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Biomedical subjects

W G Nash

Publications and source records attributed to W G Nash.

35 records · Page 2Linked to original sources
PubMed1984

ERV3, a full-length human endogenous provirus: chromosomal localization and evolutionary relationships.

A full-length human endogenous provirus termed ERV3 was isolated from a human fetal recombinant DNA library by low stringency hybridization with two probes: baboon endogenous virus LTR; and a pol-env subclone from the endogenous chimpanzee provirus, CH2. DNA sequencing within the clone and comparisons with other retroviruses revealed that ERV3 contains gag and pol gene sequences that are significantly related to those of mammalian type C retroviruses and previously described human endogenous proviruses. The ERV3 genome was determined to reside at a single locus on human chromosome 7 using a panel of rodent X human somatic cell hybrids.

Amino Acid Sequence↗
PubMed1984

Gene for T-cell growth factor: location on human chromosome 4q and feline chromosome B1.

T-cell growth factor (TCGF) or interleukin-2 (IL-2), an immunoregulatory lymphokine, is produced by lectin- or antigen-activated mature T lymphocytes and in a constitutive manner by certain T-cell lymphoma cell lines. By means of a molecular clone of human TCGF and DNA extracted from a panel of somatic cell hybrids (rodent cells X normal human lymphocytes), the TCGF structural gene was identified on human chromosome 4. In situ hybridization of the TCGF clone to human chromosomes resulted in significant labeling of the midportion of the long arm of chromosome 4, indicating that the TCGF gene was located at band q26-28. Genomic DNA from a panel of hybrids prepared with HUT-102 B2 cells was examined with the same molecular clone. In this clone of cells, which produces human T-cell leukemia virus, the TCGF gene was also located on chromosome 4 and was apparently not rearranged. The homologous TCGF locus in the domestic cat was assigned to chromosome B1 by using a somatic cell hybrid panel that segregates cat chromosomes. Linkage studies as well as high-resolution G-trypsin banding indicate that this feline chromosome is partially homologous to human chromosome 4.

Animals↗
PubMed1984

The human homologs of the raf (mil) oncogene are located on human chromosomes 3 and 4.

Two human genes that are homologous to both the murine transforming gene (oncogene) v-raf and the chicken transforming gene v-mil have been mapped by means of human-rodent somatic cell hybrids to human chromosomes previously devoid of known oncogenes. One gene, c-raf-2, which appears to be a processed pseudogene, is located on chromosome 4. The other gene, c-raf-1, which appears to be the active gene, is located on chromosome 3 and has been regionally mapped by chromosomal in situ hybridization to 3p25. This assignment correlates with specific chromosomal abnormalities associated with certain human malignancies.

Adenocarcinoma↗
PubMed1984

Chromosomal organization of the human dihydrofolate reductase genes: dispersion, selective amplification, and a novel form of polymorphism.

The human dihydrofolate reductase (DHFR; tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.3) gene family includes a functional gene (hDHFR) and at least four intronless genes. Three intronless genes (hDHFR-psi 2, hDHFR-psi 3, and hDHFR-psi 4) are identifiable as pseudogenes because of DNA sequence divergence from the functional gene with introns, while one intronless gene (hDHFR-psi 1) is completely homologous to the coding sequences of the functional gene. Analysis of genomic DNA from two panels of somatic human-rodent cell hybrids with specific molecular probes provide insight into the chromosomal organization and assignment of these genes. The five genes are dispersed in that each one is found on a different chromosome. The functional gene hDHFR has been assigned to chromosome 5, and one pseudogene (hDHFR-psi 4), to chromosome 3. In a human cell line (HeLa) that was selected for methotrexate resistance, the functional locus became amplified, while there was no amplification of the four intronless pseudogenes. hDHFR-psi 1 was found to be present in DNA of some individuals and absent from DNA of others, consistent with a recent evolutionary origin of this gene originally suggested by its sequence identity to the coding portions of the functional gene. The presence or absence of this intronless pseudogene represents a previously unreported form of DNA polymorphism.

