Arylamidase of Cephalosporium acremonium and Its Specificity for Cephalosporin C

Three aggregational forms of arylamidase are produced by Cephalosporium acremonium. The exocellular enzyme, with an approximate molecular weight of 60,000, was purified 300-fold by diethylaminoethyl cellulose chromatography, gel filtration, and gel electrophoresis. With l-leucyl-beta-naphthylamide as the substrate, the K(m) is 4.2 x 10(-4)m; the optimum pH, 7.7; and the temperature optimum, 35 C. The enzymatic hydrolysis of l-leucyl-beta-naphthylamide is inhibited by a number of cephalosporins, whereas a variety of penicillins show no effect. Alternatively, the enzyme specifically catalyzes the beta-lactam hydrolysis of a number of cephalosporins; a number of penicillins are resistant. The K(m) for cephalosporin C is 9.09 x 10(-4)m.     

Comparison by Gas-Liquid Chromatography of the Fatty Acids of Mycobacterium avium and Some Other Nonphotochromogenic Mycobacteria

Fifty-eight strains of nonphotochromogenic mycobacteria representing nine different serotypes were studied, including 38 strains of Mycobacterium avium and 20 strains of Battey bacilli. The lipids were extracted from whole cells, saponified with potassium hydroxide, and esterified with diazomethane. The fatty-acid profiles determined by gas-liquid chromatography included saturated fatty acids ranging from C(8) to C(24), plus some unsaturated analogues and a branched-chain acid. No consistent differences in the fatty-acid profiles were observed between strains of M. avium and Battey bacilli. Quantitative differences in the means (significant at P < 0.01) were observed in the relative amounts of 14:0, 16:1, 18:0, 18:1, and a branched-chain acid among strains of the same serotype. We were unable to differentiate the fatty-acid profiles of recently isolated strains or those maintained in culture for more than 2 years.     

Electrical Properties and Ultrastructure of Mycoplasma Membranes

Mycoplasma, in particular species laidlawii and gallisepticum, are found to have a very small, low frequency conductivity as would be predicted by the dielectric model for bacteria and their apparent lack of cell wall structure. Membrane capacitance values for the two organisms are both about 0.9 μF/cm², although electron micrographs show that the membrane of M. gallisepticum is 20-40 A thicker than that of M. laidlawii.     

Variations des activités peroxydasique et phénoloxydasique au cours de la croissance de Coleus blumei Benth. var. Automne

Summary The specific peroxidase (1.11.1.7) and phenoloxidase (1.10.3.1) activities are quantitatively measured during the life of Coleus, from germination until flowering. In most organs investigated, the peroxidase activity increases rapidly with growth while the phenoloxidase activity remains low. The latter activity is higher in root apices than in more differentiated regions of roots. From the results obtained it may be concluded that the phenoloxidase activity accompanies cellular proliferation. It is suggested that the peroxidase activity plays an indirect role in root initiation through its role in cellular differentiation.

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Extrait d'une thèse de doctorat soutenue à la Faculté des Sciences de l'Université de Liège.     

Comparative Zone Electrophoresis of Enzymes of Pseudomonas solanacearum and Pseudomonas cepacia

The technique of starch-gel electrophoresis with specific staining for a series of enzymes was used to compare 21 Pseudomonas strains representing both P. cepacia and P. solanacearum. These experiments produced no evidence for close similarity of the two species. Twelve strains of P. solanacearum were compared by means of data obtained from nine different enzymes, and the data indicate that these strains belong in two biotypes. Except for the assignment of two strains, these groups are the same as the two major groups previously derived from nutritional properties and from deoxyribonucleic acid hybridization experiments. Eleven enzymes were available for comparisons of the P. cepacia strains. Eight of these strains form a homogeneous group, but the last strain, number 249, differs considerably from the other representatives of the species.     

Localization of Two Functions of the Phosphoribosyl Anthranilate Transferase of Escherichia coli to Distinct Regions of the Polypeptide Chain

The trpD gene specifies a polypeptide which has both glutamine amidotransferase and phosphoribosyl anthranilate (PRA) transferase activities. Deletions fusing segments of trpD to the gene preceding it in the operon, trpE, were selected in strains carrying various trpD point mutations. The selection procedure required both that a deletion enter trpE and that it restore the PRA transferase activity which the parent trpD point mutant lacked. Deletion mutants were found which had PRA transferase activity although the first third of trpD was deleted. The existence of the mutants proves that a terminal segment of trpD is sufficient to specify a polypeptide having PRA transferase activity. The location of the deletion end points on the genetic map of trpD defines the extent of the trpD segment required for PRA transferase activity. This segment did not overlap the initial region of trpD required to specify the glutamine amidotransferase function of the trpD polypeptide. These results support the hypothesis (M. Grieshaber and R. Bauerle, 1972; H. Zalkin and L. H. Hwang, 1971) that the bifunctional trpD polypeptide might have evolved by fusion of a gene specifying a glutamine amidotransferase with a gene directing PRA transferase synthesis.     

Change in Properties of Physarum polycephalum Amoebae During Extended Culture

During two years of passage, several myxamoebal strains of Physarum polycephalum changed with regard to their properties in crosses and plaque morphology. These changes have been correlated with increased nuclear deoxyribonucleic acid content.     

The Direction of Linkage Disequilibrium

The previous paper (Langley, Tobari and Kojima 1974) reports that the directional linkage disequilibria, D_ω = P_ABP_ab-P_AbP_aB, tend to be negative for data between allozymes and linked to inversions. A and B stand for the two alleles with the greatest frequency in the population. In this paper we show that linkage disequilibrium in this direction is produced at equilibrium when double homozygotes have fitnesses that are a constant fraction of the product of the two component single homozygote fitnesses, a pattern that is frequently observed in experimental data.     

The isolation of cholest-5-ene-3β,26-diol from human brain (Short Communication)

Cholest-5-ene-3beta,26-diol, isolated from human brain, was further characterized by oxidation to 3-oxocholest-4-en-26-ol and to 3-oxocholest-4-en-26-oic acid. Identification was achieved by comparison (by t.l.c., g.l.c. and g.l.c.-mass spectrometry) with corresponding reference compounds derived from kryptogenin.