Biology Commons^™

Methylation Patterns Across Tissue Type And Time In Peromyscus Leucopus: A Targeted Museum Study, Loryn Smith

Master's Theses

Museum specimens are a vital data source for many types of studies. One relatively new use includes studying methylation patterns. Methylation patterns are a form of epigenetics or how gene expression changes without alteration of the genetic code. These patterns have been examined in many mammals. However, the focus has previously been on overall epigenetic patterns. Few studies have investigated whether methylation patterns differ across tissue types, time, or preservation method. In this study, I compared methylation patterns in muscle, liver, toe pads, and nasal bones from Peromyscus leucopus (white-footed mouse) museum specimens collected in 2022, 2018, 2014, and 2008 …

Population Genetics Of Cownose Rays, Rhinoptera Spp. In The Western Atlantic, Helen Weber

Master's Theses

Using molecular tools (e.g., the NADH subunit II mitochondrial gene), this study was the first to document the Brazilian cownose ray, Rhinoptera brasiliensis, within the northwestern Atlantic (NWA), and was the first study to examine population structure in R. brasiliensis within the NWA or northern Gulf of Mexico (GMX), revealing novel insights into the population biology of the animal and extending its range by nearly 1,500 km. This study also examined the sympatrically occurring American cownose ray, R. bonasus, and found population structure between the NWA and the GMX and the NWA and the southwestern Atlantic (SWA). High …

Assessment Of Genetic Diversity In Largetooth Sawfish, Pristis Pristis, Populations Over The 20th Century, Ann Fearing

Master's Theses

The Critically Endangered Largetooth Sawfish, Pristis pristis, experienced global declines in range and abundance over the past century and Australia is now their last stronghold. This research aimed to understand whether these declines have been accompanied by a reduction in levels of genetic diversity. Using P. pristis tissue samples sourced from natural history specimens, three fragments (616-bp, 386-bp, 141-bp) in the mitochondrial DNA (mtDNA) control region were PCR-amplified. At each fragment, significant genetic structure was found in P. pristis overall (Φ_ST=0.946, N=9; 0.813, N=54; 0.771, N=99). The Indo-West Pacific and Atlantic/Eastern Pacific each harbor genetically distinct lineages of …

Using Crispr-Cas9 As A Restriction Enzyme, Zack Crawley

Master's Theses

Restriction digests are a commonly utilized process for cleaving DNA at specific, but relatively common sites. Restriction enzymes have widespread use in DNA manipulation. CRISPR/Cas9 is a recently identified endonuclease which utilizes a customizable guide sequence to recognize and cut specific ~20 bp sites located in a DNA sequence. This preliminary research aimed to exploit the potential benefit of DNA restriction using the CRISPR/Cas9 procedure through alterations of different components involved in that system. We sought to refine existing CRISPR/Cas9 protocols and make a budget friendly, user-selectable CRISPR/Cas9 restriction digest protocol. The motivation for this research was to simplify and …

The Role Of Orphan Nuclear Receptor Dax-1 (Nr0b1) In Human Breast Cancer Cells: Expression, Proliferation And Metastasis, Erin Dishington

Master's Theses

The orphan nuclear hormone receptor DAX-1 (Dosage Sensitive Sex Reversal, Adrenal Hypoplasia Congenita on the X Chromosome, gene 1) plays an important role in the development of adrenal and gonadal tissues and functions as a global negative-regulator of steroidogenesis. In addition, it is known to be involved in several diseases including some cancers. Herein, we describe our examination of the role of DAX-1 in breast cancer, specifically its influence on proliferation and metastasis and its expression during progressive stages of disease. In an effort to understand how DAX-1 influences breast cancer cell proliferation and metastasis, we used MCF7 breast cancer …

The Population Genetics Of Morro Bay Eelgrass (Zostera Marina), Julia Gardner Harencar

Master's Theses

Seagrass populations are in decline worldwide. Zostera marina (eelgrass), one of California’s native seagrasses, is no exception to this trend. In the last 8 years, Morro Bay, California has lost 95% of its eelgrass. Eelgrass is an ecosystem engineer, providing important ecosystem services such as sediment stabilization, nutrient cycling, and nursery habitats for fish. The failure of recent restoration efforts necessitates a better understanding of the causes of eelgrass decline in this estuary. Previous research on eelgrass in California has demonstrated a link between population genetic diversity and eelgrass bed health, ecosystem functioning, and resilience to disturbance and extreme climatic …

The Conservation Genetics Of Two Emydid Turtles: Emydoidea Blandingii And Malaclemys Terrapin, Charlotte Lizana Petre

Master's Theses

Conservation of turtles is complicated by their sensitivity to habitat degradation and overexploitation. I used microsatellites and standard population genetic analyses to explore genetic diversity, population structure, paternity and demographic history in two emydid turtles that are currently experiencing threats to their survival. The Blanding’s turtle, Emydoidea blandingii, has experienced habitat fragmentation throughout its range, and this study focuses on a population in Massachusetts where hatchlings from one population are being translocated to establish a new population. I found evidence of multiple paternity within clutches and found no significant reduction in genetic diversity when comparing the source population and …

Determining Parentage And The Effects Of Relatedness On Play Partner Preference In Belding's Ground Squirrels, Jessica Weidenbach

Master's Theses

I investigated 1) multiple paternity in Belding’s ground squirrels (Urocitellus beldingi) and 2) social partner preferences in juvenile U. beldingi. Prior work with blood allozymes demonstrated multiple paternity in U. beldingi litters. I evaluated paternity using microsatellite DNA analysis, which is more accurate than examining blood allozymes. My results indicate that multiple paternity in U. beldingi is more extensive than previously shown, occurring in about 90% of litters with more than one juvenile, and averaging 2.95 fathers in multiply sired litters. I also evaluated the hypothesis that play and other social behavior promotes bonding among juvenile female …

Investigating The Roles Of Ndj1 And Tid1 In Crossover Assurance In Saccharomyces Cerevisiae, Rianna Knowles

Master's Theses

Meiosis is the specialized process of cell division utilized during gametogenesis in all sexually reproducing eukaryotes, which consists of one round of DNA replication followed by two rounds of chromosome segregation and results in four haploid cells. Crossovers between homologous chromosomes promote proper alignment and segregation of chromosomes during meiosis.

Crossover interference is a genetic phenomenon in which crossovers are non-randomly placed along chromosomes. Crossover assurance ensures that every homologous chromosome pair obtains at least one crossover during Prophase I. Crossovers physically connect homologous pairs, allowing spindle fibers to attach and separate homologs properly. However, some organisms have shown an …

Investigating The Roles Of Ndj1 And Tid1 In Distributive Segregation Using Non-Exchange Chromosomes, Jonathan V. Henzel

Master's Theses

Meiosis is a specialized cell division that leads to a reduction of ploidy in sexually reproducing organisms through segregation of homologous chromosomes at the first meiotic division. Improper segregation of chromosomes during meiosis results in anueploidy, which is usually fatal during embryonic development. The meiotic process is therefore tightly regulated. Typically, proper segregation of homologs at meiosis I requires pairing of homologous chromosomes, followed by crossover recombination between homologs. Crossovers enable proper chromosomal segregation during the first meiotic division in part by establishing tension in the meiotic spindle. However, in the absence of crossovers, some cells maintain the ability to …