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Biomedical subjects

B Allet

Publications and source records attributed to B Allet.

15 recordsLinked to original sources
PubMed1979

Biochemical properties and localization of the chromosomal protein IP25.

The protein IP25, which has previously been reported to accumulate in the chromatin during erythroid differentiation of Friend-virus-transformed erythroleukemia cells (FL cells), is shown to behave like histone H1 without being structurally related to it. Like H1, IP25 is not released by digestion of FL cells nuclei with DNAse I. After micrococcal digestion IP25 and H1 are differentially distributed in the nucleosome monomers and dimers. This distribution suggests an internucleosomal location for IP25 and H1. Different rates of digestion are observed between nuclei of differentiating and non-differentiating FL cells with both DNAse I and micrococcal nuclease. These differences could be due to the presence of IP25 in the chromatin of differentiating cells.

Cell Nucleus↗
PubMed1979

Mu insertion duplicates a 5 base pair sequence at the host inserted site.

Nucleotide sequences were analyzed across the two ends of lysogenic Mu DNA. These ends were cloned separately in lambdapMu hybrid particles that derived from a single Mu lysogen in the lac Z part of lambdaplac5. The obtained data imply that Mu lysogenization was associated with the duplication of 5 base pairs present in lac DNA at the Mu insertion site. As a result of this duplication, Mu DNA is flanked by two copies of five identical base pairs oriented as direct repeats. A similar conclusion has been obtained independently by other investigators with the use of a different Mu lysogen (D. Kamp and R. Kahmann, personal communication). Thus Mu insertion seems to have a striking similarity to typical IS-mediated insertions that were found to be associated with a short DNA duplication at the target site.

Base Sequence↗
PubMed1979

Structure analysis at the ends of the intervening DNA sequences in the chloroplast 23S ribosomal genes of C. reinhardii.

All of the chloroplast 23S ribosomal genes of C. reinhardii are interrupted by a 0.87 kb sequence (Rochaix and Malnoë, 1978). We have sequenced the DNA across the two ends of this intervening element. In parallel, we have examined the nucleotide sequences in the corresponding part of the 23S ribosomal RNA. This allowed us to locate precisely the boundaries between the coding (that is, transcribed into mature 23S rRNA) and the noncoding DNA. The results show that the intervening sequence is flanked by two identical sets of 3 bp (5'-CGT) oriented as direct repeats. In addition, a sequence of 5 bp (5'-CGTGA) lies exactly next to one end and is found very close (16 bp) to the other end, in the coding part of the gene. These two sets are also oriented as direct repeats. Finally, sequences near one end of the intervening element are found with a few alterations near the other end, but in an inverted orientation. Possible interpretations of these results are discussed.

Base Sequence↗
PubMed1979

Restriction enzyme cleavage map of Tn10, a transposon which encodes tetracycline resistance.

A cleavage map of a recombinant plasmid carrying Tn10 was constructed for 13 different restriction enzymes. The Tn10 region of this plasmid contains cleavage sites for BamHI, AvaI, BglI, BglII, EcoRI, XbaI, HincII, HindIII, and HpaI. Restriction enzymes PstI, SmaI, KpnI, XhoI, SalI, and PvuI do not cleave within the Tn10 element. This map confirms the previously reported structure of this transposon; it is composed of a unique sequence (approximately6,400 base pairs long), which in part codes for the tetracycline resistance functions and is bounded by inverted repeats (approximately 1,450 base pairs long).

Coliphages↗
PubMed1978

Nucleotide sequences at the ends of bacteriophage Mu DNA.

The nucleotide sequences were analysed at the two ends of bacteriophage Mu DNA. Such analyses reveal the existence of a short stretch of common sequences that are located at the termini and are orientated as inverted repeats. They also confirm that the heterogeneous bacterial DNA covalently bound to the ends of vegetative Mu DNA is totally removed during lysogenisation.

Base Sequence↗
PubMed1977

Involvement of IS1 in the dissociation of the r-determinant and RTF components of the plasmid R100.1.

The formation of the r-determinant pLC1 and of the RTF pAR132 from the composite plasmid R100.1 was investigated. The general location of IS1 sequences on the three plasmids was established by hybridization of lambdar14 CII::IS1 DNA to EcoRI generated fragments of the various plasmids separated by agarose gel electrophoresis and transferred directly to nitrocellulose filters. The position of IS1 sequences on these fragments and the homologies between fragments were analyzed by electron microscopy of heteroduplex molecules. The results show that the excision of both pLC1 and pAR132 occurred by an exchange between the two IS1 sequences present on R100.1.

Base Sequence↗
PubMed1977

Appearance of a chromatin protein during the erythroid differentiation of Friend virus-transformed cells.

Chromatin proteins from erythroleukemia cells transformed by Friend virus were analyzed by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. A new chromosomal protein, apparent molecular weight 25,000, was shown to appear during erythroid differentiation of the cells induced by dimethyl sulfoxide or hexamethylenebisacetamide. This protein is tightly bound to the chromatin and does not appear to be related to any of the known histones. It is also demonstrated that this protein is not induced in a dimethyl sulfoxide-resistant variant of these cells.

Cell Differentiation↗
PubMed1976

Two forms of simian-virus-40-specific T-antigen in abortive and lytic infection.

Simian-virus-40-specific T-antigen was isolated by immunoprecipitation. From other studies we have proof that the T-antigen described in this work is coded by the viral DNA. The molecular weight estimated from electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels of T-antigen isolated from nonpermissive mouse cells in abortive infection is 86,000 and from permissive monkey cells in lytic infection is 82,000. The 86 kilodalton T-antigen is readily converted in vitro into an 82 kilodalton form by incubation with extracts from permissive monkey cells but not with extracts from nonpermissive mouse or hamster cells. This and the results of fingerprinting analysis of tryptic peptides suggest that T-antigen may be processed in permissive cells.

Animals↗
PubMed1976

Mapping of the three species of polyoma mRNA.

The polyoma mRNA's present in the cytoplasm of primary cultures of mouse kidney cells during lytic infection were characterized by sedimentation velocity analysis and by hybridization to polyoma DNA fragments generated by a specific endonuclease of Hemophilus parainfluenzae (Hpa II).

Base Sequence↗
PubMed1975

Transposition of R factor genes to bacteriophage lambda.

Transpositions of segments of R factor (antibiotic resistance plasmids) to bacteriophage lambda have been selected and characterized. Cells of Escherichia coli harboring R factors that determine kanamycin resistance were infected with phage lambda, and lambdakan transducing lines were obtained. Each of the three examined is unusual when compared to lambda transducing phages containing E. coli chromosomal genes: the kan insertions (a) occur at several sites, each well removed from the integration region POP', (b) are not associated with deletion of lambda phage DNA, and (c) are separable from the lambda genome during transduction or during lytic growth. Two insertions from the same R factor contain 1.5 kilobase sequences repeated in inverted order. The properties of the lambdakan phage suggest that R factors contain systems capable of mediating genetic exchange in the absence of extensive DNA homology. It is suggested that such systems of exchange may have played important roles in R factor evolution.

Chromosome Mapping↗