scholarly journals Gene Mapping in Marsupials and Monotremes, V. Synteny between Hypoxanthine Phosphoribosyltransferase and Phosphoglycerate Kinase in the Platypus

1988 ◽  
Vol 41 (2) ◽  
pp. 231 ◽  
Author(s):  
Jaclyn M Watson ◽  
Jennifer A MarshalI Graves
Keyword(s):  
X Chromosome ◽  
Chromosomal Location ◽  
Chinese Hamster ◽  
Low Frequency ◽  
Phosphoglycerate Kinase ◽  
Chromosomal Assignment ◽  
Hypoxanthine Phosphoribosyltransferase ◽  
Syntenic Group ◽  
Chinese Hamster Cells ◽  
Synteny Group

In order to extend comparative mapping studies to the monotreme mammals (subclass Prototheria), somaticcell hybrids were obtained between Chinese-hamster cells deficient in hypoxanthine phosphoribosyltransferase (HPRT) and platypus fibroblasts. The characteristics of these hybrids closely resemble those of metatherian x eutherian hybrids, in that they are recovered at low frequency and they rapidly segregate and fragment platypus chromosomes. Biochemical and cytological studies of the hybrids, their subclones and HPRT-deficient revertants indicate that phosphoglycerate kinase is syntenic with HPRT in the platypus (as it is in other mammals); however, the studies do not permit chromosomal assignment of the syntenic group. The implications of the chromosomal location of this ancient synteny group for the evolution of the mammalian X chromosome are discussed.

scholarly journals Differential activation of the hprt gene on the inactive X chromosome in primary and transformed Chinese hamster cells.

1989 ◽  
Vol 9 (4) ◽  
pp. 1635-1641 ◽  
Author(s):  
S G Grant ◽  
R G Worton
Keyword(s):  
Cell Lines ◽  
X Chromosome ◽  
Gene Activation ◽  
Chinese Hamster ◽  
Fibroblast Cell ◽  
Dna Demethylation ◽  
Hprt Gene ◽  
Primary Fibroblast ◽  
Chinese Hamster Cells ◽  
Inactive X Chromosome

We have investigated the genetic activation of the hprt (hypoxanthine-guanine phosphoribosyltransferase) gene located on the inactive X chromosome in primary and transformed female diploid Chinese hamster cells after treatment with the DNA methylation inhibitor 5-azacytidine (5azaCR). Mutants deficient in HPRT were first selected by growth in 6-thioguanine from two primary fibroblast cell lines and from transformed lines derived from them. These HPRT- mutants were then treated with 5azaCR and plated in HAT (hypoxanthine-methotrexate-thymidine) medium to select for cells that had reexpressed the hprt gene on the inactive X chromosome. Contrary to previous results with primary human cells, 5azaCR was effective in activating the hprt gene in primary Chinese hamster fibroblasts at a low but reproducible frequency of 2 x 10(-6) to 7 x 10(-6). In comparison, the frequency in independently derived transformed lines varied from 1 x 10(-5) to 5 x 10(-3), consistently higher than in the nontransformed cells. This increase remained significant when the difference in growth rates between the primary and transformed lines was taken into account. Treatment with 5azaCR was also found to induce transformation in the primary cell lines but at a low frequency of 4 x 10(-7) to 8 x 10(-7), inconsistent with a two-step model of transformation followed by gene activation to explain the derepression of hprt in primary cells. Thus, these results indicate that upon transformation, the hprt gene on the inactive Chinese hamster X chromosome is rendered more susceptible to action by 5azaCR, consistent with a generalized DNA demethylation associated with the transformation event or with an increase in the instability of an underlying primary mechanism of X inactivation.

Radiosensitization of X Chromosome of Chinese Hamster Cells Related to Incorporation of 5-Bromodeoxyuridine

Science ◽  
1966 ◽  
Vol 152 (3721) ◽  
pp. 519-521 ◽  
Author(s):  
W. C. Dewey ◽  
B. A. Sedita ◽  
R. M. Humphrey
Keyword(s):  
X Chromosome ◽  
Chinese Hamster ◽  
Chinese Hamster Cells

scholarly journals Activation of the hprt gene on the inactive X chromosome in transformed diploid female Chinese hamster cells

1989 ◽  
Vol 92 (4) ◽  
pp. 723-732
Author(s):  
S.G. Grant ◽  
R.G. Worton
Keyword(s):  
Cell Line ◽  
X Chromosome ◽  
Chinese Hamster ◽  
Dna Demethylation ◽  
Hprt Gene ◽  
Similar Treatment ◽  
Chinese Hamster Cells ◽  
Inactive X Chromosome ◽  
Diploid Female ◽  
Phenotypic Reversion

