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Biomedical subjects

B J Rapp

Publications and source records attributed to B J Rapp.

5 recordsLinked to original sources
PubMed1987

Genetic transfer in Desulfovibrio desulfuricans.

An apparently defective bacteriophage capable of mediating transduction has been identified in culture filtrates of Desulfovibrio desulfuricans (American Type Culture Collection 27774). Phage-mediated intraspecies transfer of antibiotic resistance markers occurs with a frequency of 10(-5) to 10(-6) per recipient cell. The vector contains linear fragments of double-stranded DNA of about 13.5 kilobase pairs, which appear to be random pieces of bacterial DNA. As yet, neither induction nor plaque formation has been observed. To our knowledge, a system of genetic exchange has not been described before for a member of the sulfate-reducing bacteria.

Journal Article↗
PubMed1987

Modifying acute pain by matching cognitive style with cognitive treatment.

To test whether congruence between cognitive style and cognitive coping would facilitate the attenuation of pressure pain, 30 verbalizers and 30 visualizers were assigned in equal numbers (ns = 10) to pleasant imagery, rational thoughts, and expectancy conditions. Separate 2 X 3 (cognitive style X experimental condition) analyses of covariance on pain tolerance and subjective discomfort indicated that imagery was superior to expectancy in raising tolerance. These findings are discussed in terms of the flexibility of cognitive coping and the content of the images and thoughts which were used.

Adaptation, Psychological↗
PubMed1980

Pyruvate dehydrogenase complex from germinating castor bean endosperm.

Subcellular organelles from castor bean (Ricinus communis) endosperm were isolated on discontinuous sucrose gradients from germinating seeds which were 1 to 7 days postimbibition. Marker enzyme activities of the organelles were measured (fumarase, catalase, and triose phosphate isomerase) and the homogeneity of the organelle fractions was examined by electron microscopy. Pyruvate dehydrogenase complex activity was measured only in the mitochondrial fraction and attempts to activate or release the enzyme from the proplastid were not successful. A pathway is proposed for the most efficient use of endosperm carbon for de novo fatty acid biosynthesis that does not require the presence of the pyruvate dehydrogenase complex in the proplastid to provide acetyl-coenzymeA.

Journal Article↗
PubMed1979

Isolation of a non-tumor-inducing mutant of the Ti plasmid of Agrobacterium tumefaciens strain B6.

A nonpathogenic mutant of Agrobacterium tumefaciens strain B6 was isolated and its properties compared with the parental strain in an effort to localize the mutation. Both B6 and its mutant (B6-95) had similar colony color and morphology, were ketolactose positive, utilized octopine, and contained plasmid DNA. Kinetic analysis of DNA reannealing showed that total DNA homology and plasmid DNA homology between B6 and B6-95 was at least 90%. The length of both plasmids was found to be 58 micrometer. Plasmid DNA from both B6 and the mutant was digested with endonucleases and the fragments separated by agarose gel electrophoresis. In all cases the pattern for B6 was identical with that of B6(-95). The Ti plasmid from B6 and the mutant was transferred to an avirulent, plasmidless strain of A. tumefaciens by in vitro conjugation and transformation. All of the B6 transconjugants and transformants were virulent, whereas all of the mutant transconjugants and transformants were avirulent. Electrophoretic patterns of endonuclease-digested plasmid DNA from transformants were identical to those of plasmid DNA from B6. Therefore, we conclude that the virulence mutation lies on the Ti plasmid.

Conjugation, Genetic↗