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Biomedical subjects

T Shibata

Publications and source records attributed to T Shibata.

At least 1,135 records · Page 63Linked to original sources
PubMed1975

In vitro modification and restriction of phage phi-105c DNA with Bacillus subtilis N cell-free extract.

The enzymes involved in host-controlled modification and restriction by Bacillus subtilis strain N were detected in cell free extracts. In the presenct of Mg2+ the N-specific endonucleases cleaved unmodified DNA but did not attack phi-105C. N DNA carrying N-specific modification. The restriction endonuclease required neither SAM nor ATP for its activity. The N-specific modification enzyme was active only in the presence of SAM, indicating that modification in this syteem is a methylation of DNA.

Adenosine Triphosphate↗
PubMed1975

Heavy metals in normal Japanese tissues. Amounts of 15 heavy metals in 30 subjects.

To obtain the usual values of arsenic, beryllium, bismuth, cadmium, chromium, cobalt, copper, mercury, methyl mercury, manganese, molybdenum, nickel, lead, antimony, vanadium, and zinc in the normal human body, the amounts of 15 metals were determined in 15 male and 15 female Japanese cadavers (average weight, 55 kg [121 lb]). The content of metals found ranged as follows: Zn, 1,800 mg; Cu, 65 mg; Cd, 35 mg; Pb, 25 mg; Mn, 8 mg; Ni, 6 mg; Cr, 4 mg; Hg, 3 mg; Sb, 0.7 mg; MeHg, 0.4 mg. Cadmium and mercury were higher in Japanese blood than in blood of other people. Cadmium and mercury were absorbed by the metabolic tissues; Cr, Ni, and Pb showed higher concentration in tissue exposed to the environment. Concentrations of Cd, Pb, and Hg tended to be higher in females, and Cr Cu, MeHg, and Mn concentrations tended to be higher in males.

Adolescent↗
PubMed1975

A nucleoside triphosphate-dependent deoxyribonuclease from Bacillus laterosporus. The mode of action of the enzyme.

The acid-soluble products of exhaustive digestion of native DNA with Bacillus laterosporus DNase consist of 6.5% of mononucleotides and 93.5% of oligonucleotides with an average chain length of 3.2. The results of viscometric studies and inactivation of transforming DNA indicate the existence of acid-insoluble intermediates and the selective degradation of the population of substrate molecules rather than a random nucleolytic action. Furthermore, sucrose density gradient analysis of partially digested DNA showed that the initial DNA added as a substrate disappeared progressively during the reaction, being replaced by much more slowly sedimenting acid-insoluble materials, which were eventually degraded into acid-soluble end products during the reaction; products intermediate in size between these two components were not detectable. Studies with DNA labeled at the 3'-terminus indicate that Bacillus laterosporus DNase does not attack DNA from 3'-hydroxyl ends to yeild acid-soluble or acid-insoluble materials in a random manner. The results presented in this paper indicate that the nature of the attack of B. laterosporus nuclease is similar to that previously proposed for Micrococcus luteus DNase. The possibility of the sequential release of acid-insoluble intermediate fragments as well as acid-soluble products from the terminal portion of DNA by the enzyme is discussed.

Bacillus↗
PubMed1975

A nucleoside triphosphate-dependent deoxyribonuclease from Bacillus laterosporus. Purification and characterization of the enzyme.

A deoxyribonuclease, which requires nucleoside triphosphate for reaction, has been purified about 150-fold from extracts of Bacillus laterosporus. Potassium phosphate and ethylene glycol stabilize the purified enzyme. The enzyme degrades double-stranded DNA about 100 times faster than heat-denatured DNA in the presence of nucleoside triphosphate. Double-stranded DNA is not degraded to any measurable extent in the absence of ATP, but the enzyme exhibits activity toward denatured DNA in the absence of nucleoside triphosphate, and this activity seems to be an intrinsic property of this enzyme protein. The optimum pH is 8.5 and the maximum activity is obtained in the copresence of Mg2+ (8.0 X 10(-3)M) and Mn2+ (7.0 X 10(-5)M). ATP and dATP are most effective and nucleoside di- or monophosphates are ineffective. ATP is converted to ADP and inorganic phosphate during the reaction and the ratio of the amount of ATP cleaved to that of hydrolyzed phosphodiester bonds of DNA is about 3:1. An inhibitor of the enzyme was observed in bacterial extracts prepared by sonic disruption; the inhibitory substance is produced in the bacteria in the later stages of cell growth. Preliminary results show that the inhibitor emerged near the void volume of a Sephadex G-200 column, and was relatively heat-stable, RNase-resistant, and DNase-sensitive.

Adenosine Triphosphate↗
PubMed1975

Repair of UV-induced DNA damage in recombination-deficient strains of Bacillus subtilis.

To clarify the role of gene products for genetic recombination which might be concerned in excision repair, the repair of DNA lesions induced by ultraviolet (UV) irradiation was examined under non-growing conditions with a variety of recombination deficient (Rec-) mutants of Bacillus subtilis. The extent of repair was estimated by the recovery of transforming activity of DNA extracted from the cells during the post-irradiation incubation period (the assay method was termed as marker-repair experiment). The marker repair seemed to be accomplished by the excision repair as assumed from the effects of inhibitors. Among Rec- mutants tested, a mutant strain UVS80TH (rec-80) exhibited a normal level of marker repair activity, whereas strains GSY1025 (recA1), GSY1028 (recB2) and GSY908 (rec-4) exhibited reduced marker repair activities. These results and the data on UV sensitivity of the mutants indicate that (1) the products of all these Rec genes are related to UV resistance of the cell viability and are factors functioning through mechanisms other than excision repair, (2) the products of recA, recB and rec-4 genes display some roles in maintenance of a level of excision repair activity, and (3) the product of the rec-80 gene does not participate at all in excision repair.

Acriflavine↗
PubMed1974

Genetic mapping in Bacillus subtilis by 5-bromouracil sensitization to ultraviolet inactivation of transforming activities.

A new method for chromosome mapping of Bacillus subtilis Marburg is presented which is based on the sensitization to ultraviolet irradiation of transforming deoxyribonucleic acid that has incorporated 5-bromouracil instead of thymine. Deoxyribonucleic acid was extracted at intervals from the outgrowing spores of a thymine-requiring mutant incubated with 5-bromodeoxyuridine and subjected to a definite dose of ultraviolet irradiation. The residual activities of various genetic markers were assayed by transformation. The marker activity of deoxyribonucleic acid that had incorporated 5-bromodeoxyuridine was approximately 10 times as sensitive to ultraviolet irradiation as that of normal deoxyribonucleic acid. The markers proximal to the replication origin were sensitized at earlier times of outgrowth than distal markers. The chromosome replication in outgrowing spores was sufficiently synchronous and allowed the definite determination of when a marker became sensitized by incorporation of 5-bromodeoxyuridine. The time, designated "sensitization time," was estimated by plotting the logarithmic values of relative residual activities versus incubation times. The map constructed with sensitization times as a measurement showed good agreement with those constructed by other methods. The replication of the chromosome under the described conditions appeared to occur in the following marker order: (purA, hisA)-(purB)-(thr, pyrA)-(metC)-(leuA)-(lys, trpC, metB).

Bacillus subtilis↗