- Oct 17, 2011
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[Some] "fish that ply the sea at depths greater than sunlight can penetrate have developed super-vision, highly attuned to the faint glow and twinkle given off by other creatures. They owe this power, evolutionary biologists have learned, to an extraordinary increase in the number of genes for rod opsins, retinal proteins that detect dim light. Those extra genes have diversified to produce proteins capable of capturing every possible photon at multiple wavelengths—which could mean that despite the darkness, the fish roaming the deep ocean actually see in color.
Most fish have one or two RH1 opsins, like many other vertebrates, but four of the deep-sea species stood apart, the researchers report this week in Science. Those fish—the lantern-fish, a tube-eye fish, and two spinyfins—all had at least five RH1 genes, and one, the silver spinyfin (Diretmus argenteus), had 38. "This is unheard of in vertebrate vision," says K. Kristian Donner, a sensory biologist at the University of Helsinki.
To make sure the extra genes weren't just nonfunctional duplicates, the team measured gene activity in 36 species, including specimens of 11 deep-sea fish. Multiple RH1 genes were active in the deep-sea species, and the total was 14 in an adult silver spinyfin, which thrives down to 2000 meters.
The deep-sea fish had a total of 24 mutations that alter the function of their RH1 proteins, fine-tuning each to see a narrow range of blue and green wavelengths—the colors of bioluminescence.
Mutations creating variations upon which selective pressures [particularly in an extreme situation with very low light levels] can act. Lovely piece of research.
Most fish have one or two RH1 opsins, like many other vertebrates, but four of the deep-sea species stood apart, the researchers report this week in Science. Those fish—the lantern-fish, a tube-eye fish, and two spinyfins—all had at least five RH1 genes, and one, the silver spinyfin (Diretmus argenteus), had 38. "This is unheard of in vertebrate vision," says K. Kristian Donner, a sensory biologist at the University of Helsinki.
To make sure the extra genes weren't just nonfunctional duplicates, the team measured gene activity in 36 species, including specimens of 11 deep-sea fish. Multiple RH1 genes were active in the deep-sea species, and the total was 14 in an adult silver spinyfin, which thrives down to 2000 meters.
The deep-sea fish had a total of 24 mutations that alter the function of their RH1 proteins, fine-tuning each to see a narrow range of blue and green wavelengths—the colors of bioluminescence.
Mutations creating variations upon which selective pressures [particularly in an extreme situation with very low light levels] can act. Lovely piece of research.
