Responses Of Different Varieties(Family Strains) Of Apostichopus Japonicus Adaptation To Environmental Factors And Vibrio Splendidus Stress

Apostichopus japonicus,has high edible and medicinal value.The aquaculture of Apostichopus japonicus in China has developed rapidly after entering this century.However,the Apostichopus japonicus industry is affected by diseases with rotten skin syndrome(the main bacterial pathogen is Vibrio splendidus)as an important epidemic disease,the lack of improved varieties and the change of breeding environment,which limits the sustainable development of the industry.In this study,the new variety of"Shenyou No.1","Qingqing No.1",Sino Russian orthogonal strain and Sino Russian reciprocal cross strain were taken as the research objects,and the important environmental factors such as temperature and salinity were selected as variable parameters to determine the growth and survival,respiratory metabolic intensity,immune enzyme activity and to explore the adaptability of different varieties(family strains)of Apostichopus japonicus to typical environmental factors under the stress of Vibrio splendidus,and analyze its adaptation mechanism.The main results are as follows:1.The ecological adaptability of different varieties(family strains)of Apostichopus japonicus in response to temperature changes under the stress of Vibrio splendidusIn this study,temperature control group(22℃,24℃,26℃,27℃,29℃)and temperature infection group(at each temperature were set 1×10~5CFU/m L Vibrio splendidus infection)to explore the adaptability difference of different selected varieties(family strains)of Apostichopus japonicus in response to temperature change under Vibrio splendidus stress,determine the temperature tolerance threshold of different selected varieties(family strains),and elaborate its adaptation mechanism.The results showed that different varieties(family strains)of Apostichopus japonicus had different adaptability to temperature changes under the stress of Vibrio splendidus,.According to the experimental growth results of four kinds of Apostichopus japonicus,the nonlinear regression equation of SGR under temperature change is obtained,and the temperature when SGR is 0 is taken as the maximum growth temperature.The maximum growth temperature of Apostichopus japonicus"Shenyou No.1","Qingqing No.1",Sino Russian orthogonal strains and Sino Russian reciprocal cross strains were 24.8℃、24.1℃、24.7℃and 23.8℃respectively.Under the stress of Vibrio splendidus,the increase of temperature will reduce the survival rate and SGR of four varieties(family strains)of Apostichopus japonicus.At 29℃,the survival rate and SGR of"Shenyou No.1"were 74.44%and-2.639%/d respectively,and the survival rate and SGR of Sino Russian cross strains Apostichopus japonicus were 62.22%and-3.707%/d respectively(P<0.05).The results of respiratory metabolism showed that under the stress of Vibrio splendidus,"Shenyou No.1"and"Qingqing No.1"had the highest oxygen consumption rate at 27℃,and the two Sino Russian hybrid strains had the highest oxygen consumption rate at 29℃.The temperature change under the stress of Vibrio splendidus had little effect on the O:N of the four varieties(family strains)of Apostichopus japonicus,all less than 10.Under the stress of Vibrio splendidus,the SOD and LZM of four kinds of Apostichopus japonicus were less affected by temperature;The ACP activity of Chinese Russian cross strainss of Apostichopus japonicus decreased significantly at 29℃(P<0.05),and the other three Apostichopus japonicus decreased significantly at 24℃(P<0.05);The AKP activity of"Shenyou No.1"and the anti cross strains between China and Russia decreased,and the AKP of the other two species of Apostichopus japonicus changed little.The increase of temperature under the stress of Vibrio splendidus could lead to the decrease of digestive enzyme activities of four kinds of Apostichopus japonicus.The trypsin activities of"Shenyou No.1"and"Qingqing No.1"of Apostichopus japonicus decreased significantly at 26℃(P<0.05),and the trypsin activities of two Sino Russian hybrid strains decreased significantly at 24℃(P<0.05);At the same temperature,the amylase activity of Sino Russian hybrid strainss was lower than that of the other two species of Apostichopus japonicus.Under the stress of Vibrio splendidus,Bacteroidetes,Firmicutes and Prevotella in the intestine of Apostichopus japonicus"Shenyou No.1"The proportion of 9 genera and faecalis increased,and the proportion of Proteus decreased,which was significantly different from the other three species of Apostichopus japonicus(P<0.05).The results showed that the increase of temperature under the stress of Vibrio splendidus could reduce the activity of non-specific immune enzymes,digestive enzymes and change the structure of intestinal flora,so as to inhibit the growth and survival of four varieties(family strains)of Apostichopus japonicus.2.The ecological adaptability of different varieties(family strains)of Apostichopus japonicus in response to salinity changes under the stress of Vibrio splendidus.In this study,salinity group(20,24,28,32,36)and