Transcriptome Analysis of the <em>Octopus vulgaris</em> Central Nervous System

<div><h3>Background</h3><p>Cephalopoda are a class of Mollusca species found in all the world's oceans. They are an important model organism in neurobiology. Unfortunately, the lack of neuronal molecular sequences, such as ESTs, transcriptomic or genomic information, has limited the development of molecular neurobiology research in this unique model organism.</p> <h3>Results</h3><p>With high-throughput Illumina Solexa sequencing technology, we have generated 59,859 high quality sequences from 12,918,391 paired-end reads. Using BLASTx/BLASTn, 12,227 contigs have blast hits in the Swissprot, NR protein database and NT nucleotide database with E-value cutoff 1e⁻⁵. The comparison between the <em>Octopus vulgaris</em> central nervous system (CNS) library and the <em>Aplysia californica</em>/<em>Lymnaea stagnalis</em> CNS ESTs library yielded 5.93%/13.45% of <em>O. vulgaris</em> sequences with significant matches (1e⁻⁵) using BLASTn/tBLASTx. Meanwhile the hit percentage of the recently published <em>Schistocerca gregaria</em>, <em>Tilapia</em> or <em>Hirudo medicinalis</em> CNS library to the <em>O. vulgaris</em> CNS library is 21.03%–46.19%. We constructed the Phylogenetic tree using two genes related to CNS function, Synaptotagmin-7 and Synaptophysin. Lastly, we demonstrated that <em>O. vulgaris</em> may have a vertebrate-like Blood-Brain Barrier based on bioinformatic analysis.</p> <h3>Conclusion</h3><p>This study provides a mass of molecular information that will contribute to further molecular biology research on <em>O. vulgaris</em>. In our presentation of the first CNS transcriptome analysis of <em>O. vulgaris</em>, we hope to accelerate the study of functional molecular neurobiology and comparative evolutionary biology.</p>