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

The goal of this study was to identify and map genes expressed during the e longation phase of embryogenesis in swine. Expressed sequence tags were ana lysed from a previously described porcine cDNA library prepared from elonga ting swine embryos. Average insert length of randomly selected clones was a pproximately 600 bp, with a range from <100 to >2500 bp, Single-pass, codin g strand sequences from 1132 independent clones were compared with the GenB ank non-redundant (nr) database via BLASTN analysis to identify potential p orcine homologous of known genes. Among these sequences, 781 (69%) showed s ignificant (score >300) homology to nonmitochondrial sequences previously d eposited in GenBank. Sequences matching interleucin 1 beta and thymosin bet a 10 were most frequently observed (24 and 18 clones, respectively), in add ition to matches with 310 other distinct genes, No significant match in the GenBank nr database was obtained for 303 sequences. Analysis demonstrated that 151 (50%) had open reading frames (ORF) extending at least 50 codons f rom the first base of the clone insert. Genetic markers were developed and used to map a subset of 17 genes, selected on the basis of function or of t he ability to design primers that successfully amplified porcine genomic DN A, to 10 different porcine chromosomes, providing a set of mapped markers c orresponding to genes expressed during conceptus elongation.