Transcriptome analysis of the central nervous system of the mollusc Lymnaea stagnalis
1 Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
2 Terrence Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario M5S 3E1, Canada
3 Department of Molecular & Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, The Netherlands
4 Department of Cell Physiology & Pharmacology, University of Leicester, Leicester LE1 9HN, UK
5 Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
6 Department of Biological Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
7 School of Pharmacy & Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK
8 Molecular Physiology, School of Medicine, and the Molecular Medicine Research Group, University of Western Sydney, NSW, Australia
9 Departments of Physiology & Biophysics and Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
10 Department of Physiology and Biophysics, Dalhousie University, Faculty of Medicine, Halifax, Nova Scotia B3H 1X5, Canada
11 Departments of Cell and Systems Biology and Ecology and Evolutionary Biology, Toronto, ON M5S 3G5, Canada
BMC Genomics 2009, 10:451 doi:10.1186/1471-2164-10-451Published: 23 September 2009
The freshwater snail Lymnaea stagnalis (L. stagnalis) has served as a successful model for studies in the field of Neuroscience. However, a serious drawback in the molecular analysis of the nervous system of L. stagnalis has been the lack of large-scale genomic or neuronal transcriptome information, thereby limiting the use of this unique model.
In this study, we report 7,712 distinct EST sequences (median length: 847 nucleotides) of a normalized L. stagnalis central nervous system (CNS) cDNA library, resulting in the largest collection of L. stagnalis neuronal transcriptome data currently available. Approximately 42% of the cDNAs can be translated into more than 100 consecutive amino acids, indicating the high quality of the library. The annotated sequences contribute 12% of the predicted transcriptome size of 20,000. Surprisingly, approximately 37% of the L. stagnalis sequences only have a tBLASTx hit in the EST library of another snail species Aplysia californica (A. californica) even using a low stringency e-value cutoff at 0.01. Using the same cutoff, approximately 67% of the cDNAs have a BLAST hit in the NCBI non-redundant protein and nucleotide sequence databases (nr and nt), suggesting that one third of the sequences may be unique to L. stagnalis. Finally, using the same cutoff (0.01), more than half of the cDNA sequences (54%) do not have a hit in nematode, fruitfly or human genome data, suggesting that the L. stagnalis transcriptome is significantly different from these species as well. The cDNA sequences are enriched in the following gene ontology functional categories: protein binding, hydrolase, transferase, and catalytic enzymes.
This study provides novel molecular insights into the transcriptome of an important molluscan model organism. Our findings will contribute to functional analyses in neurobiology, and comparative evolutionary biology. The L. stagnalis CNS EST database is available at http://www.Lymnaea.org/ webcite.