Lowered sensitivity of bitter taste receptors to β-glucosides in bamboo lemurs: an instance of parallel and adaptive functional decline in TAS2R16?

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 288; no. 1948; p. 20210346
• Main Authors: Itoigawa, Akihiro, Fierro, Fabrizio, Chaney, Morgan E, Lauterbur, M Elise, Hayakawa, Takashi, Tosi, Anthony J, Niv, Masha Y, Imai, Hiroo
• Format: Journal Article
• Language: English
• Published: England The Royal Society 14.04.2021
• Subjects: Evolution; lemur; cyanide; glucosides; bitter taste receptor; homoplasy; molecular adaptation
• ISSN: 0962-8452; 1471-2954
• DOI: 10.1098/rspb.2021.0346

Bitter taste facilitates the detection of potentially harmful substances and is perceived via bitter taste receptors (TAS2Rs) expressed on the tongue and oral cavity in vertebrates. In primates, TAS2R16 specifically recognizes β-glucosides, which are important in cyanogenic plants' use of cyanide as a feeding deterrent. In this study, we performed cell-based functional assays for investigating the sensitivity of TAS2R16 to β-glucosides in three species of bamboo lemurs ( and ), which primarily consume high-cyanide bamboo. TAS2R16 receptors from bamboo lemurs had lower sensitivity to β-glucosides, including cyanogenic glucosides, than that of the closely related ring-tailed lemur ( ). Ancestral reconstructions of TAS2R16 for the bamboo-lemur last common ancestor (LCA) and that of the LCA showed an intermediate sensitivity to β-glucosides between that of the ring-tailed lemurs and bamboo lemurs. Mutagenetic analyses revealed that and had separate species specific substitutions that led to reduced sensitivity. These results indicate that low sensitivity to β-glucosides at the cellular level-a potentially adaptive trait for feeding on cyanogenic bamboo-evolved independently after the - split in each species.