摘要:

AbstractThe ability ofPyricularia oryzaeto grow and sporulate under various artificial environmental conditions was investigated. The pathogen grew best on Potato Dextrose Agar and sporulated best on one percent Soluble Starch Yeast Extract Agar. Ammonium chloride medium as nitrogen source favoured its growth and conidia production. The pathogen utilized xylose, arabinose, starch, glucose and inulin for growth and conidia production. The minimum, optimum and maximum temperatures for growth and conidia production were 10°, 25° and 37°C. The humidity treatment increased conidia production from 8.0 × 103to 18.4 × 103conidia/ml. The optimal pH range for growth was 5.5–10.5 and 5.5–7.0 for conidia production. Exposing cultures to continuous artificial illumination enhanced conidia pr

ISSN:0233-111X    

DOI:10.1002/jobm.3620310302

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

摘要:

AbstractA total of 161 strains, including 144 aeromonads, of which 100 had been isolated from water and sediment samples from the Chesapeake Bay, five clinical and 33 Anacostia River isolates ofAeromonas hydrophila, sixAeromonas sobria, and ten reference cultures were examined in a numerical taxonomy study in which each of the strains were examined for 56 unit characters. Similarity between strains was computed using the simple matching (SSM) and Jaccard (SJ) coefficients. The strains were clustered by unweighted average linkage and single linkage algorithms. Results of all analyses yielded similar clusterings of strains. Of the 161 strains included in the study, 148 were recovered in seven major clusters. A large cluster ofAeromonas hydrophilayielded two sub‐clusters. From the results of the taxonomic analysis it is concluded that several biovars ofAeromonas hydrophilacan be isolated from the aquatic environment, but geographical or site specific distribution of the biovars could not be detecte

ISSN:0233-111X    

DOI:10.1002/jobm.3620310303

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

摘要:

AbstractThe conversion of l‐[α‐2H]alanine in H2O and unlabeled l‐alanine in2H2O into d‐alanine, under nearly irreversible conditions, with the amino acid racemase fromPseudomonas striatashowed significant internal transfer of the α‐hydrogen. This result has been interpreted as being indicative of a single base mechanism for the racemization.The relative rates of deuterium incorporation into unlabeled d‐ and l‐methionine by the two amino acid racemases of broad substrate specificity fromP. striataandAeromonas caviae, were measured in2H2O. The results showed a markedly different pattern, dependent upon the configuration of the initial substrate; with d‐methionine as substrate deuterium is incorporated into both enantiomers at approximately the same rate, but with l‐methionine as substrate deuterium is incorporated considerably faster into the d than the l enantiomer. These results argue against a single base mechanism of racemization for these enzymes and are best rationalized in terms of a double base model where only one of the bases undergoes proton (deuterium) exchange with the solvent while the amino acid is enzyme‐bound. The interpretation of the earlier experiment needs to be considered in l

ISSN:0233-111X    

DOI:10.1002/jobm.3620310304

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

摘要:

AbstractThe addition of d(+)‐glucose (final concentration 50 mm) to a cell suspension of yeasts (wild type and several mutants of the cell cycle, the cAMP‐dependent protein kinase system, and a mutant of the adenylate cyclase gene) triggers a rapid increase in the concentrations of cAMP and cGMP in the wild strain. In contrast to cAMP, an increase of cGMP was also found in the mutants.cAMP and cGMP have been characterized as second messengers in eucaryotic cells. Cyclic nucleotide activation of the protein kinases enables them to perform their only known function in eukaryotes, the phosphorylation of substrate proteins.The results, described here by using selected yeast mutants as a model for higher eukaryotes, indicate that there exist two different regulatory systems for the control of the cAMP and cGMP lev

ISSN:0233-111X    

DOI:10.1002/jobm.3620310305

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

摘要:

