July 21, 2024

Early Sharks had the Ability to Perceive Bitter Substances, Study Reveals

Researchers from the University of Cologne, in collaboration with the Leibniz Institute for Food Systems Biology, have made a groundbreaking discovery – the presence of bitter taste receptors in twelve different species of cartilaginous fish, including sharks and rays. These receptors, known as taste receptors type 2 (T2R), are responsible for the perception of bitterness in humans and other vertebrates. This finding challenges the previous assumption that such receptors only existed in bony vertebrates. The study, titled “A singular shark bitter taste receptor provides insights into the evolution of bitter taste perception,” was recently published in Proceedings of the National Academy of Sciences (PNAS).

In the past, studying sharks at a molecular level has been challenging due to their relatively large genomes. However, advancements in sequencing techniques have provided researchers with a deeper understanding of the gene sequences of various cartilaginous fish species. Utilizing these techniques, neurobiologists Dr. Maik Behrens and Tatjana Lang from the Leibniz Institute for Food Systems Biology, together with Professor Dr. Sigrun Korsching from the Institute of Genetics at the University of Cologne, specifically searched for bitter taste receptors in cartilaginous fish.

Out of the seventeen cartilaginous fish genomes studied, twelve were found to contain genes for taste receptors type 2. Strikingly, each species only carried a single T2R gene, which the researchers named T2R1. This indicates that the single T2R gene is an ancestral form of these bitter taste receptors, suggesting that it has not undergone gene duplication and subsequent specialization like its counterparts in other animals.

Dr. Sigrun Korsching explains, “These findings provide us with new insights into the evolution of these receptors. We can trace the molecular and functional origins of the entire family of bitter taste receptors back almost 500 million years, to the last common ancestor of cartilaginous and bony fish.” To further support their findings, the researchers introduced the T2R1 gene from the bamboo shark (C. plagiosum) and the catshark (S. canicula) into immortalized cell lines. The results demonstrated that both sharks were able to taste bitter substances, including compounds perceived as bitter by humans, such as colchicine and bile acid.

Additionally, a screening of ninety-four human bitter substances identified eleven compounds that could also activate the sharks’ bitter taste receptors. Some of these compounds were also found to activate the bitter taste receptors of the ancient bony fish species, coelacanth (Latimeria chalumnae), as previously shown in another study. Dr. Sigrun Korsching emphasizes, “The degree to which this function has been conserved is remarkable, spanning the entire evolution of vertebrates.”

This groundbreaking study sheds light on the evolutionary origin of bitter taste perception and enhances our understanding of the sensory abilities of early sharks. It offers valuable insights into the conservation of bitter taste receptors across different species, showcasing the remarkable similarities in taste perception spanning hundreds of millions of years in vertebrate evolution.


1. Source: Coherent Market Insights, Public sources, Desk research
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