SUMMARYThe influence of casein hydrolysate and certain amino acids on the uptake and utilization of tryptophan and other precursors of nicotinic acid biosynthesis by a mutant of Neurospora crmsa which can grow on tryptophan or nicotinic acid was investigated. Whereas casein hydrolysate and certain amino acids inhibited the growth of the organism when tryptophan, kynurenine, or 3-hydroxykynurenine was present in the medium, they had no effect in the presence of other precursors, i.e. 3-hydroxyanthranilic acid or nicotinic acid. Studies have been made with wild strain and the mutant on the amount of tryptophan taken up from the medium a t different periods of growth of the organism.
Panicker, Radha K., and E. R. B. Shanmugasundaram. (U. Madras, India.) Temperature‐independent riboflavineless mutants of Aspergillus nidulans. Amer. Jour. Bot. 49(6): 555–559. Illus. 1962.—Studies on the biosynthesis of riboflavine using 5 non‐allelic, riboflavineless mutants of Aspergillus nidulans show that: (1) all of them are temperature‐independent; (2) optimal amounts of the vitamin required for maximal growth vary from one mutant to the other; (3) the riboflavine activity of purines and pyrimidines on the mutants are none too different from the earlier observations on Neurospora crassa, Eremothecium ashbyii and Ashbya gossypii; and (4) the isoalloxazine and alloxazine derivatives are not only devoid of vitamin activity but also slightly inhibit the growth of the mutants in presence of the vitamin.
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