This color-blind zebrafish tells you how color vision evolved

A research team from the University of Tokyo has discovered how some animals regulate their ability to see blue light through zebrafish research

Professor Yoshitaka Fukada from the Faculty of Science at the University of Tokyo said: “When I started to study the evolution of vision in 1989, the textbook said that both photosensitivity and color discrimination come from the same protein

Most vertebrates retain a four-color vision system that can distinguish four different colors of light: near ultraviolet, blue, green, and red

For thousands of years, some ancestral species have lost the genes responsible for producing one or two chromophores

Through the study of mice, researchers have figured out how the sensitivity to purple and red wavelengths is regulated, but mice have lost the ability to distinguish blue and green wavelengths during the evolutionary process

In 2019, the research team led by Fukada combined novel gene editing tools with the color vision research of zebrafish, which is an animal with all four color-sensing proteins

The researchers first identified three genes: six6b, six7 and foxq2

In previous studies, they observed that reducing the expression of six6b and six7 (either in combination or alone) eliminated the blue and green vision of zebrafish

In this recent study, researchers figured out how different foxq2 activities help zebrafish distinguish between blue and green

They believe that foxq2-dependent sws2 expression is a highly conserved regulatory mechanism, acquired in the early stages of vertebrate evolution

Co-corresponding author Daisuke Kojima of the University of Tokyo explained: “In the long run, such basic biological research on how color vision is formed may ultimately help treat color blindness

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Yohey Ogawa, Tomoya Shiraki, Yoshitaka Fukada and Daisuke Kojima.