Brown M W, Shurben D, Solbe J F, Cryer A, Kay J
Comp Biochem Physiol C Comp Pharmacol Toxicol. 1987;87(1):65-9. doi: 10.1016/0742-8413(87)90182-4.
Two species of coarse fish that are relatively resistant to cadmium poisoning were exposed to sub-lethal concentrations of the metal in their aquarium water. Thus, roach were exposed to cadmium concentrations between 30 and 500 micrograms/l for periods of 14-70 days whereas stone loach were exposed to 1250 micrograms Cd/l for 21-77 days. Under all conditions of exposure, it was found upon analysis of the major organs of accumulation of cadmium in the two species that the toxic metal was sequestered by a single isoform of metallothionein. The amino acid compositions of roach and stone loach metallothionein were determined and found to be similar to those reported for other piscine metallothioneins. The two proteins were found to contain Cd:Zn:Cu in approximate ratios of 4:1:2 per mole of protein. The sequestration of Cd by metallothionein in the two resistant species of fish is contrasted with the situation observed previously in a cadmium-sensitive species, the rainbow trout.
将两种对镉中毒具有相对抗性的杂鱼置于水族箱水中，使其接触亚致死浓度的该金属。因此，拟鲤接触的镉浓度为30至500微克/升，接触时间为14至70天，而石爬鮡接触的镉浓度为1250微克/升，接触时间为21至77天。在所有接触条件下，通过分析这两种鱼体内镉的主要蓄积器官发现，有毒金属被一种金属硫蛋白异构体螯合。测定了拟鲤和石爬鮡金属硫蛋白的氨基酸组成，发现与其他鱼类金属硫蛋白的报道相似。发现这两种蛋白质每摩尔蛋白质中镉、锌、铜的比例约为4:1:2。这两种抗性鱼类中金属硫蛋白对镉的螯合情况与之前在对镉敏感的虹鳟鱼中观察到的情况形成对比。
