Lipid studies in breath-hold diving mammals and obese, pre-diabetic mice.

Lipidology, or the scientific investigation of cellular lipids in biological systems, as well as their pathways and networks, is becoming an increasingly integral component in the investigation of metabolic disease and, outside the healthcare fields, in the elucidation of adaptations to specific environmental stressors. Sphingolipid and whole phospholipid profiles were examined in several species of marine mammals (and in two tissue types in one marine mammal species), as well as in the skeletal muscle of obese, pre-diabetic mice. The fatty acid composition of the cells (the sum total of intracellular lipid and the fatty acids of membrane phospholipids) was also examined in obese, pre-diabetic skeletal muscle of the mouse. Marine mammal species were compared based on diving ability. Shallower divers (harbor seals, Phoca vitulina) demonstrated significantly higher C16 ceramide, 16:0 sphingomyelin, and dipalmitoylphosphatidylcholine (DPPC) levels compared to deeper divers (Weddell seals, Leptonychotes weddellii). Additionally, in comparing ringed seal (Pusa hispida) skeletal muscle to liver tissue, liver tissue showed significantly higher levels of C16:0 sphingomyelin, dipalmitoylphosphatidlycholine, and C16 ceramide. Pre-diabetic mice were found to have no significant changes in sphingolipids or whole phospholipids after high-fat diet (HFD) feeding compared to controls, but had statistically significant elevations of PUFAs (particularly omega-6s), and statistically significant declines in MUFAs. These results suggest that harbor seals are under greater stress than Weddell seals, based on upregulated levels of C16 ceramide and 16:0 sphingomyelin, and this increased stress likely results from an increased time at depth. Likewise, the liver of ringed seals shows significant signs of physiological stress, but here, the difference may be one of varying blood flow between the liver and skeletal muscle during diving. DPPC levels were higher in ringed seal liver, as well as harbor seal skeletal muscle, suggesting these tissues are more susceptible to hydrostatic pressure-related complications. Finally, the HFD-fed mice demonstrated a trend toward pro-inflammatory fatty acid pools with an increase in PUFAs, and specifically N6s. The results reported here contribute to our knowledge of the importance of biological membranes and the composition of fatty acid pools within cells to healthy physiological functioning.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Doctoral

Grantor

Baylor University.

Year dc:date.issued

2013

Author dc:creator

• Young, Kathryn, 1984-

Advisor dc:contributor.advisor

• Lee, Myeongwoo.

• Lipid studies.
• Pre-diabetes.
• Insulin resistance.
• C57BL/6J mice.
• Marine mammal.
• Breath-hold diving.
• Sphingolipids.
• Phospholipids.
• Ceramide.

Statement dc:rights

• Baylor University works are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact libraryquestions@baylor.edu for inquiries about permission.

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2104/8925

OAI identifier oai:identifier

oai:baylor-ir.tdl.org:2104/8925