No abstract

Taste receptor family 1 member 3, TAS1R3, is shown to be involved in sweet and umami tastes in mouse, and the nucleotide sequence of the gene has been reported in rat, gorilla, and human. Pigs are frequently used as models for human diseases, and are also considered to be source animals for xenotransplantation to humans due to their anatomical and physiological similarities to humans. Therefore, in the present study, the genomic structure of the swine TAS1R3 gene was determined, and TAS1R3 expression was studied in various swine tissues. The gene was shown to reside on swine chromosome 6q22→q23, from which three types of mRNAs were generated: 3,752 bp derived from six exons in tongue, 3,704 bp from six exons and 3,630 bp from seven exons in testis. The 6 exons/5 introns were structurally similar to those of humans and mice, but the 7 exons/6 introns structure of TAS1R3 was first observed in swine. High expressions of TAS1R3 were revealed in tongue, kidney, and testis by real-time PCR. The expression profile of the tissues except for kidney was similar to that of mouse. When in situ hybridization using an RNA probe for TAS1R3 was performed on swine tongue and testis tissues, TAS1R3 expressions were revealed in tongue circumvallate papillae, fungiform papillae, mucosal epithelium, follicular B lymphocytes, lymphocytes in submucosal tissues of lingual tonsil, and spermatogenic cells. Using peripheral mature B lymphocytes, the expression of TAS1R3 in B lymphocytes was further confirmed by real-time PCR and sequencing of the real-time PCR product.

A swine resource family was constructed at the National Institute of Animal Industry, Japan, in order to determine the genetic regions responsible for economically important traits, including fetus development. To identify genes expressed in the early stage of embryo development, we cataloged and mapped genes expressed in a 28-day-old normal pig embryo. In this effort, we have mapped 64 genes, which have map information in human genome onto a swine radiation hybrid (RH) map, IMpRH. These mappings provided additional chromosomal homologies between swine and human to improve the comparative map between the two species. The distribution of the genes assigned to swine chromosomes are as follows: 9 genes were assigned on SSC6; 6 genes each assigned on SSC5 and SSC14; 5 genes each assigned on SSC3, SSC4, and SSC8; 4 genes each assigned on SSC1, SSC7, SSC9, and SSC15; 3 genes each assigned on SSC2, SSC13 and SSCX; and 1 gene each assigned on SSC10, SSC11, and SSC16. Moreover, the present findings revealed 18 new chromosomal homologies between pig and human. Briefly, SSC3 regions were indicated to correspond with HSA1 and HSA10; SSC4 with HSA6; SSC5 with HSA2, HSA15, and HSA16; SSC6 with HSA3, HSA6, and HSA20; SSC7 with HSA11; SSC8 with HSA3, HSA6, and HSA7; SSC9 with HSA8; SSC13 with HSA1; SSC14 with HSA13; SSC15 with HSA19; SSC16 with HSA9.