PubMed Health⌕ Search

Biomedical subjects

S J Goss

Publications and source records attributed to S J Goss.

At least 19 recordsLinked to original sources
PubMed1994

Demonstration of the X-linkage and order to the genes GLA, G6PD, HPRT, and PGK in two vole species of the genus Microtus.

Using a variety of genetic methods, it is shown in this paper that the genes GLA, G6PD, HPRT, and PGK are X-linked in the vole Microtus subarvalis. The order of these genes has been investigated in two vole species, M. subarvalis and M. kirgisorum, by using the mapping technique of Goss and Harris (1977a, b), which depends on the analysis of gamma-ray-induced gene segregation. The experimental data were processed with the computer programme RHMAP (Ginsburg et al., 1993). The analysis indicated that the correct gene order in M. subarvalis is PGK-HPRT-G6PD-GLA, and the same gene order was found to be the most probable for M. kirgisorum. The relative distances between the genes in the two vole species are apparently the same. The RHMAP programme has also been applied to data previously reported for the same set of X-linked genes in the American mink (Zhdanova et al., 1988), the Australian marsupial Planigale maculata (Dobrovic and Graves, 1986), and man. The evolutionary conservation of the linear order of these X-linked genes in different mammalian taxa is discussed.

Animals↗
PubMed1991

BWTG3 hepatoma cells can acquire phenylalanine hydroxylase, cystathionine synthase and CPS-I without genetic manipulation, but activation of the silent OTC gene requires cell fusion with hepatocytes.

The mouse hepatoma BWTG3 has been tested for its ability to grow in three different media that select for traits normally expressed in adult liver: homocysteine medium to select for cystathionine synthase (CS), tyrosine-free medium for phenylalanine hydroxylase (PH), and ornithine medium for carbamylphosphate synthetase-I (CPS-I) and ornithine transcarbamylase (OTC). In no case were the cells immediately capable of bulk growth, showing that all these traits were in some degree deficient. However, the cultures in homocysteine medium and in tyrosine-free medium both gave rise, spontaneously, to growing clones with frequencies of approximately 10(-3) and 10(-5), respectively. The deficiencies of CS and PH were accordingly excluded from further study, in view of their inherent instability. In contrast, no colonies ever formed in ornithine medium. Though neither CPS-I nor OTC were detectable in stock BWTG3 cells, it was found that CPS-I was readily inducible by hormones. The deficiency of OTC, however, appeared to be totally stable showing no reversion in response either to hormones or to azacytidine treatment. This deficiency was investigated by fusing the hepatoma to OTC+ liver cells prepared from normal or sparse-fur (spf) mice. Sparse-fur mice were used because their OTC is mutant and has a distinctive pH-dependence. OTC+ hybrids were readily produced, without the need for any specific selection for OTC, and, in one case at least, with only minimal chromosome segregation. In all the OTC+ hybrids made with spf cells, there was clear reactivation of the wild-type, hepatoma-derived OTC gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Retroviral vector infection and transplantation in rats of primary fetal rat hepatocytes.

Retroviral vectors were used to transduce recombinant DNA encoding firefly luciferase, Escherichia coli beta-galactosidase or human factor IX into fetal rat hepatocytes in primary culture. Hepatocytes were transduced optimally during a restricted time interval, 2-4 days post-plating. Although efficient and stable expression of reporter gene products was observed in vitro, it was affected differentially by culture conditions (plating density, media constituents) and chemical modulators of hepatocyte growth and differentiation (gelatin, hydrocortisone, isobutylmethylxanthine). Cultured cells, mock-infected or infected with a luciferase-expressing vector, were harvested non-enzymatically and injected subcutaneously into the dorsal neck fascia of neonatal syngeneic rats. Tissue isolated from injection sites one week later contained hepatocyte foci. In animals transplanted with infected cells, the preliminary results suggest that luciferase activity was present at these sites in proportion to the numbers of injected cells. These findings and previous observations made with hepatocytes from neonatal and adult primary cultures, indicate that from day 19 in utero through maturity the transient temporal 'period of susceptibility' to infection in vitro is independent of the developmental state of starting tissue. Transplantability of cultured fetal hepatocytes infected with retroviral vectors and stably expressing reporter gene products suggests that such cells might provide promising models for liver gene therapy.

Animals↗
PubMed1989

Androgen receptor locus on the human X chromosome: regional localization to Xq11-12 and description of a DNA polymorphism.

The gene for the androgen receptor, mutations at which cause the X-linked androgen insensitivity syndrome, has been localized to the q11----q12 region of the human X chromosome by analysis, using a cloned cDNA for the androgen receptor, of somatic cell hybrid panels segregating portions of the X chromosome. A moderate-frequency HindIII RFLP has been found which should be useful in genetic linkage analysis of the various inherited forms of androgen insensitivity.

