Graduate Program

Chemistry

Degree Name

Master of Science (MS)

Semester of Degree Completion

2005

Thesis Director

Barbara Lawrence

Thesis Committee Member

Marina Marjanovic

Thesis Committee Member

Unknown

Abstract

31P NMR spectroscopy was used to study freeze tolerance of the wood frog, R. sylvatica. Spectra were obtained of living whole body samples and isolated thigh muscle tissue. These results were compared to R. pipiens which is freeze sensitive. R. sylvatica was found to have significantly higher levels of glucose-6-phosphate and several phosphodiesters. Both seasonal and environmental stresses were studied to determine the effect of freezing conditions on the phosphorus compounds present in R. sylvatica. The results show that R. sylvatica is capable of tolerating stresses that are associated with freezing without any drastic changes in the levels of metabolic compounds present. Phosphodiester loading experiments showed that phosphatidylcholine passes through muscle cell membranes via active transport while phosphorylcholine is unable to pass through cell membranes.

H and 3¹P NMR spectroscopy were used to determine which organic compounds are present in the ooplasm of Antarctic dragonfish, G. acuticeps, eggs as osmolytes. Previous work had shown that the osmolarity was 832 mM, but only 569 mM was accounted for by Na, K+, and Cl. Proposed osmolytes were identified as trimethylamine-N-oxide, TMAO (78 mM ± 23 mM) and phosphorus compounds that are present at chemical shifts common to phosphodiesters (145 mM ± 25 mM). Urea is thought to be present, but was not identified by H NMR possibly because its peak falls under the water peak. Urea is an osmolyte commonly found with TMAO that although undetected may still be present in concentration high enough to account for remaining 40 mM of osmolarity.

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