Life Sciences Commons^™

Phenotypic Plasticity And The Post-Modern Synthesis: Integrating Evo-Devo And Quantitative Genetics In Theoretical And Empirical Studies, Alison G. Scoville

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Mainstream evolutionary biology lacks a mature theory of phenotype. Following from the Modern Synthesis, researchers tend to assume an unrealistically simple mapping of genotype to phenotype, or else trust that the complexities of developmental architecture can be adequately captured by measuring trait variances and covariances. In contrast, the growing field of evolutionary developmental biology (evo-devo) explicitly examines the relationship between developmental architecture and evolutionary change, but lacks a rigorous quantitative and predictive framework. In my dissertation, I strive to integrate quantitative genetics and evo-devo, using both theoretical and empirical studies of plasticity. My first paper explores the effect of realistic …

Evolutionary Genetics Of Tetrodotoxin (Ttx) Resistance In Snakes: Tracking A Feeding Adaptation From Populations Through Clades, Chris R. Feldman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Understanding the nature of adaptive evolution has been the recent focus of research detailing the genetic basis of adaptation and theoretical work describing the mechanics of adaptive evolution. Nevertheless, key questions regarding the process of adaptive evolution remain. Ultimately, a detailed description of the ecological context, evolutionary history, and genetic basis of adaptations is required to advance our understanding of adaptive evolution. To address some of the contemporary issues surrounding adaptive evolution, I examine phenotypic and genotypic changes in a snake feeding adaptation.

Adaptations can arise through fixation of novel mutations or recruitment of existing variation. Some populations of the …

Ecotypic Variation In Elymus Elymoides Subspecies Brevifolius Race C In The Northern Intermountain West, Matthew C. Parsons

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Little information is available on the extent of local adaptation for many native grass species. This is the case for squirreltail (Elymus section Sitanion), despite this group's prevalence and importance in rangeland restoration efforts. I evaluated 32 populations of E. elymoides ssp. brevifolius race C, a phylogenetic subdivision of bottlebrush squirreltail (E. elymoides) centered in the northern Intermountain West, for phenotypic variables and neutral genetic markers to measure their association with geographical origin. Phenotypic traits were measured in common field and greenhouse environments, and genetic diversity was assessed using Amplified Fragment Length Polymorphism. Three factors were extracted from the phenotypic …

Functional Characterization Of Hexokinase-Like 1 (Hkl1) From Arabidopsis Thaliana, Abhijit Karve

All Dissertations

Arabidopsis hexokinase1 (AtHXK1) is a moonlighting protein with roles in both glucose signaling and catalysis. In this study, we first cloned and characterized the six HXK related genes from Arabidopsis. Three of the six encoded proteins were shown not to phosphorylate hexoses and thus, are designated as hexokinase-like (HKL) proteins. Though they are only 50% identical to HXK1, the amino acid sequences of HKL1 and HKL2 both have well conserved glucose binding domains and other recognized structural elements. The possible basis for their lack of catalytic activity was further probed by site-directed mutagenesis and ultimately was attributed to a suite …

The Genetics Of Colonization In Two Amphibian Species After The 1980 Eruption Of Mount St. Helens, Kristin Ann Bakkegard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The genetics of colonization is understudied in salamanders but has large conservation implications as new habitats are formed or restored to their previous condition. The 1980 eruption of Mount St. Helens provided a natural experiment to study the genetic effects of a large infrequent environmental disturbance on two species of salamander, Taricha granulosa (Rough-skinned newt) and Ambystoma gracile (Northwestern salamander). Both these species breed in ponds, and are thought to exhibit high breeding site fidelity and low vagility. I designated three treatments based on the effects of the eruption: new ponds (created by the eruption, immigrants only), recovery lakes (in …

Utilizing Multiplex Ligation-Dependent Probe Amplification To Detect Novel X-Linked Microduplications Which Cause Intellectual Disability, Dianne Cohn

