Effects of nitrate and atrazine on larval development and sexual differentiation in the northern leopard frog Rana pipiens
Effects of nitrate and atrazine on larval development and sexual differentiation in the northern leopard frog Rana pipiens
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DOI：
10.1897/05-136r.1
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发表时间：
2006-01-01
影响因子：
4.1
通讯作者：
Handy, RD
中科院分区：
文献类型：
--
作者：
Orton, F;Carr, JA;Handy, RD
农用化学品造成的污染可能是全球两栖动物数量减少的原因之一。测试了硝酸盐和/或阿特拉津的环境相关浓度对卵子发育和性腺分化的影响。从Taylor-Kollros阶段2至3到23至34阶段，将4个重复的20只蝌蚪（80只/处理）暴露于10 mg/L硝酸盐、10 μ g/L阿特拉津、10 mg/L硝酸盐加10 μ g/L阿特拉津的组合暴露，或未经处理的对照组。没有观察到对体重、鼻口通气或后肢长度或前肢出现时间的治疗依赖性影响。与对照组相比，各处理的雌性比例均有所增加，尤其是联合处理（chi(2) = 17.90, df = 6, p = 0.0065，联合处理的雌性比例为66.4%，对照组的雌性比例为41%）。所有治疗中双性人的发生率均较低。对生精细胞总数没有影响，但细胞类型的比例不同，与对照组相比，处理组动物睾丸的精原细胞更多，精母细胞更少，精母细胞更多（显著差异，Kruskal-Wallis, p < 0.05）。卵巢前用硝酸盐或阿特拉津处理的动物表现出较大的未成熟（卵黄前）和成熟（卵黄原）卵泡，但联合处理的卵巢只有较大的未成熟卵泡。单独使用硝酸盐、单独使用阿特拉津以及对照组均可观察到睾丸卵母细胞，而联合使用则无。总的来说，这项研究表明，与单独接触这些化学物质相比，硝酸盐/阿特拉津联合暴露对性别比例的影响更为显著。组织学证据表明，在幼虫发育过程中，硝酸盐和/或阿特拉津暴露可能导致性腺早熟。
Pollution from agrochemicals may be contributing to the global decline in amphibian populations. Environmentally relevant concentrations of nitrate and/or atrazine on anuran development and gonadal differentiation were tested. Four replicates of 20 tadpoles per tank (80/treatment) were exposed from Taylor-Kollros stage 2 to 3 to stage 23 to 34 to either 10 mg/L nitrate, 10 mu g/L atrazine, a combined exposure of 10 mg/L nitrate plus 10 mu g/L atrazine, or untreated controls. No treatment-dependent effects on weight, snout-vent or hind limb length, or time to forelimb emergence were observed. The proportions of females increased in all treatments compared to the controls, especially in the combined treatment (chi(2) = 17.90, df = 6, p = 0.0065, combined = 66.4% female, control = 41% female). The frequency of intersex was low in all treatments. No treatment-related effects on the total number of spermatogenic cells were observed, but the ratio of cell types differed in that testes from animals in the treated groups exhibited more spermatogonia, fewer spermatocytes, and more spermatids than the control (significantly different, Kruskal-Wallis, p < 0.05). Ovaries front animals treated with nitrate or atrazine exhibited larger immature (previtellogenic) and mature (vitellogenic) follicles, but ovaries from the combined treatment had larger immature follicles only. Testicular oocytes were observed in the nitrate-only and atrazine-only treatments, and the control treatment, but not the combined treatment. Overall, this study has demonstrated changes in sex ratios that are more marked in response to combined nitrate/atrazine exposure than with these chemicals alone. Histological evidence suggests that premature maturation of gonad may occur as a result of nitrate and/or atrazine exposure during larval development.