De novo assembly and annotation of the whole transcriptome of Sepiella maindroni

As an important cephalopods species, Sepiella maindroni fishery has suffered a severe decline due to over-fishing since the 1980s. Stock enhancement has been applied to the resource recovery of this species, but a sexual precocity appeared in breeding process. In order to understand the regulatory mechanism of this phenomenon, we generated the whole transcriptome of S. maindroni based on the total RNA of tissue samples (eyestalk, peduncle, tentacle, gill, muscle and ovary) using Illumina RNA-seq technology. De novo assembly was performed using Trinity software and a total of 31,979,244 high-quality clean reads were randomly assembled to produce 74,245 contigs. All contigs were further assembled and clustered into 58,224 unigenes. Among the predictable unigenes, a total of 14,346 unigenes were annotated based on protein databases. We assessment the annotation completeness using BUSCO software package and the result showed that 91.5% protein-coding genes were found in our assembled transcripts. At last, we predicted the structure of all unigenes using TransDecoder software and MIcroSAtellite identification tool, respectively. Result showed that a total of 26,037 nucleotide sequences of coding regions (direction of the sequences is 5′ → 3′) were confirmed to the protein database and a total of 13,471 simple sequence repeats were identified. Our goal was to provide an important foundation for future genomic research on the cephalopod and further evaluate the effectiveness of stock enhancement.