Wheelock C E, Wolfe M F, Olsen H, Tjeerdema R S, Sowby M L
Department of Entomology, University of California, Davis, California 95616, USA.
Arch Environ Contam Toxicol. 1999 Apr;36(3):281-7. doi: 10.1007/s002449900472.
Hsp60 induction was selected as a sublethal endpoint of toxicity for Brachionus plicatilis exposed to a water accommodated fraction (WAF) of Prudhoe Bay crude oil (PBCO), a PBCO/dispersant (Corexit 9527(R)) fraction and Corexit 9527(R) alone. To examine the effect of multiple stressors, exposures modeled San Francisco Bay, where copper levels are approximately 5 microgram/L, salinity is 22 per thousand, significant oil transport and refining occurs, and petroleum releases have occurred historically. Rotifers were exposed to copper at 5 microgram/L for 24 h, followed by one of the oil/dispersant preparations for 24 h. Batch-cultured rotifers were used in this study to model wild populations instead of cysts. SDS-PAGE with Western Blotting using hsp60-specific antibodies and chemiluminescent detection were used to isolate, identify, and measure induced hsp60 as a percentage of control values. Both PBCO/dispersant and dispersant alone preparations induced significant levels of hsp60. However, hsp60 expression was reduced to that of controls at high WAF concentrations, suggesting interference with protein synthesis. Rotifers that had been preexposed to copper maintained elevated levels of hsp60 upon treatment with WAF at all concentrations. Results suggest that induction of hsp60 by chronic low-level exposure may serve as a protective mechanism against subsequent or multiple stressors and that hsp60 levels are not additive for the toxicants tested in this study, giving no dose-response relationship. The methods employed in this study could be useful for quantifying hsp60 levels in wild rotifer populations.
选择热休克蛋白60（Hsp60）的诱导作为褶皱臂尾轮虫（Brachionus plicatilis）暴露于普拉德霍湾原油（PBCO）的水相组分（WAF）、PBCO/分散剂（Corexit 9527®）组分以及单独的Corexit 9527®时的亚致死毒性终点。为了研究多种应激源的影响，实验模拟了旧金山湾的环境，那里铜含量约为5微克/升，盐度为千分之二十二，有大量的石油运输和精炼活动，且历史上曾发生过石油泄漏。轮虫先暴露于5微克/升的铜中24小时，然后再暴露于其中一种油/分散剂制剂中24小时。本研究使用分批培养的轮虫来模拟野生种群，而非休眠卵。采用使用hsp60特异性抗体的SDS - 聚丙烯酰胺凝胶电泳（SDS - PAGE）和化学发光检测来分离、鉴定并测量诱导产生的hsp60，并将其作为对照值的百分比进行测量。PBCO/分散剂制剂和单独的分散剂制剂均诱导产生了显著水平的hsp60。然而，在高WAF浓度下，hsp60表达降至对照水平，这表明蛋白质合成受到了干扰。预先暴露于铜的轮虫在所有浓度的WAF处理后，hsp60水平均维持升高。结果表明，慢性低水平暴露诱导hsp60可能是一种针对后续或多种应激源的保护机制，并且在本研究中测试的毒物中，hsp60水平不存在相加性，也没有剂量 - 反应关系。本研究中采用的方法可能有助于量化野生轮虫种群中的hsp60水平。
