Investigating Heat Shock Induced Double Strand Breaks in Caenorhabditis elegans Spermatocyte
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Date
2017
Authors
Schoellhorn, Kaycee Marie
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Meiosis is a specialized form of cell division that occurs in sexually reproducing organisms to generate haploid gametes, such as sperm and eggs. Double strand DNA breaks (DSBs) are a form of DNA damage and are intentionally induced in cells during meiosis. It is necessary that these breaks are properly repaired because improper repair can cause infertility, birth defects, miscarriages, or cancer. Unlike other tissues in the body, sperm are known to be sensitive to small fluctuations in temperature; the inability of sperm to thermoregulate in response to high temperature is known to cause male infertility. Previous research in Caenorhabditis elegans has shown that heat shock of adult males results in a dramatic increase in DSBs in the developing sperm of the germline. This phenotype is specific to spermatocytes and independent of spo-11, the enzyme that induces DSBs. This paper examines the effect of a spectrum of heat shock temperatures on the induction of DSBs in C. elegans spermatocytes. Adult male worms were heat shocked and the gonads were dissected and stained with antibody to mark DSBs. The results show a relatively uniform quantity of breaks from 25-33°C with a threshold increase in the number of breaks happening at 34°C. Additional DSBs were induced at heat shock temperatures above 34°C. These results indicate that spermatocytes are extremely sensitive to a slight fluctuation in temperature and that deviation from a narrow isotherm leads to the induction of an abundance of DNA damage. This work has helped to increase our understanding of how small temperature fluctuations contribute to the induction of DNA damage in spermatocytes, which can ultimately lead to male infertility.
Description
42 pages. A thesis presented to the Department of Biology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2017
Keywords
Meiosis, DNA damage, Spermatocytes, Male infertility, DSB, Heat shock