| The Chinese mitten crab(Eriocheir sinensis)is one of the most commercially important aquaculture species in China.The colour is one of the major factors affecting nutritional quality of E.sinensis.The colour is largely dependent on the amount,type and isoform of carotenoids in the crustacean.This study firstly estimates the heritability,genetic and phenotypic correlation of colour-related traits and carotenoids,and the relationship between colour and carotenoids in the E.sinensis.Secondly,the comparison of the nutrition content,reproductive performance and offspring culture performance between purple and greenblack E.sinensis broodstock.Finally,the astaxanthin-binding protein(crustacyanin)was discussed the effect of colour regulation on the E.sinensis.These results can be used to provide theoretical and practical about colour and carotenoids for the nutritional quality selective breeding of E.sinensis.Mainly included the following contents:(1)Estimates of genetic parameters for colour and carotenoids traits in the Chinese mitten crab E.sinensisFirstly,estimates of genetic parameters for colour-related traits lightness(L*),redness(a*),yellowness(b*)and colour difference(dE*)in the carapace,hepatopancreas,and ovaries of E.sinensis.The parentage of the 678 individuals was identified from 25 fullsib families using 10 microsatellite markers.The colour parameters(L*,a*,b*,dE*)of the carapace,hepatopancreas,and ovaries had very low heritabilities,and the heritabilities of carapace colour L*,a*,b* and dE* were 0.05 ± 0.04,0.00 ± 0.03,0.00 ± 0.01 and 0.04 ± 0.03,respectively.The heritabilities of hepatopancreas colour L*,a*,b* and dE* were 0.00 ± 0.00,0.00 ± 0.00,0.00 ± 0.02 and 0.00 ± 0.03,respectively.The heritabilities of ovarian colour L*,a*,b* and dE* were 0.00 ± 0.02,0.09 ± 0.06,0.00 ± 0.04,and 0.00 ± 0.03,respectively.The genetic and phenotypic correlation between dE* and a* was strongest in cooked carapace.L* and b* had the strongest positive genetic and phenotypic correlation in the hepatopancreas,while dE* and b* had the strongest positive genetic and phenotypic correlation in the ovaries.Secondly,this study assessed the correlation between the carapace,hepatopancreas and ovarian colour of E.sinensis,and analyzed the correlation between ovarian colour and carotenoids content.The results showed that the carapace a* of female crab was significantly higher than that of the male crab.Despite carapace or hepatopancreas,the astaxanthin content of the female crab was significantly higher than that of the male crab.There was no significant correlation between the a* of female hepatopancreas and the L*,a*,b* and dE* of carapace,while the a* of male hepatopancreas was significantly negatively correlated with the b* and dE* of carapace.The a* of ovarian was significantly negatively correlated with the a* and dE* of hepatopancreas and carapace.Despite of female or male,the carapace a* was significantly correlated with total carotenoids and astaxanthin.There was significant correlation between the hepatopancreas a* and astaxanthin content in the hepatopancreas.The hepatopancreas b * was significantly correlated with β-carotene in the hepatopancreas.The ovarian a* was significantly positively correlated with total carotenoids,astaxanthin,lutein and canthaxanthin,and the b* was significantly associated with β-carotene in the ovarian.Finally,this study assesses heritability,genetic and phenotypic correlation of the carotenoids of 309 female crabs from 25 full-families in the E.sinensis.The results showed that the heritabilities of total carotenoids,astaxanthin,and zeaxanthin of carapace were 0.07 ± 0.06,0.08 ± 0.07,0.04 ± 0.06,respectively.The heritabilities of total carotenoids,astaxanthin,and β-carotene of hepatopancreas were 0.08 ± 0.12,0.06 ± 0.09,0.06 ± 0.20,respectively.The heritabilities of total carotenoids,astaxanthin,lutein,zeaxanthin,canthaxanthin and β-carotene of ovaries were 0.14 ± 0.08,0.11 ± 0.07,0.10 ± 0.07,0.09 ± 0.07,0.01 ± 0.04,and 0.10 ± 0.07,respectively.It was strongest in phenotypic and genetic correlation for the carapace and ovaries were between total carotenoids and astaxanthin,for the hepatopancreas were between total carotenoids and β-carotene.In conclusion,the heritabilities of colour and carotenoids in E.sinensis were very low.(2)Comparison of the broodstock carotenoids,reproductive performance,and culture performance of first generation between purple and greenblack E.sinensis.Firstly,this study was conducted to investigate colour parameters and nutritional composition between purple and greenblack crabs.Despite of female or male,the redness(a*)values of carapace,hepatopancreas,and ovaries of purple crabs were significantly higher than those of greenblack crabs.Generally,except for female hepatopancreas,purple crabs had the significantly higher contents of total astaxanthin and ester astaxanthin(P <0.05)in carapace,hepatopancreas and ovaries than those of the greenblack crabs.Despite of males or females,purple crabs had the higher ratios of ester astaxanthin/total astaxanthin in all tissues than greenblack crabs,but the differences were not significant.For hepatopancreas,purple crabs had the significantly higher contents of total carotenoids and β-carotene than greenblack crabs for males and females.For ovaries,purple crab also had the significantly higher contents of total carotenoids and lutein than greenblack crabs.Overall,the purple and greenblack E.sinensis had the similar fatty acids composition in hepatopancreas,gonads and muscle in gonads and muscle for both female and male.Interesting,female purple crabs had the significantly higher percentage of C20:5n3 and the ratio of n-3/n-6 PUFA ere in all edible parts than greenblack crabs,while male purple crabs had the significantly higher C20:4n6 levels in hepatopancreas and muscle than greenblack crabs.Secondly,this study was designed to determine and compare the reproductive performance,egg quality,colouration,proximate,fatty acid composition and carotenoids of purple and greenblack E.sinensis broodstock.The results showed that the survival rate of purple E.sinensis broodstock was higher than that of greenblack.The purple E.sinensis broodstock had the slightly higher percentage of females spawned,egg production,fecundity and reproductive effort than the greenblack females,but there was no significant differences between two treatments.The egg diameter,wet weight and dry weight of