Treatment with 5-azacytidine, a potent inhibitor of DNA methylation, was used to induce activation of the selectable hprt gene on the inactive X chromosome in a diploid female Chinese hamster cell line. The transformed, stably diploid cell line F3B was selected in media containing the lethal purine analogue 6-thioguanine, to generate a phenotypically HPRT- mutant, F3BT1, of presumed genotype hprt-/hprt(+), where (+) represents the presumably wild-type allele on the inactive X chromosome. Treatment of F3BT1 with 5-azacytidine resulted in phenotypic reversion to HPRT+ at a frequency greater than 10(−3). Similar treatment of 6-thioguanine-resistant control lines derived from male cells, or from CHO (which has no inactive X chromosome), had no effect on the frequency of phenotypic reversion, indicating that activation of the hprt(+) allele, rather than reversion of the hprt- is responsible. This conclusion is substantiated by documentation of the low mutagenic capacity of 5-azacytidine in this system. Proof that the hprt(+) allele can be activated by 5-azacytidine treatment was obtained in somatic cell hybrids in which hprt gene products from the active and inactive X chromosomes could be distinguished by isoelectric focusing. Our results demonstrate that X-linked gene activation associated with generalized DNA demethylation occurs with high frequency in transformed diploid Chinese hamster cells.

Differential activation of the hprt gene on the inactive X chromosome in primary and transformed Chinese hamster cells

1989 ◽  
Vol 9 (4) ◽  
pp. 1635-1641
Author(s):  
S G Grant ◽  
R G Worton
Keyword(s):  
Cell Lines ◽  
X Chromosome ◽  
Gene Activation ◽  
Chinese Hamster ◽  
Fibroblast Cell ◽  
Dna Demethylation ◽  
Hprt Gene ◽  
Primary Fibroblast ◽  
Chinese Hamster Cells ◽  
Inactive X Chromosome

We have investigated the genetic activation of the hprt (hypoxanthine-guanine phosphoribosyltransferase) gene located on the inactive X chromosome in primary and transformed female diploid Chinese hamster cells after treatment with the DNA methylation inhibitor 5-azacytidine (5azaCR). Mutants deficient in HPRT were first selected by growth in 6-thioguanine from two primary fibroblast cell lines and from transformed lines derived from them. These HPRT- mutants were then treated with 5azaCR and plated in HAT (hypoxanthine-methotrexate-thymidine) medium to select for cells that had reexpressed the hprt gene on the inactive X chromosome. Contrary to previous results with primary human cells, 5azaCR was effective in activating the hprt gene in primary Chinese hamster fibroblasts at a low but reproducible frequency of 2 x 10(-6) to 7 x 10(-6). In comparison, the frequency in independently derived transformed lines varied from 1 x 10(-5) to 5 x 10(-3), consistently higher than in the nontransformed cells. This increase remained significant when the difference in growth rates between the primary and transformed lines was taken into account. Treatment with 5azaCR was also found to induce transformation in the primary cell lines but at a low frequency of 4 x 10(-7) to 8 x 10(-7), inconsistent with a two-step model of transformation followed by gene activation to explain the derepression of hprt in primary cells. Thus, these results indicate that upon transformation, the hprt gene on the inactive Chinese hamster X chromosome is rendered more susceptible to action by 5azaCR, consistent with a generalized DNA demethylation associated with the transformation event or with an increase in the instability of an underlying primary mechanism of X inactivation.

Isolation of phosphoglycerate kinase genes from Chinese hamster cells

1987 ◽  
Vol 15 (3) ◽  
pp. 463-464
Author(s):  
STEPHEN RAWSON ◽  
MICHAEL MORGAN ◽  
PELIN FAIK
Keyword(s):  
Chinese Hamster ◽  
Phosphoglycerate Kinase ◽  
Chinese Hamster Cells

Expression of a human phosphoglycerate kinase cDNA in Chinese hamster cells

1987 ◽  
Vol 15 (3) ◽  
pp. 463-463
Author(s):  
JAMES I. H. WALKER ◽  
MICHAEL J. MORGAN ◽  
PELIN FAIK
Keyword(s):  
Chinese Hamster ◽  
Phosphoglycerate Kinase ◽  
Chinese Hamster Cells
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