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Biomedical subjects

M C Young

Publications and source records attributed to M C Young.

62 records · Page 4Linked to original sources

Nucleic acid-specific suppressor T cells.

The concept of using cell-bound antigens as tolerogen was applied to nucleic acid. Nucleoside was linked directly to spleen cell suspensions. Intravenous administration of nucleoside coupled to isogeneic spleen cells into mice generated suppressor cells that diminished the formation of antibody-forming cells either to a T-dependent antigen in vivo or to a T-independent antigen in vitro. Suppressor cells were nucleoside specific, but the specificity of immune suppression seems to be somewhat broader than that of tolerance to a single nucleoside. The ability to raise nucleic acid-specific suppressor T cells may have implications for both the pathogenesis and treatment of systemic lupus erythematosus.

Animals↗

Positive control in the D-serine deaminase system of Escherichia coli K-12.

Two new types of D-serine deaminase (Dsdase)-negative mutants have been isolated and characterized. The first fails to synthesize a functional dsdC gene product as a result of dsdC- (regulator negative) mutations. The mutations lie in the dsdC region, are cis and trans recessive to dsdC+, and give rise to revertants of novel regulatory phenotype. The second class consists of Dsdase-negative lysogens in which the phenotype is the result of the integration of lambdac1857 Sam7 into the dsdC region. Lambda lysates derived from two of the Dsdase-negative lysogens can transduce the structural gene for Dsdase (dsdA) but not the dsdC region. The dsdC+ gene product had no repressor effect on constitutive synthesis in a strain containing a dsdO (initiator constitutive) and a dsdC- mutation. These and other findings indicate that control of Dsdase synthesis is strictly positive. The partial trans effect of the dsdC+ gene product on constitutive synthesis in dsdCc (regulator constitutive) strains can thus be explained by "subunit mixing" between active dsdCc subunits and dsdC+ subunits which are inactive in the absence of the inducer, D-serine. The order of genes in the dsd region is supN-dsdC-dsdP-dsdA-aroC.

Chromosome Mapping↗