抄録
Bitter perception is mediated by G protein-coupled receptors TAS2Rs and plays an important role in avoiding toxins’ ingestion by inducing innate avoidance behavior in mammals. One of the best-studied TAS2Rs is TAS2R38, which mediates the perception of the bitterness of synthetic phenylthiocarbamide (PTC). In previous studies, we characterized the function of TAS2R38 in four allopatric species of Sulawesi macaques on Sulawesi Island from central to northern Sulawesi. We found variation in PTC taste perception both within and across species. In most cases, TAS2R38 was sensitive to PTC, with functional divergence among species. In the present study, we expand our samples to the south part of Sulawesi to determine whether this kind of divergence also exists in the South Sulawesi macaque species. We predict that some of the TAS2R38 in South Sulawesi macaques will have a different genetic background compared to the North Sulawesi macaques. We characterized the TAS2R38 of three Macaca species of Southern Sulawesi; M. maurus, M ochreata and M. brunnescens. We did experimental behavior on 12 individuals of M. maurus, 4 individuals of M. ochreata and 6 individuals of M. brunnescens, and found that 4 M. maura and 1 M. ochreata individuals cannot detect the bitterness of 2mM PTC, and thus called PTC-non-sensitive. Nucleotide sequence analysis revealed that the TAS2R38s are intact in all individuals of M.maurus and M. brunnescens. Three PTC non-sensitive individuals of M. maurus possessed TAS2R38 with intraspecific amino acid substitution at position 123 (R123C), while another individual possessed TAS2R38 with amino acid substitutions at positions 117, 130, and 134, which also exist in some individuals of M. tonkeana from central Sulawesi. We confirmed the PTC-non-sensitive of the TAS2R38 by functional assay. PTC non-sensitive individuals of M. ochreata lost two nucleotides at positions 505 and 506, resulting in a truncated protein. These results imply that there are also functional divergences of TAS2R38 in the southern species of Sulawesi macaques. Functional diversity of TAS2R38 might act as an adaptation to the local environment.
