Acetylsalicylic acid (ASA)-sensitive 3-hydroxy (3-OH) oxylipins were
uncovered in 1991 in the yeast Dipodascopsis uninucleata. Since then,
various similar oxylipins were found to be widely distributed in fungi.
Interestingly, 3-OH oxylipins were reported to play a role in ascospore release
from enclosed asci, where they are involved in assisting nano-scale gear-like
(D. uninucleata); sliding (Dipodascus); drilling (Eremothecium sinecaudum)
and piercing movements (E. ashbyi and E. coryli). In Ascoidea africana, a 3-
OH 10:1 oxylipin was found to be associated with hat-shaped ascospores
carried inside ellipsoidal asci. However, in this study no function was
proposed for this oxylipin. Since only one species representing the genus
Ascoidea was studied, it became the aim to further expand this study to also
include A. corymbosa and A. rubescens. Using confocal laser scanning
microscopy (CLSM) on cells stained with fluorescein-coupled 3-OH oxylipin
specific antibodies, this study suggests that oxylipins are specifically
associated with ascospores and not vegetative cells of A. corymbosa and A.
rubescens. Using gas chromatography - mass spectrometry (GC-MS) the
oxylipin, 3-OH 17:0, was identified in A. corymbosa. Here, oxylipin-coated
razor sharp ascospore brims may play a role in rupturing the ascus to affect
forced release of hat-shaped ascospores. Literature suggests that 3-OH
oxylipins are produced by β-oxidation or fatty acid synthesis in mitochondria of
yeasts. Since these oxylipins accumulate in sexual cells (asci), increased
mitochondrial activity is therefore expected in these structures. Strikingly, this
assumption is supported in this study. Using selective fluorescence
mitochondrial staining and CLSM, evidence is provided that mitochondrial
function is much higher in asci containing increased amounts of 3-OH oxylipins compared to the corresponding asexual vegetative cells.
Furthermore, when ASA, a mitochondrial inhibitor, was added in increased
concentrations to cultures of Ascoidea, the sexual stage was found to be
more sensitive. Ascospore liberation from asci was first inhibited followed by
asci formation while some vegetative growth could still be observed.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-12102007-081315 |
| Date | 10 December 2007 |
| Creators | Ncango, Desmond Mbulelo |
| Contributors | Dr M Joseph, Prof PWJ van Wyk, Dr CH Pohl, 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-12102007-081315/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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