individual egg were similar between two treatments.The eggs from purple E.sinensis broodstock was significantly lower lutein contents than of the eggs produced by the greenblack broodstock,however,there are no significant differences for L*,a*,b*,dE*,total carotenoids,astaxanthin,zeaxanthin,canthaxanthin and β-carotene.There are no significant differences were found for the moisture,total protein and total lipids contents between the purple and greenblack treatments.The eggs from purple broodstock had the significant higher percentages of C20:4n6,and C22:5n3 than the eggs produced by the greenblack broodstock.Finally,the survival rate,weight gain rate(WGR),specific growth rate(SGR),size and colour of the purple and greenlack first generation were compared.The results showed that the average body weight,weight gain ratio,WGR and SGR of the purple population were significantly than greenblack population during nursery phase stage,while there was no significant difference for the survival rate.Despite female or male,the average body weight of the purple population was significantly higher than that of the greenblack population in September and October,and the purple had the significantly higher WGR and SGR than those of greenblack population during the periods June to August to September,however,there was no significant difference during the June to July and July to August.The survival rate of females in the purple population was significantly lower than that of the greenblack population,while there no significant difference in the male and pooled.There was no significant difference in the yield of juvenile between the purple and greenblack populations.The final mean weight of female juvenile purple was significantly higher than that of the greenblack population.As for the size distribution of juvenile crabs,the ratio of ranges of 8-11.99 g and 6-7.99 g of female purple were significantlu higher than those of greenblack female population,while the ratio of ranges of ≥ 12 g and 8-11.99 g of male purple were significantly higher than those of greenblack population.Despite female or male,the proportion of < 4 g of purple was significantly lower than that of greenblack population.The redness a* value of the purple broodstock was significantly higher than that of the green broodstock,but there was no significant difference in the shell colour of the juvenile between purple and greenblack populations.In conclusion,the culture performance of the first generation population of purple is better than those of the greenblack population,but there is no difference in the colour of the juvenile between the two groups.(3)Cloning and expression analysis of crustacyanin in the Chinese mitten crab E.sinensisThis study the function of crustacyanin(CRCN)in colour regulate and ovarian development.The full-length ORFs of three subtypes of CRCR-C1,CRCN-C2 and CRCN-A1 were cloned,which were 591 bp,579 bp and 594 bp,respectively.Sequence alignment revealed that the three CRCN genes,CRCN-C1,CRCN-C2 and CRCN-A1 have the conserved regions SCR-1,SCR-2,and SCR-3 in the lipocalin family.The mRNA expression levels of three genes in different tissues indicated that CRCN-C1 is mainly expressed in muscle,hepatopancreas and ovary.CRCN-C2 is mainly expressed in hepatopancreas,and CRCN-A1 is relatively high in epidermis.From I to V stage of ovarian development,the expression level of CRCN-C1 in hepatopancreas reached the highest level in stage IV,and the expression of CRCN-C2 was not significantly different at each stage and reached the lowest level in III,and the expression level of CRCN-A1 in I stage was significant higher than the II,III,IV stage.From I to V stage of ovarian development,there was no significant difference in the expression in the ovary of CRCNC1 in each stage,and the expression level of CRCN-C2 reached the highest level in III stage,and the expression level of CRCN-A1 was the lowest in III stage.(4)Comparison of reproductive performance and genetic diversity between wildcaught and pond-reared Chinese mitten crab E.sinensis from Yangtze populationThis study was designed to determine and compare the reproductive performance,egg quality,colouration,proximate and fatty acid composition of wild-caught and pondreared E.sinensis broodstock.The results showed that: the wild-caught E.sinensis broodstock had the slightly higher egg production,fecundity and reproductive effort than the pond-reared females,but there was no significant differences between two treatments.The egg diameter,wet weight and dry weight of individual egg were similar between two treatments.The eggs from pond-reared E.sinensis broodstock were significantly higher redness(a*),yellowness(b*)and total carotenoids contents than of the eggs produced by the wild-caught broodstock,however,there are no significant differences for lightness(L*)and colour difference(dE*).As for proximate composition of eggs,no significant differences were found for the moisture,total protein and total lipids contents between the wild-caught and pond-reared treatments.The eggs from wild-caught broodstock had the significant higher percentages of C18:1n9,C18:1n7,C20:4n6,C22:5n3 and C22:6n3 than the eggs produced by the pond-reared broodstock,but the C18:2n6 and C18:3n3 their eggs than the wild-caught broodstock.This study assesses the changes in genetic diversity in G3 and G0 generation of earlyand late-maturing strains of E.sinensis using 30 microsatellite markers with high polymorphism.The mean average number of alleles(N)in the founder population(G0)and third generation(G3)of the early-maturing strain were 18.367 and 16.533,respectively;while in late-maturing strain the values were 18.500 and 16.533,respectively.Likewise,there was a slight decline in average allelic richness(Rs).In both strains,the mean observed heterozygosity(Ho)remained relatively constant for the earlymaturing strain the values were 0.655 and 0.705,respectively;and for the late-maturing strain these were 0.665 and 0.702,respectively.There was a decrease in effective population sizes(Ne)of the early-maturing strain with successive generations: values were 492.2,and 193.2,respectively;while the values in the late-maturing strain were 1268.5,and 97.2,respectively.In conclusion,these results suggest that mass selection of E.sinensis did not significantly diminish genetic diversity,although there was a decline for the Ne. |
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