Castañaga Luis A, Asorey Cynthia M, Sandoval María T, Pérez-Coll Cristina S, Argibay Teresa I, Herkovits Jorge
Instituto de Ciencias Ambientales y Salud, Fundación PROSAMA, Paysandú Street 752, Ciudad Autónoma de Buenos Aires, 1405 Buenos Aires, Argentina.
Environ Toxicol Chem. 2009 Feb;28(2):427-33. doi: 10.1897/08-144.1.
The adverse effects of ultraviolet B radiation from 547.2 to 30,096 J/m2 on morphogenesis, cell differentiation, and lethality of amphibian embryos at six developmental stages were evaluated from 24 up to 168 h postexposure. The ultraviolet B radiation lethal dose 10, 50, and 90 values were obtained for all developmental stages evaluated. The lethal dose 50 values, considered as the dose causing lethality in the 50% of the organisms exposed, in J/m2 at 168 h postexposure, ranged from 2,307 to 18,930; gill circulation and blastula were the most susceptible and resistant stages, respectively. Ultraviolet B radiation caused malformations in all developmental stages but was significantly more teratogenic at the gill circulation and complete operculum stages. Moreover, at the gill circulation stage, even the lowest dose (547.2 J/m2) resulted in malformations to 100% of embryos. The most common malformations were persistent yolk plug, bifid spine, reduced body size, delayed development, asymmetry, microcephaly and anencephaly, tail and body flexures toward the irradiated side, agenesia or partial gill development, abnormal pigment distribution, and hypermotility. The stage-dependent susceptibility to ultraviolet B radiation during amphibian embryogenesis could be explained in the framework of evoecotoxicology, considering ontogenic features as biomarkers of environmental signatures of living forms ancestors during the evolutionary process. The stage-dependent susceptibility to ultraviolet B radiation on Rhinella (Bufo) arenarum embryos for both lethal and teratogenic effects could contribute to a better understanding of the role of the increased ultraviolet B radiation on worldwide amphibian populations decline.
评估了547.2至30,096 J/m²的紫外线B辐射在暴露后24至168小时对六个发育阶段两栖动物胚胎的形态发生、细胞分化和致死率的不利影响。获得了所有评估发育阶段的紫外线B辐射致死剂量10、50和90值。暴露后168小时，以J/m²为单位的致死剂量50值（即导致50%暴露生物死亡的剂量）范围为2,307至18,930；鳃循环期和囊胚期分别是最敏感和最具抗性的阶段。紫外线B辐射在所有发育阶段均导致畸形，但在鳃循环期和完全鳃盖期致畸性明显更高。此外，在鳃循环期，即使是最低剂量（547.2 J/m²）也会导致100% 的胚胎出现畸形。最常见的畸形包括持续的卵黄栓、脊柱裂、体型减小、发育延迟、不对称、小头畸形和无脑畸形、尾巴和身体向受辐射侧弯曲、鳃发育不全或部分鳃发育、色素分布异常以及活动过度。考虑到个体发育特征作为进化过程中生物祖先环境特征的生物标志物，两栖动物胚胎发育过程中对紫外线B辐射的阶段依赖性易感性可以在生态毒理学框架内得到解释。莱茵蟾蜍（Bufo）沙蟾胚胎对紫外线B辐射的致死和致畸效应的阶段依赖性易感性，可能有助于更好地理解紫外线B辐射增加对全球两栖动物种群数量下降的作用。
