Document Type

Thesis

Date of Award

5-2012

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Biology

First Advisor

Dr. Fawzia H. Abdel-Rahman

Abstract

Space exploration has fascinated scientist for centuries but the repercussions of zero gravity upon an organism must be understood in detail. Changes at the cellular, molecular, and organism level must be understood to prevent, reduce and/or reverse detrimental effects caused by zero gravity to ensure the safety of future human travelers into space. The use of Caenorhabditis elegans as a model organism to study space--like conditions will provide new proof that changes do occur when exposed to zero gravity for various lengths of time. Studying various exposure lengths of space--like conditions will provide a better understanding of when changes may occur within an organism. Due its small size, rapid life cycle, completely sequenced genome, availability of mutants, well-defined pattern of development and the ability to live and reproduce in both defined liquid or agar media. C. elegans have been used in providing optimal results in various fields of biological research. To investigate the effects of simulated microgravity (SMG), c. elegans in liquid cultures seeded with Escherichia coli OP50 were exposed for different time intervals using a rotary cell culture system recommended by NASA. Several flasks were used and maintained on a shaker to 1 2 serve as the control group. For each treatment day a final population, that included a count of all developmental stages, were obtained. Population of C. elegans exposed to SMG revealed a decline numbers proper devolvement when compared to the control; in all treatments. The brood size (progeny) for each hermaphrodite was lower in exposed nematodes than the control. Developmental stages using the light microscope revealed that different morhormetrics were smaller ill the exposed nematodes to simulated microgravity than the control. Light microscopy examination of the exposed adult hermaphrodites has revealed a congested digestive system with unprocessed E. coli OP50 as well as hatched offspring within its body. The longer the exposure the more congestion is seen in the digestive tract. To counteract the biological changes may be cause by space=like conditions several phytochemicals such as terpenoids found in essential oils of many plants and with potential antioxidant properties have been screened. The toxicity of 34 individual essential oil constituents (monoterpenoid hydrocarbons, monoterpenoid alcohols, monoterpenoid ketones, monoterpenoid phenols, and few others) was investigated against C. elegans. The toxicity varied from no to low toxicity and moderate to highly toxic. Essential oils with high mortality (toxicity) were tested further to determine the LCso for each tested chemical. Within the highly toxic chemicals (ten) the values of LCso varied from 3 ug/ml, to 30 ug/ml.,

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