Genetic and developmental analysis of the sex-determining gene ‘double sex' (dsx) of Drosophila melanogaster

Sex determination in Drosophila depends on the ratio of X chromosomes to sets of autosomes (X:A). This chromosomal signal is used to regulate a few control genes whose state of activity selects either the male or the female sexual pathway. We have studied the structure and function of dsx (double sex) which appears to be the last regulatory gene on whose function the sexual pathway eventually depends. We have mutagenized the locus, varied the doses of dominant dsx-mutations and wildtype alleles, and combined different dsx-alleles with recessive mutations in other sex-determining genes, such as ix, tra-2 and tra. The locus dsx harbours two genetic functions, dsxm to implement the male program, dsxf to implement the female program. We found that dsxm and dsxf can mutate independently although most mutations abolish both functions. We conclude that dsxm and dsxf each have their specific domain, but also share a large region of DNA that is essential for both functions. We present evidence that the dominant mutations correspond to a constitutive expression of the male-determining function dsxm, with the simultaneous abolishment of the female-determining function dsxf. This effect can be counteracted by two doses of expressed dsxf so that a female phenotype results. The products of one dose of expressed dsxm and one dose of expressed dsxf in the same cell appear to neutralize each other which leads to a null phenotype. The mutant combinations suggest that the product of dsxf requires the products of ix+, tra-2+ and tra+ to become functiona

Genetic and developmental analysis of the sex-determining gene ‘double sex’ ( dsx) of Drosophila melanogaster

Sex determination in Drosophila depends on the ratio of X chromosomes to sets of autosomes (X:A). This chromosomal signal is used to regulate a few control genes whose state of activity selects either the male or the female sexual pathway. We have studied the structure and function of dsx (double sex) which appears to be the last regulatory gene on whose function the sexual pathway eventually depends. We have mutagenized the locus, varied the doses of dominant dsx-mutations and wildtype alleles, and combined different dsx-alleles with recessive mutations in other sex-determining genes, such as ix, tra-2 and tra. The locus dsx harbours two genetic functions, dsxm to implement the male program, dsxf to implement the female program. We found that dsxm and dsxf can mutate independently although most mutations abolish both functions. We conclude that dsxm and dsxf each have their specific domain, but also share a large region of DNA that is essential for both functions. We present evidence that the dominant mutations correspond to a constitutive expression of the male-determining function dsxm, with the simultaneous abolishment of the female-determining function dsxf. This effect can be counteracted by two doses of expressed dsxf so that a female phenotype results. The products of one dose of expressed dsxm and one dose of expressed dsxf in the same cell appear to neutralize each other which leads to a null phenotype. The mutant combinations suggest that the product of dsxf requires the products of ix+, tra-2+ and tra+ to become functiona

Diagnostic de la mort dans le contexte de la transplantation d'organes : directives médico-éthiques de l'Académie suisse des sciences médicales, approuvées par le Sénat de l'ASSM le 24 mai 2005

Le diagnostic de la mort repose sur l'interprétation de l'ensemble des informations issues de l'anamnèse, des résultats des examens complémentaires et sur la présence des signes cliniques de la défaillance du cerveau. Les directives définissent des critères cliniques et des examens techniques complémentaires qui permettent d'établir l'irréversibilité de la défaillance du cerveau. Ainsi, le diagnostic de la mort peut être établi avec certitude aussi bien dans les hôpitaux régionaux que dans les grands centres hospitaliers. Les présentes directives portent exclusivement sur le diagnostic de la mort. D'autres questions médico-éthiques, surtout celles qui concernent le don d'organes et l'arrêt de traitements vitaux, sont traitées dans les directives pour la transplantation d'organes et celles qui se rapportent aux problèmes éthiques survenant dans les soins intensifs