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Title: The genetics of hyphal morphology in Aspergillus nidulans
Author: Leeder, Abigail Claire
ISNI:       0000 0001 3607 5918
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2007
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The molecular biology behind the development ofAspergillus nidulans has been studied for many years. Although the physiology of mycelia can be altered by varying the growth medium, it has been shown that there is a very strong genetic contribution to the process. This study examined the role of three proteins in A. nidulalls hyphal growth. It was found that bemA (the orthologue of S. cerevisiae BEMl) is not essential, as previous studies had suggested, and that its deletion has only a moderate effect on cell growth. Deletion of the SH3-1 domain of bemA has no effect on cell growth, but its overexpression in the absence of native bemA results in a polarity defect. It was also shown that BemA has roles in asexual development and in the promotion of vacuolar fusion. BemA localises to the polarisome, not previously seen in A. Ilidulans, and shown to be distinct from the spitzenkorper. It is suggested that BemA is required for stable polarisome formation, similar to S. cerevisiae Bemlp. It was found that the polarisome is required for proper spitzenkorper formation, as well as an efficient secretory system. Depletion of HbrB, a filamentous fungi orphan, also affects cell morphology. The effect of depletion of HbrB on various elements of the secretory system was studied. Evidence presented suggests that HbrB may be involved in protein recycling at the late Golgi. It is known that repression of colA, the orthologue ofNeurospora crassa cal-I, causes a severe growth defect. In this study, the specific effect of CotA on growth regulation was studied. It was found that neither overexpression nor repression significantly affected the spitzenkorper, but that both had an effect on polarisome formation. CotA was found in punctate regions of fluorescence along the hyphae and occasionally at the tip (similar to Cotl).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available