Department of Biology, McMaster University, Hamilton, Ontario, L8S 4K1 Canada.
Environ Sci Technol. 2010 Feb 15;44(4):1431-7. doi: 10.1021/es9023892.
When fish are exposed to sublethal, environmentally relevant Cu concentrations, olfactory acuity is impaired. The goals of the present study were to investigate the binding dynamics of waterborne Cu in the olfactory epithelium (OE), to examine the influence of calcium (Ca(2+)) on Cu binding, and to link Cu-OE binding to changes in olfactory acuity. Using short-term in vivo waterborne exposures to (64)Cu, we found that Cu accumulates rapidly in the OE, reaching a plateau by 3 h. The binding affinity (log K(Cu-OE)) and binding capacity (B(max)) of (64)Cu in the OE were 6.7 and 10.0 nmol Cu g(-1), respectively. As waterborne Ca(2+) was increased from 50 to 1000 microM L(-1), the B(max) of Cu decreased by approximately 50% while the log K(Cu-OE) remained constant, indicative of noncompetitive inhibition. Using electro-olfactograms (EOG), short-term exposures to 160 and 240 nmol Cu L(-1) were found to reduce olfactory responses to 10(-5) M l-arginine by 72 and 79%, respectively. Short-term exposure to 160 nmol Cu L(-1) also caused a 15-fold reduction in behavioral responses to a food stimulus. Interestingly, increasing waterborne Ca(2+) did not reduce the effects of Cu on EOG or behavioral responses. These results demonstrate that short-term, environmentally realistic concentrations of Cu not only bind to the OE of fathead minnows but also impair their olfactory sensitivity and behavioral responses to olfactory stimuli. Waterborne Ca(2+) reduces Cu-OE binding but does not protect against olfactory impairment.
当鱼类暴露于亚致死、与环境相关的铜浓度下时，其嗅觉敏锐度会受损。本研究的目的是研究水相中铜在嗅觉上皮（OE）中的结合动力学，研究钙离子（Ca(2+)）对铜结合的影响，并将铜-OE 结合与嗅觉敏锐度的变化联系起来。使用短期的水相（64）Cu 体内暴露实验，我们发现 Cu 迅速在 OE 中积累，3 h 时达到平台期。（64）Cu 在 OE 中的结合亲和力（log K(Cu-OE)）和结合容量（B(max)）分别为 6.7 和 10.0 nmol Cu g(-1)。随着水相 Ca(2+)从 50 增加到 1000 microM L(-1)，Cu 的 B(max)降低了约 50%，而 log K(Cu-OE)保持不变，表明存在非竞争性抑制。使用电嗅觉图（EOG），发现短期暴露于 160 和 240 nmol Cu L(-1)分别使 10(-5) M l-精氨酸的嗅觉反应降低了 72%和 79%。短期暴露于 160 nmol Cu L(-1)还导致对食物刺激的行为反应降低了 15 倍。有趣的是，增加水相 Ca(2+)并没有减少 Cu 对 EOG 或行为反应的影响。这些结果表明，短期的、与环境相关的真实浓度的 Cu 不仅与胖头鱼的 OE 结合，而且还损害其嗅觉敏感性和对嗅觉刺激的行为反应。水相 Ca(2+)减少了 Cu-OE 的结合，但不能防止嗅觉受损。
