Analysis of a full-length cDNA library constructed from swine olfactory bulb for elucidation of expressed genes and their transcription initiation sites

The olfactory system is indispensable to the survival of animals in finding foods and for the reproductive process. Odorant signals are conveyed through olfactory sensory neurons to the olfactory bulb, which modifies the signals and relays them to the neocortex. In the present study, a "full-length" cDNA library was constructed from the main and accessory olfactory bulbs of 5-week-old male pigs, in order to elucidate the expressed genes. The average insert size of the library was estimated to be 1.7 kb based on 54 randomly-selected clones. One thousand randomly selected clones were subjected to sequencing, and the resulting 883 sequences were then clustered into 753 sequences based on similarity. Since 723 of the 753 sequences had sufficient sequence information for homology analysis, the 723 sequences were subjected to BLAST analysis against GenBank/EMBL/DDBJ; 655 out of the 723 sequences showed similarities with known genes, and the remaining 68 were indicated to be novel sequences. The full-length rate of the library was estimated to be ca. 80%, using 70 sequences corresponding to human full-length cDNAs. The full-length cDNA sequences of a single gene appearing more than 6 times in the analysis were aligned to determine major transcription initiation sites for SLC25A, CKB, TUBB4, TUBB, YWHAH, TUBB2, and CNP genes.