3-OH oxylipins are saturated and unsaturated oxidized fatty acids which are produced in
mitochondria via incomplete b-oxidation or fatty acid synthesis type II. These
compounds possibly play an important role in the sexual cycle of yeasts by assisting
with ascospore liberation. Literature suggests that 3-OH oxylipins act as a lubricant
during ascospore liberation, thereby ensuring efficient release of ascospores.
Since the discovery of oxylipins i.e. 3-hydroxy (OH) oxylipins in the early 1990âs, these
compounds were found to be distributed in various species of the fungal domain.
Studies performed thus far, however, focused mainly on non-fermenting yeast species
such as Ascoidea, Dipodascopsis and Eremothecium.
According to various studies performed so far, 3-OH oxylipins were found to accumulate
specifically in the sexual structures (asci and surrounding ascospores) of various nonfermenting
yeasts. These studies also revealed that the sexual stages of nonfermenting
yeasts are most susceptible to acetylsalicylic acid (ASA), a known
mitochondrial (respiration and 3-OH oxylipin production) inhibitor.
No information regarding oxylipin accumulation in asci or ASA-sensitivity of fermentative
yeasts, however, has so far been reported. Using confocal laser scanning microscopy in
combination with an oxylipin probe for 3-OH oxylipins and coupled to a fluorescing
secondary antibody, the accumulation of these oxylipins was discovered in the asci of the following fermentative yeasts i.e. Pichia anomala, Pichia farinosa and
Schizosaccharomyces octosporus. Interestingly, no 3-OH oxylipin accumulation was
observed in the asci of the fermenting yeast Zygosaccharomyces bailii. This could be
ascribed to the fact that this yeast depends more on a fermentative pathway for growth
and sexual reproduction, than on mitochondrial respiration.
Since 3-OH oxylipins are produced in the mitochondria, it is expected that there should
be an increase in mitochondrial activity associated with these sexual structures. Using
confocal laser scanning microscopy and a mitochondrial fluorescing probe (Rhodamine
123), an increase in mitochondrial activity was also observed in the asci of the
fermenting yeasts tested, again with the exception of Z. bailii.
Furthermore, during this study links between yeast sexual reproduction, 3-OH oxylipin
accumulation/production, mitochondrial activity and oxygen requirement were
established. This study revealed that fermenting yeasts are more resistant to ASA than
non-fermenting yeasts when grown in liquid media. This is probably due to the fact that
these yeasts can use either aerobic respiration or a fermentative pathway for growth
and reproduction. This research prompted the development of a bio-assay that may find
application in screening for effective antimitochondrial antifungals.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08192008-085628 |
| Date | 19 August 2008 |
| Creators | Swart, Chantal Wendy |
| Contributors | Dr CH Pohl, Prof PWJ van Wyk, Prof JLF Kock |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08192008-085628/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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