Transformation of white locus DNA in Drosophila: Dosage compensation, zeste interaction, and position effects

Analysis of cis-acting requirements of the Rh3 and Rh4 genes reveals a bipartite organization to rhodopsin promoters in Drosophila melanogaster.

“…One line, P[Rh3.2600CAT]4, exhibits unusually high CAT activity in both the body and the head, although the proper cell-type specificity is preserved within the photoreceptors. The behavior of this line typifies the occasional position effect associated with P-element-mediated germ line transformation (Spradling and Rubin 1983;Hazelrigg et al 1984;Levis et al 1985).…”

“…Hybrid promoter CAT assays were allowed to proceed for 5 hr at 37°C due to their low levels of expression. For autosomal inserts, male transformants were assayed, whereas for X-linked inserts, female transformants were as-sayed to avoid dosage compensation effects (Spradling and Rubin 1983;Hazelrigg et al 1984). Standard genetic crosses were employed to produce transformant flies of the appropriate mutant genotypes using the following stocks: sevd2; ry s°6 (sevd~: Banerjee et al 1987), boss 3991 ry s°6 (boss3991: , gl 3 ry sa6 (glS: Moses et al 1989), so;TM3ryS°6/ + (so: Lindsley and Grell 1968), cm ct 6 oc ptg/CIB; ry s°6 (oc: Lindsley and Grell 1968) and In(2LR)noc 4 b cn sp/CyO; ry s°6 (noc4: Ashburner et al 1983).…”

polyhomeotic regulatory sequences induce developmental regulator-dependent variegation and targeted P-element insertions in Drosophila.

“…Normally, variegated eyes are observed when a chromosomal rearrangement places the euchromatic white gene next to heterochromatin, and this phenomenon is called positioneffect variegation (PEV) (for reviews, see Eissenberg 1989;Henikoff 1990;Tartof and Bremer 1990;Reuter and Spierer 1992 (Hazelrigg et al 1984;Levis et al 1985). No more than 1% of anomalous expression of white was detected when hundreds of lines carrying a P-lacW insertion were made (Dura et al 1993).…”

L’effet de position télomérique

“…Ainsi, le TPE endogène aux extrémités présentant uniun lien entre la position de l'insertion d'un transgène dans le chromosome et son niveau d'expression, un phénomène décrit sous le nom de position effect variegation (PEV). Dans ces études, les auteurs ont montré que l'ADN du locus white sauvage n'était pas toujours capable de complémenter le phénotype white -des mouches mutantes [3,4]. Des expériences d'hybridation in situ ont alors révélé que ce défaut de complémentation pouvait résulter de l'insertion de l'ADN white à proximité immédiate de régions péricentromériques ou de répétitions télomériques.…”