Characterization of an Atlantic cod (Gadus morhua) embryonic stem cell cDNA library

We sequenced 3,935 EST clones using a directional cDNA library made from pooled ES cells harvested at the blastula stage. Quality filtering of these ESTs allowed identification of 2,719 high-quality sequences with an average length of 442 bp containing 368 contigs and 1,276 singletons (1,644 unique sequences). BLASTX searches produced 889 significant (E-value < 10-3) hits, of which 698 (42.5%) were annotated with Gene Ontology terms (E-value < 10-6). The number of unknown unique sequences was 946 (57.5%). All the high-quality EST sequences have been deposited in GenBank (GenBank: 2,719 sequences in UniGene library dbEST id: 22,021). Gene discovery and annotations are presented and discussed.This set of ESTs represents one of the first attempts to describe mRNA in ES cells from a marine cold-water fish species, and provides a basis for gene expression studies of Atlantic cod ES cells.Embryonic stem (ES) cells in culture and their development into different lineages is a unique model system that provide means to identify extracellular factors that influence embryonic cell differentiation and proliferation. ES cells are unique in their capacity to self-renew and to differentiate into multiple cell types. During differentiation, specific transcription factors activate the expression of genes that are required for each cell lineage. In addition, epigenetic regulation also appears to be a key mechanism for maintaining pluripotency and determining lineage specification [1]. ES and embryoid bodies (partly differentiated cells) can be utilized to identify and characterize factors or genes including nutrients, growth factors and hormones that may affect cell proliferation, lineage differentiation and the expression of specific genes and proteins during developmental differentiation. In fish, mRNA in oocytes and early blastocyte embryos are thought to be exclusively of maternal origin; expression of embryonic genes occurs later, at the late-blastula or gastrula stage, the exac