CYTOGENETIC AND GENETIC-EVIDENCE OF MALE SEXUAL INVERSION BY HEAT-TREATMENT IN THE NEWT PLEURODELES-POIRETI

Larvae of P. poireti were maintained during their development at a high temperature (31.degree. C). In several species of amphibians, such a treatment is known to change the sex ratio through the inversion of genotypic females into phenotypic males. P. poireti is an exception. It is the first reported amphibian in which heat induces an inversion of genotypic males into functional phenotypic females. The sexual genotype of standard and experimental phenotypic females was determined through heterochromosomes in lampbrush stage. Another technique was utilized for identification of sexual genotype, applicable to both phenotypic males and females. It is based on the differential expression of a sex-linked gene, the peptidase 1.