The experiment simulated the logistical transportation of Penaeus monodon. It set four distinct gradient Vitamin C (Vc) addition levels, including 0mg/L, 111mg/L, 222mg/L, and 333mg/L, to investigate the impact of Vc on the anti-stress ability of P. monodon during transportation. And the survival rate following transportation and a 15-day interim rearing period were recorded. Moreover, the alterations in tissue structure and activity of the enzymes alkaline phosphatase (ACP), alkaline phosphatase (AKP), total superoxide dismutase (T-SOD), and total superoxide dismutase (T-AOC) were checked. The results showed that with the increase of Vc supplemental level, the survival rate of P. monodon after transportation and after 15 days of temporary rearing increased to varying degrees. ACP and AKP in the hepatopancreas increased first and then decreased. T-SOD activity in the 0mg/L group was the lowest and then decreased gradually. The activity of total antioxidant capacity (T-AOC) in the 0mg/L group was the lowest and then stabilized. The branchial tissue structure also changed. The branchial tissue blood cell disorder decreased, the diaphragm gradually narrowed, the cornered cortex gradually recovered, and the swelling decreased. In conclusion, Vc positively affects the survival rate of P. monodon after transportation and temporary cultivation and alleviates the stress of P. monodon. The amount of Vc added at about 333mg/Lin, the transportation of P. monodon could play a positive role. The experimental results provide primary data for the transportation of P. monodon.

Doublesex (Dsx) is a polymorphic transcription factor of the DMRTs family, which is involved in male sex trait development and controls sexual dimorphism at different developmental stages in arthropods. However, the transcriptional regulation of the Dsx gene is largely unknown in decapods. In this study, we reported the cDNA sequence of PmDsx in Penaeus monodon, which encodes a 257 amino acid polypeptide. It shared many similarities with Dsx homologs and has a close relationship in the phylogeny of different species. We demonstrated that the expression of the male sex differentiation gene Dsx was predominantly expressed in the P. monodon testis, and that PmDsx dsRNA injection significantly decreased the expression of the insulin-like androgenic gland hormone (IAG) and male sex-determining gene while increasing the expression of the female sex-determining gene. We also identified a 5′-flanking region of PmIAG that had two potential cis-regulatory elements (CREs) for the PmDsx transcription. Further, the dual-luciferase reporter analysis and truncated mutagenesis revealed that PmDsx overexpression significantly promoted the transcriptional activity of the PmIAG promoter via a specific CRE. These results suggest that PmDsx is engaged in male reproductive development and positively regulates the transcription of the PmIAG by specifically binding upstream of the promoter of the PmIAG. It provides a theoretical basis for exploring the sexual regulation pathway and evolutionary dynamics of Dmrt family genes in P. monodon.

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