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M Botchan

Publications and source records attributed to M Botchan.

48 records · Page 3Linked to original sources
PubMed1974

Viral DNA in transformed cells. III. The amounts of different regions of the SV40 genome present in a line of transformed mouse cells.

(32)P-Labeled SV40 DNA was treated sequentially with restricting endonucleases EcoRI and Hpa I, and the resulting four fragments of DNA were separated by gel electrophoresis. The kinetics of renaturation of each of the fragments and of complete SV40 DNA were measured in the presence of DNA extracted from the SVT2 line of SV40-transformed mouse cells. It was found that these cells contain about six copies of a segment of DNA which includes the early region of the SV40 genome, and about one copy of the late viral sequences. To map the region of the viral genome which is transcribed in SVT2 cells, separated strands of each of the four fragments were prepared and hybridized to total transformed cell RNA. Part of the E strands of the two DNA fragments (A and C) which span the early region of the SV40 genome were found to enter the hybrid.

Animals↗
PubMed1971

Isolation and chromosomal localization of highly repeated DNA sequences in Drosophila melanogaster.

The nuclear DNA of D. melanogaster contains DNA sequences that are repeated between ten and a hundred times more often than the next class of redundant DNA. This DNA, as a renatured duplex isolated on the basis of its renaturation kinetics, has a buoyant density of 1.691 (g/ml). In its native state it bands within the unique nuclear DNA peak (rho = 1.701). These sequences have been localized by "in situ" hybridization in the chromocenter of the chromosomes of the salivary gland. The properties of centromeres are discussed in terms of the occurrence of repeated sequences at this locus.

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PubMedDate not supplied

Expression of enhanced levels of small RNA polymerase III transcripts encoded by the B2 repeats in simian virus 40-transformed mouse cells.

Although specific viral genes are known which are sufficient to transform certain types of cells, viral transformation has been shown to be accompanied by a change in the level of expression of cellular genes. Assuming that this latter class of genes is involved in some way in the establishment of the transformed state, we and others have sought to characterize them. To this end, we constructed a complementary DNA library from a simian virus 40 (SV40)-transformed mouse cell line and screened this library for induced genes. Here we focus on the characterization of a specific cDNA clone called 10 lambda 5. We show that the clone 10 lambda 5 contains a B2 repeat, and that the levels of the small heterogeneously sized B2 cytoplasmic RNAs homologous to 10 lambda 5 are enhanced in transformed cells. Our studies show that these RNAs are a specific class of polymerase III transcripts containing a highly conserved 5' end. SV40 transformation results, therefore, in the activation of specific polymerase III transcripts as well as specific polymerase II transcripts.

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