Toxicology Graduate Program, University of Saskatchewan , Saskatoon, Saskatchewan, Canada S7N 5B3.
Stantec Consulting Ltd. , Burnaby, British Columbia, Canada V5H 0C6.
Environ Sci Technol. 2015 Nov 17;49(22):13658-66. doi: 10.1021/acs.est.5b04303. Epub 2015 Nov 9.
Selenium (Se) is a developmental toxicant in oviparous vertebrates. The adverse reproductive effects of Se toxicity have been predominantly investigated in fishes and birds with only a few studies focusing on amphibians. The objective of this study was to determine tissue-based toxicity thresholds for early life stage Se toxicities in Xenopus laevis as a consequence of in ovo exposure through maternal transfer of dietary Se. Following a 68-day dietary exposure to food augmented with l-selenomethionine (SeMet) at measured concentrations of 0.7 (control), 10.9, 30.4, or 94.2 μg Se/g dry mass (d.m.), adult female X. laevis were bred with untreated males, and resulting embryos were incubated until 5 days postfertilization (dpf). The measured Se concentrations in eggs were 1.6, 10.8, 28.1, and 81.7 μg Se/g d.m., respectively. No biologically significant effects were observed on fertilization success, hatchability, or mortality in offspring. Frequency and severity of morphological abnormalities were significantly greater in 5 dpf tadpoles from the highest exposure group when compared to the control, with eye lens abnormalities being the most prominent of all abnormalities. The estimated EC10 value for frequency of total early life stage abnormalities was 44.9 μg Se/g egg d.m., which suggests that this amphibian species is less sensitive to in ovo Se exposure than most of the fish species studied to date.
硒（Se）是卵生脊椎动物的发育毒物。硒毒性对生殖的不良影响主要在鱼类和鸟类中进行了研究，只有少数研究关注两栖动物。本研究的目的是确定 Xenopus laevis 早期生活阶段硒毒性的基于组织的毒性阈值，这是由于母体通过饮食硒传递进行了胚胎内暴露。在通过测量浓度为 0.7（对照）、10.9、30.4 或 94.2 μg Se/g 干重（d.m.）的 l-硒代蛋氨酸（SeMet）强化的饮食中暴露 68 天后，成年雌性 Xenopus laevis 与未经处理的雄性繁殖，然后将所得胚胎孵育至受精后 5 天（dpf）。卵中的测量硒浓度分别为 1.6、10.8、28.1 和 81.7 μg Se/g d.m.。在后代中，受精成功率、孵化率或死亡率没有观察到生物学上显著的影响。与对照组相比，来自最高暴露组的 5 dpf 幼体的形态异常频率和严重程度显著更高，晶状体异常是所有异常中最突出的。总早期生活阶段异常频率的估计 EC10 值为 44.9 μg Se/g 卵 d.m.，这表明与迄今为止研究的大多数鱼类物种相比，这种两栖动物对胚胎内硒暴露的敏感性较低。
