Copy number control of a transposable element, the I factor, a LINE-like element in Drosophila

Copy number control of a transposable element, the I factor, a LINE-like element in Drosophila

^*Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette, France; and ^†Institute of Cell and Molecular Biology, University of Edinburgh, King’s Buildings, Edinburgh, EH9 3JR, Scotland

Edited by Margaret G. Kidwell, University of Arizona, Tucson, AZ, and approved August 6, 1998 (received for review April 13, 1998)

Abstract

The I factor is a LINE-like transposable element in Drosophila. Most strains of Drosophila melanogaster, inducer strains, contain 10–15 copies of the I factor per haploid genome located in the euchromatic regions of the chromosome arms. These are not present in a few strains known as reactive strains. I factors transpose at low frequency in inducer strains but at high frequency in the female progeny of crosses between reactive and inducer flies. We have found that the activity of the I factor promoter is sensitive to the number of copies of the first 186 nucleotides of the I factor sequence, which constitutes the 5′-untranslated region. The activity of the I factor decreases as the copy number of this sequence increases.

transposition/regulation/cosuppression

Footnotes

↵ § Present address: Institut de Génétique Humaine, Centre National de la Recherche Scientifique, 141, rue de la Cardonille, 34396 Montpellier cedex 5, France.
↵ ‡ To whom reprint requests should be addressed at: MDC, Robert Rossle Strasse 10, 13122 Berlin Buch, Germany. e-mail: mchabo{at}mdc-berlin.de.
This paper was submitted directly (Track II) to the Proceedings Office.
ABBREVIATIONS:

UTR,

untranslated region;

CAT,

chloramphenicol acetyl transferase