Life Sciences Commons^™

The Effect Of Protein Import On Membrane Potential, Ruth Hartke

Student Theses and Dissertations

Mitochondria are essential organelles often referred to as the “power plants” of eukaryotic cells. Energy conversion in mitochondria relies on oxidation of metabolite intermediates by protein components of the electron transport chain and establishment of an electrochemical gradient across the inner membrane. Some of the proteins involved are encoded by mitochondrial DNA, but the vast majority, over 98%, has to be imported from the cytosol. Protein import complexes form pores in the outer and inner membranes to mediate the process. However, opening of these pores would in theory jeopardize formation of the electrochemical gradient. In this study we examined this …

Comparative Population Genomics And Speciation Of Snakes Across The North American Deserts, Edward A. Myers

Dissertations, Theses, and Capstone Projects

Understanding the process of speciation is of central interest to evolutionary biologists. Speciation can be studied using a phylogeographic approach, by identifying regions that promote lineage divergence, addressing whether speciation has occurred with gene flow, and when extended to multiple taxa, addressing if the same patterns of speciation are shared across codistributed groups with different ecologies. Here I examine the comparative phylogeographic histories and population genomics of thirteen snake taxa that are widely distributed and co-occur across the arid southwest of North America. I first quantify the degree to which these species groups have a shared history of population divergence …

Computerized Classification Of Surface Spikes In Three-Dimensional Electron Microscopic Reconstructions Of Viruses, Younes Benkarroum

Dissertations, Theses, and Capstone Projects

The purpose of this research is to develop computer techniques for improved three-dimensional (3D) reconstruction of viruses from electron microscopic images of them and for the subsequent improved classification of the surface spikes in the resulting reconstruction. The broader impact of such work is the following.

Influenza is an infectious disease caused by rapidly-changing viruses that appear seasonally in the human population. New strains of influenza viruses appear every year, with the potential to cause a serious global pandemic. Two kinds of spikes – hemagglutinin (HA) and neuraminidase (NA) – decorate the surface of the virus particles and these proteins …

The Regulation Of The Phosphatidate Phosphatase Gene Pah1 And Its Regulatory Role On Cell Homeostasis, Goldie Libby Sherr

Dissertations, Theses, and Capstone Projects

The Saccharomyces cerevisiae gene, PAH1, encodes a phosphatidate (PA) phosphatase that plays a fundamental role in lipid metabolism. PA phosphatases are key enzymes that catalyze the PA dephosphorylation reaction to form diacylglycerides, the first step in the synthesis of triacylglycerols. Pah1p, one of the main PA phosphatases in yeast, has not only emerged as a key player in lipid biosynthetic pathways, but also acts as an important regulator of nuclear membrane biogenesis, the transcriptional regulation of many inositol-sensitive upstream activating sequence (UAS_INO)containing genes needed for phospholipid synthesis, vacuole homeostasis, and lipid droplet formation. Due to its …

Mechanisms Of Immune Activation And Suppression By Parasitic Wasps Of Drosophila, Johnny R. Ramroop

Dissertations, Theses, and Capstone Projects

Drosophila melanogaster has served as an excellent model organism to study the molecular processes of innate immunity. Flies essentially lack adaptive immunity and the innate immune system is often divided into the humoral and cellular responses (Lemaitre and Hoffmann 2007). The humoral arm involves the production of antimicrobial peptides, secreted from the fat body, to combat bacterial and fungal infections. The cellular response involves the production of hemocytes (blood cells: crystal cells, plasmatocytes, and lamellocytes) in the larval lymph gland, in the sessile pools, and in circulation (Gold and Bruckner 2014). Microbial pathogens are phagocytosed by plasmatocytes whereas larger parasites …

Effect Of Cntf Derived Peptide, P021 On Cognition And Pathology In 3xtg-Ad Mouse Model Of Alzheimer's Disease, Narjes Baazaoui

Dissertations, Theses, and Capstone Projects

Studies described in this thesis deal with the preventive effects of a neurogenic/neurotropic peptidergic compound, P021, on neurogenesis and synaptic deficits, neurodegeneration, cognitive impairment, and Ab and tau pathologies in a 3xTg-AD mouse model of Alzheimer’s disease (AD).

Background: AD is a chronic progressive neurodegenerative disease. Its multifactorial nature and the heterogeneity make its treatment especially challenging. Although it is a major burden in society, at present there is no drug that can stop or slow down the progression of the disease. Currently, the only available treatments are symptomatic and for mild to severe stages. The development of a drug …

Study Of Alternative Functions Of The Mitochondrial Protein Bak, Ma Su Su Aung

Student Theses and Dissertations

Research in the past 15 years has established roles for the pro-apoptotic proteins Bax and Bak in release of death signaling molecules from mitochondria. The process involves relocation of cytoplasmic Bax into the mitochondrial outer membrane to form a giant pore, MAC. Another MAC component, Bak, is constitutively present in the outer membrane regardless of apoptotic stimulation. In this study we investigated the role of Bak in mitochondrial function outside the context of apoptosis. We examined the effects of Bak elimination on emission of reactive oxygen species from mitochondria. Our results indicate a disturbance of free-radical production both in cultured …

Chamber-Specific Patterns Of Epicardium Formation In Zebrafish, Sana Khan

Dissertations, Theses, and Capstone Projects

The outer cardiac layer, the epicardium, coordinates the final steps of vertebrate heart development. This cardiac tissue arises from cells in the proepicardial organ (PEO) that forms around the base of the inflow tract. Its general location is conserved across species despite morphological differences. Cellular mechanisms of migration differ across species. Three strategies of PEO migration are described: 1) The floating cyst model - PEO cells released into the pericardial cavity are directed by fluid movements to migrate onto the myocardium; 2) Villi transfer - cardiac contractions may mediate multicellular PEO villi contact to the myocardium; and 3) Tissue bridge-mediated …

