Unit of Marine and Environmental Toxicology, Sfax University, IPEIS, BP 1172, 3018, Sfax, Tunisia.
Laboratory of Ecotoxicology, UMR-I 02 SEBIO, Normandie University, BP 540, 76058, Le Havre, France.
Environ Sci Pollut Res Int. 2017 Dec;24(34):26670-26680. doi: 10.1007/s11356-017-0146-4. Epub 2017 Sep 27.
Bivalve species may be susceptible to environmental estrogenic compounds including estradiol (E). However, they are able to biotransform the hormone quite readily and inactivate its estrogenic action. To study the long-term effects of elevated free E tissue levels, we transiently exceeded the biotransformation capacity of the clam Ruditapes decussatus by exposing them with high E concentrations (400 ng/L) and subsequently study the consequences on gametogenesis during the following reproductive cycle. Exposure to 400 ngE/L led to a significant increase in tissue free E levels, which reached 10-50 ng EEq/gww. No deleterious effect on gonado-somatic index (GSI), condition index (CI), or ability to respond to the stress on stress test could be detected after a month of exposure, suggesting the absence of negative effects on the clam's health. However, a marked increase in gametogenesis could be observed in both sexes during the exposure. Subsequent transplantation of the clams in the field allowed the normal development of the male clams and maturation of the gonads without any detrimental effect observed after 4 months. In contrast, in early July, all female clams formerly exposed to E showed lower health status, and only ovaries with atretic oocytes while all control and indigenous females were normal and mature. These results show a sex-specific effect of high E exposure and suggest either a direct or indirect role for E in R. decussatus' reproduction.
双壳类物种可能易受包括雌二醇 (E) 在内的环境雌激素化合物的影响。然而，它们能够很容易地将激素生物转化，并使其雌激素作用失活。为了研究高水平游离 E 组织水平的长期影响，我们通过用高浓度 E（400ng/L）暴露贻贝来暂时超过它们的生物转化能力，随后在接下来的生殖周期中研究配子发生的后果。暴露于 400ngE/L 会导致组织中游离 E 水平显著增加，达到 10-50ngEEq/gww。暴露一个月后，性腺体指数（GSI）、条件指数（CI）或对压力测试的应激反应能力均未受到损害，这表明对贻贝健康没有负面影响。然而，在暴露期间，雌雄两性的配子发生都明显增加。随后将贻贝移植到野外，允许雄性贻贝正常发育和性腺成熟，在 4 个月后没有观察到任何不利影响。相比之下，在 7 月初，所有以前暴露于 E 的雌性贻贝的健康状况都较低，只有卵巢中存在退化的卵母细胞，而所有对照和本地的雌性贻贝都正常且成熟。这些结果表明高 E 暴露具有性别特异性效应，并表明 E 在 R. decussatus 繁殖中具有直接或间接作用。
