) was cloned and sequenced from) strains developed by successive and directional selective breeding. In addition, the under low temperature treatments Sequence analysis showed that Nile tilapia untranslated region (UTR), a 783 bp open reading frame (ORF) and a 279 bp 3 UTR. Multiple alignment and homological analysis revealed Nile tilapia AQP1 protein shared high levels of amino acid identity with AQP1 from Rhabdosargus sarba (92%), Anguilla anguilla (83%), (59%) and (59%). A phylogenetic tree was constructed using the neighbor-joining method with the deduced amino acid sequences of . As expected from the sequence alignment, tilapia AQP 1 first, and then clustered with the other teleost species. To investigate the , we examined the expression of mRNA at different temperatures (30) for 48 h using mRNA levels in the muscle and liver from 20radually from 30℃ to 10℃. In the muscle of the cold-tolerant tilapia strain, and were , and then at 10The expression of the gene in the control group was followed by reduced expression at 10℃ which induced an 11.30 foldAQP1 muscle under cold stress were significantly different between the cold-tolerant tilapia strain and the control groupAQP1 mRNA expressions were 3.38 and 1.42 fold , 18.85 and 9.01 fold . This showed that cold stress had no significant effects on liver mRNA expression between the cold-tolerant tilapia strain and the control group (AQP1 is sensitive to tempera tilapia strainAQP1 at low temperatures. These results suggest that the gene plays an important role in low temperature acclimation and might be one of the cold tolerance-related genes in Nile tilapia. The present results provide a theoretical basis for studying the molecular mechanism of cold tolerance and fish stress resistance breeding.