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Biomedical subjects

Y Mizuguchi

Publications and source records attributed to Y Mizuguchi.

At least 109 records · Page 6Linked to original sources
PubMed1979

Interaction between 30 S ribosomal components in a viomycin resistant mutant of Mycobacterium smegmatis.

A high level viomycin resistant mutant of Mycobacterium smegmatis ATCC 14468 (AC16) was analyzed genetically and biochemically in an attempt to understand the mechanisms of expression of high level viomycin resistance and co-resistance to kanamycin and streptomycin. Genetic analysis has shown that at least three different genes (vicC, str, and kan) were involved in the phenotypic expression of drug resistance in AC16, and high level resistance to viomycin was due to interactions between the products of these genes.

Chemical Phenomena↗
PubMed1978

Physicochemical and biological properties of mycobacteriocin M12 produced by Mycobacterium smegmatis ATCC 25855.

A mycobacteriocin (M12) produced by Mycobacterium smegmatic ATCC 25855 was partially purified by ammonium sulphate precipitation followed by DEAE-cellulose chromatography and Sephadex G100 chromatography. Production of M12 was maximal when bacteria were harvested after 3 d cultivation in liquid medium and disrupted by sonication. The molecular weight of M12, estimated by Sephadex G100 chromatograpy, was about 85000. M12 was sensitive to proteolytic enzymes but resistant to DNAase and RNAase, and was relatively stable to heat treatment, sonication, ultraviolet irradiation and pH over the range 4 to 8. When sensitive bacteria were exposed to the mycobacteriocin, the number of viable cells began to decrease after about 6 h incubation. The killing curve of M12 thus appeared to be a multiple-hit curve. Electron microscopic observation revealed that the mycobacteriocin induced morphological changes in the cells; these were partial loss of ribosomes, enlargement of lipoidal inclusion bodies and thickening of the cell envelope. The activity spectrum of M12 was restricted to the genus Mycobacterium.

Bacteria↗
PubMed1976

Multiple mating types of Mycobacterium smegmatis.

Multiple mating systems were found in the strains of Mycobacterium smegmatis. Nineteen wild type strains were classified into five different groups according to their mating behavior. All crosses between substrains derived from the same wild type strain or between substrains belonging to the same group were infertile, while eight different intergroup crosses were fertile. It was suggested that in most of the fertile crosses, chromosome transfer was unidirectional. Genes controlling matings were resistant to curing by acridine dye, sodium dodecyl sulfate and higher temperature suggesting that they were chromosomal genes. However, the location of these genes could not be demonstrated because none of the chromosomal markers tested was found to be linked to these mating genes.

Acriflavine↗
PubMed1976

Altered ribosomes in antibiotic-resistant mutants of Mycobacterium smegmatis.

Two alleles for viomycin-capreomycin resistance (vic) in Mycobacterium smegmatis affect ribosome structures. One (vicA) affects a component of 50S subunits and the other (vicB) affects a component of 30S subunits. The locus for neomycin-kanamycin resistance (nek), which is linked to vicA and vicB, affects a component of 30S subunits. Although the erythromycin resistance locus (ery) is linked to vic and nek, no ribosomal alterations could be detected. Mutations at the streptomycin locus (str) not linked to vic and nek caused alterations of 30S subunits.

Anti-Bacterial Agents↗
PubMed1975

World Health Organization studies on bacteriophage typing of mycobacteria. Subdivision of the species Mycobacterium tuberculosis.

The ability of lytic mycobacteriophages to subdivide the species Mycobacterium tuberculosis reliably has been studied using a series of 100 strains isolated from cases of tuberculosis in the Netherlands. Techniques for the propagation and application of the viruses have been standardized, as have the conditions for growth and preparation of bacterial strains. On the basis of lytic results with 11 mycobacteriophages, it is proposed that the species Mycobacterium tuverculosis may be subdivided into at least 3 major phage types, A, B, and C, and into 2 subjects, Ax and A2. The reliability of the individual bacteriophage lytic result has been assessed, and the relationship between phage reliability and the degree of certainty with which a strain may be assigned to a phage type is described. The effect of rigorous standardization of techniques on the reliability of bacteriphage typing is demonstrated, and a standard protocol is proposed.

Bacteriophage Typing↗
PubMed1973

Genetic recombination in mycobacteria.

Evidence for genetic recombination between Mycobacterium smegmatis strain Rabinowitchi (Rab) and strain Jucho or PM5 is presented. Backcrosses of recombinants by either parental strain indicated four different types of mating behavior, suggesting that the mycobacterial compatibilities are controlled by at least two different factors. No sex factor that transfers at a high frequency or that is sensitive to acridine dyes was detected. Analysis of segregation of unselected markers revealed that strain Jucho, or PM5, contributes the majority of alleles in almost all recombinants obtained from different selective media. Efforts to construct linkage maps for the markers employed failed because of ordering ambiguities. Mating medium containing streptomycin prevented genetic recombination when strain Rab was resistant to the antibiotic and Jucho, or PM5, was sensitive, but it did not prevent recombination when Rab was sensitive to streptomycin and Jucho, or PM5, was resistant. Very low frequency of recombinant formation was observed when Jucho, or PM5, had been treated with streptomycin, whereas recombinants were formed at fairly high frequencies when Rab had been treated with the antibiotic, suggesting that the roles of parental strains in zygote formation were not identical. The results suggest a polar transfer of genetic material from Rab to Jucho, or PM5, although an alternative possibility of cell fusion followed by exclusion could not be excluded.

Acridines↗