Shari Galvin

Document Type

Thesis

Date of Award

Spring 5-20-2015

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Biology

First Advisor

Professor Ayodotun Sodipe

Abstract

Tardigrades are well known for being resistant to extreme conditions, including tolerance to ionizing and UV radiation in both the hydrated and dehydrated state. It is well known that exposure to these factors may cause damage to DNA. The ability of tardigrades to survive high levels while in both states, may suggest that perhaps tardigrades rely on efficient DNA repair mechanisms. Although several studies have been done that observe their survival and reproductive ability to ionizing radiation, there have been few studies that focus on the expression of DNA repair genes. Gamma radiation has been known to induce significant amounts of stress within organisms and damage to DNA by causing single and double strand breaks. Due to these damaging effects the r. DNA repair proteins that were chosen for observation were hsp70, rad51. Heat shock protein hsp70 is wide-spread stress protein that has been hypothesized to aid in the radiotolerance of tardigrades but very little is known regarding its expression. The recombinase rad51 allows for the repair of the damaged strand of DNA using 1 2 homologous non-damaged strands as a template. To investigate the differences in the expression of DNA repair genes in Hypsihius dujardini, hydrated and anhydrobiotic animals were exposed to varying levels of radiation (510Gy, 1485Gy, and 2003Gy). RTqPCR was used to observe the mRNA expression at the moment of irradiation (0 hr.) and 24 hr. post radiation. The results of this study shows that both genes are highly expressed in hydrated samples and play a role in repairing DNA damage caused by radiation. Although the desiccated state provides some protection against some damage caused by gamma radiation, we were able to observe some expression of the rad51 gene. Future studies are required to understand the importance of these genes in organisms undergoing anhydrobiosis.

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