Influence de la nystatine,un antibiotique polyénique,sur la formation des stérols liés par complexes et sur la conidiation du Coprinus cinereus

Summary In contrary to the wild strain, a monocaryotic mutant of Coprinus cinereus (basidiomycete) does not contain hydrosoluble, complex-bound sterols. Under nystatine-treatment, however, the mutant is induced to produce this kind of stereols in abundance. Furthermore, nystatine highly increases sporulation of the mutant and decreases sporulation of the wild strain.

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Supporté par le Fond National Suisse, requête no 3.280.74.     

Mutants of Bacillus thuringiensis with altered sporulation: morphologic responses to several treatments applied in the exponential phase]

During log-phase of growth, wild strain and and oxytetracycline-resistant mutants with altered sporulation exhibit distinct responses to some treatments, autolysis, osmotic pressure, ultraviolet irradiation and bacteriophage infection.     

Comparison of exogenous cell fusion induced by a wild and two mutant strains of sheep Visna virus]

Exogen cell fusion induced in vitro by a wild strain of Visna virus of Sheep is compared with two mutant strains isolated from the precedent. One of them produces large plaques in vitro (strain LPF), and the other produces small plaques (strain SPF). These strains behave in different ways according to infection multiplicity, type of cells, temperature and timing of fusing activity. Taking the wild strain K 796 as a base of reference, the strain SPF seems to have a higher rate fusing activity and the strain LPF lower rate of fusing activity.     

Symbiotic efficiency in spontaneous mutants of Rhizobium legumino-sarum resistant to streptomyocin, spectinomycin, or kanamycin]

Symbiotic effectiveness of 45 mutant strains selected from four wild effective strains of Rhizobium leguminosarum for resistance to streptomycin, spectinomycin or kanamycin was determined on Vicia faba. Loss of effectiveness occurred in twenty of these mutants; distribution of ineffective mutants was uniform among the three types of antibiotic resistant mutants but varied with the parent strain from which mutants have been derived.     

Sclerotial and low aflatoxigenic morphological variants from haploid and diploidAspergillus parasiticus

Summary Serial transfer of mycelial macerates of a wild type, haploid, aflatoxigenic strain ofAspergillus parasiticus in a defined liquid medium resulted in the production of three new morphological classes: a sclerotial form with high aflatoxin production, and two variant forms (fan andfluff) with lowered sporulation, no sclerotia, and attenuated levels of aflatoxin. A genetically marked diploid containing mutant markers for aflatoxin pathway intermediates yielded the same three morphological classes upon serial transfer of macerated mycelia. When these diploid variants were treated with a haploidization agent, and the phenotypes of the resultant segregants scored, a low frequency of colonies producing aflatoxin pathway intermediates was recovered. These genetic data indicate that the structural genes for the aflatoxin pathway are present but somehow attenuated in thefan andfluff strains.This work was supported by a Cooperative Agreement from the U.S. Department of Agriculture, (58-7B30-3-556).     

Stimulation of sporulation ofClostridium perfringens by papaverine

Summary Papaverine induced sporulation inClostridium perfringens, strains FD-1 and PS52; growth was markedly slowed under these conditions. Papaverine induced sporulation in the presence of glucose, a sporulation repressor, although increasing glucose concentrations overcame the papaverine effect. Papaverine induced sporulation of strain FD-1 more effectively than did theophylline.The author wishes to thank Mrs P.A. Thompson for excellent technical assistance.     

Genetic localization of a mutation rendering the growth of E coli K12 insensitive to illumination at 365 nm]

The genotype of the Nop mutant recently isolated from the E. coli K 12 strain AB 1157 has been characterized. This mutant lacks 4-thiouridine in its tRNA and is much less susceptible to near ultraviolet-induced growth delay than wild type cells. This phenotype results from a single mutation called nuv which has been localized on the E. coli genetic map. nuv is found by conjugation to lie between the origins of injection of Hfr P4X and Hfr cavalli in the vicinity of the lac gene. Cotrans-duction with bacteriophage P1 more precisely maps nuv at 0.3 min. clockwise from tsx.     

Ammonia assimilatory enzymes in a nif−III mutant ofAzotobacter chroococcum

Summary The levels of ammonia assimilatory enzymes have been studied in a nif^–III mutant and a wild strain ofAzotobacter chroococcum grown in media containing different nitrogen sources. It is suggested that the nif^–III mutant may be defective in transport or incorporation of molybdenum.     

Stimulation of sporulation by ppApp in a conditionally asporogenous rifampin-resistant mutant in Bacillus subtilis

Addition of ppApp to Sterlini-Mandelstam medium stimulates sporulation of a conditionally asporogenous rifampin-resistant mutant of Bacillus subtilis to the same extent as the effect of 4 amino acids. Mutant cells sporulating in the presence of amino acids also produce 2 phosphorylated nucleotides one of which comigrated with ppApp on PEI thin layer chromatogram.     

A new type of mutant ofEuglena which produces permanently bleached progeny by darkness

Summary A new type of mutant ofEuglena gracilis strain Z was isolated. In the light-grown culture, it contains 5–20% of bleached cells which have irreversibly lost the ability of chloroplast formation. When once grown in the dark, differing from the case with the wild type, it segregates only bleached cells, probably due to the inability of the replication of proplastids in darkness. Cell multiplication under the inhibition of chlorophyll synthesis or photosynthesis in the light also produces bleached cells.     

