Abstract
The taste receptor gene family has been extensively studied in human and some genes have been linked to food preferences and addiction; however, research in foraging ruminants is limited. Identification of taste receptor genes in the sheep genome may provide insight regarding individual dietary range plant preferences. Bitter taste has been a large focus of research since Arthur Fox accidentally discovered the bitter tasting compound phenylthiocarbamide (PTC) and observed that bitter taste perception in humans is a variable trait. In theory, individuals who are sensitive to bitter taste will likely consume less bitter tasting foods, which are often antioxidant rich, and be more prone to disease and illness. The objective of this study was to examine known taste receptor genes in sheep and cattle and compare them with humans to determine similarities and differences. Type 2 taste receptors (T2R’s) are the only receptor of the taste gene family to perceive bitterness in foods. Using NCBI genome data viewer, the taste genes were identified on the human (GRCh38.p12), cattle (ARS-UCD1.2), and sheep (Oar_4.0; OORI1) genomes. All 3 species have one T2R gene cluster in common, which includes T2R genes 3, 4, 5, 38, 39, 40, 60, and 41. The span of this cluster is similar for humans (1,457,940 bp), sheep (1,541,593 bp), and cattle (1,594,610 bp). One gene in particular (T2R38) has been associated with PTC sensitivity and linked to aversion of some bitter tasting food in humans. Previous research on T2R38 identified 5 haplotypes, each expressing aversion to bitter taste differently. There is another T2R gene cluster which contains 10 annotated genes in sheep and cattle genomes; however, this region contains an additional 10 genes annotated in the human genome. Understanding genetic variation in TAS2R genes may translate to dietary preferences of sheep grazing on rangelands.