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Biomedical subjects

H Shizuya

Publications and source records attributed to H Shizuya.

48 records · Page 3Linked to original sources
PubMed1977

A radiomicroassay for cytotoxic antibody to human spermatozoa. Quantification by tritiated actinomycin d.

A radiomicroassay for titration of spermocytotoxic antibody is described. The assay used [3H]AACTINOMYCIN D ([3H]Act D) to label damaged spermatozoa in a fashion analogous to penetration by vital dye. Optimal conditions for and some kinetics of the assay are presented. The assay is sensitive, reliable, simple to perform and uses only small amounts of serum and spermatozoa. Applied to sperm antibody positive human postvasectomy sera, the assay compared favourably in sensitivity eith vital dye microscopic observations and with parallel titration by the Isojima's immobilization tests.

Antibodies↗
PubMed1976

Deoxyribonucleic acid polymerase II activity in an Escherichia coli mutator strain.

The polB gene encoding deoxyribonucleic acid (DNA) polymerase II has been located close to a mutator gene, mutT1, in Escherichia coli. We find the DNA polymerase II prepared from mutT1, strains to be normal in reaction requirements, heat stability, and ability to remove mismatched bases at termini. Recombinants formed from a mutant defective in DNA polymerase II (polB100) and mutT1 are deficient in polymerase II and have the same mutator phenotype as mutT1. Our linkage analysis indicates that mutT1 and polB100 are not isoallelic.

Cell-Free System↗
PubMed1974

Synthesis of bacteriophage lambda DNA in vitro: requirement for O and P gene products.

We have developed a cell-free system to study bacteriophage lambda DNA replication. Maximal DNA synthesis in vitro requires the four deoxynucleoside triphosphates, ATP, and exogenous lambda DNA. DNA synthesis requires the products of the phage O and P genes but is not inhibited by lambda repressor. The kinetics of synthesis is linear for 10-15 min; however, the product of synthesis amounts to only 0.5-1% of the added template DNA. As judged by isopycnic analysis, extensive regions of the template are copied. Sedimentation analysis indicates that all of the product consists of short (11S) DNA chains. Fractions partially purified from lambdaO(+)P(+)-infected cell extracts will complement extracts prepared from lambdaO(-) or lambdaP(-)-infected cells.

Adenosine Triphosphate↗
PubMed1974

Isolation of a specialized transducing bacteriophage lambda carrying the polC locus of Escherichia coli.

We have isolated a specialized transducing phage carrying the polC locus of E. coli K-12. A strain of E. coli lacking the lambda attachment site was infected with bacteriophage lambda. Lysogens carrying lambda at the tonA locus were isolated by selecting lambda-immune, T5-resistant strains. Transducing phages of dapC, dapD and polC, which map within 0.2 min of tonA, were obtained in lysates prepared from two of the lysogens. The isolated phage, lambdadpolC, is defective but can transduce four different polC temperature-sensitive mutants. After lysogenation with the transducing phage, DNA polymerase III activity is restored to normal levels in extracts of a polC strain lacking polymerase III activity. However, attempts to obtain increased levels of DNA polymerase III in extracts of induced lysogens carrying lambdadpolC have been unsuccessful.

Chromatography, Ion Exchange↗
PubMed1974

Mapping of a mutation, polB100, affecting deoxyribonucleic acid polymerase II in Escherichia coli K-12.

Direct assay for deoxyribonucleic acid polymerase II in extracts has been used to screen recombinants for the polB allele in Hfr x F(-) crosses, F-ductants in episome transfer, and transductants in generalized transduction by phage P1. The polB gene is located at 2 min on the Escherichia coli linkage map; it is 39 to 64% co-transducible with leu. A mutant, E. coli polA1 polB100 polC (ts), deficient in deoxyribonucleic acid polymerases I and II and having a thermolabile deoxyribonucleic acid polymerase III, has been prepared by the P1-mediated cross: P1 (HMS85 polB100) x E. coli BT1026 polA1 polC (ts) leu(-).

Cell-Free System↗
PubMed1974

DNA polymerase I-dependent mutants of coliphage lambda.

Mutagenized lysates of bacteriophage lambda were screened for mutants unable to plate on DNA polymerase I-deficient (polA(-)) hosts. The mutants obtained were all recombination deficient (red(-)). These mutants, like red(-) and gam(-) mutants previously isolated by others, grow more poorly than wild-type lambda even on polA(+) hosts (burst size 14 to 30% of wild-type lambda.) In a polA(-) host, the burst size of red(-) and gam(-) mutants is reduced an additional five- to tenfold, and lysis is delayed. Wild-type lambda grows normally in polA(-) hosts. Neither lambdaN(-)nin (which doesn't express red or gam) nor lambdabio phages (from which all or part of the red-gam region is deleted) form plaques on polA(-) hosts. Apparent revertants, able to plate on polA(-) hosts, have been selected from both lambdaN(-)nin and lambdabio. Those derived from N(-)nin seem to be N(-)nin cro(-) mutants; whereas those coming from lambda bio have a new bypass mutation (pas) that lies between genes P and Q.

Chromosome Mapping↗
PubMed1972

Conditional lethality of deletions which include uvrB in strains of Escherichia coli lacking deoxyribonucleic acid polymerase I.

Deletions of the uvrB gene were not obtained in polA1 strains of Escherichia coli either by selecting for spontaneous deletions or by transduction from strains carrying such deletions. A strain forming a temperature-sensitive deoxyribonucleic acid polymerase I and carrying a deletion of the uvrB gene is inviable at the nonpermissive temperature.

Cell Survival↗