Abstract: To explore a suitable live holding method for soft-shell mud crabs (Scylla paramamosain), enzymatic assays and polymerase chain reaction (PCR) were employed to compare the effects of different live holding conditions, namely, room temperature (25 ℃, control), low-temperature sweater (14 ℃, LT), ice storage (ICE), and low-temperature acidified seawater (14 ℃, pH 7.6; LTA), on crab shell hardening and physiological responses. The results showed that both ICE and LTA delayed crab shell hardening, with shells remaining at a “soft-paper” stage 48 h after molting. All three live holding methods down-regulated the relative expression of pfk and pepck in the hepatopancreas, with LTA being the most effective, followed by ICE and LT. ICE and LTA treatment reduced glucose levels in the hemolymph, with ICE having a more pronounced effect. All three methods led to an initial decrease followed by an increase in lactate dehydrogenase activity in the hemolymph. ICE promoted the accumulation of triglycerides (TG) in the hemolymph to the greatest extent, while all three methods reduced TG levels in the hepatopancreas. Additionally, at different time points, all live holding methods significantly modulated key gene expression in the hepatopancreas: they down-regulated acox1 and acc, up-regulated hsp70 and hsp90, and initially up-regulated and then down-regulated cpt1 and fas. Moreover, they increased total cholesterol and cortisol accumulation in the hepatopancreas and/or hemolymph, with ICE and LTA having greater effects than LT. ICE and LTA reduced fluctuations in malondialdehyde (MDA) levels in the hepatopancreas. However, all three methods enhanced the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as glutathione levels, with ICE having the most pronounced effect, followed by LTA and LT. LTA increased the total antioxidant capacity (T-AOC) in the hepatopancreas more rapidly than LT, while ICE decreased T-AOC levels. All three methods also down-regulated the relative expression of p53 and bcl-2, with ICE having the greatest effect on p53 and LTA having the greatest effect on bcl-2. In conclusion, ICE and LTA are more suitable for the live holding of soft-shell crabs.

Key words: Scylla paramamosain; soft-shell crab; live holding; shell hardening