模拟空运过程中克氏原螯虾生理生化指标的变化规律

【目的】明确空运过程中影响克氏原螯虾存活率的关键环境因子，为有针对性地进行空运前预处理提供科学依据。【方法】模拟克氏原螯虾空运条件，将克氏原螯虾放入泡沫箱中，加入冰瓶后进行完全密封（密封组）或打孔通气（打孔组）。模拟空运过程实时监测泡沫箱内的含氧量、温度和相对湿度；模拟空运18 h后采集克氏原螯虾的血清、肝胰腺、鳃丝及中肠等组织样品，分别测定血清溶菌酶（LZM）活性、多酚氧化酶（PPO）活性、超氧化物歧化酶（SOD）活性及丙二醛（MDA）含量，肝胰腺SOD活性、总抗氧化能力（T-AOC）、MDA含量及蛋白质羰基含量，以及鳃丝Na+K+-ATP活性；并制作克氏原螯虾肝胰腺、鳃丝及中肠组织石蜡切片，统计模拟空运结束后克氏原螯虾的存活率。【结果】在模拟空运过程中，相对湿度变化不明显，温度和含氧量的变化引起克氏原螯虾应激反应，是影响空运的主要环境因子。经模拟空运后，密封组克氏原螯虾血清LZM活性、PPO活性及MDA含量显著升高（P<0.05，下同），SOD活性显著降低；肝胰腺蛋白质羰基含量、MDA含量和T-AOC水平均显著高于打孔组及模拟空运前，而SOD活性变化不显著；密封组和打孔组克氏原螯虾经模拟空运18 h后，其鳃丝Na+K+-ATP活性均显著高于模拟空运前。克氏原螯虾经模拟空运18 h后其存活率较高，但模拟空运后暂养1周发现密封组和打孔组的克氏原螯虾存活率均从第4 d开始显著下降，至暂养第7 d密封组克氏原螯虾的存活率仅为59.33%；且其鳃丝有大量附着物，微血管腔结构已完全消失，大部分呼吸上皮细胞脱落、坏死，鳃膜结构遭到破坏。【结论】温度和含氧量是影响克氏原螯虾空运存活率的主要环境因子。模拟空运对克氏原螯虾造成严重损伤且不可逆，在模拟空运结束后克氏原螯虾因自身缺乏修复能力而大量死亡。因此，实际生产中可通过在运输前投喂免疫增强剂，或在运输后优化其暂养环境等方式以提高克氏原螯虾空运存活率，进而确得其引种成功。

Changes in physiological and biochemical indexes of Procambarus clarkii during simulated air transport

【Objective】To identify the key environmental factors affecting Procambarus clarkii survival during air transportation and to provide the scientific basis for targeted pre- and post-transport treatments to improve survival rates.【Method】The conditions of air transportation were simulated by placing the crayfish in foam boxes under ice-cold conditions with(perforated group) or without(sealed group) ventilation. Real-time monitoring of oxygen content, temperature and relative humidity in the foam box was performed during simulated air transportation. After 18 h of simulation, the serum, hepatopancreas, gill filament and midgut samples were collected and the serum activities of lysozyme, polyphenol oxidase(PPO), superoxide dismutase(SOD) and malondialdehyde(MDA) were determined. Hepatopancreas SOD activity, total antioxidant capacity(T-AOC), MDA content, protein carbonyl content and gill filament Na+ K+ -ATPASE activity were used, together with paraffin sections of the hepatopancreas, gill filaments and midgut, to calculate the survival rate of P. clarkii after simulated air transport.【Result】During simulated air transport, the relative humidity was not obviously altered, while the changes in temperature and oxygen content were significantly affected and observed to cause stress reactions in P. clarkii. After the simulation, the activities of lysozyme, PPO and MDA in the serum of the sealed group were significantly increased(P<0.05, the same below), while the activities of SOD were significantly decreased. Hepatopancreas protein carbonyl content, MDA content and T-AOC level were significantly higher than those in the perforated and control groups, while SOD activity showed no significant change. The activity of Na+K+-ATP in gill filaments of both the sealed and perforated groups was significantly higher than that of the control group. After simulated air transport for 18 h, the cray-fish survival rate was higher. However, the survival rate of both the sealing and perforated group decreased significantly from the 4th day, and only 59.33% of the sealed group was alive on the 7th day. Most of the respiratory epithelial cells were exfoliated and necrotic, and the branchial membrane structure was destroyed.【Conclusion】The changes of temperature and oxygen content are the main environmental factors affecting the survival rate of P. clarkii during air transportation. The simulated air transport caused serious and irreversible damage to P. clarkii and a large number of P. clarkii died after their return to control conditions. Therefore, the survival rate of air-transported P. clarkii can be improved by feeding immune enhancers before transportation or optimizing the environmental conditions following transport to improve recovery rates.