Five Novel Taste Receptor Genes Identified

The sense of taste, a crucial aspect of identifying beneficial foods and avoiding harmful substances, has been a focus of much research to understand the origins and evolution of taste receptors. In a new study, a team led by Associate Professor Hidenori Nishihara from Kindai University and Professor Yoshiro Ishimaru from Meiji University, Japan, has identified five new groups within the taste receptor family, challenging previous assumptions and offering insights into the evolutionary history of taste receptors.

Published in Nature Ecology & Evolution, the study conducted a genome-wide survey of jawed vertebrates, encompassing major fish groups. The researchers discovered novel taste receptor genes, named TAS1R4, TAS1R5, TAS1R6, TAS1R7, and TAS1R8, expanding the known repertoire of taste receptors. Contrary to the traditional belief that only three T1R family members have been retained during evolution, the study revealed that the vertebrate ancestor possessed more T1Rs.

The distribution of these newly identified genes among species with a common ancestor provided valuable insights. TAS1R4, for instance, was found in lizards, axolotl, lungfishes, coelacanth, bichir, and cartilaginous fishes but absent in mammals, birds, crocodilians, turtles, and teleost fishes. The researchers observed close evolutionary relationships between TAS1R5, TAS1R1, and TAS1R2, indicating shared ancestry. TAS1R6 was exclusively present in cartilaginous fishes, originating from the same ancestral gene as TAS1R1, TAS1R2, and TAS1R5. TAS1R7 and TAS1R8 were identified in specific species, showcasing their origin in the common ancestor of jawed vertebrates.

Additionally, the study uncovered diversity in existing TAS1R genes, challenging conventional ideas. TAS1R3 of bony vertebrates, for example, was divided into TAS1R3A and TAS1R3B. The findings also suggested that the first TAS1R gene appeared around 615–473 million years ago in jawed vertebrates, undergoing duplications to produce nine taste receptor genes in the common ancestor of bony vertebrates.

Beyond enriching our understanding of evolutionary history, the research has practical applications. The newfound knowledge about taste preferences across diverse vertebrates could be applied to develop tailored pet foods and attractants for fish, amphibians, and reptiles, according to Professor Nishihara.