Ammonia nitrogen is an important source of water pollution that severely limits the development of aquaculture. Macrobrachium nipponense is widely cultivated due to its delicious meat, strong reproductive ability and short reproductive cycle, but the problems caused by germplasm degradation are becoming increasingly concerning.Hybridization is an efficient means to solve this problem. In this study, the parental population, Dianshan Lake (DS) and the hybrid population, DS ♀ × CD (Changjiang, CJ ♂ × Dongting, DT ♀ [SCD]) were exposed to 0, 1 or 10 mg/L total ammonia nitrogen (TAN) for 28 days. Our results indicated that the number of gill-positive cells and the apoptosis rate of the two groups showed an upward trend with the ammonia nitrogen concentration increased. The ammonia metabolism-related substance levels and the detoxifying enzyme activities in the gills of shrimp in the SCD group exposed to 10 mg/L of TAN were significantly higher than shrimp in the DS group (p < 0.05). As the TAN concentration increased, the respiratory-related genes displayed a downward trend and the nitrogen metabolism-related genes presented an upward trend.Our results suggest that the SCD population had a stronger detoxifying capacity and a greater stress resistance ability than the DS population when subjected to the same concentration of ammonia nitrogen stress.

No abstract

Penaeus vannamei, a high yield economical shrimp, is confronting germplasm degradation in the brine culture environments found in China. Genetic improvement by hybridization is an effective way to solve this problem. In this study, EB and CE hybrid was obtained from Guam wild B, C and E families from Shanghai Ocean University. EB and CE were used as parents to obtain genetic hybrids suitable for freshwater culture. The control group was shrimp imported from the Hainan Lutai Company. The two groups of shrimp were cultured for 3 months under salinities of 1‰, 5‰, and 15‰. Growth performance-related indicators, biochemical composition, and growth-related gene expression were examined. The results showed that at salinities of 1‰ and 5‰, the survival rate and growth performance of the low salt breeding group were better than those of the imported population. The digestive enzyme activity in the low salt breeding group was higher, which was consistent with its better growth performance, and was also associated with higher triglyceride, total cholesterol, and glycogen content. Lower levels of lactic acid indicated less anaerobic metabolism and better adaptability to the environment. The amino acid analysis of fatty acids showed that levels of essential amino acids and high unsaturated fatty acids were both higher in the low-salt breeding group than in the imported shrimp cultured in low salinity. The expression levels of genes associated with growth and hair removal were also higher in the low salt breeding group than in the imported shrimp group. The results indicated that the hybrid shrimp showed better growth performance and nutritional advantages compared with the imported shrimp under salinities of 1‰ and 5‰. This research provided a valuable reference for subsequent genetic breeding and shrimp culture.

No abstract