To investigate the ion regulation of large yellow croaker (Larimichthys crocea) under hypoxia and acidification stresses, we investigated the effects of hypoxia (dissolved oxygen DO 3.5 mg·L-1, pH 8.1), acidification (DO 7.0 mg·L-1, pH 7.35) and combined stresses of hypoxia and acidification (DO 3.5 mg·L-1, pH 7.35) on gill tissue structure and physiological indices related to ion regulation of juvenile L. croaker. The results showed that, under hypoxia stress, gill Na+/K+-ATPase activity, serum Na+, Ca2+ and Cl- contents of juvenile L. croaker decreased first and then increased. Under acidification stress, gill Ca2+-ATPase activity, serum Na+ and Ca2+ contents of juvenile L. croaker increased first and then decreased. Under the combined stresses of hypoxia and acidification, Na+/K+-ATPase activity and Na+, K+ and Ca2+ contents increased first and then decreased, while Ca2+-ATPase activity and Cl- content decreased first and then increased. The results of gill histology showed that hypoxia and acidification stresses led to the detachment of gill epithelial cells, and the combined stresses of hypoxia and acidification led to proliferation, hypertrophy and swelling of gill epithelial cells. Comprehensive analysis showed that hypoxia and acidification stress affected the activities of major ion regulatory enzymes in juvenile L. croaker and caused different degrees of damage to gill tissue, resulting in imbalanced ion regulation in juvenile L. croaker.
为探讨大黄鱼幼鱼在低氧及酸化胁迫下机体离子调节情况,本研究探讨了低氧(溶解氧量DO 3.5 mg·L-1,pH 8.1)、酸化(DO 7.0 mg·L-1,pH 7.35)以及低氧酸化协同胁迫(DO 3.5 mg·L-1,pH 7.35)对大黄鱼幼鱼鳃组织结构以及离子调节相关生理指标的影响。结果表明: 低氧胁迫下,大黄鱼幼鱼鳃Na+/K+-ATP酶活力、血清Na+、Ca2+及Cl-含量随胁迫时间的延长呈先递减后递增的趋势。酸化胁迫下,大黄鱼幼鱼鳃Ca2+-ATP酶活力、血清Na+及Ca2+含量呈先递增后递减的趋势。低氧酸化协同胁迫下,Na+/K+-ATP酶活力及Na+、K+、Ca2+含量呈先递增后递减的趋势,Ca2+-ATP酶活力、Cl-含量则呈先递减后递增的趋势。鳃组织学结果表明,低氧、酸化胁迫均导致鳃小片上皮细胞出现脱离现象,低氧酸化协同胁迫导致鳃小片上皮细胞出现增生、肥大、隆起现象。综合分析表明,低氧及酸化胁迫影响了大黄鱼幼鱼主要离子调节酶活力并对鳃组织造成了不同程度的损伤,最终导致了大黄鱼幼鱼体内离子调节失衡。.
Keywords: Ca2+-ATPase; Na+/K+-ATPase; acidification; hypoxia; large yellow croaker; serum ion.