Samson J C, Goodridge R, Olobatuyi F, Weis J S
Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
Aquat Toxicol. 2001 Feb;51(4):369-76. doi: 10.1016/s0166-445x(00)00128-4.
Since previous short-term bioassays of methylmercury (MeHg) indicated no morphological effects in zebrafish (Danio rerio) after embryonic exposures below 20 microg/l MeHg, studies were done to determine whether embryonic exposure to MeHg at lower concentrations would induce behavioral effects. Newly fertilized embryos were exposed to 0, 5, 10 or 15 microg MeHg/l for selected exposure durations: single day, multiple day or continuous exposure from fertilization through hatching. Larvae were maintained in an essential salt solution after hatching. Spontaneous swimming performance and prey capture experiments were conducted. Continuous embryonic exposure to 15 microg/l caused delayed mortality syndrome (DMS). These larvae hatched normally and appeared normal, but beginning at Day 3 post-hatch (ph), general activity was severely reduced and by Day 5 ph, larvae were completely moribund; many had faint heartbeats, severely enlarged body cavities and upward flexures of the spinal cord. Most of these larvae were dead by Day 6 ph. Multi- and single-day embryonic exposures to 15 microg/l caused reduced swimming activity and prey capture ability, and by Day 4 ph, these larvae also began to show signs of DMS. Continuous embryonic exposure to 10 microg/l significantly reduced spontaneous swimming activity, which did not improve after 5 days in clean water. Similar results were seen in larvae exposed during the last 24 h of embryonic development. Prey capture ability was also impaired in larvae exposed continuously to 10 microg/l, even after 4 days in clean water. Single-day exposures to 10 microg/l did not affect prey capture ability. Larvae from the 5-microg/l exposures were not significantly different from controls for either parameter. This study reinforces the idea that functional impairment is a more subtle response to developmental toxicants than mortality or the production of morphological defects.
由于之前对甲基汞（MeHg）的短期生物测定表明，斑马鱼（Danio rerio）胚胎在低于20微克/升的MeHg暴露后未出现形态学影响，因此开展了研究以确定较低浓度的MeHg胚胎暴露是否会诱发行为影响。将新受精的胚胎暴露于0、5、10或15微克MeHg/升的环境中，持续选定的暴露时长：单日暴露、多日暴露或从受精到孵化的连续暴露。孵化后，将幼虫饲养在基本盐溶液中。进行了自发游泳性能和捕食实验。胚胎持续暴露于15微克/升会导致延迟死亡综合征（DMS）。这些幼虫正常孵化且外观正常，但在孵化后第3天（ph）开始，总体活动严重减少，到孵化后第5天ph时，幼虫完全濒死；许多幼虫心跳微弱，体腔严重肿大，脊髓向上弯曲。这些幼虫中的大多数在孵化后第6天死亡。胚胎多日和单日暴露于15微克/升会导致游泳活动和捕食能力下降，到孵化后第4天ph时，这些幼虫也开始出现DMS迹象。胚胎持续暴露于10微克/升会显著降低自发游泳活动，在清洁水中放置5天后也未改善。在胚胎发育最后24小时暴露的幼虫中也观察到了类似结果。持续暴露于10微克/升的幼虫的捕食能力也受到损害，即使在清洁水中放置4天后也是如此。单日暴露于10微克/升对捕食能力没有影响。5微克/升暴露组的幼虫在这两个参数上与对照组均无显著差异。这项研究强化了这样一种观点，即功能损害是对发育毒物比死亡或形态缺陷产生更微妙的反应。
