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D E Pettijohn

Publications and source records attributed to D E Pettijohn.

50 records · Page 3Linked to original sources
PubMed1976

Prokaryotic DNA in nucleoid structure.

Recent studies of the structure of the bacterial nucleoid are reviewed. In the past 4 to 5 years results of electron microscopic and physical-chemical investigations of the isolated bacterial nucleoids have greatly advanced our understanding of this comparatively simple chromosome. Evidence for both long-range and short-range conformational organization of the packaged DNA has emerged, and preliminary characterization of the molecular interactions organizing this structure has been accomplished.

Amino Acids↗
PubMed1971

The folded genome of Escherichia coli isolated in a protein-DNA-RNA complex.

The DNA of Escherichia coli has been isolated in a compact structure containing small amounts of protein and RNA and having a sedimentation coefficient of approximately 3200 S. The molecular weight of the DNA in the complex is very large (probably higher than 10(9)); the protein is predominantly core RNA polymerase; the RNA is chiefly nascent messenger and ribosomal chains. Solutions containing the complex have low viscosities; this plus its sedimentation rate suggest that the DNA is in a tightly folded conformation. The DNA unfolds after exposure to RNase or heat; this indicates that an RNA component of the complex is involved in stabilizing the structure.

Bacterial Proteins↗
PubMedDate not supplied

Oligosaccharide Le(a)-Le(x): a cell surface marker for carcinomas derived from embryonic endoderm.

An immunohistochemical evaluation of Le(a)-Le(x) expression by adenocarcinomas of the biliary tree, pancreas, colon and stomach was undertaken as examples of epithelial tumors derived from embryonic endoderm. This complements previous studies showing that Lea-Lex was present on the cell surface of non-small cell lung carcinomas, some non-lung carcinomas, and is a prognostic marker for squamous cell lung carcinomas. All of the tumor specimen evaluated were positive and no expression of Le(a)-Le(x) was detected in derivatives of neural, connective or muscle tissues. These findings indicate that it could be informative to examine the biological significance of Le(a)-Le(x) not only in carcinogenesis but during embryogenesis, as well.

Adenocarcinoma↗