salinity infection group(at each salinity were set 1×10~5CFU/m L Vibrio splendidus infection)to determine the growth and survival,respiratory metabolic intensity,nonspecific immune enzyme activity,digestive enzyme activity and intestinal flora structure of different selected varieties(family strains)of Apostichopus japonicus in response to salinity changes under Vibrio splendidus stress,determine the appropriate salinity range of different selected varieties(family strains),and elaborate their adaptive mechanism.The results showed that different varieties(family strains)of Apostichopus japonicus had different adaptability to salinity and Vibrio splendidus stress.According to the experimental growth results of four kinds of Apostichopus japonicus,the nonlinear regression equation of SGR under salinity change is obtained,and the salinity at the highest SGR is taken as the optimal growth salinity.The optimum growth salinity of Apostichopus japonicus"Shenyou No.1"is 24～36,and the optimum growth salinity is 32.3;The optimum growth salinity of Apostichopus japonicus"Qingqing No.1"is 20～36,and the optimum growth salinity is 30.6;The suitable growth salinity of Sino Russian orthogonal strains is 20～36,and the optimum growth salinity is 30.6;The suitable growth salinity of Chinese and Russian reverse cross strains is 24～36,and the optimum growth salinity is 31.3.At 20 salinity,the survival rates of"Shenyou No.1","Qingqing No.1",Sino Russian orthogonal strains and Sino Russian reciprocal cross strains were 87%,88%,88%and 68%respectively,and the SGR were-0.206%/D,-0.316%/D,-0.328%/D and-0.522%/D respectively.The survival rate and SGR of Sino Russian reverse cross were significantly lower than those of the other three kinds of Apostichopus japonicus(P<0.05).Under salinity stress,the growth of other species of Apostichopus japonicus increased significantly(P<0.05).Under the stress of Vibrio splendidus,the respiratory metabolic intensity of four varieties(family strains)of Apostichopus japonicus was lower at salinity 32,28,28 and 32 respectively.Under the stress of Vibrio splendidus,the O:N ratios of"Shenyou No.1","Qingqing No.1"and Sino Russian orthogonal strains were less than 10,and the Sino Russian reciprocal cross strains were less than 10 at salinity 28～36.Under the stress of Vibrio splendidus,the ACP,AKP and LZM activities of four varieties(family strains)of Apostichopus japonicus increased first,then decreased and then increased with the increase of salinity,and the SOD activity showed an inverted"V"change.The SOD activity of the four kinds of Apostichopus japonicus reached the highest value at salinity 32,28,28 and 32,respectively.Under the stress of Vibrio splendidus,the trypsin and amylase activities of four varieties(family strains)of Apostichopus japonicus increased first and then decreased with the increase of salinity.Under the same salinity,the digestive enzyme activities of the two Sino Russian hybrid strains were lower than those of the other two Apostichopus japonicus.Under the stress of Vibrio splendidus,the intestinal flora structure of the four kinds of Apostichopus japonicus had no significant change at low salinity,while the abundance and diversity of the intestinal flora of the four kinds of Apostichopus japonicus decreased and the flora structure changed greatly at high salinity.Among them,the proportion of intestinal Lactobacillus of Apostichopus japonicus"Shenyou No.1","Qingqing No.1"and Sino Russian orthogonal strains decreased and uncultured＿bacterium＿f＿Rhodobacteraceae increased significantly(P<0.05).It was found that the salinity change under the stress of Vibrio splendidus could affect the growth and survival of four varieties(family strains)of Apostichopus japonicus by affecting the activity of non-specific immune enzymes,digestive enzymes and the structure of intestinal flora."Qingqing 1"has good adaptability in response to salinity change and Vibrio splendidus stress;"Shenyou 1"has strong adaptability to Vibrio splendidus infection and poor adaptability to low salinity;The Chinese and Russian orthogonal strains had strong adaptability to salinity changes,but poor adaptability to Vibrio splendidus infection;Chinese and Russian reverse cross strains showed poor adaptability in response to salinity changes and Vibrio splendidus infection.In general,Apostichopus japonicus"Shenyou 1"has strong adaptability to temperature change and Vibrio splendidus infection,but weak adaptability to low salinity;"Qingqing 1"has good adaptability in response to salinity and temperature changes,and its adaptability to resist Vibrio splendidus infection at high temperature is weak;The Chinese and Russian orthogonal strains had strong adaptability to the changes of salinity and temperature,and poor adaptability to the infection of Vibrio splendidus;The Chinese and Russian anti cross strains had weak adaptability to salinity,temperature changes and Vibrio splendidus infection.The research results can provide a theoretical basis for scientifically guiding the layout of improved variety breeding and improving the contribution rate of improved variety production.