Annual Report 2003

Fig. 2Dot-plot analysis on the region including TRDJ-TRDC-TRAJ-TRAC between human and swine. Whole structureof this region was highly conserved within mammals.Fig. 3Comparison of J segments between humans and swine.Joining segments on the same location have higher similarity.An efficient EST-mapping method usinga BAC libraryYuji Yasukochi, Kotaro Baba, Kazuei MitaGenome Research DepartmentFig. 1Increase in the number of mapped BACs, BAC contigs and ESTs during thepast year.Recently, sequence information on silkwormESTs is accumulating rapidly and itsutilization of this information for linkageanalysis is essential to construction of adense expression map. PCR-based methodsare commonly used for linkage analysis ofsmall animals like insects due to the relativelylow yield of genomic DNA from oneindividual. However, it is difficult to designadequate PCR primers from cDNA sequenceswithout prior knowledge about the locationof exon-intron junctions. In addition, errorsfrequently occur during single path sequencingof ESTs. Therefore, we attempted toidentify BAC clones harboring ESTs andmap the clones instead of ESTs directly.First, in-situ hybridization was performedusing high-density replica filters dotted with18,432 BACs. More than 3,000 EST cloneswere used as probes. Positive clones wereidentified from 1,487 hybridizations excludingresults derived from multi-copy sequences,and sorted into 943 putative contigs. In addition,PCR screening for BAC libraries wasalso performed using DNA markers, andBAC contigs containing 1733 BACs (7.53% of4 Annual Report 2003