Making flies sick reveals new role for growth factors i...(lly and functionally very similar a tes...)

"Dpp from flies has been shown to be completely functional in mammalian cells, and the human version of Dpp BMP 2/4 also works just fine when injected into flies," explains Newfeld.

Newfeld's research builds on earlier observations made by Aaron Johnson, then a graduate student in the Newfeld lab, now a postdoctoral fellow with University of Texas Southwestern Medical Center in Dallas, Tex. Johnson first observed that fruit fly mutants that lacked the ability to generate Dpp protein in one tissue (at a particular time in embryonic development) suffered from excess cell growth in the neighboring tissue. The lack of communication between the tissues resulted in uncontrolled cell growth, in this case in the heart. "Dpp mutant flies have large hearts which are stiffer and beat inefficiently," says Newfeld.

Johnson went on to uncover Dpp's role in heart development. He discovered that when the embryo is nearly ready to hatch, Dpp signals tell heart cells to stop growing. These instructions also insure a proper boundary between the heart and surrounding muscle tissue.

While these were fundamentally exciting discoveries, Newfeld made them even more so when he extended Johnson's project. Since both the heart and the lymph glands in the fly originate from the same tissue (cardiogenic mesoderm), he postulated that when heart development goes awry in fruit fly Dpp mutants that the lymph glands might also be affected.

"One of the functions of the lymph gland in fruit flies is to produce blood cells," notes Newfeld. "This is in contrast to humans where the processes take place in our bone marrow."

With support from Science Foundation Arizona, Frandsen built on Johnson and Newfeld's early discoveries by looking into the mutant fruit fly's immune system and blood cells. He noticed that, in addition
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