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首页> 外文期刊>Environmental toxicology and chemistry >MATERNAL TRANSFER EFFICIENCY AND TRANS GENERATIONAL TOXICITY OF METHYLMERCURY IN DAPHNIA MAGNA
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MATERNAL TRANSFER EFFICIENCY AND TRANS GENERATIONAL TOXICITY OF METHYLMERCURY IN DAPHNIA MAGNA

机译：丹参中甲基汞的物质传递效率和产生性毒性

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摘要

We examined maternal transfer efficiency, retention by subsequent generations, and transgenerational toxicity of meth-ylmercury (CH_3Hg or MeHg) in a population of freshwater zooplankton (Daphnia magna). The effect of dietary MeHg residence time in the daphnids on the efflux system also was quantified. After ingesting a relatively high dosage of MeHg, D. magna exhibited a reduction of live neonates and an increase of undeveloped eggs (or embryos), which reflected the sublethal toxicity of MeHg. The daily maternal transfer efficiency of MeHg to both reproductive outputs ranged from 0.42 to 4.9% over different ages of the parental daphnids, which was dependent on the daily reproductive output. During the lifetime of D. magna, reproduction contributed to 10.8% +- 1.74% (n = 3) SD of total MeHg loss from the parental daphnids. The percentage of MeHg retention by the second generation (F_1) of D. magna (40-60%) was generally higher than that by the parental generation (F_0; ～25%) after 20 d of depuration. Methylmercury imposed sublethal toxicity to the F_0 and F_1 generations, but a smaller effect was observed on the F_2 generation. Because of the very low MeHg body burden in the subsequent generations, we hypothesized that factors other than MeHg, such as nutritional deficiency in the offspring contributed to the transgenerational toxicity. Different MeHg residence times did not significantly affect the efflux rate of MeHg but did significantly affect the relative importance of reproduction as the elimination pathway for MeHg. Based on the MeHg body burden of neonates, we estimated that MeHg took 2.5 to 3.0 d to be optimally transferred from assimilation (e.g., gut) to the site of egg development (e.g., brood chamber) in D. magna. Our study demonstrated that maternal transfer of MeHg in freshwater zooplankton is an important predictor of MeHg concentration in their offspring and is a time-dependent and highly dynamic process.
机译：我们检查了淡水浮游动物（水蚤）中甲基汞（CH_3Hg或MeHg）的母体转移效率，后代保留率和跨代毒性。还定量了饮食中甲基汞在residence中的停留时间对外排系统的影响。摄入相对较高剂量的MeHg后，D。magna的活新生儿减少，未发育的卵（或胚胎）增加，这反映了MeHg的亚致死毒性。 MeHg在两个年龄段的亲本蚤中的每日母体向两个生殖输出的转移效率在0.42％至4.9％的范围内，这取决于每天的生殖输出。在D. magna的一生中，繁殖造成了父母亲水蚤损失的总MeHg的10.8％±1.74％（n = 3）SD。净化20天后，第二代（F_1）的D. magna（40-60％）的MeHg保留率通常高于亲代（F_0;〜25％）。甲基汞对F_0和F_1世代具有致命性，但对F_2世代的影响较小。由于后代的MeHg身体负担非常低，我们假设除MeHg之外的其他因素，例如后代的营养缺乏，都可导致跨代毒性。不同的MeHg停留时间不会显着影响MeHg的外排率，但会显着影响繁殖作为MeHg消除途径的相对重要性。根据新生儿的MeHg身体负担，我们估计MeHg最好在2.5到3.0 d内从同化（例如肠道）转移到D. magna的卵发育部位（例如育雏室）。我们的研究表明，淡水浮游动物中母体MeHg的转移是其后代中MeHg浓度的重要预测指标，并且是时间依赖性且高度动态的过程。

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