Animals↗
PubMed1987

Routes of viral spread in the von Szily model of herpes simplex virus retinopathy.

Intraocular inoculation of herpes simplex virus type 1 (HSV-1) in one eye of rabbits results in encephalitis and contralateral necrotizing viral retinopathy. The effects of viral inoculation site and optic nerve (ON) transection on the spread of virus to the brain and contralateral eye in this model were investigated. A surgical technique was developed for transection of the retrobulbar optic nerve posterior to the entrance of the central retinal vessels. HSV-1 was inoculated into the AC or vitreous of one eye in normal rabbits and in rabbits with one ON transected, either ipsilateral or contralateral to the side of inoculation. Animals were followed clinically for signs of disease. Encephalitis and contralateral retinopathy (CR) occurred following both AC and vitreous inoculation of virus, although CR developed later in AC-inoculated rabbits. Ipsilateral retinopathy (IR) developed in 83% of vitreous-inoculated rabbits, but in only 5% of AC-inoculated animals. IR developed 8 days after the onset of CR in the AC-inoculated group. ON transection on the side of virus inoculation prevented development of CR only in vitreous-inoculated rabbits. ON transection on the side opposite virus inoculation prevented CR regardless of the site of inoculation. These findings suggest that HSV-1 can leave the inoculated eye by multiple routes depending on the site of virus inoculation, but that virus reaches the retina of the contralateral eye via the optic nerve.

Animals↗
PubMed1986

Characterization of cystathionine synthase as a selectable, liver-specific trait in rat hepatomas.

Cell growth using homocysteine as a source of cysteine-sulphur requires two enzymes, cystathionine synthase (CS) and gamma-cystathionase (CT). The second of these enzymes, CT, is apparently present in most cell lines regardless of their tissues of origin, since most cells can grow in vitro in the absence of cystine if they are provided with cystathionine, the intermediate in the pathway. Likewise, homocysteine will support the growth of many human cells. However, of a wide range of rodent cells, only well-differentiated rat hepatoma cells were found to grow using homocysteine in place of cystine. It is shown that cell growth in homocysteine-medium correlates well with the presence in the cells of detectable levels of CS. Furthermore, in cells able to grow in homocysteine-medium, it is possible to demonstrate the homocysteine-dependent trans-sulphuration of serine to cysteine. Growth in homocysteine-medium is not dependent on the release of preformed cysteine from disulphide complexes with serum proteins. In cell hybrids, and in 'dedifferentiated' variants of rat hepatomas, CS, but not CT, is subject to extinction coordinately with well-characterized liver-specific traits. For rodent cells, homocysteine-medium thus acts as a selective medium requiring the expression of a single liver-specific trait, CS. In addition it is shown that, in certain hepatoma variants, CS is regulated co-ordinately with a urea-cycle enzyme (carbamoyl phosphate synthetase I) by glucocorticoids and cyclic-AMP. Cell death through cysteine starvation is briefly considered. The immediate cause of death is apparently an insufficient supply of reduced glutathione. Selenium and vitamin E assist cell growth when the supply of cysteine is limiting.

Animals↗
PubMed1985

Regional localization of the phosphoglycerate kinase gene and pseudogene on the human X chromosome and assignment of a related DNA sequence to chromosome 19.

We have used a cDNA clone for human phosphoglycerate kinase (PGK) to examine the chromosomal localization of three members of the human PGK gene family. Using somatic cell hybrids segregating portions of several X-autosome translocations as well as a clone panel of hybrids segregating radiation-induced fragments of the human X chromosome, we assign a PGK pseudogene to the region Xq11-Xq13, proximal to the functional X-linked PGK gene located in Xq13. In addition, using a panel of 24 somatic cell hybrids, we assign an autosomal PGK-related DNA sequence to human chromosome 19.

Animals↗
PubMed1984

Arginine synthesis by hepatomas in vitro. I. The requirements for cell growth in medium containing ornithine in place of arginine and the isolation and characterization of variant hepatomas auxotrophic for arginine.

Cell growth in 'ornithine-medium' requires the expression of two liver-specific genes, those for ornithine transcarbamoylase (OTC) and carbamoyl phosphate synthetase I (CPS-I). CPS-II appears unable to replace CPS-I in this system. The need for N-acetylglutamate (to activate CPS-I) can be met, at least in part, by providing it in the medium. The other gene products involved in arginine biosynthesis are probably all ubiquitous (i.e. not tissue-specific). In an attempt to study the factors responsible for the expression of liver-specific genes, variant hepatomas are isolated that have lost the ability to grow in ornithine-medium. Two classes of 'orn-' variants are identified: unstable variants that require dexamethasone for adequate CPS-I production, and 'stable' variants that have lost many liver-specific traits. Studies on one stable variant show that it can revert (though rarely), and that it regains its various liver-specific traits in a non-coordinate fashion.

