Biomedical subjects

C E Thornton

Publications and source records attributed to C E Thornton.

3 recordsLinked to original sources

PubMed2000

Cryoconservation--archiving for the future.

Mouse genetics is set to play a pivotal role in the key post-genome challenge-the study of mammalian gene function. Addressing this challenge will involve the development and application of systematic mutagenesis approaches. The expanding mouse mutant resource that will result threatens to overwhelm the currently available animal facility space. Cryopreservation of both mouse embryos and spermatozoa is currently widely employed for the efficient archiving of mouse stocks. Distribution and dissemination of new and existing mouse strains is simplified by the availability of extensive frozen archives. Also, the availability of archives of frozen spermatozoa provides a potential powerful route for the production of backcross progeny for rapid genetic mapping. Moreover, frozen oocytes and ovaries may offer a valuable addition to the current cryopreservation approaches. Comprehensive mouse mutant archives will provide an essential resource for mammalian genetics throughout the 21(st) century.

Animals↗

PubMed1999

Large numbers of mice established by in vitro fertilization with cryopreserved spermatozoa: implications and applications for genetic resource banks, mutagenesis screens, and mouse backcrosses.

Recent advances in the methodologies for cryopreservation of mouse spermatozoa have opened up a number of opportunities for mouse geneticists. We have investigated various applications for this relatively new technology and have explored the potential of sperm freezing coupled with IVF for archiving, stock building, and the rapid establishment of backcrosses. Firstly, we investigated the use of sperm freezing for the archiving of (C3H/HeH x BALB/c)F(1) progeny from a large-scale mutagenesis program. We have demonstrated that it is possible to establish efficient, comprehensive, and deep archives and that potentially thousands of offspring can be derived from the frozen spermatozoa of a single mutant male mouse. Secondly, we examined the efficacy of sperm freezing for a number of other genotypes. For at least some genotypes, frozen spermatozoa can be utilized to rapidly build stock far more quickly than by conventional methods. Finally, we demonstrated that it is feasible to use frozen spermatozoa from the mouse mutant archive for the rapid generation of mutant backcross progeny.

Animals↗

PubMed1995

Y chromosome short arm-Sxr recombination in XSxr/Y males causes deletion of Rbm and XY female sex reversal.

We earlier described three lines of sex-reversed XY female mice deleted for sequences believed close to the testes-determining gene (Sry) on the Y chromosome short arm (Yp). The original sex-reversed females appeared among the offspring of XY males that carried the Yp duplication Sxr on their X chromosome. Earlier cytogenetic observations had suggested that the deletions resulted from asymmetrical meiotic recombination between the Y and the homologous Sxr region, but no direct evidence for this hypothesis was available. We have now analyzed the offspring of XSxr/Y males carrying an evolutionarily divergent Mus musculus domesticus Y chromosome, which permits detection and characterization of such recombination events. This analysis has enabled the derivation of a recombination map of Yp and Sxr, also demonstrating the orientation of Yp with respect to the Y centromere. The mapping data have established that Rbm, the murine homologue of a gene family cloned from the human Y chromosome, lies between Sry and the centromere. Analysis of two additional XY female lines shows that asymmetrical Yp-Sxr recombination leading to XY female sex reversal results in deletion of Rbm sequences. The deletions bring Sry closer to Y centromere, consistent with the hypothesis that position-effect inactivation of Sry is the basis for the sex reversal.

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