Effects of different temperature and salinity on the expression of adenine nucleotide translocase 2(ANT2) m RNA in the mud crab, Scylla paramamosain

The mud crab Scylla paramamosain, a eurythermal and euryhaline species, is a commercially exploited crab inhabiting the southeastern coast of China. In recent years, mud crab aquaculture has suffered as a result of unsettled weather, which has led to a seasonal temperature and salinity changes in the sea water. This study aims to explore the molecular mechanism of cold tolerance in S. paramamosain by examining the expression of adenine nucleotide translocase 2(ANT2) at different temperatures and salinities. ANT belongs to the mitochondrial carrier superfamily(MCF). It is the most abundant inner membrane protein of the mitochondrion and is responsible for the transport of ADP and ATP in the cytoplasm and mitochondrial matrix through the inner mitochondrial membrane. In this study, the relative expression of ANT2 m RNA was detected using real-time quantitative polymerase chain reaction at different temperatures(10℃, 15℃, 20℃, 25℃), and low temperatures(10℃, 15℃) combined with salinity(10, 35) in mud crabs(carapace width 3.7–5.8 cm, body weight 80–100 g). Real-time q PCR indicated that, at different temperatures, ANT2 was expressed in the hepatopancreas, muscle and gill. The relative expression of ANT2 m RNA was lowest in the hepatopancreas, at a medium level in muscle, and highest in the gill, and the results indicated that the expression of ANT2 was tissue-specific. With declining temperature, the expression of ANT2 m RNA decreased generally, but at 15℃ in the muscle(1–12 h) and gill, the expression of ANT2 was significantly higher than that at 20℃(P0.05). The expression pattern of ANT2 at different temperatures demonstrated that it might be associated with energy metabolism, and participate in stress responses at a certain range of low temperatures, stimulating the expression of ANT2 in the mud crab. At the same temperature, the expression of ANT2 at a salinity of 10 was significantly higher than at the higher salinity of 35(P0.05), which indicated low salinity might be helpful for metabolism in mud crabs, enhancing cold resistance. This research might provide theoretical guidance for crab aquaculture and management to some extent.