Wednesday, August 10, 2005

Downy chick feathers and tufted branches

I am always facinated by researchers when they study for years at a time a very specific and undoubtedly esoteric question, and I continue to admire the patience it takes.

A study about how bird feathers are formed was reported in the prestigious journal Proceedings of the National Academy of Sciences this week.

In a previous study, according to the press statement (yes reporters are really interested in this stuff) John F. Fallon showed that Sonic hedgehog (Shh) and bone morphogenetic protein 2 (Bmp2) must be expressed in order to produce barb ridges, which are among the first structures to form in the tufted branches of the simple downy chick feather. The two proteins, which tend to play off each other in organ development, also are involved in the embryonic development of limbs, lungs, teeth and the gut.

In the current study, a team of scientists showed that "during the development of barbs-filamentous structures that form the feather, the function of these two proteins interact. SHH up-regulates its own expression and that of Bmp2, and Bmp2 then signals the down-regulation of Shh expression. This dynamic signaling interaction fits a longstanding mathematical model known as an activator-inhibitor mechanism," says the press statement.

Researchers say these findings suggest that simple relationships between developmental genes can provide the basis for the formation of complex forms. They predict that a more complicated version of the model can be applied to the formation of more complex feathers.

Bottom line: "Our model supports paleontologic evidence that pennaceous feathers are more advanced than plumalaceous feathers." I know, you are going to consider becoming a paleontologist after this exciting news!

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