Presence of the deleted hobo element Th in Eurasian populations of Drosophila melanogaster

Abstract

Summary — Molecular analysis has revealed the presence of a specific deletion-derivative hobo element, the Th element, in all current strains of Drosophila melanogaster examined throughout the Eurasian continent. The Th element is characterized by an internal deletion of 1.5 kb as compared to the complete hobo element. The presence of this element in natural populations raises the question of its possible role in the regulation of the hobo system. Drosophila-transposable elements -hobo-populations Résumé — Présence de l'élément hobo délété Th dans les populations eurasiennes de Drosophila melanogaster. Un élément hobo défectif (élément Th), présentant une délétion interne de 1,5 kb a été mis en évidence par analyse moléculaire. Cet élément est présent dans toutes les souches actuelles de Drosophila melanogaster examinées sur le continent eurasien. Sa présence dans les populations naturelles pose la question de son rôle éventuel dans le mécanisme de régu-lation du système hobo.

Patterns of hobo elements and their effects in natural populations of Drosophila melanogaster in Japan

“…We found no hobo elements in the Hikone-R strain, collected in 1952, but we did detect them in the Hikone- hobo elements in Japanese populations of D. melanogaster K Kikuno et al H and Mino-H strains, collected in 1957. This is consistent with the hypothesis that hobo transposable elements invaded the D. melanogaster genome in the mid1950s in America, France, USSR, China, and Africa (Periquet et al, 1989a(Periquet et al, , b, 1990Boussy and Daniels, 1991;Pascual and Periquet, 1991). Around 1950, in HikoneCity large quantities of DDT and pyrethrum were used for several years to kill mosquitoes for malaria control, and the insecticide-resistant strain, Hikone-R (E), was isolated (Ogaki and Tsukamoto, 1953).…”

“…The deletion of the 1.6 kb fragments is the central portion of the full-sized element. The 2.2 and 2.0 kb deleted hobo elements have not been obviously present in the surveys of populations from other countries (Periquet et al, 1989a(Periquet et al, , b, 1990Boussy and Daniels, 1991;Pascual and Periquet, 1991;Kim and Kim, 1999). Therefore, they seem to be defective hobo derivatives unique to Japanese Drosophila populations.…”

“…All lines examined had many hobo copies in their genomes (Figure 3). Besides the 2.6 kb XhoI fragment of full-sized hobo elements and the 1.1 kb fragments of the Th elements (Periquet et al, 1989a), lines from Honshu and Hokkaido also show 1.6 and 1.8 kb XhoI fragments (Figure 3). Furthermore, most of isofemale lines showed a 1.3 kb XhoI fragment apparently corresponding to the 1.7 kb Kh element, described as characteristic of Korean populations (Kim and Kim, 1999).…”

“…Strains collected before the mid-1950s lack hobo elements (E strains), while recently collected ones have complete and defective derivatives (H strains). These surveys revealed the presence of locally characteristic defective hobos, for example, the 1.5 kb Th elements, first found in Eurasian populations (Periquet et al, 1989a), the 1.9 kb Oh element in the Oregon-R s strain (Pascual and Periquet, 1991), and the 1.7 kb Kh elements in Korean strains (Kim and Kim, 1999). Also shown in all strains tested was the presence of hobo-hybridizing sequences that generate high molecular weight (43 kb) XhoI fragments (Streck et al, 1986;Boussy and Daniels, 1991;Pascual and Periquet, 1991;Boussy and Itoh, 2004).…”

Are Drosophila melanogaster populations under a stable geographical differentiation due to the presence of P elements?

“…In contrast, all recently derived and present-day populations that have been tested carry numerous hobo elements. A recent study has shown a high frequency of a derivative-deleted element of 15 kb (Th), in all populations tested from France to China, and in the Americas, a distribution which is highly similar to that of KP elements (Periquet et a!., 1989b).…”