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Hemocyanins are large extracellular respiratory proteins distributed within the hemolymph of arthropods, molluscs and larval stages of certain insects. In the present study, we characterized the humoral immune functions of cation specific antibacterial hemocyanin (Ab-Hcy) from mud crab, S. serrata . The bacteriolytic activity of Ab-Hcy was against pathogenic and non-pathogenic to crustaceans which includes, Bacillus sp. N1, B. flexus N3, E. coli , P. aeruginosa , V. harveyi , V. parahaemolyticus and V. vulnificus and also expressed bacteriostatic activity against E. coli , B. flexus N3 and V. harveyi . The agglutination activity of Ab-Hcy ranged from 4-16 against B. flexus N3, E. coli , V. harveyi and V. vulnificus and Ab-Hcy also agglutinated with rat and human O erythrocytes (HA titer: 2). The Ab-Hcy lysed the panel of mammalian erythrocytes and strong hemolytic activity of 1.40, 1.28 and 1.22 units·min − 1 ·mg protein − 1 against human A, B and O erythrocytes respectively. It was also found that the Ab-Hcy possess phenoloxidase (PO) activity by oxidizing L-DOPA. These results suggest that Ab-Hcy from the serum of mud crab, S. serrata , is capable of performing multiple humoral immune functions in addition to oxygen transportation. Statement of relevance This manuscript deals with the humoral immune functions, particularly antibacterial property of hemocyanin in crustacean. In this paper we report the different type of antibacterial activity and other humoral immune functions of a hemocyanin isolated from the serum of mud crab, Scylla serrata . This work will help to understand the role of respiratory molecule in immune system, also will be helpful improve disease free crustacean aquaculture industry. And we also state this research work is relevant and suitable to publish in the Journal “Aquaculture”. [ABSTRACT FROM AUTHOR]

As an important step toward development of a formulated diet for hatchery culture of the mud crab, Scylla serrata, this paper reports on laboratory experiments to assess the potential of a microbound diet (MBD) as a replacement for Artemia nauplii fed to megalopal larvae of S. serrata. The effects of different proportions of dietary MBD and Artemia on survival and moulting success of megalopa to the crab stage were investigated. In the first experiment, megalopae were reared communally and fed either 100% MBD, 100% Artemia or different combinations of the two (75%:25%, 50%:50%, 25%:75%). The experiment was terminated when all larvae had either metamorphosed or died. Larvae fed a combination of 25% MBD and 75% Artemia consistently showed the highest survival among all treatments throughout the experiment. Survival of larvae fed 100% MBD was the lowest early in the experiment but improved to become the second highest toward the end of the culture period. Overall survival of larvae fed 100% MBD did not differ significantly from that of larvae fed 100% Artemia. Moulting to the crab stage began on day 7 for larvae in the treatment receiving a 50%:50% combination of MBD and Artemia. On day 8, all larvae in treatments receiving greater than 25% MBD had some first stage crabs. Larvae fed Artemia only were the last to moult to the juvenile crab stage, but moulting occurred simultaneously on day 10. Because of cannibalism observed in the first experiment, a second experiment was conducted where megalopae were reared individually and fed either 100% Artemia or 100% MBD. Ninety percent of larvae from both treatments successfully moulted to the crab stage. Again, megalopae fed MBD began moulting 1 day ahead of those fed Artemia. The results of these studies show that the MBD used contained all necessary nutrients to sustain successful moulting of S. serrata megalopae to the crab stage. The acceptability of MBD by S. serrata larvae suggests significant potential for using the MBD in future experiments to investigate larval nutritional requirements of this commercially important crab species. Indeed, the more rapid moulting of larvae fed MBD in both experiments suggests that the MBD may have contained certain beneficial nutrients that were not provided by Artemia alone. The fact that no significant differences in survival between megalopae fed 100% MBD and those fed 100% Artemia in both communal and individual rearing experiments suggests that total replacement of Artemia with MBD is possible for S. serrata megalopae. This could result in substantial savings in operating costs for S. serrata hatcheries. [Copyright &y& Elsevier]

This paper reports on experiments to determine particle size preference and optimal ration for the various larval stages of the mud crab, Scylla serrata, fed microbound diets (MBD). All experiments used 14C-labelled rotifers as components of MBD, and ingestion was determined by assessing the 14C content of S. serrata larvae after feeding on the MBD. Five size ranges of MBD (<150, 150–250, 250–400, 400–600 and 600–800 μm) were used to assess ingestion by Zoea I, Zoea III, Zoea V and Megalopa. All were fed a ration equivalent to twice the equivalent dry weight of live foods provided to each larval stage under standard rearing conditions (standard ration). MBD particle size preference increased with increasing larval development. Highest ingestion rates by Zoea I, Zoea III, Zoea V and Megalopa were found for particle size ranges of <150, 150–250, 250–400 and 400–600 μm, respectively. MBD within these particle size ranges were used in subsequent experiments to assessed optimum rations for each of the four larval stages. Larvae were fed rations based on multiples or fractions of the standard ration (100%): 12.5%, 25%, 50%, 100%, 200% and 300%. There were no significant increases in ingestion, for any of the four larval stages, when ration was increased above 100%. For Zoea I, Zoea III and Zoea V larvae, there was no significant difference in the rate of MBD ingestion when ration was reduced to 50%; however, a 25% ration brought about a significant decrease in ingestion. There was no significant decrease in the rate of ingestion by Megalopa when ration was reduced from 100% to either 50%, 25% or 12.5%. The results suggest that rations currently used for larval rearing of S. serrata may be excessive. Little is currently known of the feeding behaviour and nutritional requirements of S. serrata larvae, and the results of this study are a significant development in this field. [Copyright &y& Elsevier]