title: Parental exposure to low-dose X-rays in Drosophila melanogaster induces early emergence in offspring, which can be modulated by transplantation of polar cytoplasm.
abstract: In recent years there has been growing concern over the biological effects of low-dose X-rays, but few studies have addressed this issue. Our laboratory had observed flies (Drosophila melanogaster) irradiated with low-dose X-rays tend to emerge earlier than normal flies. This observation led us to quantitatively examine the effects of low-dose X-irradiation on development in the fly. Following exposure of prepupal (day 5) flies to 0.5 Gy X-rays, the time to emergence was slightly shorter than in the sham controls. This tendency was increased when the X-ray exposure came during the pupal stage (day 7). In these flies, the time to eclosion decreased significantly, by an average of 30 h sooner than sham controls. A further experiment examined whether such radiation effects could be observed in the unexposed F1 generation of exposed individuals. Greater radiation effects on early F1 emergence were seen when the time between exposure and mating was 3 days, indicating an effect on early spermatid development. Early F1 emergence was also observed after exposure of female flies to X-rays during late previtellogeny. Furthermore, rapid emergence could be induced in the F1 embryos of unexposed parents by transferring the polar cytoplasm (precursor cells of the germ cell line) from F1 embryos of exposed flies. These results show that radiation-induced effects can be transmitted to the next generation through the germ cell line.
authors.affiliation: Department of Radiological Sciences, International University of Health and Welfare, Kitakanemaru 2600-1, Ohtawara-shi, Tochigi-ken 324-8501, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kanao
authors.forename: Takehito
authors.initials: T
authors.lastname: Okamoto
authors.forename: Yukihisa
authors.initials: Y
authors.lastname: Miyachi
authors.forename: Norimasa
authors.initials: N
authors.lastname: Nohara
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000637:transplantation*; D004307:Dose-Response Relationship, Radiation; D004331:Drosophila melanogaster / Q000196:embryology / Q000254:growth & development / Q000528:radiation effects*; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000528:radiation effects*; D005260:Female; D005854:Germ Cells / Q000528:radiation effects; D008297:Male; D011247:Pregnancy; D011679:Pupa / Q000528:radiation effects; D013087:Spermatids / Q000528:radiation effects; D013997:Time Factors; D014965:X-Rays