Scientist at the University of Alberta report a zebrafish's stem cells can selectively regenerate damaged photoreceptor cells.
Geneticists have known for some time that unlike human stem cells, stem cells in zebrafish can replace damaged cells involved in many components of eyesight.
Rods and cones are the most important photoreceptors. Rods provide night vision while cones give a full color view during daylight.
To date almost all success in regenerating photoreceptor cells has been limited to rods, not cones, the researchers said.
What had not been determined, Alberta biologist Ted Allison said, was whether stem cells could be instructed to only replace the cones in a retina, with important implications for human eyesight.
"This is the first time in an animal research model that stem cells have only repaired damaged cones," Allison said. "For people with damaged eyesight repairing the cones is most important because it would restore daytime color vision."
The next research, he said, is to identify the particular gene in the zebrafish genome that activates repair of damaged cones.