Effects Of Sodium Alginate And Chitosan On The Immune Response Of Chinese Mitten Crab Eriocheir Sinensis

Sodium alginate is one kind of natural polysaccharide extracted from algal cell wall, it is linear macromolecule in substance.Chitosan is one kind of linear macromolecule polysaccharides'ramification own amidogens that deacetylation derivative of chitin. It is the only one kind of alkalescence polysaccharides in nature. Recent researches demonstrate that sodium alginate and chitosan are efficiency immunopotentiator for shrimp. They can significant enhance immune response and resistance of shrimp by injection or dietary. But there is no report of deeply researches about these two polysaccharides affect immune response and resistance of Chinese mitten crab.Crab were coelom injected with 10,30,90 mg and dietary with 0.2,1.0,5.0 g sodium alginate kg?1 crab weight in the first experiment; Crab were coelom injected with 2,6,18 mg and dietary with 0.2,1.0,5.0 g chitosan kg?1 crab weight in the second experiment. Crab were injected with 0.1mL saline or dietary with basic diet regard as controls.The total haemocyte count (THC), different haemocyte count (DHC), the haemocyte phagocytic activity, respiratory burst (release of superoxide anion), the total phenoloxidase(POT)in haemocyte lysate supernatant (HLS), phenoloxidase (PO), lysozyme (LSZ), acid phosphatase (ACP), alkaline phosphatase (ALP), superoxide dismutase (SOD),peroxidase (POD) activity in the serum were examined at 0, 1, 3, 5, and 8 days after coelom injection of polysaccharide and examined at 1, 3, 5 and 7 weeks after 7-days dietary. Crab were challenged at 1.2×107 colony forming units (cfu)/kg crab weight with a virulent strain of Aeromonas hydrophila (CL99920) of E. sinensis at the second sampling time, and mortalities were recorded over a 10-day period. The results showed that the THC, GC and HC, the phagocytic activities, POT and respiratory burst of haemocytes, the PO, LSZ, ACP, ALP, SOD, POD in serum of E. sinensis were significant higher than those of the control group and saline control group (P<0.05). Furthermore, the crabs administered with sodium alginate or chitosan were the more resistant. It was concluded that sodium alginate or chitosan could enhance the non-specific immune response and resistance to A. hydrophila of E. sinensis.