Conidiation in Neurospora

Two growth stages, conidia (C) and mycelium (M), and two media, minimal medium (MM) and complete medium (MC), were compared in 10 strains of M. anisopliae, and two strains of M. anisopliae var. majus were similar in percentages of total lipids. Tukey test for average of lipid content in conidia (C) and mycelia (M) cultured on minimal (MM) and complete (MC) media showed significant differences between means at the 5% level for mycelia and conidia, indicating variability in total lipid production and storage during growth. Strains 5 and 7, both variety majus, did not present sizable differences from variety anisopliae. For fatty acids, C18:1 and C18:2, oleic and linoleic, respectively, the differences were all highly significant (p= 1%) with the highest means being obtained for conidia for fatty acid C18:1 and for myclelia for fatty acid C18:2.

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“…In fungi in general, lipids have been reported to be important for germination, in addition to having other functions (4,15,23)…”

Section: Resultsmentioning

confidence: 99%

Total lipids and fatty acids of strains of Metarhizium anisopliae

Pupin¹,

Messias²,

Piedrabuena³

et al. 2000

Braz. J. Microbiol.

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“…crassa offers many advantages for studying the mechanisms of sporulation, with its huge resource of genetic, molecular and developmental information. Valuable information is available on conidiation (Urey, 1971 ;Turian & Bianchi, 1972;Berlin & Yanofsky, 1985;Springer & Yanofsky, 1989). A wild isolate of N .…”

Section: -6792 0 1991 Sgmmentioning

confidence: 99%

Microcycle conidiation and its genetic basis in Neurospora crassa

Maheshwari

1991

Journal of General Microbiology

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Some wild isolates of Neurospora show microcycle conidiation in liquid culture under continuous agitation. Macroconidia from agar-grown mycelial cultures germinated in liquid and the germlings spontaneously produced conidia with no intervening mycelial phase. Three types of microcycle conidiation were seen among progeny of N. crussu Vickramam A x N. crussu u wild-type: (1) multinucleate blastoconidia produced by apical budding and septation, (2) multinucleate arthroconidia produced by holothallic septation and disarticulation of cells, and (3) uninucleate microconidia produced directly from conidiogenous cells of the germlings. Two genes were identified which control specific patterns of microcycle conidiogenesis. A single gene rncb in linkage group VR near uf-3 (3.2% recombination) controls blastoconidiation. This gene is epistatic to gene rncrn located in linkage group IIL, very near ro-7 (1.4 %). rncrn controls both microconidiation and arthroconidiation depending on temperature. Strains of genotype rncrn produce microconidia almost exclusively at 18-22 "C, but arthroconidia with few or no microconidia at 30 OC. Because they result in rapid and synchronized conidiation in liquid culture, the two genes should be useful for studies of developmental gene regulation. rncrn makes it possible to obtain large quantities of pure microconidia rapidly for experimentation.

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“…This suggested a derepression effect which we have studied further in relation to the conidium-inducing effect of our low-sugar ammonium medium. Isocitrate lyase has been included for comparison with the oxidative activity of ADH because of its sensitivity to glucose or catabolite repression (Kornberg, 1959;Flavell & Woodward, 1970;Heick, 1971) and the common link of these enzyme activities with the acetate, conidiogenous metabolism (Turian, I 961 ;Turian & Bianchi, 1972).…”

Section: Induction Of Conidium Formation Inmentioning

confidence: 99%

“…For some reason, for example concurrent pentose-phosphate shunt stimulation through NADP-NADPH, shuttle (Turian & Bianchi, 1972), nitrate counteracted the repressive effect of 2.0 yo (w/v) sucrose, as expressed by the enzyme activities measured as well as by its conidiogenous activity even in the presence of high sucrose concentrations (Hanks & Sussman, 1969). The sugar repression, probably through effects on cyclic AMP or adenyl cyclase, was effective only on the ammonium medium, with high reductive alcohol -dehydrogenase activity as its most evident sign.…”

Section: E T H O D Smentioning

confidence: 99%

Induction of Conidium Formation in Neurospora by Lifting of Catabolite Repression

Turian

1973

Journal of General Microbiology

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I N T R O D U C T I O NIn a synthetic, liquid medium with ammonium instead of nitrate as nitrogen source and sucrose (2 yo) as the main carbon source, formation of macroconidia on the mycelial mat of Neurospora crassa is prevented (Turian, I 964). The anticonidial (repressive) effect of such a medium (M-medium) is reinforced by increasing the sucrose concentration but nullified by lowering it (Oulevey-Matikian & Turian, 1968). The same repressive effect is produced with glucose, and is accompanied by increased ethanol liberation through alcohol dehydrogenase (ADH) reductive activity (Turian, I 972). Acrylamide-gel electrophoresis of mycelial cultures of Neurospora crassa grown on the ammonium M-medium revealed only one wide alcohol-dehydrogenase band, but a second presumed to be an ADH with oxidative activity was detected in extracts of conidium-forming, nitrate-grown cultures (DelVecchio & Turian, 1968). A similar oxidative ADH was found by Zink (1969) to be synthesized in Neurospora grown on ethanol or in older, sugar-depleted cultures. This suggested a derepression effect which we have studied further in relation to the conidium-inducing effect of our low-sugar ammonium medium. Isocitrate lyase has been included for comparison with the oxidative activity of ADH because of its sensitivity to glucose or catabolite repression (Kornberg, 1959; Flavell & Woodward, 1970; Heick, 1971) and the common link of these enzyme activities with the acetate, conidiogenous metabolism (Turian, I 961 ; Turian & Bianchi, 1972). M E T H O D SNeurospora crassa (wild-type Lindegren A) was grown on modified Westergaard & Mitchell's media (1947), containing either nitrate and I O -~ M-potassium citrate to provide a conidiogenous medium, or I o -~ M-diammonium citrate replacing the above compounds to provide a myceliogenous medium. The standard 2.0% (w/v) sucrose content of these media was lowered to 0.2% (w/v) in half of the ammonium-containing cultures (Turian, For studies in enzyme activities, 250 ml Erlenmeyer flasks containing 50 ml liquid media were inoculated with 0.2 ml heavy conidial suspension and incubated for 60 h at 25 "C in partial darkness (short, daily light exposures to stimulate conidiation). The thick vegetative or thinner conidiated mycelia were harvested, washed with distilled water, dried between filter paper and disrupted with quartz sand in cold 0-1 M-tris-HCI buffer at pH 8.5. The homogenates were centrifuged at 10000 g for 20 min at o "C and the supernatants used in assays as alcohol-dehydrogenase(s) without any attempt to fractionate this total ADH into its isozymes. For the reductive assay of ADH, the reaction mixture consisted of: 0.

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Conidiation in Neurospora

Cited by 84 publications

References 114 publications

Total lipids and fatty acids of strains of Metarhizium anisopliae

Total lipids and fatty acids of strains of Metarhizium anisopliae

Microcycle conidiation and its genetic basis in Neurospora crassa

Induction of Conidium Formation in Neurospora by Lifting of Catabolite Repression

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