Life Sciences Commons^™

Understanding Neonicotinoid Related Immunosuppression: A Potential For Beneficial Bacterial Intervention, John A. Chmiel

Electronic Thesis and Dissertation Repository

The use of neonicotinoid pesticides has been implicated in the recent decrease of honey bee (Apis mellifera) populations. In this thesis, a Drosophila melanogaster model was used to characterize immune impairment associated with imidacloprid (neonicotinoid) exposure and test the ability of beneficial bacteria (lactobacilli) to alleviate these harmful effects. The experiments outlined in chapters 2 and 3 demonstrate that imidacloprid alters the gut microbiota by exploiting the cooperation between gut immune pathways. The pesticide reduces expression of Duox via dysregulation of the immune deficiency pathway resulting in decreased hydrogen peroxide production. This contributes to the microbiota changes but …

Mushroom Body-Specific Gene Regulation By The Swi/Snf Chromatin Remodeling Complex, Kevin Cj Nixon

Electronic Thesis and Dissertation Repository

Over the lifetime of an organism, neurons must establish, remodel, and maintain precise connections in order to form neural circuits that are required for proper nervous system functioning. Disruptions in these processes can lead to neurodevelopmental disorders such as intellectual disability (ID) and autism spectrum disorder. Mutations in genes encoding subunits of the SWI/SNF chromatin remodeling complex have been implicated in ID, yet the role of this complex in neurons is poorly understood. In this project, I established cell-type specific methods to examine the effect of SWI/SNF subunit knockdowns on gene transcription and chromatin structure in the memory-forming neurons of …

The Fruitless Gene Influences Female Mate Preference In Drosophila, Tabashir A. Chowdhury

Electronic Thesis and Dissertation Repository

Species can arise as a result of reproductive barriers that prevent gene flow between diverging populations that force them to remain isolated from one another. Behavioural isolation is one of the earliest acting reproductive barriers determined by the evolution of mating preferences that prevent inter-specific matings. Several traits have been identified that contribute to behavioural isolation, but the genetic basis of interspecific female preference is yet to be determined. I used genetic mapping techniques to identify and confirm that the fruitless gene is affecting species-specific female rejection of interspecies males, contributing to the behavioural isolation between Drosophila melanogaster and D. …

The Leucine-Rich Domain Of Rgnef: A Modifier Of Tdp-43 Toxicity In Drosophila Melanogaster., Benjamin Martin Withers

Electronic Thesis and Dissertation Repository

Abstract

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the progressive degeneration of motor neurons. Rho Guanine Nucleotide Exchange factor (RGNEF) like other RNA-binding proteins, has been observed to form inclusions in the spinal cord motor neurons of both sporadic and familial cases of ALS. RGNEF has been determined to be a pro-survival factor under stress conditions. When comparing expression of different constructs of RGNEF in HEK293T cells, a Leucine-rich domain containing fragment of RGNEF (L-Rich) was found to form aggregates under metabolic stress that co-aggregated with TDP-43, another ALS-linked RNA-binding protein.

In this thesis, I used both …

Characterizing Mekk1: Candidate Behavioural Isolation Gene, Caryn Dooner

Electronic Thesis and Dissertation Repository

Behavioural isolation can occur due to divergence in aspects of courtship and mating, and can contribute to reproductive isolation. The purpose of this study is to determine how a gene, Mekk1, contributes to female rejection behaviour between D. melanogaster and D. simulans. Unique polymorphisms were identified within D. simulans Mekk1 that could contribute to behaviour, most of which are non-coding. Both transcripts of Mekk1 appear to be expressed at similar levels in D. simulans and D. melanogaster. These data also indicate that Mekk1 may be expressed in a specific region of the brain called the mushroom body, …

The Genetic And Environmental Basis For Chc Biosynthesis In Drosophila, Heather Ke Ward

