P element

They referred to strains as P of paternal and M of maternal if they contributed to hybrid dysgenesis in this reproductive role.

This inhibitor reduces the disruption to the genome caused by the movement of P elements, allowing fertile progeny.

Evidence for this comes from crosses of laboratory females (which lack the P transposase inhibitor) with wild-type males (which have P elements).

In the absence of the inhibitor, the P elements can proliferate throughout the genome, disrupting many genes and often proving lethal to progeny or rendering them sterile.

The P element is a class II transposon, and moves by a DNA-based "cut and paste" mechanism.

The hybrid dysgenesis syndrome is marked by temperature-dependent sterility, elevated mutation rates, and increased chromosomal rearrangement and recombination.

The eggs of P strain females contain high amounts of a repressor protein that prevents transcription of the transposase gene.

The eggs of M strain mothers, which do not contain the repressor protein, allow for transposition of P elements from the sperm of fathers.

[3] This effect contributes to piRNAs being inherited only in the maternal line, which provides a defense mechanism against P elements.

Transposase regulates and catalyzes the excision of a P element from the host DNA, cutting at the two recognition sites, and then reinserting randomly.

To use this as a useful and controllable genetic tool, the two parts of the P element must be separated to prevent uncontrolled transposition.