The Transcriptomic Analysis Of Large Yellow Croaker During Embryo Development

L.crocea(Larimichthys crocea)is a China’s unique economic fish;it’s located in the head of the four major marine fishing fish.Although the breeding industry of L.crocea has been formed a complete system from artificial insemination to breeding,but the expression transformation for L.crocea during embryogenesis genes is still indistinct.Therefore,it is necessary to study the transcriptomeic analysis of various stages in the L.crocea’s embryonic development.In this study,the embryo of fertilized eggs in 0.5h,1 h,1.5h,2h,3h,7.5h,14.5h and 22h(corresponding to 1-cell,2-cell,8-cell,16-cell,256-cell,blastula stage,gastrula stage,pharyngeal sac stage)were collected,the total RNA was extracted to construct the c DNA Library.After quality inspection,Hi Seq2000 sequencing platform was used for deep sequencing.A total number of 53,004,265 reads were obtained;which 70.69%-73.46% of the read can be mapped into the genome.The principal component analysis(PCA)method and hierarchical clustering analysis were used and results showed that the 8 samples were clustered into two classes.The blastula stage and the stage before blastula stage gathered for a class while the glastula and the pharyngula stage gathered for another class.The gene expression between the blastula and gastrula embryos had greatly changed.28 couples were used to compare with each other,the biggest differences occurred between the glastula and the pharyngula stage consist with the sample analysis.We suspect that this was caused by the zygotic gene activation and the maternal factors degradation.Weighted gene co-expression network analysis was used and divided genes into 13 modules with gene expression analysis,KEGG analysis were did and 4 modules were significant enriched with specific expression genes.Through the analysis of the expression of maternal genes,we found that maternal factors involved in the regulation of a variety of events including embryonic development,cell cycle regulation,maternal gene degradation,zygotic gene initiation,differentiation,endoderm differentiation,and immune system development.After the analysis of amino acids,fatty acids,TCA and the oxidative phosphorylation related genes,we believe that embryos consumed less energy during the division,embryo firstly using the energy of amino acids and fatty acid metabolism.Then,energy consumption of embryonic differentiation in tricarboxylic acid cycle and oxidative phosphorylation were strengthened.Organogenesis related gene expression analysis showed that muscle tissue development were slightly later than eye development,which is different from what we observed that myomere earlier than eye development.The muscle of L.crocea in embryo may develop after the formation of 26 pairs of sarcomere began.In order to verify the accuracy of the transcriptomic results,quantitative real-time PCR was used to verify the expression changes of 16 significant genes.β-actin and GAPDH were selected as internal reference.The results were greatly matched with transcriptomic data.These results provide the comprehensive insights into the embryo development of L.crocea and it’s an important resource of molecules for searching development related genes and breeding work in the future.