Analysis And Evaluation The Candidate Strain Of Anti-vibriosis Of Portunus Trituberculatus

Portunus trituberculatus has became one of the most popular seafood for its delicioustaste, which has large market demand in china and advantaged in marine products export.However, due to the over fishing and water pollution, the natural resource of Portunustrituberculatus is close to the level of exhaustion. For this reason, the industry of artificialculturing got rapidly development. In recent years, artificial rearing faced disease problemespecially the emulsified muscle disease caused by Vibrio alginolyticus which has causedmass mortality of Portunus trituberculatus. The characteristics of the emulsified muscledisease are quick onset and short course of disease. Many people were accustomed to useantibiotics to prevent and treat vibriosis, it caused environmental pollution, drug residue andquality loses of Portunus trituberculatus. Therefore, the effective way to eradicate thisphenomenon is to improve autoimmunity of Portunus trituberculatus.Firstly, we used V. alginolyticus as antigen to infect Portunus trituberculatus to acquirefine varieties according to resistance avoiding the negative impacts of using drugs. And thenthis V. alginolyticus-resistant Portunus trituberculatus strain had been breeding continuousmulti-generation, that the crabs we used in this paper were the5th generation. Meanwhile, weused the single basket breeding technology. According to the national standard GB20556-2006of Portunus trituberculatus, we evaluated various indexes such as morphological features,molting cycle, molecular genetic characteristics, fertility and immune index betweenenhanced and normal crabs.â… .Germplasm analysis of the V. alginolyticus-resistant Portunus trituberculatus strainsWe measured the adult individual morphological indexes from strain crabs andcommon crabs respectively. The results indicated that the strain crabs put up growthdisadvantage in9morphological indexes. The results of one-way ANOVA and Coefficient ofvariation showed that4morphological indexes had significant difference, but the differencenot reached subspecies level.Using single basket breeding technology, we tracked crabs after C6molting cycle.Compared two groups of crabs in the same breeding condition, and recorded the molting cycle and wet weight. We found th at there were some differen ces in morphological indexesbetween the two groups after C9, and the differences b ecame obviously alo ng with moltingcycle.The biochemical variation anal ysis of isoenzymes from different organs used thediscontinuous polyacrylamide gel vertical electrophoresis. The results showed not significantdifference.Amplified and sequenced the16S rRNA gene of two groups, we got564bp nucleotidesequences. There are11Polymorphic loci in new strains, and only one variable site in normalcrabs by compared those two sequences to markers (GB20556-2006)16S rRNA genes.We measured the reproductive capacity of strain crabs and common crabs respectively.The results showed significantly difference.(P<0.05) And this index was in proportion to thesize of parent crabs.â…¡.Evaluation the candidate strain of anti-vibriosis of Portunus trituberculatus.The results of V. alginolyticus infection test between two groups of crabs showed thesurvival rate of new strains was63.3%and normal group was15%.The POD and ACP enzyme activity and hemocyanin content in new strains weresignificantly higher then normal crabs, but ALP and T-SOD activity showed contrary results(P<0.05) in biochemical tests.