title: Exposure to low-dose X-rays promotes peculiar autophagic cell death in Drosophila melanogaster, an effect that can be regulated by the inducible expression of Hml dsRNA.
abstract: We previously reported that to induce an early emergence effect with low-dose X-irradiation in Drosophila, exposure during the prepupae stage is necessary. The present study examined the mechanism by which low-dose radiation rapidly eliminates larval cells and activates the formation of the imaginal discs during metamorphosis. Upon exposure to 0.5 Gy X-rays at 2 h after puparium formation (APF), the larval salivary glands swelled and were surrounded by remarkably thick structures containing an acid phosphatase (Acph) enzyme, implicating a peculiar autophagic cell death. TUNEL staining revealed the presence of DNA fragmentations compared with cells from sham controls which remained unchanged until 12 h APF. Additionally, the salivary glands of exposed flies were completely destroyed by 10 h APF. Furthermore, exposure to 0.5 Gy X-rays also facilitated the activity of the engulfment function of dendritic cells (DCs); they were generated in the larval salivary glands, engulfed the cell corpses and finally moved to the fat body. Data from an experiment demonstrating the inducible expression of Hml double-stranded RNA (dsRNA) indicate that a slow rate of engulfment of larval cells results in a longer time to emergence. Thus, the animals subjected to low-dose X-rays activated autophagic processes, resulting in significantly faster adult eclosion.
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: Yukihisa
authors.initials: Y
authors.lastname: Miyachi
mesh_terms: D000818:Animals; D001343:Autophagy / Q000528:radiation effects*; D003713:Dendritic Cells / Q000166:cytology; D004307:Dose-Response Relationship, Radiation; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D018507:Gene Expression Regulation, Developmental; D020287:In Situ Nick-End Labeling; D007814:Larva / Q000166:cytology; D037102:Lectins / Q000235:genetics*; D011679:Pupa / Q000166:cytology; D012330:RNA, Double-Stranded / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D012469:Salivary Glands / Q000166:cytology / Q000528:radiation effects; D013997:Time Factors; D014965:X-Rays
chemical_list: D029721:Drosophila Proteins; C476120:Hml protein, Drosophila; D037102:Lectins; D012330:RNA, Double-Stranded