Secret behind hard exoskeletons, spreading wing...( specific unique configuration. Protei...)

"The exciting thing is that this is the first cystine knot protein with a function that has been found in insects," Honegger said. "What you can gather from that is that nature is really very conservative. It creates the same structure but uses it for different functions."

Honegger and his colleagues then wanted to take their findings to the next level and determine that the genetic sequence they had found was in fact coding for bursicon.

"Based on previous research, we knew that certain nerve cells produce bursicon and that the very same cells produce another protein, crustacean cardioactive peptide (CCAP)," Honegger said. "We used a molecular probe that would attach to bursicon messenger RNA and an antibody that would work against CCAP. From the reaction, we saw that the same cell was producing both. The molecular probe showed us that we really had the right stuff."

Honegger's colleague at Cornell, John Ewer, then made transgenic fruit flies by using a "death gene" that targeted CCAP cells. The cells disappeared, prohibiting the production of bursicon and confirming that the genetic sequence the researchers had for the hormone was correct.

In the final test, Susan McNabb from the University of Washington looked at mutant fruit flies whose outer shells showed defects or did not harden completely. She found that all of the mutants had mutations in the gene they had identified for bursicon.

To determine that decreased levels of bursicon were responsible for the defects to the mutants' shells, the researchers used a test previously used to demonstrate that bursicon levels in the central nervous system are responsible for shell hardening and pigmentation. The shells of blow flies that are treated shortly after they leave their pupae to prevent them from releasing their own bursicon will harden and darken if they are inje
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Contact: Melanie Catania
melanie.catania@vanderbilt.edu
615-322-7970
Vanderbilt University
12-Jul-2004