Genetic evidence for repression of somatic P element movements in Drosophila melanogaster consistent with a role for the KP element

Abstract

The P family of transposable elements in Drosophila melanogaster has, since its introduction into D. melanogaster populations in this century, diversified into a number of internally deleted forms. One of these, the KP element, is abundant in the genomes of flies from populations from Asia, Europe and Africa. There is some evidence that this sequence can act as a repressor of transposition. We have studied a mutation, singedv k(snvw) in which a KP element is one of two P elements inserted into the 5' exon of the X-linked singed gene. These elements can be mobilized by a trans-acting dominant mutation, Mo, with a maternal effect, on the second chromosome. The rate of somatic reversion of sn induced by Mo is reduced threefold if the mother herself possesses Sfl on her X chromosomes. This implies that snw may be responsible for a form of repression of P element movements. The cause of this effect may be related to transcription of the KP element in However, an effect of other genomic P elements in the repression of somatic reversion of cannot be entirely excluded.

Copy number of P elements, KP/full-sized P element ratio and their relationships with environmental factors in Brazilian Drosophila melanogaster populations

“…Itoh and Boussy (2002) wondered whether this could be the final equilibrium state of the D. melanogaster genomes in nature, and suggested that further surveys of wild populations are required. These authors recommended these surveys especially because such predominance was not predicted by any of the theoretical models that have been carried out to evaluate P element population dynamics (Brookfield, 1991(Brookfield, , 1996Anxolabéhère, 1997, 1998). Moreover, our study shows that the Brazilian populations seem to be more similar to the Eurasian than the North American ones.…”

Full-size P and KP elements predominate in wild Drosophila melanogaster.

“…This seems to contradict the original observations of KP elements as specific to the genomes of M' (Black et al, 1987) or Q strains having biparentallytransmitted repression (Jackson et al, 1988). Genomic KP elements may not have a direct or large influence on the phenotypes in the P-M system, although individual KP elements have been shown to have the potential of repressing transposase activity (Andrew and Gloor, 1995;Lee et al, 1996;Brookfield, 1996a). Complete P elements, in contrast, are required as a source of transposase for P transposition induction.…”

P elements and P-M characteristics in natural populations of Drosophila melanogaster in the southernmost islands of Japan and in Taiwan

“…Second, the majority of the P element sizes seen were those of entirely full‐size P and KP elements, as mentioned above. Third, KP elements appeared not as important as full‐size P elements in determination of P‐M phenotype, although the KP element was shown to have a repression potential of P transposition (Black et al ., 1987; Jackson et al ., 1988; Andrew & Gloor, 1995; Brookfield, 1996). KP elements were detected in all lines with a wide divergence in the phenotypes, whereas a line with no full‐size P element could not be P type, for example, KR‐7 (M′) in this study.…”