Department of Biology, Ecology and Earth Sciences (DiBEST), University of Calabria, Via P. Bucci 4B 87036 Rende (CS), Italy.
Aquat Toxicol. 2013 Oct 15;142-143:164-75. doi: 10.1016/j.aquatox.2013.08.002. Epub 2013 Aug 28.
Endosulfan is a persistent organic pollutant (POP) that has lethal and sublethal effects on non-target organisms, including amphibians. In a laboratory study, we investigated direct and post-exposure effects of endosulfan on Bufo bufo tadpoles. For this purpose we exposed the tadpoles to a single short-term contamination event (96 h) at an environmentally-realistic concentration (200 μg endosulfan/L). This was followed by a recovery period of 10 days when the experimental animals were kept in pesticide-free water. The endpoints were assessed in terms of mortality, incidence of deformity, effects on behavior, and the morpho-functional features of the epidermis. We found that a short-term exposure to the tested concentration of endosulfan did not cause mortality but induced severe sublethal effects, such as hyperactivity, convulsions, and axis malformations. Following relocation to a pesticide-free environment, we noted two types of response within the experimental sample, in terms of morphological and behavioral traits. Moreover, by using both ultrastructural and a morpho-functional approach, we found that a short-term exposure to endosulfan negatively affected the amphibian epidermis. We also observed several histo-pathological alterations: increased mucous secretion, an increase in intercellular spaces and extensive cell degeneration, together with the induction of an inducible isoform of nitric oxide synthase (iNOS). Following the post-exposure period, we found large areas of epidermis in which degeneration phenomena were moderate or absent, as well as a further increase in iNOS immunoreactivity. Thus, after 10 days in a free-pesticide environment, the larval epidermis was able to partially replace elements that had been compromised due to a physiological and/or a pathological response to the pesticide. These results highlight the need for both exposure and post-exposure experiments, when attempting to assess pollutant effects.
硫丹是一种持久性有机污染物（POP），对非靶标生物，包括两栖类，具有致死和亚致死效应。在一项实验室研究中，我们研究了硫丹对蟾蜍蝌蚪的直接和暴露后影响。为此，我们将蝌蚪暴露于环境现实浓度（200μg 硫丹/L）的单次短期污染事件（96 小时）中。然后，在没有杀虫剂的水中进行了 10 天的恢复期，在此期间，实验动物被保留。终点评估包括死亡率、畸形发生率、行为影响以及表皮的形态功能特征。我们发现，短期暴露于测试浓度的硫丹不会导致死亡，但会引起严重的亚致死效应，如过度活跃、抽搐和轴畸形。重新安置到无杀虫剂的环境后，我们注意到实验样本中出现了两种形态和行为特征的反应。此外，通过使用超微结构和形态功能方法，我们发现短期暴露于硫丹会对两栖动物表皮产生负面影响。我们还观察到几种组织病理学改变：粘液分泌增加、细胞间隙增加和广泛的细胞变性，以及诱导一氧化氮合酶的诱导型同工型（iNOS）。暴露后期间，我们发现表皮中出现了大片区域，其中退化现象适度或不存在，并且 iNOS 免疫反应进一步增加。因此，在无杀虫剂环境中 10 天后，幼虫表皮能够部分替代因对杀虫剂的生理和/或病理反应而受损的元素。这些结果强调了在尝试评估污染物影响时，需要进行暴露和暴露后实验。
