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.
Kuhfittig
S
S
Institute of Genetics, Martin Luther University, D-06120 Halle, Germany.
Szabad
J
J
Schotta
G
G
Hoffmann
J
J
Máthé
E
E
Reuter
G
G
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