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Title: Studies on the lipids of Emiliania huxleyi during phosphate depletion stress and viral infection
Author: Worthy, Charlotte Anne
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2013
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Coccolithophores (Haptophytes) are abundantly distributed throughout the global oceans. Emifionia huxleyi frequently blooms in the upper stratified oligotrophic and neritic depths from sub-polar to tropical latitudes and is central to carbon and sulphur biogeochemical cycling studies. E. huxleyi's biosynthesis of long chain (C31-C39) unsaturated lipids have been a biomarker for phytoplankton algae in palaeoenvironments. Here a signature fatty acid profile is presented to identify taxa and growth stage in bloom studies. Fatty acids are essential for normal cell function, and beneficial for hyperlipidaemia, suppression of hypertension, protection against renal heart failure, cardiovascular and inflammatory diseases, and cancer. The world's rapidly dwindling fish are the main natural source of o m ega~3 oils and many species may not be recoverable. At least 28% of the world's fish are over exploited or depleted and 52% fully exploited. Growing consumer omega-3 demand is driving alternative source studies with marine algae at the forefront. Through the examination of 48 stra ins of E. huxleyi, commercially valuable n-3 PUFAs have been reported in proportions of up to 70 mol% of total fatty acids in warm water strains. High cellular population densities and increased abundances of n-3 l C-PUFAs in response to phosphate enrichment give E. huxleyi potential use as a commercial organism for biotechnological applications. During laboratory based infection trials with coccolithovirus isolate 86 {EhV-86J long chain bases (lCBs) associated with structurally novel sphingolipids have been correlated with the composition of seven coccol ithovirus isolates, leading this investigation to support theories of viral trans dominant manipulation of the host E. huxley; for the increased fitness of the pathogen. By increasing the infection period and suppressing programmed cell death mechanisms the coccolithovirus is able to increase the number of progeny, and by utilising the outer plasma membrane of the host as a viral envelope, extensively increasing their titre within the water-column for future rounds of infection. These lCSs have been identified in phytoplankton blooms in the Western English Channel, making them possible chemotaxonomic biomarkers for termination of phytoplankton blooms by Phycodnaviridae members. Unlike other viruses, coccolithoviruses infects multiple stra ins of phytoplankton. A susceptibility study here involving 78 host strains demonstrated a prolific regulator of this vastly omnipresent alga. Finally, Transmission Electron Microscopy presents morphological features of nine coccolithoviruses that were previously unknown.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available