possibly inhibit growth as well.

The Effects of Mating System and Meiotic Drive on Linkage Disequilibrium in the Mimulus guttatus Species Complex

Bimal Patel

Research Advisor: Dr. Todd Vision
Research Mentor: Dr. Amy Bouck
Undergraduate Collaborator: Lindsay Bridges

 

An important descriptor of natural genetic variation is the extent of nonrandom association between alleles in a population, or Linkage Disequilibrium (LD). The extent of LD is governed by the rate at which recombination breaks up such associations, which can in turn be affected by a number of factors, including the mating system and the presence of segregation distortion.  In this study, I am measuring the extent of LD in two closely related species of monkeyflower: the outcrossing Mimulus guttatus and the selfing M. nasutus. I am testing whether LD extends over longer distances in the selfing species, and whether LD is elevated in the region of a locus that is known to undergo strong segregation distortion in crosses between the two species. Understanding the level of LD and the factors that influence it will facilitate the genetic mapping of complex traits in these species.

The Effects of Nerve Growth Factor on the Reactivity of Dorsal Root Ganglion Cells to Endogenous Neurotransmitters

Gabriel Pollock

Research Advisor: Dr. Edward Perl
Biology Sponsor: Dr. Ted Salmon
Research Mentor: Lindsay Rhodes

 

The perception of pain is mediated by sensory neurons known as nociceptors and is normally a reaction to tissue injury. However, cases of highly exaggerated levels of pain exist in a phenomenon known as hyperalgesia. Pain is regulated by the type and concentration of molecular receptors that are expressed in sensory neurons. Change in the expression of these molecular receptors is an established means of controlling the reactivity of cells, and it is hypothesized that such a change is connected to this pathological pain. It has been shown that both local and systemic application of Nerve Growth Factor (NGF) is sufficient to induce cases of hyperalgesia. The goal of this research is to show the effects that NGF has on the reactivity of sensory neurons to neurotransmitters through electrophysiological testing. By better classifying the mechanism by which hyperalgesia is induced, this project will provide insight into how the body regulates pain..

Characterization of a Novel Putative Methyltransferase that is Enriched on the Inactive X-Chromosome

Sonya Purushothaman

Research Advisor: Dr. Terry Magnuson
Biology Sponsor: Dr. Frank Conlon
Research Mentor: Dr. Sundeep Kalantry

 

X-chromosome inactivation (XCI) is the transcriptional silencing of most of the genes on one of the two X-chromosomes in cells of female mammals, and is necessary to achieve dosage compensation of X-linked genes between males and females.  The study of this phenomenon provides unique insight into epigenetics—reversible chromatin modifications which are stably inherited through cell division.  Upon immunoflourescence staining of trophectoderm stem cells (TS), we discovered that an antibody (1822) raised against the Cdx2 protein (a transcription factor) detects the inactive-X, despite the fact that Cdx2 has not been implicated in XCI.  Based on genetic, molecular, and bioinformatic analyses, we hypothesize that the 1822 antibody is detecting a novel protein that possesses methyltransferase activity, and is necessary for proper XCI.  By discovering this protein and its relation to XCI, we hope to better understand the epigenetic mechanisms that control gene expression and cellular transcriptional memory.

Anti-tumor Activity of MerTK-deficient Mice

Will Rearick

Research Advisor: Dr. Rebecca Cook
Biology Sponsor: Dr. Stephen Rogers

 

Receptor tyrosine kinases are cell membrane receptors that regulate many cellular processes and have been implicated in a variety of cancers. One such kinase, MerTK, is widely expressed in mice and humans, but its function in many tissues remains unclear. We have observed that MerTK-knockout mice are resistant to the formation of several tumor types. I am investigating this immune-mediated anti-tumor response, specifically in lympocytes known to express MerTK. I will be inoculating wild-type and MerTK-deficient mice with tumor cells and comparing the quantity of macrophages, dendritic cells, and cytotoxic T-lymphocytes at the injection sites. I am also quantifying various markers to characterize the type of response by each cell type, hoping to identify the cell type or types responsible for the tumor resistant phenotype. A better understanding of this mechanism may allow MerTK inhibition to become a viable strategy for treatment of cancer patients.

Induction of Cellulose Synthesis by Agrobacterium tumefaciens

Emily Roberts

Research Advisor: Dr. Ann Matthysse

 

Agrobacterium tumefaciens induces crown gall disease in dicotyledonous plants by transferring a segment of DNA from the tumor-inducing (Ti) plasmid to the plant. Key elements of this pathogen-host interaction include A. tumefaciens’ attachment to a plant and the induction of virulence (vir) genes located on the Ti plasmid. Binding becomes permanent once the bacteria initiate cellulose synthesis, which is known to be induced by malate, pectin or soytone. The vir genes are induced by plant-released phenolic compounds and their expression is increased by sugars such as arabinose. The A. tumefaciens gene Atu3104 encodes an α-L arabinofuranosidase, which may release arabinose from the plant cell wall. Immediately downstream, Atu3103 encodes an ABC transporter homologous to an E. coli arabinose transporter. Using genetic and molecular approaches, we are characterizing the role(s) of these genes in the overall signaling pathway that leads to the production of cellulose, resulting in permanent binding and virulence.

