22种海水鱼中ACEI的制备及其化学修饰

以取自中国黄海的22种鱼类为研究对象，测定其鱼肉组织上清液的酶解物对血管紧张素转化酶（ACE）的抑制作用。从6种商业用酶和1种新型海洋低温碱性蛋白酶（MLAP）中，筛选出MLAP作为酶解制备ACEI的理想水解酶。以该酶水解上述22种海水鱼鱼肉组织上清液，并将水解液经Sephadex G-25凝胶层析和DEAE Sepharose阴离子交换层析，得到ACEI纯品。测定各类ACEI体外抑制ACE的活性发现，这22种海水鱼中以缇鱼（Engraulis japonicus）所产ACEI活性最高，其余鱼类无显著差异。以缇鱼制备血管紧张素转化酶抑制剂（ACEI-22），并对ACEI-22作进一步研究，结果发现，ACEI-22对自发性高血压大鼠（SHR）有降压效果，但不显著；ACEI-22经聚乙二醇化学修饰后，修饰率为68％，且给药SHR后，大鼠收缩压显著降低，与相同条件下同剂量的卡托普利的降压效果相当。故聚乙二醇修饰的ACEI-22可有效地降低SHR的血压。     

Social learning in fishes: a review

Animals acquire skills and knowledge from other animals, and fish are no exception. There is now strong experimental evidence that many species of fish exhibit social learning and traditional behaviours. Here, we review the literature pertaining to social learning in fish, focusing on (i) antipredator behaviour, (ii) migration and orientation, (iii) foraging, (iv) mate choice and (v) eavesdropping.     

Persistence of native fishes in small streams of the urbanized San Francisco Estuary,California: acknowledging the role of urban streams in native fish conservation

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