Uncovering A 400-Million-Year-Old Pheromone Sensor

A research group in Japan has discovered a pheromone-sensing gene that predates land-dwelling vertebrates.

AsianScientist (Oct. 30, 2018) – Scientists at the Tokyo Institute of Technology (Tokyo Tech), Japan, have discovered a gene that appears to play a vital role in pheromone sensing. The gene is conserved across fish and mammals over 400 million years of vertebrate evolution, indicating that the pheromone sensing system is much more ancient than previously believed. The researchers published their findings in the journal Molecular Biology and Evolution.

Most land-dwelling vertebrates have both an olfactory organ that detects odors and a vomeronasal organ that detects pheromones, which elicit social and sexual behaviors. It has traditionally been believed that the vomeronasal organ evolved when vertebrates transitioned from living in water to living on land.

In this study, researchers led by Associate Professor Masato Nikaido at Tokyo Tech suggest that the vomeronasal organ may be much older than previously believed. The V1R protein family, expressed by cells of the vomeronasal organ, is crucial for pheromone detection. Nikaido and colleagues identified a gene, ancV1R, that encodes a previously unknown member of the V1R family.

The authors identified ancV1R in 56 of 115 vertebrate genomes. ancV1R is unusual in that it is expressed in most vomeronasal sensory neurons. In contrast, other V1R proteins follow a ‘one neuron-one receptor’ rule, with only a single receptor being expressed in each neuron. This demonstrates the importance of ancV1R in pheromone sensing.

Furthermore, unlike other V1R genes, ancV1R is present not only in land-dwelling vertebrates but also in some fish lineages, indicating that it has been conserved over 400 million years of vertebrate evolution. This represents the first discovery of a V1R family gene shared between fish and mammals, the researchers said.

Interestingly, the loss of ancV1R in some vertebrate lineages, such as higher primates (including humans, chimpanzees and gorillas), cetaceans (including whales and dolphins), birds and crocodiles, corresponds with the loss of the vomeronasal organ in these lineages.

“It will be fascinating to further investigate how these patterns of expression are regulated and to determine their functional role in chemosensory signaling,” said Nikaido.

This discovery opens new avenues of research into the origin, evolution and function of pheromone signaling.

The article can be found at: Suzuki et al. (2018) A Single Pheromone Receptor Gene Conserved Across 400 Million Years of Vertebrate Evolution.


Source: Tokyo Institute of Technology; Photo: Shutterstock.
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