Kashiwada Shosaku, Tatsuta Haruki, Kameshiro Maiko, Sugaya Yoshio, Sabo-Attwood Tara, Chandler G Thomas, Ferguson P Lee, Goka Koichi
Environmental Risk Research Center, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
Environ Toxicol Chem. 2008 Nov;27(11):2397-402. doi: 10.1897/08-073.1.
Fish embryo toxicology is important because embryos are considered more susceptible than adult fish to the effects of toxic chemicals. Recently, fish embryo bioassay was proposed to replace the conventional fish acute toxicity chemical test of the Organization for Economic Cooperation and Development guidelines because it offers the advantages of fewer reagents, easy handling, and efficient data production. To accelerate the establishment of a chemical toxicity database for the protection of environmental and human health, we need to determine whether the conventional toxicity test can safely be replaced by such fish embryo toxicity tests. For instance, it is unclear how the presence of the chorion moderates the toxic effects of some chemicals. If such chemical toxicities do differ between embryos and, for example, the larval stage, then different toxic effects should appear in later life. We tested the later-life effects of the neurotoxic insecticide carbaryl at sublethal concentrations (0 [control] and 5 and 10 mg/L) in embryos and posthatch larvae of the freshwater fish medaka, Oryzias latipes. Although embryos exposed until hatching showed multiple developmental malformations and reductions in subsequent survival rates over three months, no significant reduction was observed in tolerance to starvation for 7 d and in intrinsic population growth rate (r). Exposure of larvae for 96 h resulted in dose-responsive vertebral fracture, significant reduction in tolerance to starvation for 7 d, and reduced three-month survival rate; r was reduced significantly and consistently. These results suggested that posthatch larvae were more susceptible than embryos to carbaryl exposure and that the toxic cascades may differ between larvae and embryos. The influences of carbaryl exposure on population growth rate differed significantly with developmental stage.
鱼类胚胎毒理学很重要，因为胚胎被认为比成年鱼类更容易受到有毒化学物质的影响。最近，有人提出用鱼类胚胎生物测定法取代经济合作与发展组织指南中的传统鱼类急性毒性化学测试，因为它具有试剂用量少、易于操作和数据产出高效等优点。为了加速建立一个用于保护环境和人类健康的化学毒性数据库，我们需要确定传统毒性测试是否能安全地被此类鱼类胚胎毒性测试所取代。例如，尚不清楚卵膜的存在如何调节某些化学物质的毒性作用。如果胚胎与例如幼体阶段之间的这种化学毒性确实存在差异，那么在后期生活中就会出现不同的毒性效应。我们测试了神经毒性杀虫剂西维因在亚致死浓度（0 [对照]、5和10毫克/升）下对淡水鱼青鳉（Oryzias latipes）胚胎和孵化后幼体后期生活的影响。虽然暴露至孵化的胚胎出现了多种发育畸形，并且在三个月内后续存活率降低，但在7天饥饿耐受性和内在种群增长率（r）方面未观察到显著降低。幼体暴露96小时导致剂量依赖性椎体骨折、7天饥饿耐受性显著降低以及三个月存活率降低；r显著且持续降低。这些结果表明，孵化后幼体比胚胎对西维因暴露更敏感，并且幼体和胚胎之间的毒性级联反应可能不同。西维因暴露对种群增长率的影响因发育阶段而异。