All Dissertations

ABSTRACT
A number of conditions related to X-linked intellectual disabilities (XLID) are in part due to microduplications that are not visible cytogenetically. With the focus on Rho, Ras and Rab genes, a family of genes known to be associated with intellectual disabilities, were screened for dosage aberrations (Leeuwen, F. N. 1997), (Ng, E. L. 2008), (Gissen, P. 2007), (Gurkan, C. 2005). Cohorts of intellectually disabled ID individuals were explored with new technologies. These new technologies include comparative genomic hybridization (CGH), multiplex ligation dependent probe amplification (MLPA) and quantitative PCR (qPCR) (Madrigal, I. 2007), (Hermsen, M. A. 2005), (Morey, J. S. …

Identifying The Cis-Acting Sugar Response Elements That Facilitate Glucose Signaling In Arabidopsis Thaliana, Frank Barretta, Jr.

All Theses

Identifying the initial sugar sensing and response activating mechanisms in plants has been difficult due to the dual functions of sugars as nutrients and as signaling molecules. In this study, we have examined transcript expression and promoter features of different genes encoding proteins for actin remodeling that have been implicated as targets of plant glucose signaling. Using Reverse Transcription PCR analysis, we confirmed that expression of two actin-associated genes, actin depolymerizing factor 9 (ADF9) and actin related protein 8 (ARP8), are repressed following a short-term glucose treatment of Arabidopsis thaliana seedlings. Glucose did not repress the expression of other ADF …

Gene Expression And Phenotype Response Of Drosophila Melanogaster To Selection., Kenneth W. Mcdonald

Electronic Theses and Dissertations

The evolution of phenotypic plasticity is currently a topic of paramount interest in a diverse field of sub-disciplines. Salience is placed by all fields in describing the interaction of selection and phenotypic plasticity and the consequence of this interaction more broadly on evolution. Lacking in the discussion is substantial empirical description of genotype/phenotype interactions that by definition constitute the plastic response to novel and stressful environments. Here, I present empirical observations that bring the interaction of genotype and phenotype into focus. Drosophila melanogaster populations subjected to selection for tolerance to low food or high alcohol conditions each exhibited an enhancement …

Dna Sequence Analysis Of A Bioluminescent Marine Bacterium, Benjamin Ryder

Master's Theses, Dissertations, Graduate Research and Major Papers Overview

Studies the sequencing of the DNA fragment containing the gene phaC (PHA synthase) and undertakes the search for open reading frames and putative gene matches in a bioluminescent marine bacterium.

Oxidative Stress-Mediated Anticancer Activity Of Novel Ahr Modulators Af & 5f203, Lancelot S. Mclean

Loma Linda University Electronic Theses, Dissertations & Projects

Estrogen receptor positive (ER+) breast cancer tends to respond to anti-estrogen agents such as Tamoxifen. Approximately 40% of ER+ breast cancer is resistant to these agents and those that initially respond often acquire resistance. Estrogen receptor negative (ER-) breast cancer remains largely unresponsive to these agents. It is therefore vital to discover drugs that are potent in both forms of breast cancer. Aminoflavone, (5-amino-2, 3-fluorophenyl)-6,8-difluoro-7-methyl-4H-l-benzopyran-4-one; AF; NSC 686288) and 5F203, (2-[-Amino-3-methy phenyl]-5-flurobenzothiazole) are novel anticancer candidate agents that display potent in vitro and in vivo anti-proliferative activity against select human tumor cells with a unique anticancer activity profile in the …

Novel Binding Domains Mediate Binding Of Hpv 16 E6 To Fadd And Procaspase 8, Sandy S. Tungteakkhun

Loma Linda University Electronic Theses, Dissertations & Projects

To evade the host response to infection, viruses have developed means to survive and propagate. HPV 16, a causative agent of cervical cancer and of some cases of oropharyngeal cancers, is one example. We have reported that the early viral protein E6 binds to proteins necessary for propagation of the apoptotic signal following receptor/ligand interactions, such as those mediated by FADD DED and procaspase 8 DED. E6 expression leads to the dose-dependent accelerated degradation of FADD and the protection of E6-expressing cells from Fas-induced apoptosis. Surprisingly, the splice isoforms of E6, E6_large and E6*, affect the stability of procaspase …

