| Based on nine inbreeding generations of full-sib families Portunus trituberculatus for experimental material, using the single factor analysis of variance(One- Way ANOVA), least significant difference(LSD), multiple comparison analysis, analysis of covariance and monadic linear regression analysis, we compared the female parents’ reproductive performance,these filial generations’ growth,survival and yield of nine inbreeding generations and hybridization experiment groups. So as to quantify the effects of inbreeding on some economic characters such as reproductive performance,growth,survival and related to the survival of some economic characters such as yield of domesticated Portunus trituberculatus evaluate,and the influence of immune and antioxidant capacity between different inbreeding experiment family. The main results were as follows:1. The influence of inbreeding on the swimming crab, Portunus trituberculatus, breeding performance and growthAccording to our research of the effects on inbreeding Portunus trituberculatus, the conclusion was made. To make this assessment, we systematically bred nine generations of Portunus trituberculatus within same family(F1~F9). To reveal the influence of inbreeding on Portunus trituberculatus, and acquire result of breeding performance and growth, we assessed the breeding and growth with ANOVA statistical analysis on one direction. The experimental results show that, on yield, it’s not a linear relationship between each generation of F1~F9, and there is no obvious uptrend or downtrend during the experiment, but we found that the survival rate at each stage from zoeaⅠto megalopa of every generation is into a downward trend on the whole. Especially the survival rate of F9 inbreeding generation is the least in nine inbreeding generations: the survival rate of F9 from Z1-Z2 is 74.87%±13.18%, Z2-Z3 is 73.50%±14.77%, Z3-Z4 is 59.17%±13.58%,Z4-M is 41.96%±18.74%. In terms of morphology, there is not much morphological difference between each generation in the 80 days(P>0.05). And with the increase of age growth, the difference of each generation growth statistic data become significant gradually, with which the inbreeding generation and inbreeding degree are increasing. All of the F3~F9 inbreeding generation indices are lower than F1 and F2. Among these data, the statistic of F9 inbreeding generation is the lowest than other inbreeding generations and the difference between each generation is significant(P<0.05). However, at the harvest time, we analyzed uniformity, and then found the F9 has the least variation coefficient of all the genrations, the full carapace widths variation coefficient of F9 is 7.5444,the carapace widths variation coefficient is 7.6365, the carapace length variation coefficient is 7.5591, the body height variation coefficient is 8.3282 the body weight variation coefficient is 22.6644, which means the uniformity of F9 inbreeding generation is the best in nine inbreeding generations. All the experimental results of nine generation indicate there are several influence in different degrees on larval metamorphosis, the size of the individual form, and the growth characteristics at 150 days of age, and the results show inbreeding depression phenomenon. During the production season, compared with the F1 inbreeding generation by increase the inbreeding coefficient, except F2, the estimated inbreeding depression coefficient was-6.12% ~-21.95% in overall carapace width,-1.85% ~-16.36% in carapace width,-10.08% ~-27.66% in carapace length,-9.39% ~-22.7% in body height,-13.39% ~-47.99% in body weight,-9.03% ~-45.13% in the egg production, and the inbreeding depression coefficient of body weight and egg production is higher than other indices. These results suggest that inbreeding should be avoided in crab breeding programs. We should have a purpose in a planned way selective breeding. Only in that way can we improve the Portunus trituberculatus economical benefit extremely on genetic.2. Comparison of immune responses and antioxidant status of individuals with different body weight in Portunus trituberculatusVibrio alginolyticus is a virulent pathogen that affects crab aquaculture. The immune and antioxidant systems can protect the host against foreign microorganisms. In the present study, the immune responses and antioxidant status of Portunus trituberculatus with different body weight to V. alginolyticus challenge were studies. Results showed that total haemocyte count(THC), phagocytic rate, pro-phenoloxidase(proPO) and phenoloxidase of BIs were higher than the SIs after 72 h V. alginolyticus challenge. Antioxidant status showed a similar pattern: total antioxidant capacity, superoxide dismutase(SOD) activity and GSH/GSSG in the cell-free haemolymph and hepatopancreas have a body-dependent manner(P<0.05). There were no significant differences in α2-macroglobulin, antibacterial and bacteriolytic activities in the cell-free haemolymph and glutathione peroxidase activity in the cell-free haemolymph and hepatopancreas. Gene expression levels of proPO and crustin in haemocytes and SOD in haemocytes and hepatopancreas wer also increased significantly as the body weight increased. The results suggest that compared with the BIs, the SIs posses higher resistance to V. alginolyticus infection.3. Comparison of immune responses and antioxidant status of different generations of growth-selected Portunus trituberculatus familiesThe purpose of this study was to investigate the effects of inbreeding on the immune responses and antioxidant status of Portunus trituberculatus juveniles. Results showed that inbreeding affected the total haemocyte count, and phagocytic, pro-phenoloxidase(proPO), phenoloxidase and antibacterial activities decreased after the seventh generation. Antioxidant status showed a similar pattern: total antioxidant capacity, superoxide dismutase(SOD) activity and GSH/GSSG in the cell-free haemolymph and hepatopancreas decreased, while catalase activity in the cell-free haemolymph increased(P<0.05). There were no significant differences in α2-macroglobulin and bacteriolytic activities in the cell-free haemolymph and glutathione peroxidase activity in the cell-free haemolymph and hepatopancreas among nine inbreeding generations. Gene expression levels of proPO and crustin in haemocytes and SOD in haemocytes and hepatopancreas also decreased significantly as the inbreeding generations increased. The results suggest that a high level of inbreeding could severely reduce the physiological health of P. trituberculatus. Our obtained data would be particularly useful for P. trituberculatus breeding programs. |
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