The present study was designed to examine the physiological responses of juvenile managua cichlid, Cichlasoma managuense under short‐term salinity stress, that is transferring C. managuense from freshwater to brackish water of salinity 0 (control group), 3‰, 6‰, 9‰, 12‰ or 15‰ for 48, 96, 144 and 192 hr respectively. The results showed that gill Na⁺/K⁺‐ATPase (NKA) activity revealed a decreased (48 hr), increased (96 hr) and then slightly decreased (144 hr, 192 hr) response with increasing salinity and the lowest NKA level was consistently detected at 9‰ salinity treatment; gill Ca²⁺/Mg²⁺‐ATPase (CMA) activities in all salinity treatments were significantly higher than that of the control group (p < .05) before 144 hr; the RNA/DNA ratio was significantly reduced when exposed to high salinities (≥9‰), suggesting growth inhibition; serum cortisol level gradually decreased at low salinities (up to 6‰) but dramatically increased at high salinities of 12‰ and 15‰; and both serum glucose/lactic acid levels and heat shock protein 90 (HSP90) level in liver/muscle were decreased at the salinity between 9‰ and 6‰ but increased at the salinity between 12‰ and 15‰, which was a U‐shape response curve. Taken together, our data suggest that C. managuense can adapt well at salinity up to 0‰–9‰ and high salinity may cause detrimental effects.

中文翻译：

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Managua Cichlid，Cichlasoma managuense对盐分胁迫的生理响应

本研究的目的是检查的少年马那瓜鲷，生理反应紫红managuense短期盐度胁迫下，即转移C. managuense从淡水盐度0（对照组），3的微咸水‰，6‰，9分别为48、96、144和192小时的‰，12‰或15‰。结果表明，随着盐度的增加，g Na ⁺ / K ⁺ -ATPase（NKA）活性显示出降低（48小时），增加（96小时），然后轻微降低（144小时，192小时）的响应，最低的NKA水平为在9‰的盐度处理中始终被检测到；Ca Ca ²⁺ / Mg ²⁺在所有盐度处理中，‐ATPase（CMA）活性在 144小时之前均显着高于对照组（p <.05）。当暴露于高盐度（≥9‰）时，RNA / DNA比例显着降低，表明其生长受到抑制；低盐度（最高6‰）时血清皮质醇水平逐渐降低，而高盐度（12‰和15‰）时血清皮质醇水平显着升高；盐度在9‰至6‰之间时，肝脏/肌肉的血清葡萄糖/乳酸水平和热休克蛋白90（HSP90）水平均降低，但在盐度在12‰至15‰之间时升高，呈U形。响应曲线。综上所述，我们的数据表明曼氏梭菌可在高达0‰–9‰的盐度下很好地适应，而高盐度可能会造成有害影响。