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From Second Creek To New Pangea: A Multi-Scale Analysis Of Patterns And Trends In Aquatic Biodiversity, Jeffrey Robert Duncan

Doctoral Dissertations

The Earth’s freshwater ecosystems are undergoing a period of dramatic change. The simultaneous expansion and contraction of aquatic species’ ranges is leaving an indelible mark on the evolutionary histories of the world’s freshwater species. This dissertation represents a compilation of research efforts that quantify, explain, and propose policy recommendations concerning current trends in aquatic biodiversity. Part II provides an appraisal of the status of the world’s freshwater fishes that asks two primary questions—are all taxonomic groups equally susceptible to extinction, and can we identify a unifying suite of extinction risk factors? Although I concluded, that extinction risk is not randomly …

Comparative Anatomy Of The Lower Respiratory Tract Of The Gray Short-Tailed Opossum (Monodelphis Domestica) And North American Opossum (Didelphis Virginiana), Lee Anne Cope

Doctoral Dissertations

The present study describes the lower respiratory tract anatomy of the gray short-tailed opossum (Monodelphis domestica) and North American opossum (Didelphis virginiana). The trachea of the gray short-tailed opossum consists of 25 c-shaped tracheal cartilages. The trachea of the North American opossum consists of 28 c-shaped cartilages. The right lung of both species is separated into cranial, middle, caudal and accessory lobes by interlobar fissures. The left lung consists of unseparated cranial and caudal lobes. The right and left pulmonary arteries of the gray short-tailed and North American opossums divide into pulmonary lobar arteries. The pulmonary lobar veins join to …

Functional Analysis Of Drosophila Rad51 Protein In Dna Repair, Recombination, And Apoptosis, Siuk Yoo

Doctoral Dissertations

Among proteins involved in homologous recombination, Rad51 is an essential enzyme possessing DNA binding, ATPase, and strand transfer activities. The fu nctions of Rad51 in repair of double-strand breaks (DSB) and meiotic recombination have been extensively studied in yeast and mammals, but little is known about its roles in cell cycle regulation and apoptosis. In this study, we examine the roles of Rad51dm protein in Drosophila melanogaster.

Like other Rad51 proteins, Rad51dm is involved in DNA repair and recombination. The function of Rad51dm in DNA repair was demonstrated by examining the sensitivity of transgenic animals to methyl methanesulfonate (MMS) …

Analysis Of Events Governing The Meiotic Division In Mouse Spermatocytes, Shannon Stewart Eaker

Doctoral Dissertations

The meiotic division is essential for successful gametogenesis. However, many events occurring during male and female meiotic development remain poorly understood. While it is known that chromosomes must pair, recombine, and segregate to form gametes, critical questions remain. How and when do these events occur with respect to each other? What mechanisms monitor their developmental success? Insight into these questions is provided in this dissertation, using the mouse spermatocyte as a model. The purpose of this work is to aid in the overall understanding of mammalian meiosis.

After an introduction into mammalian meiosis in Part I, a temporal order of …

Pathogenesis Of Acid Injury In The Non-Glandular Region Of The Equine Stomach: Implications In Gastric Ulcer Disease, Jenifer Ann Nadeau

Doctoral Dissertations

Forty-three horses were necropsied to determine if volatile fatty acids (VFAs)produced from fermentation of carbohydrates (acetic, butyric, propionic, and valeric acids) cause cellular injury which leads to gastric ulceration when exposed to the nonglandular mucosa of the stomach at pH 1.5, 4 and 7. In part I of the study thirty horses were necropsied to determine if acetic, butyric, or propionic acid could cause cellular injury. In part 2 of the study thirteen horses were necropsied to determine if acetic, butyric, propionic or valeric acid could cause cellular injury. In both studies the stomach was removed within one hour of …

Markov Set-Chains As Models Of Plant Succession, Corey L. Samuels

Doctoral Dissertations

In this dissertation I examine Markov set-chains as a new approach for modeling plant succession. Set-chains are an extension of Markov chains, due to Hartfiel (1991, 1998), that makes it possible to model succession when transition probabilities are uncertain or fluctuating. In Markov set-chains each transition probability is expressed as an interval containing the range of all possible values for that parameter. In turn, a set-chain predicts community composition as a range of possible frequencies for each species. First, I give an introduction to Markov set-chains and methods for iterating and finding their asymptotic behavior. I demonstrate the formulation and …

Markov Set-Chains As Models Of Plant Succession, Corey L. Samuels

Doctoral Dissertations

In this dissertation I examine Markov set-chains as a new approach for modeling plant succession. Set-chains are an extension of Markov chains, due to Hartfiel (1991, 1998), that makes it possible to model succession when transition probabilities are uncertain or fluctuating. In Markov set-chains each transition probability is expressed as an interval containing the range of all possible values for that parameter. In turn, a setchain predicts community composition as a range of possible frequencies for each species. First, I give an introduction to Markov set-chains and methods for iterating and finding their asymptotic behavior. I demonstrate the formulation and …