March 24, 2000 -- Intricate experiments on fruit fly larval tissues have provided a look at how a hormone triggers the programmed cell death that occurs when immature tissues are pruned away to make room for adult organs.

The experiments, which were designed and carried out by researchers at the Howard Hughes Medical Institute (HHMI) at the University of Utah and Massachusetts Institute of Technology (MIT), show how signals generated by the insect hormone ecdysone orchestrate programmed cell death, a process that takes place in all animals.

The research group included HHMI investigator Carl Thummel and Changan Jiang at the University of Utah, and HHMI investigator Hermann Steller at MIT, and Anne-Francoise Lamblin, who was formerly at MIT and is now at the National Institutes of Health.

In the March 24, 2000, issue of the journal Molecular Cell, the scientists report that ecdysone initiates a cascade of biochemical signals that controls genes that destroy salivary gland tissues when the larval fruit fly Drosophila melanogaster begins its metamorphosis into an adult.

"Studying the process of programmed cell death during development is nearly impossible in most animals because the cells that are affected are scattered throughout the organism," said Thummel. "As fruit flies develop, however, whole larval organs undergo dramatic mass cell death with incredible speed in order to make room for adult tissues. Using a model system in which cell death is so easily detectable, we are able to see how a hormone triggers this process, which is believed to be similar throughout the animal kingdom."

The researchers studied cell death in Drosophila salivary glands because they contain large chromosomes that form easily observable "puffs" when genes are activated. These puffs allow the
'"/>

Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
23-Mar-2000