孕激素暴露致食蚊鱼形态雄性化的生物学效应

摘要

Objective The aim of this study was to investigate the masculinizing effects of progesterone ( PRO) exposure at different concentrations on the morphology of female mosquitofish (Gambusia affinis).Methods Immature female G.affinis individuals were put into static water with 0.5, 5, 50 and 500 nmol/L progesterone (n=56), respective-ly.In addition, control group and parallel groups were set up .After 42-day-long exposure, we measured four main indexes of the G.affinis:the body length, body weight, morphological changes in the anal fin 3rd fin and the 14, 15 and 16 verte-bral ribs.We also observed the state of ovarian development .Results The body lengths (BL) of experimental groups ex-posed at concentration of 50 and 500 nmol/L progesterone for 42 d showed significant differences , respectively ( P<0.01 for both), when compared with those of the control group .The body weights (BW) of experimental groups exposed to pro-gesterone at all concentrations were significantly or very significantly decreased (P<0.05 or P<0.01).Only the proges-terone at 5 nmol/L concentration showed significant effect on the body health index (CF) (P<0.05).The section number (FJ) of the anal fin 3rd fin, the section length (FL)and the widest portion width (FW)in the experimental groups had sig-nificant difference (P<0.05), respectively, showing significant changes in morphology after the exposure to 500 nmol/L progesterone .However , there was no significant difference between the values resulted by progesterone in other concentra -tions (P>0.05).When exposed to 500 nmol/L PRO, the L, D and L:D values of the 14th, 15th and 16th vertebral ribs of the female G.affinis had very significant difference ( P<0.01 for all ) , respectively , indicating significant changes of morphological masculinization .Histological examination revealed that the developmental status of the ovaries of G.affinis in the experimental groups were to different degrees inhibited , and the nuclei appeared swelling in stage II and III oocytes . Conclusions The results of this study indicate apparent masculinizing effects of progesterone on immature female mosquit -ofish.%目的：研究不同浓度孕酮（ PRO）暴露对雌性食蚊鱼（ Gambusia affinis）的形态雄性化生物学效应。方法将性未成熟的雌性食蚊鱼个体分别静水暴露于0.5、5、50和500 nmol/L不同浓度的PRO实验组中，并设置对照组和平行组。持续暴露42 d后观察与测定食蚊鱼的体长、体重、臀鳍第3鳍条和第14，15，16椎肋骨形态雄性化变化等指标，同时观察卵巢发育状况。结果食蚊鱼暴露42 d后，与对照组相比，50和500 nmol/L实验组食蚊鱼的体长（ BL）有极显著减少（分别P＜0.01）；无论是低浓度组还是高浓度组，暴露实验后体重（ BW）都有显著性或极显著下降（P＜0.05或P＜0.01）；PRO暴露对食蚊鱼身体健康指数（CF）的影响，只有在5 nmol/L浓度时差异有显著性（P＜0.05）；500 nmol/L浓度处理后，第3臀鳍条分节数（FJ）、长度（FL）和最宽处宽度（FW）差异有显著性（P＜0.05），表明形态雄性化变化明显；其他浓度组则无明显区别（P＞0.05）；500 nmol/L PRO实验组中，雌性食蚊鱼的第14，15，16椎肋骨的L值、D值和L：D值都出现极显著性差异（分别P＜0.01），表明形态雄性化变化明显；组织切片观察揭示，暴露组食蚊鱼卵巢中的卵母细胞发育受到不同程度的抑制，II、III时相卵母细胞胞核发生肿胀现象。结论孕激素暴露诱导雌性食蚊鱼形态雄性化的生物效应十分明显。