Biomedical and Life Sciences > Encyclopedia of Genetics, Genomics, Proteomics and Informatics > Hybrid Dysgenesis
Redirected from: P Cytotype
A historical term for various genetic phenomena caused by transposable elements in Drosophila. It entails mutations and chromosomal rearrangements in hybrids of two genetic stocks. P-M system: The P-strains carry a transposable element and a suppressor of transposition. In the other strains (M), there is a genetic factor that derepresses the transposase and thus the hybrid becomes genetically unstable, while both the parental forms are stable. (The P and M originally indicate paternal and maternal conditions, respectively.). In Drosophila, over 30 different hybrid dysgenesis systems have been identified. The best known among them is the P-M system. The physical structure of a complete P element is shown in the diagram (see Fig. H80).