Apical Testis Structure and the Effects of Cadmium Treatment on Spermatogenesis in Drosophila

<p>The fruit fly <em>Drosophila melanogaster</em> is used extensively as a model for studying molecular, genetic and cellular aspects of human disease and physiology. Our lab has used <em>D. melanogaster</em> and related species to study the structure of the testis stem cell niche, as well as other aspects of spermatogenesis. We previously revealed a novel stem cell niche structure in <em>D. pseudoobscura</em>, a distant relative of <em>D. melanogaster.</em> The signaling center of the <em>D. melanogaster</em> stem cell niche has a well-characterized rosette arrangement of fasciclin-positive cells terms the “hub”. <em>D. pseudoobscura, </em>however, lacks a punctuate hub and instead displays a hemispherical fasciclin-positive zone that fills the apical end of the testis. The first aim of the current work was to characterize the stem cell niche in two additional species based on their evolutionary relationship to <em>D. melanogaster</em> and <em>D. pseudoobscura</em>: <em>D. ananassae</em> and <em>D. persimilis</em>. <em>D. persimilis</em> is part of the obscura group and is closely related to <em>D. pseudoobscura; D. ananassae</em> is part of the melanogaster group. Our work shows that <em>D. ananassae </em>has the rosette hub morphology while <em>D. persiimilis</em> displays the <em>D. pseudoobscura</em> morphology.</p> <p>The second focus of this project was to examine the effects of cadmium (CdCl₂) exposure on spermatogenesis in <em>D. melanogaster</em>. Cadmium toxicity is well-studied in mammalian testes and sperm production, but not in Drosophila. In order to assess the effects of CdCl₂ on spermatogenesis in <em>D. melanogaster</em> we developed two assays: a nuclear staining (DAPI) assay to assess cadmium dosage effects on late spermiogenesis and a Live/Dead assay to assess mature sperm viability. The results of the DAPI assay and the Live/Dead assay both show a detrimental effect by CdCl ₂on spermatogenesis in <em>D. melanogaster. </em>The goal of the DAPI assay was to examine the number and arrangement of sperm bundles in the basal end of the <em>D. melanogaster</em> testis following cadmium treatment. The DAPI assay showed that exposure to increasing concentration of CdCl₂ resulted in an increase in the appearance of abnormal sperm bundles. The Live/Dead assay showed: (1) an increase in the total number of sperm present in the seminal vesicle proportional to increasing amounts of cadmium chloride and (2) an increase in the number of dead sperm proportional to increasing amounts of cadmium chloride.</p>

Name thesis:degree_name

MS Biology

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2016

Author dc:creator

• Cardaci, Paulina J.

Contributors dc:contributor

• Angela Klaus, Ph.D
• Brian Nichols, Ph.D
• Tin-Chun Chu, Ph.D
• Jane L. Ko, Ph.D

• Stem cell niche
• Spermatogenesis
• Drosophila
• cadmium
• Biology
• Pharmacology, Toxicology and Environmental Health

Repository record dc:identifier

https://scholarship.shu.edu/dissertations/2216

OAI identifier oai:identifier

oai:scholarship.shu.edu:dissertations-3269