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Biomedical subjects

D Banville

Publications and source records attributed to D Banville.

64 records · Page 4Linked to original sources
PubMed1984

Immunological and genetic characterization of 2-deoxygalactose-resistant, galactokinase-deficient mutants of Chinese hamster cells: evidence for structural mutations at the galK locus.

Ten independent mutants resistant to 2-deoxygalactose and without any detectable galactokinase activity (null-galactokinase mutations) were isolated from mutagenized Chinese hamster somatic cells. They were analyzed for the presence of serologically cross-reacting material (CRM) with antiserum generated against highly purified Chinese hamster galactokinase. All 10 mutants contain cross-reacting material (i.e., were CRM+), indicating that all the mutations affect the correct expression of a product of the galactokinase structural gene. Complementation analysis among them shows that the 10 mutations fall in one functional genetic unit.

Animals↗
PubMed1983

The nucleotide sequence of the mRNA encoding a tadpole beta-globin polypeptide of Xenopus laevis.

We have determined the nucleotide sequence of a cloned cDNA derived from the mRNA encoding an abundant Xenopus laevis tadpole beta-globin polypeptide. The cloned sequence contains the entire coding region of the mRNA as well as most of its 5'- and 3' -noncoding regions. The complete amino acid sequence of the protein has been deduced. Comparison of this sequence with that of the major adult beta-globin polypeptide of X. laevis shows that the two gene products are highly diverged from each other, the tadpole sequence actually displaying a somewhat greater homology to the human beta-like globin sequences than to the adult frog sequence. An unusual feature of the predicted tadpole beta-globin polypeptide is the presence of a phenylalanine residue at its carboxyl terminus. All known amphibian, avian, and mammalian beta-globin polypeptides have a COOH-terminal histidine residue, and this amino acid is known to play a major role in the alkaline Bohr effect. This observation suggests that, as has been found for two fish hemoglobins which also have a COOH-terminal phenylalanine residue, the tadpole hemoglobin of X. laevis will display a much reduced alkaline Bohr effect.

Amino Acid Sequence↗
PubMed1983

Replication, methylation, and expression of X laevis globin genes injected into fertilized Xenopus eggs.

In the South African clawed toad, Xenopus laevis, the tadpole alpha-globin gene (alpha T1) and the major adult alpha- and beta-globin genes (alpha 1 and beta 1) are linked in the genome in the order alpha T1-alpha 1-beta 1. We show that cloned DNA fragments containing the Xenopus globin genes are replicated after injection into newly fertilized Xenopus eggs, reaching a maximal copy number at gastrulation. The DNA initially replicates as supercoils, but later it is found in a high-molecular-weight form, comigrating with the chromosomal DNA. In contrast to what has been found in mouse eggs, DNA does not become methylated when injected into Xenopus eggs. If, however, DNA is methylated in vitro before injection, methyl groups are retained through replication with a high efficiency. Both the adult alpha 1- and beta 1-globin genes are transcribed from their correct promoters in early embryonic stages, but the amount of transcription is relatively low and decreases in parallel with the decline in the amount of DNA retained in the embryo.

Animals↗
PubMed1982

The organization of the tadpole and adult alpha globin genes of Xenopus laevis.

Adult erythrocytes of X. laevis contain six electrophoretically resolvable globin polypeptides while tadpole erythrocytes contain four polypeptides, none of which comigrates with an adult protein. We show that three of the adult proteins are alpha globin polypeptides (alpha 1, alpha 2, alpha 3) and three are beta globin polypeptides (beta 1, beta 2, beta 3). We find that a tadpole alpha globin gene (alpha T1) is linked to the major adult locus in the sequence 5'-alpha T1-alpha 1-beta 1-3' with 5.2 kb separating alpha T1 from alpha 1. Another tadpole alpha globin gene (alpha T2) is linked to the minor adult locus in the sequence 5'-alpha T2-alpha 2-beta 2-3' with 10.7 kb separating alpha T2 from alpha 2. These linkage relationships are consistent with the major and minor loci having arisen by tetraploidization but the different separation of larval and adult globin genes at the two loci indicates the occurrence of some additional chromosomal rearrangement. Two alternative models are presented.

