| Pacific oyster Crassostrea gigas, has been an important species in the field of marine shellfish farming world-widely. In China, with the natural priority, such as the long coastline and broad area of shallow flats, the oyster farming industry has developed rapidly in recent ten years. In addition, the booming phenomenon wouldn’t come without the support of national policy and the endeavor of all crews in relevant. At present, the oyster industry has made a series of remarkable achievements, which contributes a lot to the development of the marine fishery.However, with the expanding scale of oyster production, some unfavorable factors appeared, As a result, Oyster industry began to suffer the impact of these disadvantages. Mainly due to the over-reliance on unimproved wild stocks, which would be the parents of many individuals farmed currently, a range of issues came out with the inbreeding and the loss of diversity after several generations of reproduction. These problems were reflected by slow growth, high mortality, poor meat quality and so on. At present, in order to improve the current situation, a lot of essential measures need to carry out. That is to say, breeding new varieties of C. gigas with advantages of rapid growth and high meat quality should be given more attention other than the culture environment as well as the cultivation technology.In this experiment on Pacific oyster(C. gigas), we established the fundamental stocks of C. gigas derived from Yantai Kongtong Island in 2013. Targeting the rapid growth of shell width, successive 3 generations of selective breeding program were implemented utilizing the method of mass selection from 2013 to 2015, which resulted in the setup of F1, F2, F3 selective lines. Meanwhile, three genetic parameters which contained the realized heritability, the selection response, and the genetic gains were estimated. Moreover, the genetic structure of the base stock and three successive mass selection lines of C. gigas were also analysed by examining the genetic variation by taking advantage of micro-satellite loci. Finally, in terms of the bright prospect of Near Infrared spectroscopy(Near Infrared, NIR) in the field of shellfish breeding, we attempted to establish NIR model on the essential amino acids exist in C. gigas, which could realize the rapid composition analysis of the oyster meat. The main conclusions and results are as follows:1 The estimate of genetic parameters of three mass selective populations of C.gigas for fast growth of the shell width.In the first generation, for the selected stocks of C. gigas in Yantai Kongtong island, the average Response to selection was 0.491 ± 0.26, and the average Realized heritability was 0.330 ± 0.131, respectively. In the second generation, for the selected stocks of C. gigas, the average Response to selection was 0.604 ± 0.24, and the average Realized heritability was 0.396 ± 0.135, respectively. Additionally, in the third generation, the average Response to selection was 0.764 ± 0.27, and the average Realized heritability was 0.471 ± 0.133, respectively. The mean increase in shell width for the selection stocks was 7.95~12.1% over the control groups after three generations of selection.2. The assessment of genetic structure in mass selection stocks of the Pacific oyster utilizing microsatellitesThe result indicates that all microsatellite loci in four stocks have shown a high polymorphism, as testified by large numbers of alleles per locus( NF0 = 16.5; NF1 = 12.2; NF2 = 12.8; NF3 = 10.7), and high levels of Polymorphism information content( Pic(F0) = 0. 9068, Pic(F1) = 0.8982, Pic(F2) = 0.8836, Pic(F3) = 0.8789). Observed heterozygosity values(Ho) of 10 loci were smaller than expected heterozygosity values(He) in all populations( He = 0.8897 ~ 0.9297, Ho = 0.5775 ~ 0.6484). Among all population-locus cases( 4 populations × 10 loci). 32 cases deviated from Hardy-Weinberg equilibrium( P< 0.05). Fis values ranged from 0.154 to 0.234, resulting in heterozygote deficiencies at the ten loci in each population. As for Fst values, it ranged from 0.0089 to 0.0245, which showed weak genetic differentiation between each two populations3 The establishment of NIR models for the quantitative analysis of essential amino acids on dry meat sampleIn the process of building model on essential amino acids, Parameters of Calibration were as followed, the Rcal2 = 0.9545, RMSEcal = 0.998, RPDcal = 4.34, as of Cross-Validation, Rcv2 =0.9227, RMSEcv =1.313, RPDcv = 4.40.Data above revealed that it could provide a rapid and accurate method for the analysis of the essential amino acids model. |
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