THE exquisitely regular spacing of feathers on a bird鈥檚 skin is created
by proteins that clear the area around each feather, researchers in Masschusetts
have found.
Biologists know that cells destined to grow feathers produce proteins called
BMPs. The early appearance of the proteins in these cells 鈥渟uggested they might
help feathers form鈥�, says Bruce Morgan, a developmental biologist at Harvard
Medical School in Boston. Morgan and his student Selina Noramly used viruses to
deliver genes for BMPs, or an inhibitor of them called noggin, to the backs of
chicken embryos.
Skin regions given extra doses of BMPs developed bald patches, while patches
that received noggin had tightly packed feather buds (Development, vol
125, p 3775). So the researchers conclude that the BMP proteins, far from
promoting the formation of feathers, actually inhibit them. Morgan thinks BMPs
diffuse away from each feather bud and establish a feather-free zone that
results in the perfect spacing of feathers.
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