Changes of globins expression in tongue sole, Cynoglossus semilaevis (Actinopterygii: Pleuronectiformes: Cynoglossidae) in response to short-term hypoxia

Background. Fishes live in the aquatic systems which are first affected by low or temporally changing O2 availability. Under hypoxia, the fish possess varieties of mechanism to ensure the uptake of an adequate amount of O2. Tongue sole, Cynoglossus semilaevis Günther, 1873, lives on the bottom of water where contain low O2 concentration, indicating that this species possess specific feature against hypoxia. In this study, we examined the mRNA expression of three globins in tongue sole under short-term hypoxia. Materials and methods. Using bioinformatics analysis, three globin genes including hemoglobin-α1 (Hb-α1), myoglobin (Mb), and cytoglobin (Cygb) were first obtained from tongue sole EST database. Then, their expression levels in different tissues of tongue sole under short-term hypoxia were detected using quantitative real-time PCR method. Results. Under short-term hypoxia, Hb-α1 significantly increased in all the tissues except intestine and stomach. The Cygb expression level was up-regulated from 5 min to 120 min, whilst changed to normal level at 36 h. Mb was only up-regulated in blood and heart at 120 min. But, as the hypoxia prolonged, there was a mild increase of Mb in blood, heart, spleen, and liver. Conclusion. The three globins of tongue sole were up-regulated in some tissues, but their rolemay be different in different stage of hypoxia. Hb and Cygb might play role in the earlier stage, while Mb might play role in the late stage of hypoxia.