Regulation of ppApp synthesis during sporulation of a conditionally asporogenous rifampin mutant ofBacillus subtilis

Summary The intracellular synthesis of ppApp in a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis stimulated to sporulate in the Sterlini-Mandelstam (SM) medium supplemented with ppApp is negligible and comparable to that of the non-sporulating culture. The formic acid extract from the sporulating culture stimulates sporulation of the mutant in SM medium.This paper was presented at the Annual Meeting of the American Society for Microbiology in Dallas, Texas, in March 1981. This work was supported in part by a grant from Research Corporation, New York, N.Y., USA.     

Incorporation of photolabile azido fatty acid probes inNeurospora crassa andSaccharomyces cerevisiae

Summary Photolabile azido fatty acids supported the growth of fatty acid auxotrophs, thecel mutant ofNeurospora crassa and the KD115 mutant ofSaccharomyces cerevisiae. These fatty acids were incorporated into the membrane lipids of thecel and KD115 mutants, but were not used by the wild type strain.This work was presented at the 26th International Congress of Pure and Applied Chemistry, Session 1, Tokyo, September 4–10, 1977, abstracts p. 241.Support was provided by the Govt. of India to B.C. and by NCERT, New Delhi India to D.N.C.To whom requests for reprints should be sent.     

A thermosensitive inhibitor of the replication of polyomavirus, an extract from BHK2I cells transformed by the Tsa mutant of this virus

BHK21 cells transformed by wild type or Ts3 mutant polyoma virus contain an inhibitor of polyoma virus replication when grown at permissive (36 degrees C) as well as non-permissive temperature (39 +/- 0.5 degrees C). Cells transformed by the Tsa mutant contain the inhibitor at the permissive but not at the non-permissive temperature. The inhibitor reappears in the latter cells however, upon shift from the non-permissive to the permissive temperature. If a reversible protein inhibitor (methionyl-adenylate, reversible inhibitor of the aminoacyl-t-RNA synthetase) is applied during the temperature shift experiments, the inhibitor does not reappear indicating that new protein synthesis is required for the recovery of its activity.     

Stimulation of sporulation by ppApp in a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis

Summary Addition of ppApp to Sterlini-Mandelstam medium stimulates sporulation of a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis to the same extent as the effect of 4 amino acids. Mutant cells sporulating in the presence of amino acids also produce 2 phosphorylated nucleotides one of which comigrated with ppApp on PEI thin layer chromatogram.Acknowledgment. This work was supported in part by a grant from Research Corporation, New York, New York.     

Occurrence of sepiapterin deaminase in the normal type silkworm,Bombyx mori

Summary Sepiapterin deaminase was prepared from the normal strain of the silkworm, Bombyx mori. After inhibition experiments, this enzyme was found to have the same properties as that isolated from the lemon mutant strain. Several new inhibitors and their K₁ values are described for the deaminase.The authors wish to thank Dr Wm. Gyure, Cape Cod Hospital, Hyannis, Massachusetts, USA, for his help in preparing this report.     

Phenotypic expression of the locus acute in Drosophila melanogaster]

The number of the long thoracic chaetae of heterozygote females born from crosses between a scute stock and various wild strains can be less than eight. Penetrance and dominance vary according to the wild strain considered. The phenomenon is probably connected with an anomaly of the development.     

Aminotransferase study ofNeurospora crassa ser-3 versus wild type ST4A

Summary TheNeurospora crassa serine auxotrophser-3 and the wild type ST4A were compared with respect to their phosphoserine and serine aminotransferase activities. The results obtained indicate no deficiency of either of these enzymes in the mutant strain.This work was supported in part by a grant to D.G. from the California Foundation for Biochemical Research. The authors also wish to thank Dr Robert G. Wolcott, formerly of the Department of Chemistry, California State University, Northridge, for his valuable advice and for the use of his department's liquid scintillation counting system. We acknowledge with appreciation the skilled technical assistance of Mr Tom Harper.     

Transfer of the tetracycline-chloramphenicol plasmid in Clostridium perfringens]

Two plasmids which confer resistance to Tetracycline-Chloramphenicol and Erythromycine-Clindamycine were found in a strain of Clostridium perfringens. The plasmid (Tet-Chl) was shown to be transferable to sensitive strains of C. perfringens. The transfer experiments were made with the wild type strain or strains cured by one plasmid or the other as donor strains.     

Synergism between aggregation mutants of Dictyostelium discoideum]

The cells of an aggregateless mutant of Dictyostelium disco?deum, agip 235, can cooperate with other aggregateless or wild strains to form differentiated aggregates. A soluble mediator liberated by the coaggregating cells seems responsible for the development of agip 235. In most cases, the development of mutant agip 235 stops at the aggregation stage; however, its coaggregation with the mutant 518 results in cosporulation, with the production of viable spores of each genotype, effecting a phenotypic suppression of both mutations.     

Induction by sodium dodecylsulfate of the circadian rhythm of conidiation inNeurospora crassa

Cellular and Molecular Life Sciences - The circadian rhythm of conidiation expressed by the mutantband ofNeurospora crassa can also be induced in the wild strain by Na-dodecylsulfate. This...