Amino Acid Sequence↗
PubMed1982

Effects of protein synthesis inhibition on low molecular weight RNA metabolism in tsH1, a mutant cell line with a temperature-sensitive leucyl-tRNA synthetase.

The effect of inhibition of protein synthesis on the synthesis and processing of low molecular weight RNA (LMW RNA) hs been studied on CHO-tsH1, a mutant cell line in which protein synthesis is rapidly inhibited at non-permissive temperature by inactivation of the enzyme leucyl-tRNA synthetase. The increase in temperature results in an increase in uridine uptake and in the specific activity of UTP pool which is probably not related to the mutation. We report in this paper that there is no significant alteration in the synthesis of LMW RNA (including 5S ribosomal RNA (rRNA) and tRNA) except for the inhibition of synthesis of nucleolar RNA species A. Since, in a previous paper, it has been shown that the processing of preribosomal nucleolar RNA does not proceed at 39.5 degrees C in CHO-tsH1 cells, these results are consistent with the hypothesis that nucleolar RNA species A is involved in the processing of rRNA depends on its synthesis and maturation.

Amino Acyl-tRNA Synthetases↗
PubMed1981

Synthesis and behaviour of small RNA species of CHO cells submitted to a heat chick.

Incubation of Chinese hamster ovary (CHO) cells for 1 hour at 43 degrees C results in an inhibition of high molecular weight RNA synthesis while most of the ow molecular weight RNAs are still synthesized. In cells returned to 37 degrees C, the transcription of high molecular weight RNA is reinitiated after 7 h recovery. The synthesis of snRNA A, C, D which are transcribed by RNA polymerase B (II) is inhibited in cells incubated at 43 degrees C while the synthesis of 4S, 5S, L and K components is not affected. During the recovery period the synthesis of low molecular weight RNA is increased variously according to the components relative to control cells : x 1.5 for 5S RNA to x 8 for snK. After 9 h recovery at 37 degrees C, snA and SnD are again synthesized but newly synthesized snC does not appear in the nucleus while a putative preC component accumulates in the cytoplasm. On the other hand, the distribution of all the pre-existing low molecular weight RNAs is not affected by the heat shock.

Animals↗
PubMed1976

Galactokinase mutants of Chinese hamster somatic cells resistant to 2-deoxygalactose.

The growth of Chinese hamster somatic cells was inhibited by 0.2 mg/cc of 2-deoxygalactose. Mutants partially or fully resistant to 2-deoxygalactose were isolated in a single-step or two-step selection. Some of them did not grow as well as the wild type; one of them which lacked galactokinase(EC.2.7.1.6) activity did not grow at all in galactose medium. The galactokinase kinetic properties (Vmax & kmax of the other mutants and of the wild type were different. Therefore resistance resulted either from the possible absence of galactokinase synthesis or from a structural mutation, possible a missence mutation, in the galactokinase gene.- A simple diagnostic test for juvenile cataract is proposed.

Cell Line↗
PubMedDate not supplied

Primary structure of human transferrin receptor deduced from the mRNA sequence.

In vertebrates all iron is taken up via the carrier protein transferrin. The carrier first binds its receptor and the receptor-ligand complex is then internalized via coated pits. The transferrin receptor is a transmembrane glycoprotein (apparent molecular weight (MW) 180,000) composed of two disulphide-bonded sub-units (each of apparent MW 90,000) It contains three N-linked glycan units and is post-translationally modified with both phosphate and fatty acyl groups. Here we have determined the nucleotide sequence of the coding region of the human transferrin receptor mRNA and from this deduced the amino acid sequence of the protein. The receptor does not contain an N-terminal signal peptide but there is a membrane-spanning segment 62 amino acids from the N-terminus. It therefore has a somewhat unusual configuration with a small N-terminal cytoplasmic domain and a C-terminal extracellular domain of 672 amino acids.

Amino Acid Sequence↗