Electronic Thesis and Dissertation Repository

Cuticular hydrocarbons (CHCs) are produced by insects and primarily used to prevent desiccation. In Drosophila, certain compounds have secondary roles as infochemicals that may act during courtship to influence mate choice. Certain CHCs may stimulate courtship with heterospecifics or act to repel conspecifics. The CHC profile produced by an individual is the result of the interaction between its genetic background and the environment, though the genes that underlie species differences in CHC production and how the environment can modulate the abundance of individual compounds within a species is not well known. Here, candidate gene CG5946 was found to be …

Investigating The Role Of Fruitless In Behavioural Isolation Between Drosophila Melanogaster And Drosophila Simulans, Jalina Bielaska Da Silva

Electronic Thesis and Dissertation Repository

Behavioural isolation is a prezygotic mechanism that is usually determined by female preference, such as seen with the rejection behaviour exhibited by Drosophila simulans females to D. melanogaster males. To confirm the role of a previously identified candidate gene fruitless (fru) in behavioural isolation, I proposed to disrupt fru expression in both D. melanogaster and D. simulans to allow for the generation of interspecies hybrids expressing only a species-specific allele of fru. A reciprocal hemizygosity test would then be used to confirm the role of fru in behavioural isolation. Disruptions of fru in both D. melanogaster and …

Cellular/Molecular Analysis Of Interspecies Sterile Male Hybrids In Drosophila, Rachelle L. Kanippayoor

Electronic Thesis and Dissertation Repository

Over time, genetic differences can accumulate between populations that are geographically separated. This genetic divergence can lead to the evolution of reproductive isolating mechanisms that reduce gene flow between the populations and, upon secondary contact, result in distinct species. The process of speciation is, thus, what accounts for the multitude of species that contribute to the rich biodiversity on Earth. Interspecies hybrid sterility is a postzygotic isolating mechanism that affects the development of hybrids, rendering them sterile. A notable trend, known as Haldane's Rule, describes that heterogametic individual (e.g. males in Drosophila) are more susceptible to sterility than homogametic …

Genetics Of Female Interspecific Mate Rejection In Species Of Drosophila, Ryan Calhoun

Electronic Thesis and Dissertation Repository

Speciation can occur when accumulated differences in mating behavior force diverging species to remain reproductively isolated from one another. A key determinant of behavioural isolation is the evolution of female mating preferences that prevent interspecific males from mating. However, no individual genes involved in species-specific preferences of females have yet been identified. Using various genetic mapping techniques available for studying strains and species of Drosophila, I identify candidate genes involved in D. simulans female discrimination against D. melanogaster males. One candidate gene in particular, Katanin-60, was selected for further characterization. Katanin-60 is a gene encoding a microtubule severing …

The Genetic Basis Of Cuticular Hydrocarbon Production In Drosophila Melanogaster And D. Simulans, Jessica A. Pardy

Electronic Thesis and Dissertation Repository

Individuals within many species have evolved complex reproductive strategies to ensure they identify appropriate mates so as to increase their fitness. Chemical signals, which are often species- and sex-specific, are one means by which many insect species communicate. Differences in cuticular hydrocarbons (CHCs) profiles can influence reproductive isolation in Drosophila. A previous study identified large genomic regions that contain genes responsible for the different CHC profiles observed in D. melanogaster and D. simulans females. I refined these earlier results by utilizing fine-scale mapping, focusing on the entire CHC profile, in an effort to determine which genes are responsible for …

Evaluating The Rapid Divergence Of Male Genitalia In Sibling Drosophila Species, Helene M. Levasseur-Viens

Electronic Thesis and Dissertation Repository

The rapid divergence of male genitalia in a variety of animal groups is a well documented phenomenon for which there exists no universal explanation. The three prevalent hypotheses for the divergence of genitalia, the lock and key, pleiotropy and sexual selection, have all been tested in individual model organisms, but never have individual experiments been performed in one species pair to allow for direct comparison. Drosophila simulans and D. mauritiana have long been thought to be an example of the sensory lock and key model, but no concrete data has ever been presented to verify the validity of the model. …