Abstract
dc:description.abstractPathways for the biosynthesis of docosahexaenoic acid (DHA) and other polyunsaturated fatty acids (PUFA) were elucidated in two heterotrophic, marine microalgae; Schizochytrium sp. and Crypthecodinium cohnii. PUFA-requiring auxotrophs of both of these algae were created and used as tools for studying PUFA biosynthetic pathways. Additionally, equilibrium radio-labeling techniques were applied to algal cultures fed 14C-fatty acids. Both organisms were found to possess two distinct pathways for PUFA biosynthesis. One pathway, mediated by classical elongases and desaturases, was incomplete in both organisms and was not capable of complementing PUFA auxotrophic phenotypes or of producing PUFA de novo, but could produce DHA from simpler PUFA precursors. The second PUFA pathway in each organism was desaturase and elongase independent. In C. cohnii, this pathway was distinguished by a capacity to produce DHA from acetate, in a manner similar to that of Schizochytrium which was shown to employ a polyketide synthase (PKS) complex for primary DHA biosynthesis. Additionally, genes of the Schizochytrium PUFA-PKS were successfully expressed in transgenic yeast, which produced DHA. Candidates for genes encoding C. cohnii PUFA-PKS components and other genes of C. cohnii PUFA biosynthesis were identified and discussed.
Degree
thesis:*- Name dc:type.qualificationname
- PhD
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- University of Hull
- Year dc:date.issued
- 2007
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Lippmeier, James Casey
Subjects
dc:subject × 1Rights
- Language dc:language
- en
Identifiers
dc:identifier.*- Identifier
- oai:hull-repository.worktribe.com:4214319
- OAI identifier oai:identifier
- oai:hull-repository.worktribe.com:4214319