| The yesso scallop Patinopecten yessoensis is a cold-water species distributed in the northwest Pacific Ocean and is cultured commercially in Japan, Korea, and China using suspended longline aquaculture and bottom sowing culture. Bottom sowing culture can achieve higher breeding efficiency because of no need of additional breeding buoyancy. The sea raching around Zhangzidao Island is the most important area for yesso scallop bottom sowing culture. In 2008, the bottom sowing area of yesso scallops has reached 80 thousand hectares, now the permitted area of sea ranching reached 3.22 million mu. But with the development of bottom sowing culture, some new problems, such as lower ratio of recapture and smaller individual harvest sizes, have constantly emerged and seriously inhabited the bottom sowing industry development in Zhangzidao island. Since 2011, the shell yield has been stable at around 80 kg/mu and difficult to be improved. In this study, we focused on the correlation among seasonal variation of physiological, nutritional component and relative gene expression level to performance traits, trying to construct the accurate method for assessing bottom sowing efficiency on field and laboratory levels and explore the key environmental factors affecting bottom sowing aquaculture of yesso scallops. Depending on the immunology and transcriptomics research, we try to illuminate the yesso scallops’ response to heat shock and corresponding molecular mechanism. At last, a large scale yesso scallops families were instructed to select the species suitable for being bottom sown with the help of simulation experiments of bottom sowing aquaculture. We believe our research will provide useful references for the yesso scallop bottom sowing industry.1. The correlation models among performance traits and environmental factors, immunity and metabolism enzymes activities and corresponding relative expressionFrom December 2012 to December 2014, the investigation was conducted in 4 sitese located in yesso scallops’ bottom sowing ranching with the help of No. 19 research vessel affiliate to Zhangzidao Group Co., Ltd.. Through the investigation, we found bottom sowed yesso scallops’ growth rate(shell length and total tissue weight) from December to the next June was significantly higher than that from June to December. The linear regression analysis showed that environmental factors such as temperature, dissolved oxygen content(DO), chlorophyll content, suspended particulate matter(SPM) and particulate organic matter(POM) seriously affect the bottom sowed yesso scallops’ performance traits such as growth rate(shell length and total tissue weight), mortality rate, gonad index(GI), condition factor(CF). Biochemical composition(glycogen content), metabolism and antioxidant enzymes [glutamic-pyruvic transaminase(GPT), lactate dehydrogenase(LDH), superoxide dismutase enzyme(SOD) and total antioxidant capacity(TAOC)] and their relative expression also influenced the bottom sowed yesso scallops’ performance traits significantly. Through the above investigation and analysis, we suggest bottom sowing sites should be chosen in the area of low temperature to reduce mortality and improve the gonad index(GI), in the area of lower content of suspended particulate matter(SPM) region to increase growth rate(shell length and total tissue weight) and the gonad index(GI) and in the area of higher particulate organic matter(POM) content to improve the bottom sowed yesso scallops’ condition factor(CF).The immunity and metabolism enzymes and corresponding relative expression significantly related to performance traits were selected using linear regression analysis. The principal component analysis(PCA) were used to construct the models predicting the bottom sowed scallops’ performance traits based on the analysis of linear regression analysis. The models were further supplement for the traditional survey methods of yesso scallops’ performance traits. They also played a certain role in promoting the development of shellfish aquaculture. According to Pearson correlation analysis, the correlation between prediction models and the corresponding performance traits were significantly(P <0.05).2. Yesso scallops’ response to heat shock and corresponding molecular mechanismIn laboratory, the enzyme activity kits and RNAseq technology were used to explore the factors that cause the mortality of the scallops suffering from heat shock on the level of physiology and transcriptomics. The Cox model analysis showed that mortality resulting from heat shock was related to shellfish age, GPT activity, p53 content, TAOC activity and HSP70 content significantly(P < 0.05). GPT activity was negatively related to scallop mortality(B<0), while the other factors with scallop mortality was significantly positive correlation(B > 0). Besides, heat shock resulted in the reduction of heart rate and cardiac output, which implies the decreasion of oxygen supply capacity of the hemolymph for tissues, which resulted in the mortality of scallops. The transcriptome analysis showed that, the down-regulation of gene expression related to ATP synthesis resulted in the mortality of one-year elder yesso scallops after recovering for 24 h. The reasons for the two-year elder scallops included the following several factors. The gene related to ATP synthesis, the electron transfer and mismatch repair were down-regulated, which leaded to reducing the amount of ATP and increasing the amount of mismatched gene. Besides, during the recovery the oneyear elder scallops’ gene related to ribosome synthesis were up regulated. This upregulation perhaps reduced the one-year elder scallops mortality in a certain extent. These upper reasons explained the reasons for lower mortality of one-year elder scallops than that of two-year elder. For two-year elder scallops, the up-regulation of gene related to ribosome synthesis appeared in the period after recovering for 48 h, which will be one evidence for better recovery ability from heat shock in one-year elder scallops than two-year elder scallops.3. The genetics estimates of traits for bottom sowed yesso scallopsIn February 2013, 73 families of yesso scallops were bred in Zhangzidao group Co., Ltd., 35 families of these were chosen to be utilized in marked bottom sowing experiment. The comparation between the the same family’s survive of bottom sowed aquaculture and suspending longline aquaculture. The results showed that 10 families’ s survival rates were significantly higher in the s marked bottom sowed experiment. The genetic parameter estimation were processed with the help of AI-REML or QuasiREML method. The estimated breeding values(EBV) of every family and individual were calculated basing on the genetic parameter, while the comprehensive EBV were also calculated basing on the 30%:70% economic weight. At last, 21 families were chose as the parent of F2 bred in 2015. In 2015, 78 families were bred as F2 and 23 families were bred as control falimies with the parents chosen from bottom and suapending aquaculture industry of Zhangzidao Group Co., Ltd. The following exprements were conducted. |
PDF Full Text Request