To understand what controls the formation of sensory legs, it was necessary to raise robins from eggs. The researchers observed that the robin’s legs develop from three pectoral fin rays around the fish’s abdomen and separate from the fins as development progresses. Among the most active genes in the developing leg is a transcription factor (a protein that binds to DNA and turns genes on and off) known as tbx3a. Editing tbx3a in genetically engineered robins with CRISPR-Cas9 resulted in fewer legs, deformed legs, or both.
“destruction” tbx3a This results in upregulation of pectoral fin markers prior to leg separation, indicating that leg rays become more fin-like in the absence of pectoral fins. tbx3a” the researchers said in their paper. second studyalso published in Current Biology.
To see if the gene for sensory legs was a predominant trait, the researchers also attempted to create robin hybrids by crossing species with and without sensory legs. The result is offspring with sensory feet, indicating that this is a genetically dominant trait.
It’s still unclear exactly why robins evolved the way they did, but the research team came up with a hypothesis. Researchers believe that the legs of robin ancestors were originally intended for locomotion, but gradually began to acquire sensory functions, allowing them to forage on the visible surface of the ocean floor. There is. Needed to search deeper for food, these fish developed sensory feet that allowed them to taste and dig for hidden prey.
“Future research will exploit the remarkable biodiversity of robins to understand the genetic basis of novel vertebrate trait formation and diversification,” the researchers said. first study. “Our research provides a foundation for understanding how new traits evolve.”
Current Biology, 2024. DOI: 10.1016/j.cub.2024.08.014, 10.1016/j.cub.2024.08.042