COLLEGE OF ARTS & SCIENCES
ADVISORS Thomas M Williams LOCATION, TIME RecPlex, 11:00AM-12:30PM College of Arts and Sciences: Biology, Poster- Graduate Research A major goal of evolutionary-developmental biology research is to make a connection between the understanding of animal development and how development evolves. At the heart of development are gene regulatory networks (GRNs), where each network is composed of a set of transcription factors that control the expression of target genes through physical interactions (regulatory linkages) with binding sites in cisregulatory element sequences (CREs). While the regulatory linkages have been mapped for several GRNs, lacking is a characterization of a GRN for a rapidly evolving trait whose origin, diversification, and loss can be studied. Drosophila melanogaster fruit flies have a male-limited pattern of abdomen pigmentation which evolved from a monomorphic ancestor, and abdomen pigmentation has diversified and been lost between related species. Here, I studied the CREs and interacting transcription factors controlling the expression of two pigmentation enzymes with similar male-specific patterns of expression. Though these CREs direct similar patterns of expression and are controlled by some of the same transcription factors, we found that the underlying composition and organization of regulatory linkages significantly differ. We provide evidence that the repurposing of an ancestrally monomorphic pigmentation GRN to a derived dimorphic state required the de novo evolution of these two CREs. While these CREs seemed likely targets of mutations responsible for diversification and losses of pigmentation, we show that these phenotypic changes largely were driven by changes at other GRN loci. Collectively, these results show how evolution can forge similar gene expression patterns from dissimilar CRE encodings, and how a trait’s origin can require the evolution of new CREs, but that these CREs may not be the preferred GRN target for subsequent evolution
Transcriptomic and Proteomic Comparisons between Dorsal and Ventral Iris during Early Lens Regeneration in the Newt Notophthalmus viridescens Reveal Insights about the Mechanism
STUDENTS Konstantinos Sousounis ADVISORS Panagiotis A Tsonis LOCATION, TIME RecPlex, 11:00AM-12:30PM College of Arts and Sciences: Biology, Poster- Graduate Research Notophthalmus viridescens, the red-spotted newt has been mainly studied for its tremendous regenerative abilities. Among other organs, newts have the ability to regenerate the eye lens after complete removal throughout life. The mechanism of newt lens regeneration has been a mystery for more than a hundred years. Histological examination of the newt eye after lens removal has revealed that the pigmented epithelium of the dorsal iris is responsible for the regeneration while ventral iris does not participate in the process. This change in cell morphology and fate of the iris cells to make lens cells is called transdifferentiation. The cellular and molecular events characterizing the initiation and progression of transdifferentiation are largely unknown. We have employed high-throughput methods to study gene expression during lens regeneration. Microarrays and RNA-sequencing have been used to study genes at the RNA level while liquid chromatography followed by mass-spectrometry to study gene expression at the protein level. Our results showed up-regulation of genes involved in cytoskeleton, immune response, DNA maintenance, reactive oxygen species balance, cell cycle and regulation of gene expression in the dorsal iris; the site that lens will be regenerated. We believe that these events consist of a regeneration signature that needs to be applied for all tissues that undergo regeneration. In addition, our studies have identified VAX2 as a gene selectively expressed in the ventral iris, a tissue incompetent for regeneration. Our efforts are focused on inhibiting VAX2 expression using morpholino anti-sense oligos in an attempt to initiate lens regeneration from that site, an event that can lead to exploring lens regeneration potentials in other regenerating incompetent animals.
What Attracts Male Blow Flies to a Carcass – Decay Odors or Presence of Females?
STUDENTS Timothy J Lee, Casey T Walk ADVISORS Allissa M Blystone, Karolyn M Hansen LOCATION, TIME RecPlex, 11:00AM-12:30PM College of Arts and Sciences: Biology, Poster- Independent Research The blow fly, Lucilia sericata, is one of the first organisms to colonize on decaying carrion. Many papers describe how the female blow flies utilize the carcass for food and for laying eggs but there is little information in the literature about how males respond to the presence of decaying carrion. In fact, anecdotal evidence found that while females actively walk on explore the carcass, males are usually found on the periphery in 23