The Use of Four Elephant Corridors by Wild and Domestic Animals in Mudumalai Wildlife Sanctuary

Nitin Sekar

Research Advisors: Dr. Raman Sukumar, Dr. R. Haven Wiley, Dr. Jack Weiss, & Dr. Peter White

 

Large animals, such as the Asian elephant, typically require large, uninterrupted areas to provide for their basic needs. Due to habitat destruction by humans in the last centuries, much of the Asian elephant’s habitat has been cut up into fragments too small for viable populations of elephants. As a result, conservationists have begun reconnecting these patches with “wildlife corridors,” thin strips of habitat that allow animals to move between habitat patches without encountering human settlements, giving them the access to resources they need to survive. Near Masinagudi village in Mudumalai Wildlife Sanctuary, India, there are four such corridors. However, local farmers are allowed to graze their animals and collect firewood in the corridors. Using line-transect dung counts and signs of firewood collection, my research examines which animals are using the corridors and whether greater use of the corridors by humans and domestic animals correlates with reduced use by wild animals.

Menstrual Cycle Regulation of Anabolizing and Metabolizing Enzymes of Endocannabinoids in Human Endometrium

Caitlin Shaw

Research Advisor: Dr. Steven Young
Biology Sponsor: Dr. Sarah Liljegren
Research Mentor: Elizabeth Deans

 

Endogenous cannabinoids (endocannabinoids) are unsaturated fatty acids which can activate the same G-protein linked receptors that bind the psychoactive components of marijuana. Previous animal studies have demonstrated the important role of endocannabinoids in embryo implantation. Two major endocannabinoids are present in mouse endometrium, and the expression of the enzymes responsible for their synthesis and degradation is highly regulated by the mouse estrous cycle. However, very little is known about the regulation or role of endocannabinoids in human endometrium. Preliminary research has identified all the major endocannabinoid anabolizing and metabolizing enzymes in the human endometrium. Using Real-Time PCR and immunohistochemistry staining methods of human endometrial tissue, I will examine menstrual cycle-dependent changes in expression of the enzymes required for the synthesis and breakdown of endocannabinoids.  This study will hopefully lead to a better understanding of possible causes of infertility in women.

Prothoracicotropic Hormone: A Role in the Adult Insect

Chelsea Snyder

Research Advisor: Dr. Lawrence Gilbert
Research Mentor: Dr. Robert Rybczynski

 

The development of insects is controlled by a unique endocrine system. The tobacco hornworm, Manduca sexta, has provided much insight on the functioning of this novel system. In this insect, prothoracicotropic hormone (PTTH), a brain hormone, stimulates the prothoracic glands to secrete ecdysone. Ecdysone, the “molting hormone”, controls insect metamorphosis through a series of molts until maturity. In the mid-pupal stage, the prothoracic glands undergo programmed cell death because ecdysone is not needed for molting in adulthood. However, a pilot study suggested that PTTH is found in the brains of adult and near-adult Manduca sexta. The question then is: does PTTH have a new, undefined role in the adult insect, or is it merely leftover from earlier stages? In vitro experiments exploring this question have shown that PTTH present during adult life is functional in stimulating larval prothoracic glands to secrete ecdysone and that PTTH may have a role in insect reproduction by changing protein synthesis and activity.

Cell Cycle-Controlled Degradation of E2F1 in Drosophila Imaginal Discs

William Jackson Turbyfill III

Research Advisor: Dr. Bob Duronio
Research Mentor: Shusaku Shibutani

 

Progression of the cell cycle is controlled and regulated through the interaction of a collection of proteins.  E2F1 is a transcription factor that induces expression of genes involved in DNA synthesis. Previous studies have shown that E2F1 is destroyed during S-Phase in Drosophila, and we hypothesize that this is an important mechanism for regulating E2F1 activity during the cell cycle. Our preliminary data suggests that this S-phase-specific destruction of E2F1 is mediated by a Cullin 4-based E3 ubiquitin ligase complex.  This observation was made with cultured cells, and I am testing whether the Cul4 E3 ligase is responsible for E2F1 destruction in vivo.  I will analyze mutant clones of Cul4 and its adaptor DDB1 in Drosophila as well as an E2F1 mutant that contains a mutation that prevents binding to the Cul4 ligase. These experiments should expound upon the mechanism of E2F1 destruction and whether this is important for cell cycle progression in vivo.

Genetic Cloning of aik1aik2 Suppressors

Michael Westafer

Research Advisor: Dr. Joseph Kieber
Research Mentor: Shouling Xu

 

Directional expansion is responsible for the development and, ultimately, the morphology of individual plant organs.  In normal roots, cells divide at the apical root meristem and elongate before differentiating, causing the long shape of the root.  Elongation of cells has been linked to the pattern of cellulose microfibrils, which are wrapped in a spiral around the cell, preventing lateral expansion.  Two genes, AIK1 and AIK2, have been previously identified which, when both mutated, disrupt anisotropic cell elongation of roots in Arabidopsis thaliana, resulting in swollen roots as the individual cells expand radially.  Point mutations in two genes suppress the aik1aik2 swollen phenotype, thereby restoring anisotropic growth.  The goal of my research is to clone these suppressor genes. Discovering genes involved in regulating this morphology will aid in further understanding of anisotropic growth in the AIK regulated pathway as well as plant morphology in general.

Analysis of TGF-β1 Receptors as Potential Genetic Modifiers of Cystic Fibrosis Lung Disease

Kiri Wiggins

Research Advisor: Dr. Michael Knowles
Biology Sponsor: Dr. Corbin Jones
Research Mentor: Rhonda Pace

 

Cystic fibrosis (CF) is a recessive genetic disorder, most often caused by the ΔF508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which results in a single amino acid deletion.  Patients homozygous for this mutation display great phenotypic variation in CF lung disease severity.  Our goal is to study potential genetic modifiers of CF, or genes that do not cause CF but may influence disease phenotypes.  TGFβ1, the gene encoding the protein transforming growth factor β1 (TGF-β1), is a genetic modifier of CF lung disease.  My project, therefore, focuses on two receptors for TGF-β1 to determine whether an association exists between genotypes at single nucleotide polymorphisms (SNPs) within these genes and the severity of CF lung disease.