Communication of Radiation-Induced Signals in Vivo between DNA Repair Deficient and Proficient Medaka (Oryzias latipes)

• Published in: Environmental science & technology Vol. 43; no. 9; pp. 3335 - 3342
• Main Authors: Mothersill, C, Smith, R. W, Hinton, T. G, Aizawa, K, Seymour, C. B
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.05.2009
• Subjects: Animals; Apoptosis; Apoptosis - radiation effects; Applied sciences; Cell Line; Cell Survival - radiation effects; Colony-Forming Units Assay; Deoxyribonucleic acid; DNA; DNA repair; DNA Repair - radiation effects; Ecotoxicology and Human Environmental Health; Exact sciences and technology; Fish; Freshwater; Humans; Mutation; Mutation - genetics; Oryzias - metabolism; Oryzias latipes; Pollution; Proto-Oncogene Proteins c-bcl-2 - metabolism; Proto-Oncogene Proteins c-myc - metabolism; Radiation; Signal Transduction - radiation effects; Skin - cytology; Skin - metabolism; Skin - radiation effects; X-Rays; Radioactive pollution; Ionizing radiation; Repair; In vitro; Radioecology
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es8035219

Radiation-induced bystander effects are established consequences of exposure to ionizing radiation. The operation of this mechanism has been seen in vitro and also between fish, mammals, and plants in vivo where stress signals from treated organisms induce responses in neighbors. In vitro research shows that DNA repair deficient cells produce more toxic bystander responses. To test this in vivo two strains of Japanese medaka were tested. One is a mutant, repair deficient strain (ric2) and the other, the wildtype repair proficient strain (CAB). Irradiated fish swam with unirradiated partners in a strain mix and match protocol. The data suggest that medaka produce signals, when exposed to radiation, that induce unirradiated fish of the same strain swimming with them to produce an altered response to that seen in bystanders to sham irradiated fish. More apoptosis was seen in bystanders to repair deficient fish. When the strains are mixed, the bystanders of either strain respond like the donor strain. Measurements of Bcl-2 and cmyc proteins in the explants confirmed these observations. A possible role for p53 was also identified in that the use of reporters with mutant p53 demonstrated that CAB signals killed all the reporter cells by apoptosis. Use of a similar but p53 wild-type cell line had no such effect. The data add to the body of knowledge showing that bystander signals operate at hierarchical levels of organization greater than the individual and may therefore have relevance in radioecology and (eco)systems biology.