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Biomedical subjects

P Hale

Publications and source records attributed to P Hale.

30 records · Page 2Linked to original sources
PubMed1983

Carbodiimide inactivation of Escherichia coli RNA polymerase promoters on supercoiled simian virus 40 and ColE1 DNAs occurs by a one-hit process at salt concentrations in the physiological range.

A previous study (Hale, P., Woodward, R. W., and Lebowitz, J. (1980) Nature 284, 640-644) showed that Escherichia coli RNA polymerase promoters on superhelical SV40 DNA are highly selective targets for chemical modification by the water-soluble carbodiimide, N-cyclohexyl-N'-beta-(4-methylmorpholinium)ethyl carbodiimide (CMC). To extend the inactivation analysis of supercoiled DNAs, we determined the number and location of RNA polymerase binding sites on the supercoiled and linear forms of ColE1 DNA. We also determined the site distribution of [3H] CMC on the superhelical form. This information, coupled with per cent inhibition of transcription versus CMC-bound curves, allowed a test of the specificity of the CMC inactivation by the Poisson equation. Curves were obtained for supercoiled SV40 DNA modified at 0 and 100 mM NaCl (2 mM NaPi, pH 7.0) and for supercoiled ColE1 DNA modified at 0, 100, and 320 mM NaCl. For supercoiled SV40 DNA, these data, coupled to our knowledge of the number of RNA polymerase binding sites from the study cited above, revealed an excellent fit to a one-hit inactivation by the Poisson equation for DNA modified at 100 mM NaCl. For ColE1 DNA, we obtained an excellent fit to a Poisson distribution when supercoiled DNA was modified at 320 mM NaCl. The Poisson distribution can be applied to [3H] CMC restriction fragment data with equivalent results. These results suggest that promoter sites can be forced into different structural conformations with variable degrees of unpairing.

Affinity Labels↗
PubMed1982

Early social deprivation and the ontogeny of unrestricted social behavior in the laboratory rat.

The unrestricted adult social and nonsocial behavior of albino rats isolated from 21 to 70 days of age was compared with the behavior of rats receiving normal social experience. Isolated animals exhibited aberrant self-manipulative behaviors during the period of isolation, and both isolate-reared males and females were more aggressive than their group-reared counterparts. The hypothesis that females are buffered against the effects of social isolation received little support. Numerous gender differences and differences in the gender of the object of social response were found for both isolate- and group-reared rats. Gender and Rearing Conditions were relatively independent influences on behavior with few Gender x Treatment interactions reaching significance.

Aggression↗
PubMed1978

Binding and transcription of simian virus 40 DNA by DNA-dependent RNA polymerase from Escherichia coli.

Supercoiled simian virus 40 was transcribed more efficiently than nonsupercoiled DNA. The effect was increased from two- to fivefold by the addition of rifampin with triphosphates. The number and locations of polymerase binding sites with respect to Hin II-III restriction fragments were determined. The total number of binding sites was nine, as determined by UV difference spectroscopy. The locations of these binding sites were on the A, B, D, E, F, and G fragments, as determined by gel electrophoresis. The number of sites was the same for both supercoiled and relaxed or Hin II-III-digested DNA, and the point of saturation of supercoiled DNA by polymerase remained the same with increasing concentrations of rifampin from 0 to 8 microgram/ml.

Binding Sites↗
PubMed1978

Effect of chemical modification of supercoiled simian virus 40 DNA on the rate of in vitro transcription.

Superhelical simian virus 40 FI DNA could be modified with the single-strand-specific reagent N-cyclohexyl-N'-beta-(4-methylmorpholinium)ethylcarbodiimide (CMC). A limited reaction, of less than 2% of the base pairs, resulted in almost total inhibition of in vitro transcription by DNA-dependent RNA polymerase from Escherichia coli. This effect was shown to be due to DNA modification and not to inhibition of polymerase activity by the reagent. Inhibition of enzyme activity occurred if the contaminating reagent was not absorbed with another protein before polymerase addition. No inhibition was observed when DNA and polymerase were incubated together to allow the formation of pre-initiation complexes before CMC was added. Studies of template saturation with polymerase showed that the inhibition of transcription by DNA modification was due to a loss of binding ability of the enzyme to the reacted, supercoiled DNA when reaction times of less than 2 h were used.

CME-Carbodiimide↗
PubMed1978

Study on the mutagenicity of conjugated estrogens in human, animal and bacterial systems.

Conjugated estrogens were studied for mutagenicity (and implied carcinogenicity) in two strains of S. typhimurium, two normal and three neoplastic human lymphoid cell lines (the latter from Burkitt's lymphoma patients) in cell culture and a Chinese hamster cell line in diffusion chambers implanted into mice. No significant increase in mutation rate or chromosome aberrations were noticed after exposure to conjugated estrogens.

Animals↗
PubMed1976

Antibody-dependent, cell-mediated cytotoxicity with autochthonous lymphocytes and sera after infection with Moloney sarcoma virus.

Antibody-dependent, cell-mediated cytotoxicity in the Moloney sarcoma virus (MSV) system was analyzed in terms of the ability of autochthonous antibody to induce or potentiate cytotoxicity by lymphocytes from animals infected with MSV. As previously demonstrated in microcytotoxicity assays, the lymphocytes from regressor animals taken 30 days after virus infection were consistently more cytotoxic than those from tumor-bearing animals 15 days after infection. Antisera from the regressors potentiated the activity of regressor lymphocytes from the same animals. Also, antisera from tumor bearers, 15 days after virus injection, induced cytotoxicity by the animals' autochthonous lymphocytes which, by themselves, were not cytotoxic. In an independent assay for antibody, both groups of sera produced cytotoxicity by control nonimmune lymphocytes. Specificity controls indicated that both antibody and lymphocytes were required for the induction of cytotoxicity against the target cells in vitro. Normal sera placed on the target cells in the same concentrations induced no cytotoxicity by the immune lymphocytes, and immune sera alone placed on the target cells caused no cytotoxicity. The cooperative activity between antibody and lymphocytes may be a factor that accounts for the observed high incidence of spontaneous tumor regression.

Animals↗
PubMedDate not supplied

Molecular cloning of the replication terminus of the plasmid R6K.

Analyses of the intermediates of DNA replication of the R6K plasmid derivatives, RSF1040, RJHC12 and RJHC26 demonstrate the transient accumulation of open circular DNA molecules with a discontinuity in either the plus or the minus strand of the DNA. The location of this discontinuity is nonrandom and is near the terminus of DNA replication. The discontinuity is not due to the activation of a relaxation complex since neither RJHC12 nor RJHC26 are relaxable. The replication terminus is functional in a clone containing approx. a 2000 bp sub-fragment of the HindIII-2 fragment of R6K. The replication terminus temporarily arrests the progression of replication fork of the unidirectionally replicating plasmid pBR313 at a region approx. 800 bp from HindIII site located nearest to the BamHI site of the vector. Subcloning experiments reveal that the upper limit of the replication termination sequence is 216 bp in length.

Cloning, Molecular↗