Berglind R, Dave G, Sjöbeck M L
Ecotoxicol Environ Saf. 1985 Apr;9(2):216-29. doi: 10.1016/0147-6513(85)90024-7.
The effects of continuous exposure to lead for various periods and recovery in clean water on delta-aminolevulinic acid dehydratase (ALA-D) activity, hemoglobin content, growth, and reproduction were studied in Daphnia magna. Steady-state inhibition of ALA-D activity was reached within 2 days in 16, 64, and 256 micrograms Pb liter-1, but restoration in clean water was prolonged in relation to previous exposure. In spite of the inhibition of ALA-D activity hemoglobin content increased after 2 days in 16 and 24 micrograms Pb liter-1. Furthermore, hemoglobin content in previously exposed animals increased during recovery in clean water. Maximum hemoglobin content (2.9 times control value) was found after 2 days recovery of animals exposed to 64 micrograms Pb liter-1. These findings suggest that some enzyme(s) other than ALA-D in the biosynthetic pathway of hemoglobin formation is (are) more sensitive to lead. Growth, in contrast to reproduction, was stimulated by low concentrations of lead (less than 64 micrograms Pb liter-1), although in 256 micrograms Pb liter-1 growth was also significantly impaired. After 19 days the 16 and 50% reproductive impairment concentrations were less than or equal to 1 and 10 micrograms Pb liter-1, respectively.
研究了大型溞连续暴露于不同时期的铅并在清洁水中恢复后，对δ-氨基乙酰丙酸脱水酶（ALA-D）活性、血红蛋白含量、生长和繁殖的影响。在16、64和256微克/升的铅浓度下，ALA-D活性在2天内达到稳态抑制，但在清洁水中的恢复时间相对于之前的暴露有所延长。尽管ALA-D活性受到抑制，但在16和24微克/升的铅浓度下，2天后血红蛋白含量仍有所增加。此外，先前暴露的动物在清洁水中恢复期间血红蛋白含量增加。在暴露于64微克/升铅的动物恢复2天后，发现血红蛋白含量最高（为对照值的2.9倍）。这些发现表明，血红蛋白形成生物合成途径中除ALA-D之外的某些酶对铅更为敏感。与繁殖相反，低浓度的铅（低于64微克/升）刺激生长，尽管在256微克/升时生长也受到显著损害。19天后，16和50%的繁殖损害浓度分别小于或等于1和10微克/升。