Animals↗
PubMed1983

Identification of a yellow gene-specific protein in Drosophila melanogaster by two-dimensional gel electrophoresis.

Analysis of temperature-sensitive mutants suggests that the yellow (y) gene in Drosophila melanogaster is expressed at a different time in each cell type that gives rise to the various structures of the adult cuticle. An important step in analyzing the regulation of this gene requires identification of the y structural protein. A polypeptide has been identified which correlates with the presence or absence of a functional y gene. Furthermore, this protein has the tissue distribution profile expected of the y structural gene product. The ability to locate this gene was facilitated by the use of coisogenic stocks, two-dimensional electrophoretic protein separation, and an ultrasensitive silver protein stain.

Animals↗
PubMed1982

Genetic mapping in mammals: chromosome map of domestic cat.

A genetic map of 31 biochemical loci located on 17 feline syntenic (linkage) groups has been derived by somatic cell genetic analysis of cat-rodent hybrids. Most of these syntenic groups have been assigned to one of the 19 feline chromosomes. Comparative linkage analysis of the feline biochemical loci and homologous human loci revealed considerable conservation of linkage associations between the primates and the Felidae (order Carnivora). Many of these same linkage groups have not been conserved in the murine genome. The genetic and evolutionary implications of comparative mapping analysis among mammalian species are discussed.

Animals↗
PubMed1982

Conserved regions of homologous G-banded chromosomes between orders in mammalian evolution: carnivores and primates.

The recent derivation of a biochemical map of 33 loci of the domestic cat (Felis catus) revealed a striking conservation of chromosomal linkage associations between the cat and humans. A comparison of homologous (by linkage criteria) chromosomes by using conventionally extended and high-resolution G-banding of human and feline chromosomes is presented. Four criteria for establishing probable cytogenetic homologies of chromosomal regions were invoked: (i) map placement of homologous genes to the same chromosomes; (ii) cytological correlation of G-banding pattern; (iii) placement of homologous genes, by regional gene mapping, in the region of cytological homology; and (iv) a requirement that the putative region of homology be ancestral and evolutionarily conserved within their respective orders. Five subchromosomal regions (homologous to human chromosome 1p, 2p, 2q, 12, and X) were found to be conserved and homologous by all the stated criteria. The conserved regions constitute nearly 20% by length of the human chromosomal genome. The implications of conservation of chromosome homologies between mammalian orders whose last common ancestor became extinct more than 60 million years ago is discussed.

Animals↗
PubMed1978

A gene (Bevi) on human chromosome 6 is an integration site for baboon type C DNA provirus in human cells.

Human VA-2 cells infected with baboon type C virus were cloned and fused to Syrian hamster cells, and 33 primary hybrid colonies were obtained. These cells segregated human chromosomes and retained the complete hamster genome. Assays for type C viral p30 antigen and reverse transcriptase were performed in conjunction with analyses of 30 gene-enzyme systems representing 22 different human chromosomes. The results comfirmed that a gene, Bevi, previously assigned to human chromosome 6, dominantly controls baboon type C virus expression in hybrid cells. Representative hybrid colones were studied by nucleic acid hybridization techniques for the presence of integrated proviral DNA using complementary 3H-DNA transcripts of the baboon viral RNA genome. For each of 12 clones examined, there was a concordance between the presence of human chromosome 6, the presence of baboon type C proviral DNA sequences and virus expression. Clones which segregated chromosome 6 as judged by isozyme and karyological analyses lost detectable proviral DNA sequences and failed to produce virus. No syntenic association between the replication of baboon virus and the presence of 21 other human chromosomes was deteced. We conclude that Bevi is a preferred integration site for the baboon type C provirus in the human genome.

Animals↗
PubMedDate not supplied

Cytogenetic methodologies for gene mapping and comparative analyses in mammalian cell culture systems.

