The typical stenothermal tropical fish tiger barb Puntius tetrazona, also named as Systomus tetrazona, Barbus tetrazona or Puntigrius tetrazona, belongs to the family cyprinidae. Tiger barb is a popular aquarium trade fish in worldwide, originating from South-East Asia. Meanwhile tiger barb fish is an experimental fish for the study of pathogenic infection, parasitic infestation, fish diets, animal visual perception, and stomach-less teleost digestion system. The temperature window of tiger barb is relatively narrower than other tropical fish. To discover the genetic basis for improving the cold tolerance of P. tetrazona, we cloned the PtScd1 cDNA sequence and analyzed the expression profile of PtScd1 in multi-tissues under gradient cold temperature stress. The PtScd1 gene was expected to play a vital role for the P. tetrazona coping with cold stress.
The results suggested that there was a highly conserved binding site for two zinc ions, or more likely a diiron center, in the dimensional structure of PtSCD1. Two ligand sites were predicted not conserved (FIGURE 1). The PtScd1 mRNA expression was detected in adult tiger barb fish with a decreasing expression level as liver >brain >muscle >gill (FIGURE 2A). The PtScd1 mRNA expression levels increased in multi tissues of tiger barb under cold stress (FIGURE 2B). Particularly, there was negative correlation trend between the relative expression level of PtScd1 mRNA in brain tissue and the exposure temperature (FIGURE 2B). The study showed the tissue-specific expression of PtScd1 mRNA in a temperature-dependent way.