<p>Bitter taste receptors may not only help animals avoid ingesting potentially harmful poisons or foods but also be key to their survival, new research suggests.<br /><br /></p>.<p>Professor Maik Behrens from the German Institute of Human Nutrition Potsdam-Rehbruecke and colleagues examined the genetic repertoire of bitter taste receptor genes in chickens and frogs, which represent two extremes.<br /><br />Chickens only have 3 bitter taste receptor genes (Tas2rs), while frogs have more than 50.<br /><br />They studied the different molecular properties of cloned Tas2r genes and measured their responses when exposed to a panel of 46 natural or synthetic bitter compounds.<br /><br />First, they constructed a gene tree for a selection of Tas2r genes of various vertebrate species and showed that all avian genes come from the same 3 ancestral genes.<br /><br />Frogs were found to have 5 ancestral genes, indicating that their expanded repertoire was due to later gene duplication events.<br /><br />They showed that all the three chicken Tas2rs are "broadly tuned" for bitter taste, whereas six frog Tas2rs tested are mixed consisting of broadly as well as narrowly tuned receptors.<br /><br />Interestingly, both chicken and frog receptor repertoires responded to about half of the compounds, showing that the tuning range rather the number of Tas2r genes was a critical factor, researchers said.<br /><br />In general, individual substances activated different receptors in clearly separated concentration ranges, which may also provide a clue to the role of bitter taste diversity in enhancing the chance of survival.<br /><br />The authors conclude that a low number of functional Tas2r genes found in chickens can be compensated by an increased average tuning width.<br /><br />They speculate that the environmental duality of amphibian life, living on both land and water, may account for the increased Tas2r gene diversity in frogs.<br /><br />In mixed aquatic and terrestrial environments amphibians such as frogs may have encountered a larger number of bitter compounds, causing the evolutionary pressure to provide a larger taste receptor repertoire. The findings appear in the journal Molecular Biology and Evolution.</p>
<p>Bitter taste receptors may not only help animals avoid ingesting potentially harmful poisons or foods but also be key to their survival, new research suggests.<br /><br /></p>.<p>Professor Maik Behrens from the German Institute of Human Nutrition Potsdam-Rehbruecke and colleagues examined the genetic repertoire of bitter taste receptor genes in chickens and frogs, which represent two extremes.<br /><br />Chickens only have 3 bitter taste receptor genes (Tas2rs), while frogs have more than 50.<br /><br />They studied the different molecular properties of cloned Tas2r genes and measured their responses when exposed to a panel of 46 natural or synthetic bitter compounds.<br /><br />First, they constructed a gene tree for a selection of Tas2r genes of various vertebrate species and showed that all avian genes come from the same 3 ancestral genes.<br /><br />Frogs were found to have 5 ancestral genes, indicating that their expanded repertoire was due to later gene duplication events.<br /><br />They showed that all the three chicken Tas2rs are "broadly tuned" for bitter taste, whereas six frog Tas2rs tested are mixed consisting of broadly as well as narrowly tuned receptors.<br /><br />Interestingly, both chicken and frog receptor repertoires responded to about half of the compounds, showing that the tuning range rather the number of Tas2r genes was a critical factor, researchers said.<br /><br />In general, individual substances activated different receptors in clearly separated concentration ranges, which may also provide a clue to the role of bitter taste diversity in enhancing the chance of survival.<br /><br />The authors conclude that a low number of functional Tas2r genes found in chickens can be compensated by an increased average tuning width.<br /><br />They speculate that the environmental duality of amphibian life, living on both land and water, may account for the increased Tas2r gene diversity in frogs.<br /><br />In mixed aquatic and terrestrial environments amphibians such as frogs may have encountered a larger number of bitter compounds, causing the evolutionary pressure to provide a larger taste receptor repertoire. The findings appear in the journal Molecular Biology and Evolution.</p>