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Growth and morphology of Fusarium graminearum
Başlık:
Growth and morphology of Fusarium graminearum
Yazar:
Vaughan, Jacqueline, author.
ISBN:
9780438084254
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (295 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Özet:
Shear stresses in batch cultures of Fusarium graminearum affected mycelial morphology by causing fragmentation of mycelia, but had no effect on specific growth rate or hyphal growth unit length (a measure of mycelial branching). One strain of F. graminearum (CCl-1) was observed to fragment in the absence of shear stress. The amount of mycelial fragmentation occurring in continuous cultures of F. graminearum A3/5 was found to be directly proportional to the shear stress present in the culture. Low dissolved oxygen tensions in continuous cultures caused inhibition of the growth of side branches. Although neither shear stress nor dissolved oxygen tension alone affected hyphal growth unit length, a combination of low shear and low oxygen concentration in the culture increased hyphal growth unit length. Empty compartments within hyphae were investigated as possible sites of hyphal fragmentation. The similarity between the numbers of empty compartments observed under different conditions of agitation (shear stress) and the observation that hyphae usually fragmented at the septa suggest that such a role in fragmentation is unlikley. The use of low concentrations of macroconidia as inocula in non-agitated cultures caused pellet-like growth. "Staled" medium from stationary phase cultures which had been inoculated with high concentrations of macroconidia decreased branching, suggesting that hyphae produce a non-volatile compound which regulates morphology. Partially purified hyphal wall of F. graminearum A3/5 was subjected to qualitative analysis of the component carbohydrates by gas-liquid chromatography. Wall material was found to contain mannose, glucose, N-acetyl glucosamine and xylose. Successive digestion of the wall with acids and alkalis into S-glucan, R-glucan and R-glucan-chitin-complex fractions revealed the presence of glucose and mannose in the S-glucan fraction, and glucose, mannose and xylose in the acid resistant R-glucan fraction. Both the alkali-resistant R-glucan fraction and the R- glucan-chitin complex were found to contain glucose, mannose, xylose and N- acetyl glucosamine. The R-glucan-chitin complex fraction contained a higher proportion of N-acetyl glucosamine than the Alkali-resistant R-glucan fraction. Three inhibitors of beta-1,3-glucan synthase (Cilofungin, Echinocandin B and Tetrahydro-echinocandin B), an enzyme involved in wall synthesis, increased branching in F. graminearum A3/5 without affecting specific growth rate, suggesting that this enzyme has a role in the determination of hyphal morphology in this organism. Differences in morphology observed between growth on semi-solid and in liquid medium could be attributed mainly to the presence of Cellophane on the semi-solid medium. The concentration of agar present in the medium was also found to affect hyphal morphology.
Notlar:
School code: 1543
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(686899.1) | 686899-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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