Davis Corrine R, Okihiro Mark S, Hinton David E
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, One Shields Ave, Davis, CA 95616, USA.
Aquat Toxicol. 2002 Oct 30;60(3-4):185-201. doi: 10.1016/s0166-445x(02)00004-8.
Japanese medaka, Oryzias latipes, are currently used in a variety of research applications for toxicological and carcinogenesis research, yet the impact of certain husbandry factors on study outcome has received limited attention. In this study, we demonstrated significant effects of stocking density (SD), dietary restriction (DR) and photoperiod on somatic growth in medaka. Higher stocking densities significantly inhibited somatic and hepatic growth in females, while having no similar effects on males. Daily egg production declined in a step-wise manner in groups of fish stocked at densities ranging from 0.38 to 2.6 fish per l. Significantly slower somatic growth was observed in fish fed on a mildly restrictive dietary protocol compared with those fish fed to excess. Further significant declines were observed in somatic growth of fish fed at a rate comparable to that used in research studies (3-4% body weight (BW) per day). Fish reared at an 8-h light:16-h dark (8L/16D) photoperiod were significantly smaller than cohorts reared at a 16-h light:8-h dark (16L/8D) photoperiod and female sexual maturity was delayed in the short photoperiod cohort. In normal female medaka, a high degree of individual variation was observed in daily egg production, as well as diurnal fluctuations in ovarian weight, gonadosomatic index (GSI) and hepatosomatic index (HSI). These results indicate some husbandry factors affect growth, sexual maturation and egg production in medaka and should be taken into consideration in studies evaluating endpoints that may be impacted by growth and reproductive performance, i.e. carcinogenesis and endocrine disruption studies. The high degree of individual variation among normal females and daily fluctuations in organ weights should also be considered in study design.
日本青鳉（Oryzias latipes）目前被用于毒理学和致癌作用研究等多种研究应用中，然而某些养殖因素对研究结果的影响却受到的关注有限。在本研究中，我们证明了养殖密度（SD）、饮食限制（DR）和光周期对青鳉体细胞生长有显著影响。较高的养殖密度显著抑制了雌性的体细胞和肝脏生长，而对雄性没有类似影响。在每升放养密度为0.38至2.6尾鱼的鱼群中，每日产蛋量呈逐步下降趋势。与喂食过量的鱼相比，以轻度限制饮食方案喂养的鱼体细胞生长明显较慢。在以与研究中使用的速率相当（每天3 - 4%体重（BW））喂养的鱼中，体细胞生长进一步显著下降。在8小时光照：16小时黑暗（8L/16D）光周期下饲养的鱼明显小于在16小时光照：8小时黑暗（16L/8D）光周期下饲养的同龄鱼，并且短光周期组中的雌性性成熟延迟。在正常的雌性日本青鳉中，观察到每日产蛋量存在高度个体差异，以及卵巢重量、性腺体指数（GSI）和肝体指数（HSI）的昼夜波动。这些结果表明，一些养殖因素会影响青鳉的生长、性成熟和产蛋量，在评估可能受生长和繁殖性能影响的终点的研究中，即致癌作用和内分泌干扰研究中，应予以考虑。在研究设计中还应考虑正常雌性之间的高度个体差异以及器官重量的每日波动。