Animals↗
PubMed1984

Arginine synthesis by hepatomas in vitro. II. Isolation and characterization of Morris hepatoma variants unable to convert ornithine to arginine, and modulation of urea-cycle enzymes by dexamethasone and cyclic-AMP.

'77orn', a derivative of the Morris rat hepatoma 7777, stably expresses high levels of ornithine transcarbamoylase (OTC) and carbamoylphosphate synthetase I (CPS-I), and is able to grow indefinitely in ornithine-medium (medium with ornithine in place of arginine). Variants that have lost this ability are isolated from 77orn by a 'suicide' selective technique dependent on the cellular incorporation of [3H]ornithine. These variants, which have reduced levels of CPS-I, or of both CPS-I and OTC, are shown to have developed multiple hormonal requirements; their enzyme deficiencies can be reversed by use of an appropriately supplemented medium. In particular, CPS-I is inducible by dexamethasone and dibutyryl-cyclic-AMP in combination. Cholera toxin can be used instead of cyclic-AMP, but then butyrate is additionally required if the induction is to be maintained in the long term. The use of these agents in excess can depress OTC. Several other hepatomas, and alos explanted foetal rat liver cells, have similar requirements for CPS-I expression. It is argued that multiple hormonal requirements for CPS-I production are normal in liver cells in vitro, and that hormone-independent hepatomas should be regarded as abnormal. The implications of this for the somatic cell genetic investigation of differentiation are briefly discussed.

Animals↗
PubMed1984

The associated reactivation of two X-linked genes. The spontaneous and azacytidine-induced reexpression of ornithine transcarbamoylase and glucose-6-phosphate dehydrogenase in a rat hepatoma.

Two X-linked genes, specifying ornithine transcarbamoylase (OTC) and glucose-6-phosphate dehydrogenase (Glc-6-PD), are reversibly suppressed in certain derivatives of the rat H4-II-E hepatoma. Either gene can become reactivated spontaneously, and it is shown that both can be reactivated by azacytidine treatment. This gene reactivation has been investigated by enzyme assay and by the use of selective growth media ('ornithine-medium' to select for OTC, and medium containing diamide to select for Glc-6-PD). There is a clear tendency for both genes to be reactivated together, though either can become active alone. Since OTC is an enzyme of the urea-cycle, and Glc-6-PD is an enzyme of the hexose monophosphate shunt, and since these two pathways are normally under quite separate control, it would seem that the coupled regulation of the two genes in these hepatomas is abnormal. It is suggested that the suppression of the two genes resembles X-inactivation: in both cases, azacytidine treatment induces gene reactivation with a high frequency and results in different clones of cells expressing widely varying amounts of enzyme activity. The association between the re-expression of OTC and Glc-6-PD might indicate that some phenomenon like the position-effect is occurring.

Animals↗
PubMed1979

Regional localization of the gene for human phosphoribosylpyrophosphate synthetase on the X chromosome.

Sixty-eight independent hybrid clones were isolated after irradiated normal human lymphocytes were fused with Chinese hamster fibroblasts lacking hypoxanthine-guanine phosphoribosyltransferase activity. The cells were grown under selective conditions requiring retention of the X chromosome-linked locus for human hypoxanthine-guanine phosphoribosyltransferase. The frequency and patterns of cotransference of human phosphoribosylpyrophosphate synthetase with the selected marker and with additional X-linked enzymatic markers confirm X linkage of the structural gene for human phosphoribosylpyrophosphate synthetase and support assignment of this gene to a position on the long arm of the X, between the loci for alpha-galactosidase and hypoxanthine-guanine phosphoribosyltransferase.

Chromosome Mapping↗
PubMed1977

Gene transfer by means of cell fusion I. Statistical mapping of the human X-chromosome by analysis of radiation-induced gene segregation.

Hybrid cells were obtained by virus-induced fusion of hamster cells with irradiated human cells. The analysis of such hybrids permits a study of the effects of lethal doses of radiation on human cells and provides a method of sub-chromosomal genetic mapping that is independent of karyological analysis. Radiation-induced chromosome exchanges are shown to be extremely localized, and a map of 4 X-linked genes is presented.

Animals↗
PubMed1977

Gene transfer by means of cell fusion. II. The mapping of 8 loci on human chromosome 1 by statistical analysis of gene assortment in somatic cell hybrids.

A method is described which should permit determination of the order and spacing of genes on all human chromosomes by the analysis of just one set of man-mouse hybrid cells. This method is used to determine the map of 8 loci on human chromosome I. A comparison of the statistical maps of chromosome I and of the X-chromosome with the cytogenetic maps of these chromosomes at metaphase indicates that the statistically derived distances between genes are related to the amount of Giemsa light-band material between the genes.

Animals↗