The Effects of Centromeric Attachment on Kinetochore Structure in the Yeast Saccharomyces cerevisiae

Marybeth Anderson

Research Advisor:  Dr. Elaine Yeh

During cellular division, chromosomes are segregated according to their attachment to the plus-end of microtubules via a protein complex known as the kinetochore. Malfunction of the kinetochore complex leads to cellular death and various diseases resulting from aneuploidy, such as Down’s syndrome.  In the model organism, Saccharomyces cerevisiae, the kinetochore is made up of a number of distinct protein complexes; however, the full extent of the interactions between the major components is currently unknown.  Using temperature sensitive alleles and fluorescence microscopy, I am currently examining the effects of disrupting the centromeric and microtubule attachments of the kinetochore.  Results from this study will provide insight into the interdependencies of the main components of the kinetochore.

The Effects of Various Population Characteristics on Linkage Disequilibrium in
Mimulus guttatus and M. nasutus

Lindsay Bridges

Research Advisor: Dr. Todd Vision
Research Mentor: Dr. Amy Bouck
Undergraduate Colleague: Bimal Patel
 

Linkage disequilibrium (LD) is the nonrandom association of alleles at different loci.  Theoretically, evolutionary forces such as mutation, recombination, and selection, as well as demographic factors such as mating system and population structure are expected to impact the extent of LD.   My project examines LD in different populations of Mimulus guttatus and M. nasutus, which are two closely-related species of monkeyflower with differing mating systems.  By studying the patterns of LD in natural populations of these two species, I can test several theoretical predictions.  Specifically, I hypothesize (1) that LD will be greater in selfing M. nasutus than the outcrosser M. guttatus, (2) that LD will increase as more geographically widespread samples are collected, and (3)  that LD will differ among regions of the M. guttatus genome that have experienced differing regimes of natural selection.

Variation within a New Collection of Psilophyton forbesii

Karl Fetter

Research Advisor:  Dr. Patricia Gensel

Psilophyton forbesii is an Early to Middle Devonian vascular plant having a wide, ribbed and naked axis. In a new collection of fossils currently assigned to P. forbesi, there are several subtle differences which may lead to the amendment of the concept of P. forbesii or require a new taxon to be diagnosed entirely. In order to determine the taxon of fossils represented in the new collection, I am identifying new morphological characters for comparison with the accepted diagnoses of P. forbesii and other contemporaneous plants. The study aims to develop a better understanding of the taphonomy of early land plants and how those processes affect the interpretation of morphological characters.

Vegetation Dynamics of the Buck Creek Serpentine Barrens, Clay County, NC

Elizabeth Marx

Research Advisors: Dr. Robert Peet

Research Mentor: Lee Anne Jacobs

Serpentine vegetation is highly unusual, both due to vegetation structure and the presence of rare disjunct and endemic taxa. The open and well-drained conditions leave serpentine sites susceptible to more frequent fires and allow species more typical of open sites to thrive via low competition. The North Carolina Vegetation Survey initiated seven research plots at the Buck Creek serpentine barren in Clay County, NC in September of 1995. In April of that same year the US Forest Service began a prescribed fire management plan for the site. If the rare flora depend on both fire and soil chemistry, fire suppression may be reducing the success of the rare species associated with Buck Creek because the woody plants are becoming denser and shading out the rare plants. In order to test the interaction between fire and serpentine flora and thus assess the efficacy of the USFS fire management plan, six of the research plots were re-sampled. Sites that have been burned several times were compared with those that have had less fire. The soil and floristic data from the 1995 survey were compared with the more recent data.

Identification and analysis of Drosophila CNS midline cell cis-acting regulatory modules

James Oh

Research Advisors: Dr. Stephen T. Crews

Research Mentor: Dr. Joseph B. Kearney

Single-minded (sim), a transcription factor, is a master regulator of Drosophila central nervous system (CNS) midline cell development.  Sim is expressed in CNS midline cells throughout embryonic development and is required for proper midline cell differentiation.   Two putative target genes of Sim are Semaphorin-1b (Sema-1b) and vesicular glutamate transporter (VGlut).  These genes are expressed at different stages of midline cell development and understanding their transcriptional regulation may give insight into how sim functions during different phases of CNS midline cell development.  The goal of my project is to determine whether Sema-1b and VGlut are direct targets of Sim by isolating cis-regulatory modules (CRMs) of these genes and testing their transcriptional dependence on sim using transgenic and genetic methods.  Analysis of the midline CRMs will allow for the assembly of a more accurate model of how Sim and its co-activators regulate temporally-restricted transcription during multiple phases of CNS midline development.

Identification of Transcriptional Regulatory Elements in the Promoter of the Yes-Associated Protein (YAP) Gene

Robin Shah

Research Advisor: Dr. Sharon Milgram
Research Mentor: Stephen Gee/Dr. Elizabeth Morin-Kensicki
Research Sponsor: Dr. Vicki Bautch

Yes-associated protein (YAP) is a transcriptional co-activator that is critical for early embryonic development. However, little is known about how its expression is regulated. The promoter of the gene that encodes YAP lacks a traditional TATA or CAAT box, which usually controls the initiation of transcription. However, the region 150 bp upstream of the transcriptional start site is highly conserved across species and contains several putative binding sites for Sp1, a transcription factor known to activate transcription of TATA-less promoters. I have made several deletion constructs that affect the YAP promoter region and transfected them into fibroblast and epithelial cell cultures to determine the amount of activity from each construct. Studying the transcriptional regulatory elements will provide more insight into the regulation of YAP as well as knowledge about activators and repressors present in different cell types.

Development of a Novel Intra-Oral Drug Delivery Device for the Treatment of HIV/AIDS Associated Oral Infections

Garrett Stigall

Research Advisor: Dr. Sid Kalachandra
Research Sponsor: Dr. Steven Rogers
 

Oral infections, commonly the first manifestations of HIV/AIDS, are often persistent, developing rapidly, and do not respond to conventional treatment.  Our research aims to develop an intra-oral drug delivery mouth-guard made from a biocompatible copolymer called Ethylene Vinyl Acetate (EVA) that permits delivery of antimicrobial drugs directly to the site of infection.  Ideally, drugs are delivered by this device at a constant rate and are maintained at therapeutic levels over an extended period of time.  My research examines the kinetics of drug release and the corresponding factors that affect this release, as well as the physical properties of the respective drugs such as their solubility at body temperature and stability upon release from the EVA matrix.  This method eliminates the high dosages of current systemic treatment which can induce toxic effects and only serves as a short-term treatment.  We hope to apply this treatment method to other populations experiencing similar morbidity associated with oral infectious agents, often found in radiation treated oral cancer patients and other immunosuppressed individuals.