CHICAGO, Aug. 17 (UPI) -- New gene-editing techniques have revealed a connection between the genes responsible for the fin rays of fish and the genes responsible for finger and toe formation among land animals.
"For years, scientists have thought that fin rays were completely unrelated to fingers and toes, utterly dissimilar because one kind of bone is initially formed out of cartilage and the other is formed in simple connective tissue," Neil Shubin, a biologist at the University of Chicago, said in news release. "Our results change that whole idea. We now have a lot of things to rethink."
Researchers used novel gene-editing techniques to breed zebrafish without a variety of genes linked to limb-building. They also developed unique techniques for tracking the movement of embryonic cells during anatomical development.
Their research strategies revealed an overlap between the cells and genes linked to fin formation in zebrafish and the development of wrists and fingers in humans and mice.
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The scientists specifically focused on Hox genes, a group of genes that govern the body plan of a developing embryo along the head-to-tail axis for fish and the shoulder-to-fingertip axis for mammals.
In mice, the genes HoxD and HoxA dictate the development of wrists and digits. Mice bred without the two genes failed to properly develop limbs and digits. When researchers deleted the same genes in zebrafish, long fin rays failed to fully develop. Instead, cell growth was concentrated at the base of the fin.
"What matters is not what happens when you knock out a single gene but when you do it in combination," said Tetsuya Nakamura, a postdoctoral scholar in Shubin's lab. "That's where the magic happens."
The new research was published in the journal Nature.
