Nicotinic acid suppressors inAspergillus nidulans

Zusammenfassung Neun Suppressoren des Mutantennic 8 vonAspergillus nidulans wurden in der Kopplungsgruppe VII der Chromosomenkarte lokalisiert und unter verschiedenen Aspekten studiert. Eine Hypothese über die Mechanik der genetischen Regulierung der Erzeugung der Nikotinsäure wurde formuliert.     

Regulation of ammonia uptake inAspergillus nidulans

Summary The ammonia uptake inA. nidulans was found to be linear for about 20 min, and was proportional up to 1.5 mg/ml dry cell density. The transport of ammonia does not involve energy. Normal and biotin deficientA. nidulans showed an identical K_m-values of 10.26×10^–5 M ammonia for uptake. The uptake of ammonium ion has been shown to be regulated by the intracellular concentration of ammonia.Acknowledgment. The award of research fellowship by the Govt of India, Department of Atomic Energy, Bombay, to JDD is acknowledged.     

Resistance to ethidium bromide inAspergillus nidulans

Summary A mutant ofAspergillus nidulans resistant to ethidium bromide was isolated and the semi-dominant gene responsible for this resistance was allocated on linkage group II at 17.42±3.05 units of recombination from thewA₃ gene. The gene also confers cross-resistance to acriflavin, malachite green and crystal violet. It was also shown that riboflavin is antagonistic to the toxic effect of ethidium bromide, at certain concentrations. The mechanisms which could be responsible for the toxic effect of this drug are discussed and compared with those of acriflavin. The use of theEtb ₁ gene in genetical analysis through the parasexual cycle is suggested.Acknowledgements. The authors are thankful to the National Council for the Development of Science and Technology (CNPq) for financial support through PIG-SIP 04/053 FAPESP.     

Genetic and allied effects of certain esters of inorganic acids inAspergillus nidulans

Resumen Fueron investigados los efectos mutagénicos de cinco esteres de acidos inorgánicos sobre el mutante bi^–1; meth^–1 delAspergillus nidulans. El método empleado fué el teste de retrocruzamiento con algunas variaciones. El dimetil sulfato se ha mostrado como el mas poderoso mutagénico, seguido por el di-etil sulfato. El mecanismo de induccion mutacional fue discutido y se estableció una hipótesis para explicarla.     

Partial complementation inAspergillus niger heterocaryon

Zusammenfassung Erzwungene Heterokaryen-Vereinigung zwischen Hypoxanthin und Histidin abhängiger Mutanten vonAspergillus niger, die auf minimalem Nährboden ohne Sporenproduktion wachsen. Das Phänomen wird als teilweise Ergänzung bezeichnet und als Gleichgewichtsstörung der Kerntypen im Heterokaryen oder als Verdünnungseffekt eines Genproduktes zweiter Ordnung im Zytoplasma gedeutet.     

Repressible alkaline phosphotase inAspergillus niger

Summary ALP fromA. niger is a) P_i repressible enzyme; b) stimulated by addition of Zn⁺⁺ to the growth medium, and c) that EDTA inhibits the enzyme reversibly, which could be restored by addition of Zn⁺⁺ and perhaps Mg⁺⁺. This property is in contrast to the enzyme fromN. crassa, which is independent of any metal requirement.     

Metabolic status of temperature induced swollen conidia ofAspergillus nidulans

Summary There is an active synthesis of DNA, RNA, protein, and carbohydrate in conidia incubated at 48°C. DNA increases more or less 3 times; while RNA, protein and carbohydrate are synthesized at a much faster rate. Conidia do not germinate at this temperature.Acknowledgments. Grateful thanks are due to Professor B. M. Johri for valuable suggestions. R. K. S. acknowledges with thanks a Senior Research Fellowship of the Council of Scientific and Industrial Research, New Delhi.     

Induced production of cleistothecia inAspergillus unguis

Résumé SynonymieAspergillus unguis etA. nidulans basée sur l'obtention de périthèces chezA. unguis.     

Biotin and fatty acid biogenesis inAspergillus flavus

Zusammenfassung Avidin vermindert die Biosynthese von Fettsäuren inAspergillus flavus, die nur von Biotin überwunden wird. Ähnliche Phänomene werden in anderen Pilzen gefunden.     

Induced morphogenetic variations inAspergillus oryzae by 8-azaguanine

Résumé Proliférations de l'appareil sporifère d'Aspergillus oryzae traité à l'azaguanine.

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The authors are deeply indebted to Dr.O. Isler of F. Hoffmann-La Roche, Basel (Switzerland) for his generous gift of 8-azaguanine and 6-azauracil. They are also grateful to the University Grants Commission, at New Delhi, which financed this research programme by grant-in-aid No. F-8/5-63 (G), to R.K.K.     

La nidulotoxine: toxined'Aspergillus nidulans Wint

Zusammenfassung Isolierung, Charakterisierung, Reinigung und toxische Wirkung eines Toxins ausAspergillus nidulans Wint.     

Increased fusion frequency ofAspergillus nidulans protoplasts

Zusammenfassung Die Häufigkeit der Protoplastfusion auxotropher Mutanten vonAspergillus nidulans wurde durch Zugabe von 0.6M KCl oder NaCl gesteigert.

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The authors thank Dr.R. F. Rosenberger for the strainAspergillus nidulans pabal,y, ts6; ProfessorJ. G. H. Wessels and Dr.O. M. H. de Vries for discussions, and Dr.I. Rojik for help in electron microscopy.     

Heterotrophic growth in the blue-green algaAnacystis nidulans

Summary Anacystis nidulans was grown heterotrophically in the dark for the first time. Pyruvate served as the carbon source. The cells did not make pigments when grown heterotrophically, but synthesis of pigments resumed upon transfer of the cells to the light. *** DIRECT SUPPORT *** A2025089 00005     

Regulation of glucose transport in Aspergillus nidulans

Summary Pyruvate and acetate inhibited the uptake of glucose by Aspergillus nidulans; although there were significant variations in glucose uptake rate, the intracellular concentration of acetate was almost identical in biotin-supplemented, normal and deficient cells. The in vitro activity of glucose-binding protein was not affected by biotin, avidin, acetate or acetyl-CoA.J. D. Desai gratefullt acknowledges the receipt of Research Fellowship from the Govt. of India, Department of Atomic Energy, Bombay.     

Adenosine triphosphatase ofAspergillus nidulans: Stimulation by aminoacids

Summary Ca²⁺-dependent ATPase ofAspergillus nidulans was found to be stimulated by aminoacids in vitro. Both histidine and arginine stimulated the enzyme more effectively than the aromatic aminoacids. Supplementation of the growth medium with basic or aromatic aminoacids increased the enzyme activity in vivo 2–6-fold. The enhanced activity observed in these cultures in vivo was not mediated through the synthesis of new isoenzyme, as observed in proteinenriched cultures, but appeared to be through the activation of enzyme activity.     

Transfer of isolated nuclei into protoplasts ofAspergillus nidulans

Nuclei were isolated from protoplasts of a haploid auxotrophicAspergillus nidulans strain. Transformation of protoplasts prepared from a complementary haploid auxotrophic strain with these purified nuclei resulted in both heterokaryotic and diploid colonies. The nutritionally-complementing colonies appeared at a frequency of 5×10^–7 to 10^–8.