Effect Of Three Algal Baits On The Sea Urchin Strongylocentrotus Intermedius Growth,Gonadal Quality And Chondroitin Sulfate Accumulation

The sea urchin Strongylocentrotus intermedius,whose gonads have good color and delicious taste,is one of the highest valuable of sea urchin economic species.This species was originally produced in Hokkaido and other regions in Japan.It was introduced to China by Dalian Fisheries College in 1989.At present,it has become an important economic type of seawater aquaculture in China and has high commercial value.Because suitable for feeding sea urchin algae bait-Saccharina japonica and Undaria pinnatifida,its availability period is mainly in December to July of the next year,the rest of the time is the shortage of sea urchin algae bait period.Therefore,finding suitable bait for sea urchin breeding in the algal shortage period has become one of the problems to be solved in the sea urchin breeding industry.Chondroitin sulfate synthase(CSS)is the key enzyme catalyzing the synthesis of chondroitin sulfate(CS),which plays an important role in the physiological effects of viral infection,anti-inflammatory response,tumor treatment and prevention.In order to study the biological function and expression rules of chondroitin sulfate synthase gene in the sea urchin S.intermedius under different algal feeding conditions,the c DNA of chondroitin sulfate synthase gene(named Si CSS)was cloned for the first time,analyzed the sequence characteristics of the gene,the expression of Si CSS in different tissues of the sea urchin S.intermedius was determined by fluorescence quantitative PCR(q PCR),and the relative expression of Si CSS in the sea urchin S.intermedius gonads under different algal feeding conditions.Meanwhile,CSS activities and CS contents in S.intermedius gonads under different conditions were detected by ELISA.In order to further enrich the basic data of the biological function of CSS genes,and provide certain reference materials for comprehensively mastering the molecular expression and regulation rules of sea urchins under different algal bait conditions.The main study findings obtained in this study are as follows:1.Effect of different algal baits on sea urchin S.intermedius feeding and growth.The average daily feeding rate of the sea urchin S.intermedius changed from high to low is Gracilaria lemaneiformis feeding group,Saccharina japonica feeding group and Ulva pertusa feeding group.The shell diameter,shell diameter growth rate,body weight and body weight specific growth rate are Saccharina japonica feeding group,Ulva pertusa feeding group and Gracilaria lemaneiformis feeding group.The shell height of sea urchin from high to low is Ulva pertusa feeding group,Saccharina japonica feeding group and Gracilaria lemaneiformis feeding group.The intestinal index and mouth index of sea urchin,when the short time feeding group,the Saccharina japonica feeding group is higher than the other two groups,when the Gracilaria lemaneiformis and Ulva pertusa feeding group is higher than the Saccharina japonica feeding group.The shell index of the Saccharina japonica feeding group was higher than that of the other two feeding groups.2.Effect of different algal baits on gonad development in the sea urchin S.intermedius.With the increase of feeding time,the gonad index of Saccharina japonica feeding group and Gracilaria lemaneiformis feeding group did not change significantly,but the Ulva pertusa feeding group increased first and then decreased.The average gonadal index of the sea urchin Strongylocentrotus intermedius changed from high to low is the Saccharina japonica feeding group,Ulva pertusa feeding group and Gracilaria lemaneiformis feeding group.In the aspect of gonadal color,the gonadal quality of the Gracilaria lemaneiformis feeding group was better than that of the Saccharina japonica feeding group and the Ulva pertusa feeding group.3.Sequence characteristics and expression pattern of Si CSS and the effects of different algal baits on CSS activities and CS contents.The full length c DNA of Si CSS is 4914 bpwith a 2304 bp open reading frame(ORF)the 5’-UTR and 3’-UTR of Si CSS are 98 bp and 2512 bp,respectively.The predicted relative molecular weight of Si CSS was 88.37 k Da with an isoelectric point(p I)was 7.87.Further bioinformatics analyses indicated that Si CSS is a transmembrane,mild and hydrophobic protein without signal peptide.The Si CSS sequence contains the Fringe domain(107-273 aa)and the chondroitin N-acetylgalactosylaminotransferase(CHGN)domain(251-750 aa).Homology analysis revealed that the amino acid sequence of Si CSS had the highest similarity(99.87%)with the CSS sequence of S.purpuratus.The results of tissue expression pattern analysis showed that Si CSS was expressed in all examined tissues of S.intermedius.Its relative expression from low to high is: intestinal <tube foot <gonad <perioral membrane <interdental muscle.The relative expression of Si CSS genes in S.intermedius gonads was highest in the Saccharina japonica feeding group and there was no significant difference between the Gracilaria lemaneiformis feeding group and Ulva pertusa feeding groups.The chondroitin sulfate content and chondroitin sulfate synthase viability in the sea urchin Strongylocentrotus intermedius gonads were lowest in the Gracilaria lemaneiformis feeding group,and there was no significant difference in the Saccharina japonica and Ulva pertusa feeding groups.