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De novo transcriptomic analysis of gonad of Strongylocentrotus nudus and gene discovery for biosynthesis of polyunsaturated fatty acids

Wei, Zhenlin, Liu, Xiaolin, Zhou, Zunchun, Xu, Junxiao
Genes & genomics 2019 v.41 no.5 pp. 583-597
Strongylocentrotus nudus, biosynthesis, databases, enzymes, females, lipid metabolism, males, messenger RNA, polyunsaturated fatty acids, transcriptomics, unigenes
BACKGROUND: Strongylocentrotus nudus is an important cultured sea urchin species in north China, because its gonad is rich in unsaturated fatty acids, particularly long polyunsaturated fatty acids (LC-PUFAs). These PUFAs play pleiotropic and crucial roles in a wide range of biological process. OBJECTIVE: However, the genes contributing to biosynthesis PUFAs have not been elucidated yet, and the molecular mechanism relative to the difference in PUFA composition between male and female gonad as been revealed but the corresponding has not been understood. METHODS: In this paper, solexa sequencing based transcriptomic approach was used to identify and characterize the key genes relative to PUFA synthesis and further conducted different expressed genes between male and female gonad. RESULTS: A total of 130,124 transcripts and 189330 unigenes were de novo assembled from 64.32 Gb data. Next, these unigenes were subjected to functional annotation by mapping to six public databases, and this process revealed a lot of genes involving in lipid metabolism. In addition, three types of fatty acids front-end desaturase and three species of very long fatty acids elongase were identified and the pathway for PUFA biosynthesis was hypothesized. Last, comparative analysis revealed the higher expression level of Δ5 desaturase, Δ6 desaturase, ELOVL-4, -6 and -7 in male gonad compared with female. CONCLUSION: This results could plausible explain the differ in composition of PUFAs between male and female gonad of sea urchin.