2.1. Tissue material
Six mature prawns (3 males and 3 females) in good health were randomly selected as experimental specimens from Huzhou Fengsheng Bay Farm, Zhejiang province in China, and subjected to an ice bath for immobilization. Brain and thoracic ganglia tissues of each prawn (approximately 20 g) were rapidly excised and flash-frozen in liquid nitrogen. The dissected tissues of the 3 males and 3 females were mixed with those of the same sex to eliminate individual differences. These were stored at −80 °C until the total RNA was extracted. The other tissues were collected according to experimental requirements. Animal experiments were approved by Animal Ethics Committee of Shanghai Ocean University.