Griffin B R, Mitchell A J
Harry K. Dupree-Stuttgart National Aquaculture Research Center, U.S. Department of Agriculture, Agricultural Research Service, Stuttgart, AR, USA.
J Fish Dis. 2007 Oct;30(10):581-5. doi: 10.1111/j.1365-2761.2007.00838.x.
Channel catfish, Ictalurus punctatus (Rafinesque), with or without a preliminary 24 h exposure to 2 mg copper sulphate L(-1), were challenged with 7.5 x 10(6) colony forming units L(-1) of Edwardsiella ictaluri to determine the effect of copper sulphate on disease resistance. Catfish previously exposed to copper sulphate were significantly more resistant to the bacterial challenge than those not exposed. Catfish not exposed to copper sulphate suffered 35.5% mortality while catfish exposed to copper sulphate experienced 14.1% mortality. Copper concentrations were the same in tank waters of both exposed and control fish at the time of challenge, eliminating the possibility that copper in the water may have been toxic to bacteria. Copper concentrations in freeze dried and ground tissues of unexposed, exposed, and purged channel catfish were highest in fish before copper sulphate exposures suggesting that elevated tissue levels of copper were not responsible for the increased resistance to bacterial challenge. Competition for sites of bacterial attachment to gill or epithelial cells may account for the reduction in mortality; although this is not supported by the low copper content of fish tissue after copper exposure.
斑点叉尾鮰（Ictalurus punctatus，拉芬斯克命名），无论是否预先24小时暴露于2毫克/升硫酸铜环境中，均用7.5×10⁶集落形成单位/升的爱德华氏菌进行攻毒，以确定硫酸铜对疾病抵抗力的影响。预先暴露于硫酸铜的斑点叉尾鮰比未暴露的对细菌攻毒具有显著更高的抵抗力。未暴露于硫酸铜的斑点叉尾鮰死亡率为35.5%，而暴露于硫酸铜的斑点叉尾鮰死亡率为14.1%。攻毒时，暴露组和对照组鱼的养殖水体中铜浓度相同，排除了水中铜对细菌有毒性的可能性。未暴露、暴露及净化后的斑点叉尾鮰冻干研磨组织中的铜浓度，在硫酸铜暴露前的鱼体中最高，这表明组织中铜水平升高并非对细菌攻毒抵抗力增强的原因。细菌附着于鳃或上皮细胞位点的竞争可能是死亡率降低的原因；尽管铜暴露后鱼组织中铜含量较低，这一观点未得到支持。
