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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 + , Ca 2+ and Cl - contents of juvenile L. croaker decreased first and then increased. Under acidification stress, gill Ca 2+ -ATPase activity, serum Na + and Ca 2+ 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 Ca 2+ contents increased first and then decreased, while Ca 2+ -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 .

Aim: The purpose of this experiment was to investigate the cardiac physiological characteristics for adaptation to high-altitude hypoxia in chickens., Methods: Tibetan, Dwarf Recessive White and Shouguang chickens were fed at low-and high-altitude, and measurements were made in heart weights, lactic acid (LA), lactate dehydrogenase (LDH), and succinate dehydrogenase (SDH) at the age of 10 weeks., Results: The results showed that Tibetan chickens at high-altitude had lower heart weight and LA content, and similar LDH activity, and higher SDH activity when compared to Dwarf Recessive White and Shouguang chickens., Conclusion: It was concluded that the cardiac mechanisms of high-altitude hypoxic adaptation in Tibetan chickens were increasing neither heart weight, nor level of anaerobic metabolism, but the higher SDH activity was significant to the adaptation. The SDH was a symbol enzyme for hypoxic adaptation in Tibetan chicken.