Instability of an Aflatoxin-Producing Strain of Aspergillus parasiticus

Mayne, Ruth Y.; Bennett, Joan W.; Tallant, John D.

doi:10.2307/3757563

Cited by 18 publications

(11 citation statements)

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“…This change in aflatoxin-producing ability occurred both when the strains were cured of dsRNA and when they remained infected. Single conidial transfer was repeatedly reported to influence the aflatoxin-producing ability of strains (Lemke et al 1989;Schroeder 1969;Mayne et al 1971). However, generally these changes were not as consistent as those reported here.…”

Section: Effect Of Dsrna Infection On Aflatoxin Productioncontrasting

confidence: 79%

Incidence and stability of infection by double-stranded RNA genetic elements inAspergillussectionflaviand effects on aflatoxigenicity

Elias¹,

Cotty²

1996

Can. J. Bot.

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Ninety-two isolates belonging to Aspergillus sect. j7avi were analyzed for double-stranded (ds) RNA via standard cellulose chromatography. Double-stranded RNA infection was detected in fungal isolates that had been in culture for long periods (5 of 26 were infected) and in those recently isolated (5 of 66 were infected). The number of dsRNA genetic elements differed among infected isolates and no two isolates contained identical dsRNAs on the basis of electrophoretic migration in agarose gels. Addition of micronutrients to culture media affected both the amount of dsRNA produced and the number of dsRNA genetic elements detected. Attempts to cure six fungal isolates of dsRNA by serial single conidial transfer, chlorate selection for nitrogen-metabolism mutants, and cycloheximide treatment, met with variable results. The frequency at which serial single conidial transfer and nitrogen-metabolism mutant (nit) selection successfully cured six Aspergillus sect. j7avi isolates varied from 11 to 100% and 0 to loo%, respectively. The cycloheximide treatment was effective at curing 40% of the dsRNA-infected isolates. Comparison of aflatoxin production prior to and after dsRNA curing indicated that infection by dsRNA did not influence aflatoxin production. However, aflatoxin production by two isolates (91-03 1B and 91-1846) was reduced by both single conidial transfer and induction of nit mutants.RCsumC : Les auteurs ont analysC 92 isolats de 1'Aspergillus sect. j7avi pour dttecter 1'ARN doubles brins, en utilisant la chromatographie de base sur cellulose. Une infection par ARN 6 doubles brins a Ct C dtcel6e chez des isolats fongiques prialablement cultivCs depuis longtemps (5 sur 26 portent une infection) et chez ceux cultivCs depuis peu (5 sur 66 portent une infection). Les nombres d'kltments ARN 2 doubles brins diffkrent entre les isolats infect& et, sur la base de la migration ClectrophorCtique sur gels d'agarose, aucun des isolats ne contient des ARNs 6 doubles brins identiques. L'addition de micronutriments aux milieux de culture affecte la quantite d'ARN a doubles brins aussi bien que le nombre d'ClCments gCnCtiques ARN 6 double brins dttectb. Les auteurs ont obtenu des resultats variables, aprks avoir tent6 d'Climiner I'ARN 6 doubles brins chez six isolats fongiques en conduisant une sCrie de transfert a partir de conidies individuelles, en effectuant une sClection de mutants pour le mCtabolisme azotC sur chlorate ou en les traitant 6 la cycloheximide. La frtquence a laquelle les transferts de conidies isolCes et la sClection de mutant du mCtabolisme azotC (nit) ont rkussi 6 gutrir six isolats de I'Aspergillus sect. j7avi va de 11 5 loo%, et de 0 6 loo%, respectivement. Le traitement a la cycloheximide 6 permis de gutrir 40% des isolats infect& par des ARN 6 doubles brins. Une comparaison de la production d'aflatoxine, avant et aprks llClimination des ARN 6 doubles brins, indique que l'infection par ces ARNs n'influence pas la production d'aflatoxine. Cependant, la production d'aflatoxine par deux isolats (91-031B e...

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Section: Effect Of Dsrna Infection On Aflatoxin Productioncontrasting

confidence: 79%

Incidence and stability of infection by double-stranded RNA genetic elements inAspergillussectionflaviand effects on aflatoxigenicity

Elias¹,

Cotty²

1996

Can. J. Bot.

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“…For aflatoxin assays, cultures were grown on shredded wheat as described by Mayne et al (1971). For anthraquinone assays, the liquid defined medium (AM) devised by Adye & Matales (1964) was used, except that it contained sucrose (50 g 1-I) instead of glucose.…”

Section: Methodsmentioning

confidence: 99%

“…Loss or attenuation of aflatoxigenicity by originally highly toxic strains of A.flavus and A . parasiticus has been reported after serial transfers in the laboratory on synthetic and natural substrates for mass transfers (Kulik & Holaday, 1966;DeVogel et al, 1965), single spore isolates (Mayne et al, 1971) and after exposure to barium ions (Lee & Townsley, 1968).…”

Section: Introductionmentioning

confidence: 99%

Aflatoxins and Anthraquinones from Diploids of Aspergillus parasiticus

Bennett

1979

Journal of General Microbiology

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127Three spore colour, two mycelial colour and 12 auxotrophic mutants were isolated from an aflatoxigenic strain of Aspergillus parasiticus. These mutants and heterozygous diploids formed by pairwise combinations of auxotrophs were assayed for aflatoxin production ; norsolorinic acid and versicolorin A production were also assayed in the diploids. In general, introduction of an auxotrophic marker lowered aflatoxin production in haploids. The green-spored, prototrophic diploids resembled haploid wild-type strains in that they produced high levels of aflatoxin, low levels of versicolorin A, and no detectable norsolorinic acid. Parasexual analysis of segregants from four heterozygous diploids was hampered by the uniform conidiospore diameter of haploids and diploids and by the non-random recovery of genotypes among somatic segregants with and without treatment with p-fluorophenylalanine. Nevertheless, this technique is useful for recombinational analysis of mutants blocked in aflatoxin synthesis. The fortuitous association of mycelial pigmentation with certain blocked aflatoxin mutants should prove useful in future analyses of the genetics and biosynthesis of these economically important secondary metabolites.

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“…Spore concentration Most A. parasiticus strains are fairly stable in afl atoxin production in culture; however, Mayne et al (1971) found strain M-3 (the source of NRRL 2999) to be unstable. They reported that six weekly successive mass spore transfers onto agar media led to signifi cant reductions in the amount of afl atoxin produced.…”

Section: Culture Conditions Infl Uencing Afl Atoxin Productionmentioning

confidence: 98%