AbstractProtein kinases represent a diverse family of enzymes that play a critical role in regulation. Among nearly 100 known protein kinases, the cAMP‐dependent enzyme is best understood biochemically. Unlike other protein kinases, cAMP‐dependent protein kinase consists of two different types of subunits that dissociate, a regulatory subunit (R), which is the receptor for cAMP, and a catalytic subunit (C). In the absence of cAMP, the enzyme exists as an inactive tetramer, R2C2.The binding of intracellular cAMP to the R subunit decreases the affinity of the R subunit for the C subunit by approximately four orders of magnitude and, under physiological conditions, leads to dissociation of the holoenzyme into R2(cAMP)4dimer and two free C subunits that are catalytically active. Mutants of the cAMP metabolism, adenylate cyclase and cell cycle mutants, provided further information about protein synthesis and cellular growth inSaccharomyces cerevisiae.The purified protein kinases were divided into different types according to their elution profiles from the DEAE‐cellulose matrix. Two types of cAMP‐dependent and two types of cAMP‐independent protein kinases were isolated from the wild strain. Differences in the activities of the kinases in the mutants showed a close relationship to the locus of the respective mutations in the cell‐cycle. Some properties of the protein kinases are discussed with respect to individua

ISSN:0233-111X    

DOI:10.1002/jobm.3620310306

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620310308

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

摘要:

AbstractIn temperate phagexofSerratia marcescensseveral special features of different phages are combined. The unessential geneslI,iny,cIIand, at least to some extent, even the integrase geneintare not subject to negative control by the repressor, the product of genecIII. A genetic map of the prophage was established using defective, heat‐induced lysates ofint−lysogens both in vegetative crosses withsusmutants of essential genes and in transduction of the four unessential genes to lysogenic recipients. Results from reciprocal four factor‐crosses concerning the order of the four genes had to be included. The four genes are located near the right end of the prophage, whereascIIIlies near its left end. In vegetative phage all five genes lie in an interval between the essential genesTandU, comprising 10% ofx's genetic map. The right prophage end appears to face at least twotrpcistrons, among them the gene encoding anthralinate synthetase.lIencodes a product that masks the phage receptors in the cell wall. The gene product ofinyinterferes with the growth of infecting phage y. The natural function ofcIIis still unknown, but some of its mutants display a cold‐sensitive phenotype, their plaques being clear at 30°C and turbid at 37°C. Bacteria with such prophages stop producing viable progeny when the cultures are shifted from 37°C to 30°C. These cold‐sensitive mutants are partly dominant and partly recessive.Analysing a virulent mutant, a geneantencoding an antirepressor was discovered, but so far there is no evidence that it is regulated by an extra repressor. The gene is located relatively near the left prophage end.Evidence is presented that the exogenotes in transduction with the defective lysates continue to exist for some time after a first recombin

ISSN:0233-111X    

DOI:10.1002/jobm.3620310309

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

摘要:

AbstractStudies on the α‐amylase synthesis were carried out with two strains ofBacillus licheniformis: a mutant strain 44MB82 and its selected variant 44MB82‐G. The cells were cultivated in a nutrient medium containing glucose or citrate as a carbon source. The results obtained indicated that α‐amylase was produced in both strains without inducers in the medium. The variant strain 44MB82‐G, which synthesized α‐amylase in the presence of 6% glucose, showed 58‐fold increased α‐amylase activity compared to strain 44MB82 grown in the presence of 2% glucose. When cells of both strains were cultivated in a medium with 1% citrate, α‐amylase activity of the variant strain was 5 times higher than that of strain 44MB82. The effects of starch and ATP on α‐amylase synth

ISSN:0233-111X    

DOI:10.1002/jobm.3620310310

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

摘要:

AbstractOn the basis of literature data and our own experiments the “late” biosynthetic pathway to daunomycin has been interpreted from a new point of view considering both thein vivobiosynthesis and formation of shunt products. In contrast to existing hypotheses proposed by other authors we discuss a modified sequence leading to C‐11 oxidation and, as a consequence, understand ϵ‐rhodomycinone as a shunt product instead of a biosynthetic intermediate.In addition, a new hypothesis about the “early” steps of the ring formation from polyketides by a sequence of enzyme reactions has b

ISSN:0233-111X    

DOI:10.1002/jobm.3620310311

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620310301

出版商:Wiley‐VCH    

年代:1991

数据来源: WILEY