Mapping of expressed sequence tags from a porcine early embryonic cDNA library

Summary The goal of this study was to identify and map genes expressed during the elongationphase of embryogenesis in swine. Expressed sequence tags were analysed from a pre-viously described porcine cDNA library prepared from elongating swine embryos.Average insert length of randomly selected clones was approximately 600 bp, with arange from 2500 bp. Single-pass, coding strand sequences from 1132independent clones were compared with the GenBank non-redundant (nr) database viaBLASTN analysis to identify potential porcine homologous of known genes. Amongthese sequences, 781 (69%) showed significant (score >300) homology to non-mitochondrial sequences previously deposited in GenBank. Sequences matchinginterleucin 1 b and thymosin b 10 were most frequently observed (24 and 18 clones,respectively), in addition to matches with 310 other distinct genes. No significantmatch in the GenBank nr database was obtained for 303 sequences. Analysis dem-onstrated that 151 (50%) had open reading frames (ORF) extending at least 50 codonsfrom the first base of the clone insert. Genetic markers were developed and used to mapa subset of 17 genes, selected on the basis of function or of the ability to design primersthat successfully amplified porcine genomic DNA, to 10 different porcine chromo-somes, providing a set of mapped markers corresponding to genes expressed duringconceptus elongation.Keywords expressed sequence tag, mapping, porcine blastocyst.