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S M Weissman

Publications and source records attributed to S M Weissman.

246 records · Page 14Linked to original sources
PubMed1966

Genetic relatedness among mycoplasmas as determined by nucleic acid homology.

Reich, Paul R. (National Institutes of Health, Bethesda, Md.), Norman L. Somerson, James A. Rose, and Sherman M. Weissman. Genetic relatedness among mycoplasmas as determined by nucleic acid homology. J. Bacteriol. 91:153-160. 1966.-A sensitive membrane filter method to detect nucleic acid homology was used to determine genetic relatedness among mycoplasma isolates. Deoxyribonucleic acid (DNA) was isolated from mycoplasmas and used as a primer for synthesis of tritium-labeled, complementary ribonucleic acid (RNA) by the enzyme RNA polymerase. DNA from each mycoplasma isolate tested was reacted separately with complementary RNA synthesized with homologous or heterologous DNA as primer. The quantity of DNA-RNA hybrids formed was assayed by the nitrocellulose membrane filter method. The amount of radioactivity bound to the membrane filter was used to measure the degree of homology between the nucleic acids. The three mycoplasma isolates from human oral cavities (DC 63, V2785, Botteicher) and the prototype strain PG21 placed in the Mycoplasma hominis type 1 group by gel diffusion and complement-fixation testing were investigated with this technique. Analysis of the data confirmed their immunological grouping with the M. hominis type 1 and their distinction from other human mycoplasmas. In contrast to the data from immunological studies, none of the four isolates tested appeared to be identical to any other. Preliminary experiments with DNA from four other mycoplasma isolates from tissue cultures inoculated with human material revealed them to be closely related, and possibly identical. The advantages of this nucleic acid homology technique for the study of relatedness among mycoplasmas are described.

DNA, Bacterial↗
PubMed1966

Genetic differentiation by nucleic Acid homology I. Relationships among Mycoplasma species of man.

Reich, Paul R. (National Institutes of Health, Bethesda, Md.), Norman L. Somerson, Carol J. Hybner, Robert M. Chanock, and Sherman M. Weissman. Genetic differentiation by nucleic acid homology. I. Relationships among Mycoplasma species of man. J. Bacteriol. 92:302-310. 1966.-Genetic relatedness among human mycoplasmas was evaluated by measuring the amount of nucleic acid hybrid retained on a membrane filter. Hybrids were formed from deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) derived from representative strains of seven serologically distinct human Mycoplasma species. The results indicate that serologically distinct human Mycoplasma species can also be distinguished by the homology techniques. Low-level cross-reactivity was observed among nucleic acids derived from the seven species. Genetic heterogeneity was demonstrated among three strains of M. salivarium and between two strains of M. orale type 2. In contrast, comparison of three strains and three passage levels of M. pneumoniae revealed them to be indistinguishable. M. pneumoniae appears to be the most distinct of all human mycoplasmas, as shown by both homology and the high buoyant density value of its DNA. Nucleic acids from mycoplasmas which had identical buoyant densities were in some cases differentiable. Mycoplasmas with different DNA buoyant densities were invariably distinguishable by the homology technique.

Journal Article↗
PubMed1966

Genetic Differentiation by Nucleic Acid Homology II. Genotypic Variations Within Two Mycoplasma Species.

Somerson, Norman L. (National Institutes of Health, Bethesda, Md.), Paul R. Reich, Barbara E. Walls, Robert M. Chanock, and Sherman M. Weissman. Genetic differentiation by nucleic acid homology. II. Genotypic variations within two Mycoplasma species. J. Bacteriol. 92:311-317. 1966.-A deoxyribonucleic-ribonucleic acid (DNA-RNA) homology technique was used to determine genetic relatedness among the nucleic acids of eight mycoplasmas which were serologically classified as Mycoplasma hominis type 1. The DNA preparations from these organisms were each found to be distinct. No subgrouping of the M. hominis type 1 strains could be demonstrated. In contrast, when the nucleic acids from six serologically related mycoplasmas which were isolated from tissue cultures were studied, the DNA from these species could not be distinguished. The DNA buoyant densities of the tissue culture isolates were similar. These isolates were closely related genetically to a porcine mycoplasma, M. hyorhinis.

Journal Article↗
PubMed1966

Genetic differentiation by nucleic acid homology. IV. Relationships among Lancefield groups and serotypes of streptococci.

Weissman, Sherman M. (National Cancer Institute, Bethesda, Md.), Paul R. Reich, Norman L. Somerson, and Roger M. Cole. Genetic differentiation by nucleic acid homology. IV. Relationships among Lancefield groups and serotypes of streptococci. J. Bacteriol. 92:1372-1377. 1966.-A deoxyribonucleic acid-ribonucleic acid homology technique was used to measure the genetic relatedness among Lancefield groups and serotypes of streptococci. Organisms in different Lancefield groups were related, but were differentiated from each other. Serotypes within group A could be distinguished. Two isolates serologically classified in group A type 1 were indistinguishable. Streptococcus faecalis was only remotely related to streptococci of Lancefield groups A and H, whereas Diplococcus pneumoniae was more closely related to these organisms. The serological data were in good agreement with the results obtained with the homology method.

DNA, Bacterial↗
PubMedDate not supplied

A point mutation in the A gamma-globin gene promoter in Greek hereditary persistence of fetal haemoglobin.

Hereditary persistance of fetal haemoglobin (HPFH) is a benign condition characterized by the production in adulthood of more than 1% fetal haemoglobin (HbF, alpha 2 gamma 2) in the absence of erythropoietic stress. Several genetic types have been discerned based on the level of HbF produced, the relative contributions of the duplicated fetal (G gamma and A gamma) globin genes, and the presence or absence of deletions involving the beta and delta genes in cis to the mutation. Greek HPFH is a non-deletion variety in which heterozygotes produce 10-20% HbF, predominantly due to overproduction of the A gamma chain. We have cloned a 40-kilobase (kb) region of the beta-globin cluster from a Greek HPFH allele and report here that a point mutation (G----A) occurs 117 base pairs (bp) 5' to the cap site of the A gamma-globin gene, just upstream of the distal CCAAT sequence. The corresponding region of the G gamma-globin gene is normal. We discuss the implications of this finding for the developmental regulation of globin gene expression.

Base Sequence↗