Comparative genomics of the sheep Tas2r repertoire to cattle, goat, human, dog, and mice

Authors: HENSLEE, DILLAN - University Of Idaho; MURDOCK, BRENDA - University Of Idaho; YELICH, JOEL - University Of Idaho; ELLISON, MELINDA - University Of Idaho; Taylor, Joshua - Bret

Submitted to: Animal Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2020
Publication Date: 10/22/2020
Citation: Henslee, D., Murdock, B., Yelich, J., Ellison, M., Taylor, J.B. 2020. Comparative genomics of the sheep Tas2r repertoire to cattle, goat, human, dog, and mice. Animal Gene. 17-18. Article 200107. https://doi.org/10.1016/j.angen.2020.200107.
DOI: https://doi.org/10.1016/j.angen.2020.200107

Interpretive Summary: Livestock herbivores (e.g., sheep, cattle, goats) depend on a variety of taste receptors to identify and select preferred plants. Of the five taste senses, bitterness is the most sensitive of the taste senses in sheep and cattle. The type-two taste receptors (Tas2r) are the only known receptors that can sense bitterness. Other researchers have suggested that Tas2r gene expression can help predict dietary preferences of an individual. However, before extensive Tas2r genetic studies can be undertaken on grazing animals, these genes must first be identified and described in the species of interest. Accordingly, we set out to compared the genetic make-up of the Tas2r gene complexes in sheep, cattle, goat, human, dog, and mice. Based on our results, whole Tas2r gene complexes for the three herbivore species suggested that goat and cattle are similar to sheep. Further research is needed to better understand how Tas2r genes may influence diet selection in livestock herbivore species, which could provide more insight into targeted grazing management of rangelands.

Technical Abstract: Type two taste receptors (Tas2r) are the only taste receptors that distinguish bitter-tasting compounds. Human Tas2r genes have been extensively studied and associated with dietary preferences, health, substance dependence, and other diseases. Sheep are an important livestock species known for grazing vast rangelands with variable ecology and plant communities. However, limited work related to Tas2r gene repertoires in the reference genomes of grazing animals creates a challenge for understanding how these genes influence diet selection preferences. Tas2r genes typically cluster on two regions of the genome. In the second cluster of the sheep (OAR_rambouillet_1.0), goat (ARS1), and cattle (ARS-UCD1.2) reference genomes, there are six, nine, and two Tas2r genes that were not annotated, respectively. Comparative genomic strategies were used to cross-reference sheep Tas2r genes with cattle, goat, human, dog, and mice for the proposed annotations. A nucleotide similarity comparison of the whole Tas2r repertoires for the three grazing species suggested that goat and cattle are similar to sheep (' 95.5% and ' 91.9% similarity, respectively). Several Tas2r genes found in sheep, cattle, and goat are likely not found in human, dog, and mice, which may be genes reserved to ruminants or animals of similar feeding ecology. Using a comparative genomics approach, this paper proposes annotations for sheep, cattle, and goat Tas2r genes. Further research is needed to better understand how Tas2r genes may influence diet selection in grazing ruminant species, which could provide more insight into management of western rangelands through sheep grazing strategies.