The relationship between DNA structural variation and activities of P elements in P and Q strains of Drosophila melanogaster

Abstract

To characterize the relationship between P element activities and their structures, we cloned P elements from genomic libraries of three isogenic P and 0 strains derived from natural populations in Japan. These P elements were mapped with BamHl, A vail and Pstl and were classified by their size. The majority of P elements cloned were classified as either complete or relatively small P elements rather than medium size. The numbers of full length (2.9 kb) P elements per haploid genome of NP280 (P), AK194 (weak P) and WYI 13 (Q) were at least four, five and one, respectively. However, the 2,9 kb P element of WYI 13 was thought to be defective since this strain has no transposase activity. In our previous work, we demonstrated that the ORF 3-deleted P element is essential for P cytotype determination in WYI 13. A similar P element also exists in NP280, and this may have an important role for P cytotype determination in this strain. Two and one copies of the KP element, a deletion derivative of the P element, were found in NP280 and AK 1 94, respectively. One of four complete P elements in NP280 was fully sequenced, and the base sequence was completely identical to that of pr 25.1 originally derived from the U.S.A. This result is consistent with the notion that these P elements have a relatively recent origin in Drosophila melanoga sEer.

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

“…Other internally deleted elements also occur, but in lower numbers, as deduced from the signal intensity of the bands between those of 2.2 and 0.42 kb. The predominance of full-sized P plus KP elements in the genomes of most populations around the world has been pointed out by Itoh and collaborators (Itoh and Boussy, 2002;Itoh et al, 2001), based on their own surveys or on other authors (Boussy et al, 1988;Nitasaka and Yamazaki, 1994;Bonnivard and Higuet, 1999;French et al, 1999;Itoh et al, 2001;Itoh and Boussy, 2002). 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.…”

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

“…Of 293 isofemale lines from 45 localities examined, only eight lines (2.7%) lacked full-size P and four lines (1.4%) lacked KP elements; thus FP+KP predominance was seen in 96% of the lines (Itoh et al, 1999). Another line of evidence for FP+KP predominance comes from a molecular study by Nitasaka and Yamazaki (1994), who isolated all genomic P elements from three genomes from a natural population of Japan and found more than one copy each of full-size and KP elements in all three genomes examined. A single detailed analysis of a North American strain, π2, found seven complete P and two KP elements in its genome, but also 19 other defective P elements (O'Hare et al, 1992).…”

The relationship between structural variation and dysgenic properties of P elements in long-established P-transformed lines of Drosophila simulans

“…1). Both 5' and 3' regions may be affected whereas in D. melanogaster the P derivative elements described are generally deleted in the 3' region (O'Hare et a!., 1992; Nitasaka & Yamazaki, 1993). In several cases, the deletion seems to include all or a part of the inverted terminal repeat (ITR).…”

“…melanogaster such deletions have not been described (O'Hare ci' al., 1992;Nitasaka & Yamazaki, 1993). This could be fortuitous or it may result from differences in the transposition mechanism as well as in selective pressure on such derivative P elements.…”