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The colorful patterns in animals from fish to birds to insects to snakes, where do they come from?
Researchers out of the University of Wisconsin Madison published an article in Nature this week with the possible answer, at least for fruit flies: the Wingless morphogen.
In studying wing patterns of certain North American spotted fruit flies, the scientists discovered a morphogen (a substance that determines the development of cells and the position of those cells within a tissue) encoded with the Wingless gene (a specific gene that affects wing and limb development during the embryonic and metamorphosis stages).
Late in wing development, the Wingless morphogen diffuses through tissue where it prompts cells in certain areas of the wing to make pigment. “It acts by triggering responding cells to do things, in this case make color,” explains Sean Carroll, the senior author of the report.
“The Wingless molecule is deployed in this species at specific points in time and in specific places — the places where the spots are going to be.”
So the team began experimenting. Three years and thousands of fruit fly embryos later, they found that by inserting the Wingless gene into different parts of the fly’s genome, they were able to successfully manipulate the decoration of the fly’s wing, creating stripes instead of spots, and patterns not seen in nature. “We can make custom flies,” notes Carroll. By manipulating the gene, “we can make striped flies out of spotted flies.”
Although the study was conducted in teeny fruit flies, the principles uncovered by Carroll’s group, he argues, very likely apply to many animals, everything from butterflies to boa constrictors. “This is animal color patterning, how they are generated, how they evolved.”
Creative Commons image by photoholic1