The Yangtze sturgeon () is extinct in the wild; however, artificial propagation in captivity under fully controlled conditions has been successful. Sperm cryopreservation is an effective method for germplasm conservation and aquaculture. Sperm concentration affects the quality of cryopreserved spermatozoa. Thus, in this study, we optimized the concentration (0.25 × 10, 0.5 × 10, 1.0 × 10, and 2.0 × 10 spermatozoa [spz]/mL) for Yangtze sturgeon sperm cryopreservation in a 0.5 mL plastic straw. The greatest value for the kinetic parameters was achieved when sperm were cryopreserved at 0.5 × 10 spz/mL. In comparison to other concentrations, there was a notable increase in both acrosomal and plasma membrane integrity when sperm was cryopreserved at a concentration of 0.5 × 10 spz/mL. No significant difference of superoxide dismutase and glutathione peroxidase enzyme activity was present in post-thaw sperm, except in sperm cryopreserved at a concentration of 2.0 × 10 spz/mL. Catalase activity was significantly higher in post-thaw sperm at a concentration of 0.5 × 10 spz/mL than at other concentrations. Excluding sperm cryopreserved at 2.0 × 10 spz/mL, the fertilization rate of cryopreserved sperm was not significantly different among the different concentrations. This concentration optimization improves cryopreserved sperm quality and standardizes sperm cryopreservation procedures for the Yangtze sturgeon. These findings are especially beneficial for the establishment of a sperm cryobank.

中文翻译：

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精子浓度对长江鲟冷冻精子质量的影响

长江鲟（）已在野外灭绝；然而，在完全受控条件下的圈养人工繁殖已取得成功。精子冷冻保存是种质保存和养殖的有效方法。精子浓度影响冷冻精子的质量。因此，在本研究中，我们优化了0.5 mL塑料吸管中长江鲟精子冷冻保存的浓度（0.25 × 10、0.5 × 10、1.0 × 10和2.0 × 10精子[spz]/mL）。当精子以 0.5 × 10 spz/mL 冷冻保存时，动力学参数达到最大值。与其他浓度相比，当精子以 0.5 × 10 spz/mL 的浓度冷冻保存时，顶体和质膜的完整性显着增加。除以 2.0 × 10 spz/mL 浓度冷冻保存的精子外，解冻后的精子中超氧化物歧化酶和谷胱甘肽过氧化物酶活性没有显着差异。解冻后精子中过氧化氢酶活性在 0.5 × 10 spz/mL 浓度下显着高于其他浓度。排除2.0×10 spz/mL冷冻精子外，不同浓度冷冻精子的受精率没有显着差异。这种浓度优化提高了冷冻精子的质量，并标准化了长江鲟精子冷冻保存程序。这些发现对于精子冷冻库的建立特别有益。