Caterpillar Hormone Found That Initiates Metamorphosis

The finding was reported in the June 2, 2006, issue of Science.

The researchers found that by manipulating what a caterpillar eats, they could create strange chimeras that were part caterpillar and part pupa. For example, the chimeras had caterpillar mouths for plant chomping and also the nectar-sipping mouth tubes of the moth. Development of the antennae, legs, and eyes was also caught midway between what the caterpillar needs to survive and what a moth needs. Although the chimeras did not survive because they could not eat properly, they revealed the relationship between the cells that form the caterpillar and those that will form the moth.

Explained David Champlin, assistant professor of biological sciences at the University of Southern Maine (Portland, USA): "Imagine starting your car in the morning. Is it the gas that starts it? No. It's a process beginning with the starter motor. The gas merely keeps the car running once it has started. And the brakes stop the car's progress. These processes are all different but related. With the caterpillar, many scientists have studied a hormone that causes metamorphosis to advance and another hormone that represses metamorphosis but have never really asked what starts metamorphosis. When we did, we found a new role for the repressor hormone and in the process identified a hormone never before known that starts metamorphosis.”

This "starter hormone,” called metamorphosis-initiating factor, is regulated by nutritional cues in the caterpillar's food. "All of this is leading us to a better understanding of how hormones control growth in animals, including humans,” added Dr. Champlin. "This is also related to stem cell research and regenerative medicine--how to coax cells to change their fates.”

The research was conducted by Dr. Champlin, several of his students, and three colleagues who are professors at the University of Washington (Seattle, USA) and Hirosaki University (Japan). The scientists believe the findings will aid the medical community in its understanding of the role of hormones in normal development, stem-cell research, cancer, and other diseases.



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