A recent study has unveiled key aspects of feather evolution through experiments with chicken embryos, focusing on a set of molecular signals known as the Sonic Hedgehog (SHH) pathway. Researchers, led by Professor Michelle Millinkovich and postdoctoral researcher Rory Cooper, previously demonstrated that stimulating this pathway in chicken embryos resulted in feather formation instead of the typical scale-like structures. In their new study, they explored the effects of inhibiting the SHH pathway by injecting embryos with blocking molecules. This manipulation led to the development of primitive, tube-like feather structures resembling protofeathers found in some early dinosaurs, rather than complex feather buds.
However, the emergence of these primitive structures was temporary; after two weeks, wing development returned to near-normal with patches of naked skin at hatching. Remarkably, seven weeks later, the affected follicles were reactivated, resulting in the development of regular feathers. The findings emphasize the resilience of the SHH pathway in feather development, showing that while temporary disruptions can lead to protofeathers, permanently altering feather development is more challenging. Millinkovich noted the importance of understanding how genetic interactions evolve to facilitate such morphological changes, with the study published in PLOS Biology.
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