Presented here are the detailed methods employed in our laboratory for gene mapping and cytogenetic analyses in human beings, in the domestic cat, and in other mammalian species. Induced in the procedures are: 1) establishment of primary fibroblast and lymphoid cell cultures; 2) heterologous cell fusion for production of rapidly proliferating cell hybrids; 3) cellular transformation of primary fibroblasts using an oncogenic retrovirus; 4) cell synchronization for high-resolution banding of promethaphase chromosomes; 5) chromosome-banding procedures, including G-banding, alkaline G-11, and Q-banding; and 6) in situ hybridization of radiolabeled molecular clones to metaphase chromosomes for regional gene localization.

Animals↗
PubMedDate not supplied

Mapping of an endogenous retroviral sequence to human chromosome 18.

The application of recombinant DNA technologies has allowed the detection of at least three families of moderately repetitive DNA segments in the human genome that are homologous to retroviruses previously isolated from mice and primates. One of these DNA segments has been shown by nucleotide sequence comparisons to be distantly related to both Moloney murine leukaemia virus (MoMuLV) and the endogenous baboon retrovirus and to have the sequence organization characteristic of an integrated retrovirus. Isolation of the homologous locus from chimpanzee DNA indicated that the integration event preceded the evolutionary divergence of chimpanzees and man. Here we have used a panel of rodent x human somatic cell hybrids to assign the chromosomal localization of this segment, called ERV1 (endogenous retrovirus-1), to human chromosome 18 (HSA 18).

Chromosome Mapping↗
PubMedDate not supplied

A molecular solution to the riddle of the giant panda's phylogeny.

Although it is generally agreed that the giant panda (Ailuropoda melanoleuca) is a member of the order Carnivora, there has long been disagreement over whether it should be classified with bears, raccoons or as a single member of its own family. Four independent molecular and genetic measures lead to a consensus phylogeny for the giant and lesser pandas. The lesser panda diverged from New World procyonids at approximately the same time as their departure from ursids, while ancestors of the giant panda split from the ursid lineage much later, just before the radiation which led to modern bears. The giant panda's divergence was accompanied by a chromosomal reorganization which can be partially reconstructed from the ursid karyotype, but not from that of procyonids or the lesser panda. The apparently dramatic, but actually limited, distinctions between the giant panda and the bears in chromosomal and anatomical morphology provide a graphic mammalian example of the discordance of molecular and morphological (and chromosomal) evolutionary change.

Animals↗
PubMedDate not supplied

Comparative gene mapping in the domestic cat (Felis catus).

The genetic map of the domestic cat has been developed as a model for studying both feline analogues of human genetic disease and comparative genome organization of mammals. We present here the results of syntenic mapping of 35 genes based upon concordant occurrence of feline gene homologues with feline chromosomes and previously mapped loci in a panel of 41 rodent x cat somatic cell hybrids. These somatic cell hybrids retain rodent chromosomes and segregate feline chromosomes, but in different combinations in each hybrid cell line. Thirty-three of the 35 new locus assignments extend and reaffirm conserved chromosome segment homologies between the human and cat genomes previously recognized by comparative mapping and zoo-FISH. These results demonstrate the extensive syntenic conservation between the human and feline genomes and extend the feline gene map to include 105 assigned loci.

Animals↗
PubMedDate not supplied

Chromosomal mapping of beta-globin and albino loci in the domestic cat. A conserved mammalian chromosome group.

Siamese cats are homozygous for the recessive cs allele of the color (albino) locus. The c locus is shown here by backcross analysis to be linked to the beta-hemoglobin (HBB) locus in the cat at a distance of approximately eight centiMorgans. The HBB locus and, by inference, the c locus were assigned to feline chromosome D1, by analysis of genomic DNAs from a panel of rodent X cat somatic cell hybrids with a molecular clone of the human beta-globin locus. Evolutionary conservation of the synthetic homology of feline chromosome D1 and human chromosome 11 is extensive. Comparison of high resolution G-trypsin-banded preparations of the two chromosomes permitted cytological alignment of the long arm of the conserved chromosomes providing that a minimum of one paracentric inversion is hypothesized. The placement of the albino locus on conserved syntenic groups of several markers (HBB, HRAS, LDHA) in both cat and mouse strongly indicates the conservative placement of the as yet unmapped human albino locus in the homologous syntenic group on human chromosome 11p.

Albinism↗