Dataset Information

Molecular evolution of umami/sweet taste receptor genes in reptiles.

ABSTRACT: Sensory systems play an important role in animal survival. Changes to these systems may be critical in evolution of species in new environments. Previous studies exploring the correlation between feeding ecology and Tas1r evolution mainly focused on mammals and birds, and found that the relationship was complex. However, in reptiles, the correlation between Tas1r evolution and dietary preferences is still unclear. Here, we attempted to explore this relationship in representative species of the major groups of reptiles (turtles, snakes, lizards, crocodilians), for which the genome information is known. We first predicted the functionality (intact, partial, or defective) of Tas1r, and then related it to the feeding preferences. As a result, we identified 11 Tas1r1, 12 Tas1r2, and 12 Tas1r3 genes to be partial or intact and another 22 Tas1r genes to be absent or pseudogenized in the 19 reptiles. We found that, as it was revealed in some other vertebrate groups, no correlation existed between feeding ecology and Tas1r evolution in reptiles: genomic prediction indicated that the Tas1r genes possibly have been lost or pseudogenized in snakes, but in crocodylia and testudines Tas1r genes are either intact or partial, regardless of their feeding habits. Thus, we suggest that the driving force of Tas1r evolution in reptiles is complex, and the feeding habit of swallowing food whole without chewing or the absence of taste buds in certain species may account for the possible umami/sweet perception loss. In addition, we propose that caution should be taken when predicting gene functionality from the publicly available genome database.

SUBMITTER: Feng P

PROVIDER: S-EPMC6110252 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Molecular evolution of umami/sweet taste receptor genes in reptiles.

Feng Ping P Liang Shichu S

PeerJ 20180824

Sensory systems play an important role in animal survival. Changes to these systems may be critical in evolution of species in new environments. Previous studies exploring the correlation between feeding ecology and <i>Tas1r</i> evolution mainly focused on mammals and birds, and found that the relationship was complex. However, in reptiles, the correlation between <i>Tas1r</i> evolution and dietary preferences is still unclear. Here, we attempted to explore this relationship in representative sp ...[more]

PMID: 30155374

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Project description:BACKGROUND:Umami and sweet tastes are two important basic taste perceptions that allow animals to recognize diets with nutritious carbohydrates and proteins, respectively. Until recently, analyses of umami and sweet taste were performed on various domestic and wild animals. While most of these studies focused on the pseudogenization of taste genes, which occur mostly in carnivores and species with absolute feeding specialization, omnivores and herbivores were more or less neglected. Catarrhine primates are a group of herbivorous animals (feeding mostly on plants) with significant divergence in dietary preference, especially the specialized folivorous Colobinae. Here, we conducted the most comprehensive investigation to date of selection pressure on sweet and umami taste genes (TAS1Rs) in catarrhine primates to test whether specific adaptive evolution occurred during their diversification, in association with particular plant diets. RESULTS:We documented significant relaxation of selective constraints on sweet taste gene TAS1R2 in the ancestral branch of Colobinae, which might correlate with their unique ingestion and digestion of leaves. Additionally, we identified positive selection acting on Cercopithecidae lineages for the umami taste gene TAS1R1, on the Cercopithecinae and extant Colobinae and Hylobatidae lineages for TAS1R2, and on Macaca lineages for TAS1R3. Our research further identified several site mutations in Cercopithecidae, Colobinae and Pygathrix, which were detected by previous studies altering the sensitivity of receptors. The positively selected sites were located mostly on the extra-cellular region of TAS1Rs. Among these positively selected sites, two vital sites for TAS1R1 and four vital sites for TAS1R2 in extra-cellular region were identified as being responsible for the binding of certain sweet and umami taste molecules through molecular modelling and docking. CONCLUSIONS:Our results suggest that episodic and differentiated adaptive evolution of TAS1Rs pervasively occurred in catarrhine primates, most concentrated upon the extra-cellular region of TAS1Rs.

Dataset Information

Molecular evolution of umami/sweet taste receptor genes in reptiles.

Publications

Molecular evolution of umami/sweet taste receptor genes in reptiles.

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