Mechanisms Of T Helper Cell Modulation In A Simulated Space Radiation Environment, Asma Rizvi

Loma Linda University Electronic Theses, Dissertations & Projects

Exposure to solar particle events (SPEs) poses the most serious threat to astronaut health. Due to this radiation environment, exploration of the solar system beyond Earth’s orbit entails many risks for the crew on these deep space missions. Depression or dysfunction of the immune system is a major concern due to its high radio-sensitivity; potential consequences include overwhelming infection, development of cancer, fibrosis, and poor wound healing. Astronauts are also exposed to low dose/low dose rate (LDR) radiation. A three month stay at the international space station exposes them to ~ 0.05 Gy of radiation.

C57BL/6 mice received LDR gamma-radiation …

Reverse Recruitment: Activation Of Yeast Genes At The Nuclear Periphery, Terry Marvin Haley

Dissertations

The regulation of genes at the nuclear periphery is an evolutionarily conserved phenomenon in eukaryotes. The reverse-recruitment model of transcriptional activation postulates that genes are activated by moving to and contacting transcription machinery located at subnuclear structures. In Saccharomyces cerevisiae it has been reported that this platform for gene regulation may reside at the nuclear periphery. To test this hypothesis, I utilized a GFP-gene tagging technique, which uses LacI-GFP to visualize a tandem array of its DNA-binding sequence, to monitor localization ofSUC2 and GALL I found that both genes preferentially localized to the nuclear periphery when transcriptionally active. By developing …

Insight Into The Origins Of The Rumex Acetosa Sex Chromosomes And Mechanisms Causing Dimorphism, Samuel Forrest

All Dissertations

Sex conferring chromosomes are subject to rapid change throughout evolution. Y-chromosomes (male determining) are subject to extensive chromatin remodeling and higher mutation rates than the autosomes being that recombination with the X chromosome is inhibited in many regions. The non-recombining regions comprise varying proportions of Y chromosomes from species to species and they are subject to mutation acquisition including both deletions and insertions. Recently it has been shown that these insertion mutations include repetitive DNA such as satellite DNA sequences (satDNA) and transposable elements. It is thought that Y chromosomes go through many rounds of expansion and contraction throughout evolution …

Dna Methylation And Promoter Sequence Analysis Of Colon Cancer Genes, Fang Wang

All Theses

Aberrant DNA methylation in the genome is associated with human cancers. Tumor cells can undergo an overall loss of DNA methylation in non-coding repetitive regions (including the Alu elements) and at the same time maintain hypermethylation in the CpG islands in promoter region of multiple genes. We are interested in understanding the pattern of DNA methylation in the promoters of genes that may mediate the tumor genesis in colon cells. Recent literature survey suggested that about two dozens of genes, when mutated or undergone changes in DNA methylation, can directly promote the development of colon cancers. We downloaded the promoter …

Understanding The Reproductive Behavior And Population Condition Of The Sandbar Shark (Carcharhinus Plumbeus) In The Western North Atlantic: A Molecular Approach To Conservation And Management, David S. Portnoy

Dissertations, Theses, and Masters Projects

The sandbar shark, Carcharhinus plumbeus, has a discontinuous cosmopolitan distribution and is exploited throughout much of its range. In the western North Atlantic, it constitutes the majority of the directed commercial fishery. The stock has declined greatly since the fisheries' inception and has not shown signs of recovery despite the implementation of management practices. Like many highly vagile marine species, it is difficult to obtain information about the sandbar shark through direct observation. Therefore, the goal of this dissertation is to use a molecular approach to examine aspects of behavior and reproduction, providing information useful in conservation and management. to …