Role Of Bec-1/Beclin 1 And Autophagy Genes In C.Elegans Germline Cell Proliferation, Kristina Ames

Dissertations, Theses, and Capstone Projects

Autophagy is an evolutionary conserved process involved in the cellular adaptation to stress and basal levels of autophagy are crucial for cellular metabolism and homeostasis. Cellular recycling by autophagy is characterized by the formation of distinctive double-membrane vesicles (autophagosomes) that engulf unnecessary cytoplasmic components, such as organelles and long-lived proteins. Failure to remove protein aggregates and/or damaged organelles, via autophagy, has been implicated in various medical conditions such as liver disease, neurodegenerative diseases and cancer. Autophagy may suppress or promote cellular proliferation in tumors, depending on the type and metabolic state of the cell, where autophagy is generally believed to …

The Implications Of Chromatin Remodelers' Acetylation In Ino1 Activation, Michelle M. Esposito

Dissertations, Theses, and Capstone Projects

It is known that histone acetylases (HATs) regulate gene expression, but only recently have new functional implications about remodelers’ acetylation emerged. For instance, the HAT, Gcn5p, is capable of acetylating the catalytic subunit of the nucleosome remodeling complex SWI/SNF, Snf2p, which results in the dissociation of the complex from chromatin. The implications of this acetylation and subsequent dissociation have yet to be explored with regard to transcriptional regulation and other possible mechanisms. To further understand the implications of remodeler acetylation, I used a yeast model system examining the expression of the inositol-3-phosphate synthase gene INO1. Through chromatin immunoprecipitation (ChIP) …

When Human-Leopard Conflict Turns Deadly: A Cross-Country Situational Analysis, Julie S. Viollaz

Dissertations, Theses, and Capstone Projects

Habitat destruction and pollution are two of the main causes for the decline of the planet’s biodiversity. Yet environmentalists are now recognizing that illegal wildlife killings, both poaching and retaliatory killings due to human-wildlife conflict, are perhaps the next major threat. Biologists have researched illegal killings and their effect on species conservation, but few researchers have applied criminological principles of crime reduction to them. This research will explore the situational factors that drive retaliatory leopard killings in parts of South Africa, Kenya, and India. These factors, human and environmental, include local expectations from wildlife, sensitivity to environmental issues, communication between …

Revised Distributional Estimates For The Recently Discovered Olinguito (Bassaricyon Neblina), Using Museum And Science Records, Beth E. Gerstner

Dissertations and Theses

In the context of global change, a necessary first step for the conservation of species is gaining a good understanding of their distributional limits. This is especially important for biodiversity hotspots with high endemism such as the Northern Andes. The olinguito (Procyonidae: Bassaricyon neblina) is a recently described, medium-sized carnivoran found in Northern Andean cloud forests. A preliminary distributional model was published along with the original description, and I here provide revised distributional estimates using updated locality records and more current ENM methods. I build ecological niche models in Maxent using occurrence data (georeferenced museum records and citizen science-derived photo-vouchers) …

Synthetic Functionalized Scaffolds For Culture And Maintenance Of Primary Human Hepatocytes, Douglas Macpherson

Dissertations and Theses

There is deficit in the number of human livers that are available for transplantation. Additionally, there is no reliable model for the liver environment available for laboratory research. Tissue engineering provides alternatives for organ transplantation. We have created a supramolecular biomaterial out of simple peptide and saccharide building blocks to act as a hydrogel scaffold to support culture of liver cells. Using a self-­‐assembling peptide fiber decorated with functional molecules, we were able to culture primary human hepatocytes demonstrate their viability and maintenance of phenotype. The hydrogel material was formed by co-assembly in aqueous buffer and characterized using transmission electron …

"Molecular Analysis Of Virulence Factors Unique To Leptopilina Heterotoma-A Parasitic Wasp Of Drosophila Spp.", Noelle Dziedzic

Dissertations and Theses

Endoparasitioid wasps of Drosophila spp. frequently avoid or overcome the immune defense mechanisms of their fly hosts. Leptopilina heterotoma (Lh) is a generalist wasp species, successful on many Drosophila spp. world-wide. During oviposition, the female wasp introduces venom proteins and virus-like particles (VLPs) into developing fly larvae. VLPs are endocytosed by plasmatocytes, a macrophage-like blood cell that is the most abundant hemocyte present in the circulating hemolymph. Once internalized, VLPs destroy plasmatocytes by programmed cell death. To understand the contributions of VLP proteins in VLP trafficking within host cells, we took advantage of proteomic data from purified Lh VLPs. Two …

Expression And Function Of A Putative Cox-Like Gene In D. Melanogaster, Michelle S. Batchu

Dissertations and Theses

Cyclooxygenases (COX) are the enzymes that catalyze the conversion of arachidonic acid into prostaglandins. In mammals, isoform COX-1 is constitutively expressed, whereas the isoform COX-2 gene expression is induced, primarily at sites of inflammation. While eicosanoids play a major role in inflammation in insects, their existence in fruit flies has not been reported. Recent computational analyses by Qi and Singh (2014) have identified putative COX-like enzymes in the fruit fly Drosophila melanogaster. Here we compare the expression patterns of these enzymes and the effects of their knockdown in immune cells of D. melanogaster third instar larvae. Because of high genetic …