水位对黑斑侧褶蛙蝌蚪形态表型、 白细胞数量和应激反应的影响

为探究水位变化对黑斑侧褶蛙（Pelophylaxnigromaculatus）蝌蚪形态表型、免疫功能和应激反应能力的影响，实验室内测定了水位恒定组以及水位快速、中速和慢速下降组37期蝌蚪发育至变态完成期的变态时长、身体大小和血液中各型白细胞的百分比，以及嗜中性粒细胞与淋巴细胞比值的变化。结果表明，水位快速下降显著缩短了蝌蚪的变态时长（P <0.05），体长下降明显（P <0.05），体重和体宽有所降低，但组间差异不显著（P> 0.05）。嗜中性粒细胞的百分比快速下降组显著高于其他处理组，单核细胞的百分比水位恒定组显著高于中速下降组（P <0.05），嗜酸性粒细胞、嗜碱性粒细胞和淋巴细胞的百分比均无明显的组间差异（P>0.05）；嗜中性粒细胞与淋巴细胞比值快速下降组显著高于其他处理组（P <0.05）。水位加速下降导致登陆后幼蛙的个体变小，由嗜中性粒细胞和单核细胞所代表的天然免疫能力变化趋势不同，应激反应能力增强，可能不利于幼蛙的存活。

Effects of Water Level on Morphological Phenotype, Number of Leukocytes and Stress Response in Tadpoles of Pelophylax nigromaculatus

Objectives] The present study aims to investigate the effects of water level changes on morphological phenotypes, immune function and stress responsiveness ability in tadpoles of the Dark-spotted Frogs (Pelophylax nigromaculatus). Methods] The variations in metamorphosis duration, body size and percentage of different subtypes of leukocyte in the circulation blood, as well as the ratio of neutrophils to lymphocytes were measured in the laboratory in the constant water level group and in the rapid, moderate and slow reduction groups at metamorphosis completion. All statistical analyses were performed using SPSS software packages (SPSS 19.0 for windows). One-way ANOVA or one-way ANCOVA and multiple comparisons were used to compare the differences of the parameters mentioned above among different groups. Results were presented as means ± standard error, and P < 0.05 was considered to be statistically significant. Results] The results showed that the rapid reduction group significantly reduced the metamorphosis duration of tadpoles (Fig. 1a, P < 0.05); the snout to vent length (SVL) of froglets was significantly declined in the rapid reduction group compared with that of any other group (Fig. 1d, P < 0.05), both the body mass (Fig. 1b, P > 0.05) and body width (Fig. 1c, P > 0.05) displayed lower values in the rapid desiccation group, but no significant differences were found among different groups. The percentage of neutrophils was significantly higher in the rapid reduction group than that of any other group (Fig. 3c, P < 0.05), the percentage of monocytes was significantly higher in the constant water level group than that of the moderate reduction group (Fig. 3e, P < 0.05), and no significant group differences were observed for the percentage of eosinophils (Fig. 3f, P > 0.05), basophils (Fig. 3b, P > 0.05) or lymphocytes (Fig. 3a, P > 0.05). The ratio of neutrophils to lymphocytes was significantly higher in the rapid reduction group than that of any other group (Fig. 3d, P < 0.05). Conclusion] The accelerated water level reduction can lead to smaller froglet individuals, natural immunity represented by both neutrophils and monocytes displayed different patterns, and accompanying with increased stress response ability, which may be detrimental to the survival of froglets.