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Biomedical subjects

G Bertani

Publications and source records attributed to G Bertani.

At least 37 records · Page 2Linked to original sources
PubMed1975

Deletions in bacteriophage P2. Circularity of the genetic map and its orientation relative to the DNA denaturation map.

Several types of viable chromosomal deletions of bacteriophage P2 were isolated. One type gives the immunity insensitive phenotype and may extend to the genes for the immunity repressor (C) and for integrative recombination (int). Two other types delete genes (old and fun) known to be active in the lysogenic state. For such deletion mutants the relationship between particle density and DNA length was established. The deletions were located in respect to previously mapped genes and the results were compared with electron microscopical studies (by Inman and collaborators) of the P2 chromosome. It is concluded that the best representation of the genetic map of P2 is circular. The cohesive ends of the linear P2 DNA molecule are most likely formed between genes old and Q. Except for the neighborhood of gene old, the previously published, linear genetic map of P2 (Lindahl) is colinear with the melting map of the P2 chromosome (Inman). Preliminary evidence for some specific recombination event often accompanying integrative recombination between phage chromosomes is presented.

Bacteriophage P2↗
PubMed1975

Removal of unwanted proteins from cell extracts by means of antiserum.

The efficiency of removal of soluble proteins in cell-free bacterial extracts by means of antiserum from rabbits immunized with similar extracts was measured. Precipitation followed by Sephadex gel-chromatography was used. Up to 80% (exceptionally 90%) removal could be obtained. The method might be applied to enrichment for "foreign" cell-extract components, for example, viral products in virus infected cells. Tests for the specificity of the method are also presented.

Animals↗
PubMed1975

Structure and position of a complex chromosomal aberration in bacteriophage P2.

The P2 phage mutation vir56, like the previously studied vir22, is the result of an unequal replacement of a chromosome segment with non-homologous DNA. The end positions of the replacements are essentially the same in the two mutants, whereas the lengths of the replacements are quite different. A third chromosomal aberration, del3, has similar structure and position. These results strengthen the suggestion that the left ends of these three aberrations coincide with the point of exchange in integrative recombination.

Coliphages↗
PubMed1974

Constitutive expression of bacteriophage P2 early genes resulting from a tandem duplication.

A tandem-duplication mutant of bacteriophage P2 was isolated. Physically, its particles are characterized by a higher buoyant density and lower heat stability than the wild type, both consequences of increased DNA content. Genetically, the mutant is easily recognized by its insensitivity to control by the immunity-specific repressor. The duplication covers part of gene B, necessary for phage DNA replication. To explain the immunity-insensitivity of the duplication it is proposed that the promoter, but not the operator site, in the early gene operon is duplicated in this mutant. By crosses with a gene-B mutant, a recombinant carrying a heterozygous duplication was isolated.

Centrifugation, Density Gradient↗