Electrophoretic Variation for X Chromosome-Linked Hypoxanthine Phosphoribosyl Transferase (Hprt) in Wild-Derived Mice

Chapman, Verne M.; Kratzer, Paul G.; Quarantillo, Barbara A.

doi:10.1093/genetics/103.4.785

Cited by 37 publications

(1 citation statement)

References 6 publications

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“…The reason for the rarity of studies of somatic cell determinants of HPRT expression appears to be that most recognized variants of HPRT represent mutations of the HPRT structural gene which result in the virtual absence of HPRT activity in all cell types (e.g., Lesch-Nyhan syndrome in humans) (Wilson et al, 1983). We detected electrophoretically distinct forms of HPRT in samplings of feral murine populations which appear to differ from the enzyme deficiency variants described in humans, in that they are common in the populations in which they occur and they are not associated with any obvious deleterious phenotypic effect (Chapman & Shows, 1976;Chapman et al, 1983; G. G. Johnson and V. M. Chapman, unpublished results). In this report, we describe results of studies that compare the levels of HPRT in tissues of mite expressing the wild-derived murine Hprt a allele(s) (from Mus musculus 1 Abbreviations: HPRT, hypoxanthine phosphoribosyltransferase (EC 2.4.2.8); Hprt, the structural gene of HPRT; APRT, adenine phosphoribosyltransferase (EC 2.4.2.7); EDTA, ethylenediaminetetraacetic acid; P-Rib-PP, 5-phosphorylribose 1-pyrophosphate; PEI, poly(ethylenimine); SDS, sodium dodecyl sulfate.…”

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confidence: 64%

Elevated levels of erythrocyte hypoxanthine phosphoribosyltransferase associated with allelic variation of murine Hprt

Johnson¹,

Larsen²,

Blakely³

et al. 1985

Biochemistry

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Murine stocks with wild-derived hypoxanthine phosphoribosyltransferase (HPRT) A alleles (Hprt a) have erythrocyte HPRT activity levels that are approximately 25-fold (Mus musculus castaneus) and 70-fold (Mus spretus) higher than those of laboratory strains of mice with the common Hprt b allele (Mus musculus: C3H/HeHa or C57B1/6). Since the purified HPRT A and B enzymes have substantially similar maximal specific activities (64 and 46 units/mg of protein, respectively), we infer that these HPRT activity levels closely approximate the relative levels of HPRT protein in these cells. Red blood cells of HPRT A and B mice have similar levels of adenine phosphoribosyltransferase activity (APRT; EC 2.4.2.7) and reticulocyte percentages, which suggests that the elevated levels of HPRT in erythrocytes of HPRT A mice are not secondary consequences of abnormal erythroid cell development. The HPRT activity levels in reticulocytes of HPRT B mice are approximately 35-fold higher than the levels in their erythrocytes and approach the HPRT activity levels in reticulocytes of HPRT A mice. Thus, the marked differences in the levels of HPRT protein in erythrocytes of HPRT A and B mice result from differences in the extent to which the HPRT A and B proteins are retained as reticulocytes mature to erythrocytes. The substantial and preferential loss of HPRT B activity from reticulocytes is paralleled by an equivalent loss of HPRT immunoreactive protein (i.e., CRM) from that cell, and we infer that the HPRT B protein is degraded or extruded as reticulocytes mature to erythrocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

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mentioning

confidence: 64%

Elevated levels of erythrocyte hypoxanthine phosphoribosyltransferase associated with allelic variation of murine Hprt

Johnson¹,

Larsen²,

Blakely³

et al. 1985

Biochemistry

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Mapping of the mouse X chromosome using random genomic probes and an interspecific mouse cross.

Amar¹,

Arnaud²,

Cambrou³

et al. 1985

The EMBO Journal

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Two libraries enriched in murine X chromosome material have been constructed in the X vector NM 1149 from flowsorted chromosomes. Inserts of unique genomic sequence DNA were purified and their X chromosome specificity characterised by hybridisation to a panel of somatic cell hybrid lines. Of the first five such X chromosome-specific probes characterised, all detect restriction fragment length polymorphisms (RFLPs) between inbred mouse laboratory strains such as C57BL/6 and BALB/c and the SPE/Pas mouse strain established from a wild Mus spretus mouse, when their DNAs are digested with the restriction enzyme TaqI. Taking advantage of these RFLPs, all five probes have been localised on the X chromosome using an interspecific backcross between the B6CBARI and SPE/Pas mouse strains segregating the X chromosome markers hypoxanthine phosphoribosyl transferase (Hprt) and Tabby (Ta). Three of the probes map to the region between the centromere and Hprt, and two distal to Ta. Since such X-specific sequence probes detect RFLPs between M. spretus and M. musculus domesticus DNAs with high frequency, a large panel of well localised probes should soon be available for studies of biological problems associated with the X chromosome which can best be approached using the murine species.

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Mosaic expression of an Hprt transgene integrated in a region of Y heterochromatin

et al. 1994

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The sensitivity of small transgenes to position effects on their expression suggests that they could serve as indicators of the chromatin properties at their integration site. In particular, they might be expected to provide information on the functional properties of mammalian heterochromatin. We have produced a transgenic line that carries a mouse Hprt minigene on the Y chromosome. In situ hybridization localized the transgene to the heterochromatic portion of the Y. Analysis of transgene expression by isoelectric focusing indicated that the transgene is expressed in a mosaic pattern, and expressing cells have different levels of transgene activity. These findings can be explained as a position effect variegation induced by Y heterochromatin. However, two other transgenes, located at autosomal sites, also showed mosaic activity. If the mosaic transgene expression is attributed to the influence of the chromatin at the insertion site, the Y heterochromatin would appear less potent than some autosomal regions at inducing variegation. An alternative explanation consistent with our results is that the mosaic expression is a semi-autonomous characteristic of these transgene loci. Transgene-expressing and non-expressing cells differed in their ability to grow and be cloned in vitro, indicating that cellular differentiation affected the chromatin structure of the transgene locus on the Y. Karyotype analysis of male mice with the Y-linked transgene and from control male mice carrying the human HPRT transgene, or the mouse Pgk-1 gene at autosomal sites, indicated that the transgene-carrying Y is prone to non-disjunction, generating cells with two (or more) or no Y chromosomes in equal proportion. Further studies will determine if the propensity of this Y chromosome to mitotic errors is also observed in vivo.

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Electrophoretic Variation for X Chromosome-Linked Hypoxanthine Phosphoribosyl Transferase (Hprt) in Wild-Derived Mice

Cited by 37 publications

References 6 publications

Elevated levels of erythrocyte hypoxanthine phosphoribosyltransferase associated with allelic variation of murine Hprt

Elevated levels of erythrocyte hypoxanthine phosphoribosyltransferase associated with allelic variation of murine Hprt

Mapping of the mouse X chromosome using random genomic probes and an interspecific mouse cross.

Mosaic expression of an Hprt transgene integrated in a region of Y heterochromatin

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