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G Glaser

Publications and source records attributed to G Glaser.

68 records · Page 4Linked to original sources
PubMed1979

In vitro transcripts from the rrn B ribosomal RNA cistron originate from two tandem promoters.

The functional structure of the promoter region of a bacterial ribosomal operon is analyzed by in vitro transcription of linear DNA fragments derived from the hybrid Col EI plasmid pGG1. This plasmid contains the promoter region of the rrn B ribosomal cistron present in the lambdarifd18. When transcripts arising from this promoter region are terminated by restriction endonuclease cleavage of DNA, two RNA chains are resolved by gel electrophoresis that differ in length by about 100 bases. Evidence is presented indicating that these two transcripts arise from different initiation sites, each directing tandem transcription on the sense strand of the early portion of the ribosomal cistron.

Bacteriocin Plasmids↗
PubMed1979

Direct detection of methylated cytosine in DNA by use of the restriction enzyme MspI.

The extent of methylation of the internal C in the sequence CCGG in DNA from various eukaryotic sources has been determined using the restriction enzyme MspI known to be specific for this sequence. The methylation of the CCGG sequence is reflected in the restriction pattern obtained by DNA treated with MspI and its isoschizomer HpaII and analyzed by gel electrophoresis. A direct method for detection 5-methylcytosine in the sequence CCGG has been deviced. DNA fragments obtained with MspI were radioactively labeled at their 5' ends and subsequently degraded to the corresponding 5'-deoxyribonucleoside monophosphates. 5 methylcytidylic acid has been found in most of the 5' ends of MspI fragments of calf thymus DNA (about 90%) indicating heavy methylation of the sequence CCGG in calf thymus DNA. The results also reveal a symmetric methylation of both strands at this sequence in calf thymus DNA. In contrast, the CCGG sequence in other eukaryotic DNAs from organisms like Neurospora, Drosophila and Herpes virus proved to be undermethylated at this sequence.

Animals↗
PubMed1977

ColE1 cloning of a ribosomal RNA promoter region from lambdarifd18 by selection for lambda integration and excision functions.

The expression of the ribosomal RNA gene carried by the lambda transducing phage lambdarifd18 is shown to be subject to stringent amino acid control. lambdarifd18 DNA was digested with endonuclease EcoRI and ligated to similarly restricted ColE1 plasmid DNA. Selection for expression of lambda integration and excision gene activity carried by the same DNA fragment results in cloning of the promoter proximal portion of the 16S ribosomal RNA gene. The resulting chemera expresses lambda integration and excision functions as well as encoding the promoter proximal half of a 16S ribosomal RNA gene.

Bacteriocin Plasmids↗
PubMedDate not supplied

Molecular and biological features of mollicutes (mycoplasmas).

The small size of the mollicute genome considerably restricts the amount of genetic information available to the organisms. This is reflected in the relatively small number of cell proteins synthesized, the lack of many biosynthetic pathways and the marked dependence on exogenous nutrients for growth. The protein synthesizing machinery of mollicutes resembles that of eubacteria and is sensitive to the same antibiotics, except for rifampicin, to which RNA polymerases of mollicutes appear resistant. The mollicute ribosomes are built of 50 S and 30 S subunits and contain about 50 different proteins and 5 S, 16 S and 23 S rRNA, as in eubacteria. However, the 5 S rRNA in mollicutes appears shorter (107-112 nucleotides) than in eubacteria (116-120 nucleotides). We hybridized restriction endonuclease-digested DNA from a variety of Mycoplasma, Ureaplasma, Acholeplasma and Spiroplasma species with nick-translated probes consisting of defined portions of the rrnB rRNA operon of Escherichia coli and the rRNA operon of M. capricolum. The results suggest the presence of only one or two sets (operons) of rRNA genes in the genome of Mollicutes, a number falling considerably below that of the eubacteria examined so far but resembling that found in archaebacteria. Our data also indicate a marked nucleotide sequence homology along the rrnB rRNA operon of E. coli and the rRNA operons of the various mollicutes, indicating that the rRNA genes in mollicutes are linked in the classical prokaryotic fashion 16 S-23 S-5 S. Each mollicute appeared to possess, on its genome, different flanking sequences adjacent to the rRNA operon(s), resulting in species-specific hybridization patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Acholeplasma↗
PubMedDate not supplied

Characterization of the mycoplasma genome.

Recent advances on the properties of the mycoplasma genome, including size, base composition, replication, extrachromosomal DNA, and transfer of genetic material are briefly reviewed, with emphasis on their phylogenetic implications. The use of cleavage patterns of the mycoplasma genome by restriction endonucleases as "finger-prints" indicating genetic relatedness among strains is discussed. The data support the notion that strains of mycoplasma species of strict host and tissue specificity exhibit marked genetic homogeneity, suggesting a clonal origin for some species. The regions of the mycoplasma genome carrying the ribosomal RNA (rRNA) genes have been studied using restriction endonucleases, cloning, and hybridization procedures. The mycoplasmal rRNA cistrons cross-hybridized among themselves, and with the seven rRNA cistrons of Escherichia coli, demonstrating the marked conservation of structure during evolution of this part of the procaryotic genome. In most of the mollicutes tested so far the number of rRNA cistrons is two, but a few species appear to carry only one rRNA cistron in their genome.

Acholeplasma↗