pitkin(D), a novel gain-of-function enhancer of position-effect variegation, affects chromatin regulation during oogenesis and early embryogenesis in Drosophila.
The vast majority of the >100 modifier genes of position-effect variegation (PEV) in Drosophila have been identified genetically as haplo-insufficient loci. Here, we describe pitkin(Dominant) (ptn(D)), a gain-of-function enhancer mutation of PEV. Its exceptionally strong enhancer effect is evident as elevated spreading of heterochromatin-induced gene silencing along euchromatic regions in variegating rearrangements. The ptn(D) mutation causes ectopic binding of the SU(VAR)3-9 heterochromatin protein at many euchromatic sites and, unlike other modifiers of PEV, it also affects stable position effects. Specifically, it induces silencing of white+ transgenes inserted at a wide variety of euchromatic sites. ptn(D) is associated with dominant female sterility. +/+ embryos produced by ptn(D)/+ females mated with wild-type males die at the end of embryogenesis, whereas the ptn(D)/+ sibling embryos arrest development at cleavage cycle 1-3, due to a combined effect of maternally provided mutant product and an early zygotic lethal effect of ptn(D). This is the earliest zygotic effect of a mutation so far reported in Drosophila. Germ-line mosaics show that ptn+ function is required for normal development in the female germ line. These results, together with effects on PEV and white+ transgenes, are consistent with the hypothesis that the ptn gene plays an important role in chromatin regulation during development of the female germ line and in early embryogenesis.
Institute of Genetics, Martin Luther University, D-06120 Halle, Germany.
S
S
Kuhfittig
J
J
Szabad
G
G
Schotta
J
J
Hoffmann
E
E
Máthé
G
G
Reuter
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism*; D002874:Chromosome Mapping; D002875:Chromosomes / Q000648:ultrastructure; D003433:Crosses, Genetic; D004330:Drosophila / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000502:physiology*; D004742:Enhancer Elements, Genetic; D005260:Female; D005799:Genes, Dominant; D006570:Heterochromatin / Q000378:metabolism; D007247:Infertility, Female / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics* / Q000502:physiology; D008297:Male; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D009030:Mosaicism; D009035:Mothers; D016296:Mutagenesis; D009154:Mutation; D009866:Oogenesis / Q000235:genetics*; D006080:Ovarian Follicle / Q000378:metabolism; D010053:Ovary / Q000378:metabolism; D010641:Phenotype; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism; D012098:Reproduction / Q000235:genetics
D002843:Chromatin; D006570:Heterochromatin; D019476:Insect Proteins