| Myxocyprinus asiaticus belongs to Catostomidae,C ypriniformes.It is a kind of endemic species of fish in C hina.Due to destruction of habitats and overfishing,this fish population have been dec lined dramatically.Thus,it was defined as a class II protected species in China.We studied that genetic diversity of cultured population and monitored the variation of the genetic resources of the Myxocyprinus asiaticus based on microsatellite marker,aimed at providing scientific guidance for artificial breeding by selecting fine germplasm resources.Meanwhile,we analyzed the fatty acid of different growth stages based on physiological and biochemical techniques,and it could provide theoretical basis for configuration of farming feed reasonably.The main results as follows:1.The genetic diversity and genetic structure of the subgroups of the three M.asiaticus breeding bases in C hongqing Wanzhou,Jiangxi Yongfeng and Jiangxi Xingan,China,were studied by using 13 microsatellite markers.The results showed that 13 microsatellite loci were polymorp hic,the number of allele was 8~17,the observed heterozygosity ranged from 0.1081~0.8255 with an average observed heterozygosity of 0.6378 and the content of polymorphic information was 0.35~0.84,with an average polymorphic information content was 0.74.In addition,Shannon diversity index,observed heterozygosity,expected heterozygosity and Hardy-weinberg genetic deviation index were 0.35~0.84,1.61~1.64,0.1081~0.8255,0.3846~0.8568,0.7189~0.0725,respectively.At the same time,the results indicated that three cultured population had higher genetic diversity.2.The polymorphism information content of the three cultivated populations were : Xingan 0.73,C hongqing 0.69 and Yongfeng 0.62,all of which were highly polymorphic and rich in genetic diversity.According to the analysis of genetic similarity index,we found that the genetic distance of Yongfeng and C hongqing was close,while far away between C hongqing and Xingan.The average genetic differentiation coefficient among the three cultured populations was 0.075,which existed moderate genetic differentiation.The mean gene flow among populations was 4.9825,indicating that the gene exchange was sufficient,while the Structure analysis showed that there were genetic differentiation among the three populations,indicating that the gene exchange did not restrict the genetic differentiation among the geographic populations.3.There were 30 kinds of fatty acids with 10 kinds of saturated fatty acids and 20 kinds of unsaturated fatty acids,including 9 kinds of monounsaturated fatty acids and 11 kinds of polyunsaturated fatty acids.There was no difference in composition.4.After comparison of fatty acid of muscles of cultured population and field collection,it showed that the total amount of saturated fatty acids and monounsaturated fatty acids of M.asiaticus that collected in field was significantly lower than that of cultured population.For monounsaturated fatty acids of M.asiaticus,the content of C18:1ω9 of cultured population was higher than those collected in field,while for those which collected in field,the C16:1 was the main one.And the polyunsaturated fatty acid of M.asiaticus that collected in field was significant higher than cultured population,Σω3/Σω6(field samples)>1>Σω3/Σω6(cultured samples).Due to plant oil instead of other animal bait such as fish oil to feed M.asiaticus,which provided higher ω6,the ω9 unsaturated fatty acids showed accumulation while it suggested that ω3 of cultured population was insufficient,which showed that the ω3 fatty acids should be added to the bait so as to the M.asiaticus population which was used for artificial release was closer with those in the field.5.According to the analysis of fatty acid markers,the potential food resources of the M.asiaticus were phytoplankton> vascular plants> bacteria> zooplankton.Compared with three different sites(Taihe,Xiajiang,Suichuan),the fatty acid content of M.asiaticus was found to be different,and the content of 15 fatty acids was different varied with habitat environment.The green algae-main contributors to essential fatty acid of M.asiaticus were the highest levels of in Taihe.For unsaturated fatty acids,the marker fatty acids of Euglenophyta algae-C18: 3ω6 might have important physiological and biochemical effects in fish development.6.In the embryonic development stage of M.asiaticus,for the fatty acids in the eggs and larvae were saturated fatty acids> monounsaturated fatty acids> polyunsaturated fatty acids,which were different from other growth stages.The C16: 0 might be the main supple ment relative C18:0,C16: 0 might be the main contributor,the single unsaturated fatty acid C18: 1 might be the main supplement.The activity of C20: 6ω3(DHA)was significantly higher than that of C20: 5ω3(EPA),and the metabolic activity of ω6 series was higher than that of ω3 series after larvae stage. |
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