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Biomedical subjects

B G Forget

Publications and source records attributed to B G Forget.

At least 127 records · Page 7Linked to original sources
PubMed1982

The aminoacyl-tRNA population of human reticulocytes.

The aminoacyl-tRNA population of human reticulocytes has been examined. These studies include: 1) determination of the levels of amino acid acceptance for 20 aminoacyl-tRNAs; 2) comparison of 20 aminoacyl-tRNAs from human reticulocytes to those of rabbit reticulocytes by reverse phase chromatography; 3) comparison of the levels of Ile- and Leu-tRNAs in fetal and adult reticulocytes; and 4) determination of the codon recognition properties of human Ala-, Asn-, His-, Leu-, Thr-, and Val-tRNAs. These studies provide evidence that the aminoacyl-tRNA population of human reticulocytes is adapted to the requirements of protein synthesis.

Adult↗
PubMed1982

Abnormally spliced messenger RNA in erythroid cells from patients with beta+ thalassemia and monkey cells expressing a cloned beta+-thalassemic gene.

The reduced beta-globin synthesis characterizing the beta+ thalassemia phenotype has been shown to be caused by anomalous processing within the small intervening sequence (IVS1) of the beta-globin mRNA precursor. The beta-globin gene from such patients contains a single base substitution within IVS1, located 22 bp from the 3' junction between IVS1 and exon 2, creating an alternative splice site within IVS1 and resulting in retention of the 3'-terminal 19 bases of IVS1. We have identified this abnormally spliced mRNA in the reticulocyte RNA of two patients with beta+ thalassemia, by S1 nuclease mapping and primer-extension analysis. Moreover, a cloned beta+-thalassemic gene preferentially generated the anomalously spliced RNA when expressed in monkey kidney cells. The anomalously spliced RNA constituted approximately 80%--90%, and normal beta RNA approximately 10%--20%, of the total beta mRNA. In contrast, the small amount of beta mRNA present in reticulocytes from such patients consisted predominantly of normal beta mRNA. These results suggest that the reduced amount of normally functioning beta mRNA present in such patients results from preferential processing at the alternative splice site, with subsequent instability, reduced nuclear processing and/or inadequate cytoplasmic transport of the abnormal RNA species.

Animals↗
PubMed1982

Cloning and nucleotide sequence analysis of human embryonic zeta-globin cDNA.

Clones of human embryonic alpha-like zeta-globin cDNA were isolated, by detection using cross-hybridization to human alpha-globin cDNA probes, from a cDNA library derived from the mRNA of the human erythroleukemia cell line K562. Nucleotide sequence analysis of these cDNA clones revealed a coding sequence that corresponds perfectly to the independently derived amino acid sequence of the human zeta-globin chain. Comparison of the nucleotide sequence of human zeta-globin cDNA with that of human alpha-globin cDNA confirmed previous estimates of very distant evolutionary divergence between the human zeta- and alpha-globin genes. Nevertheless, the human zeta-globin cDNA sequence shares a remarkable similarity to that of the alpha-globin gene in its codon usage, high G + C base composition, and lack of bias against usage of CG dinucleotides.

Base Composition↗
PubMed1981

Base substitution in an intervening sequence of a beta+-thalassemic human globin gene.

beta globin gene fragments from a patient with homozygous beta+-thalassemia have been cloned and subjected to restriction endonuclease, nucleotide sequence, and in vitro trancription analyses. Restriction endonuclease mapping of the cloned gene fragments revealed no deletions or other rearrangements, and transcription of the thalassemic gene appeared to be normal in vitro. However, nucleotide sequence analysis of the beta+-thalassemic gene fragments permitted identification of a single base change in the body of the small intervening sequence. This nucleotide change creates a sequence much like that of the 3' splice site of the small intervening sequence. The presence of a potential anomalous splicing site as a result of this base change suggests a mechanism for defective posttranscriptional processing of beta globin mRNA precursor molecules in beta+-thalassemia.

Base Sequence↗
PubMed1981

Globin chain electrophoresis for prenatal diagnosis of beta thalassemia.

Determination of the biosynthetic beta/gamma ratio in samples of fetal blood is used for prenatal diagnosis of thalassemia. The current method, carboxymethyl cellulose chromatography (CMC), is cumbersome, slow, and expensive. Radiolabelled globin chains (A gamma, G gamma, beta, and alpha) can also be separated by electrophoresis in slab gels containing polyacrylamide, acid, urea, and Triton X-100. The radioactive bands are detected by fluorography. We determined the beta/gamma ratio in 24 samples of blood from fetuses at risk for beta thalassemia. CMC column data were compared with quantitations from fluorograms of slab gels. The beta/gamma synthetic ratios correlated (r=0.91), although the ratios were slightly less by gel than by column. The gel method is simple, inexpensive, and permits up to a dozen simultaneous analyses. Confirmatory CMC columns need only be run if the beta/gamma ratio is between 0.01 and 0.03 by gel.

Carboxymethylcellulose Sodium↗
PubMed1980

Physicochemical measurement of the base composition of mRNA-related sequences of the human alpha and beta globin genes.

Hybrids formed between human alpha and beta globin cDNA and total human cellular DNA have been studied by thermal denaturation and cesium chloride density gradient centrifugation. From these studies, the weight average G + C content of human alpha globin cDNA has been determined to be 62% +/- 2% and that of human beta globin cDNA 51% +/- 2%. These values correlate well with the results of G + C content of the human alpha and beta globin cDNAs as determined by direct nucleotide sequence analysis of the cDNAs. Thermal denaturation and cesium chloride density gradient centrifugation of DNA-cDNA hybrids can therefore provide accurate information on the base composition of mRNA related sequences of any single copy gene for which a relatively pure cDNA can be obtained, without the necessity for direct nucleotide sequence analysis.

Base Composition↗