Discovery of alternatively spliced isoforms and long non-coding RNA in full length brain transcriptomes of anadromous Hilsa shad, Tenualosa ilisha (Hamilton, 1822).

Background: Full length transcriptomes, achieved through long-read sequencing, along with the isoform analysis can reveal complexities in the gene expression profiles, as well as annotate the transcriptomes of non-model organisms.

Methods And Result: Full length transcripts of brain transcriptome of Tenualosa ilisha, Hilsa shad, were generated through PacBio single molecule real-time sequencing and were characterized. A total of 8.30 Gb clean reads were generated, with PacBio RSII, which resulted in 57,651 high quality consensus transcripts. After removing redundant reads, a total of 19,220 high-quality non-redundant transcripts and 17,341 full length ORF transcripts were classified to 7522 putative ortholog groups. Genes involved in various neural pathways were identified. In addition, isoform clusters and lncRNAs were discovered, along with Hilsa specific transcripts with coding frames and 29,147 SSRs in 944 transcripts (1141 annotated).

Conclusion: The present study provided, for the first time, a comprehensive view of the alternative isoforms of genes and transcriptome complexity in Hilsa shad brain and forms a rich resource for functional studies in brain of this anadromous fish.