Interest in Insects
For show-and-tell at his children's school, David Champlin,
assistant professor of biology, takes along a bright blue-green,
hornworm caterpillar that is his "lab rat." Despite its pretty color,
these garden giants can appear out of nowhere to devour tomato
plants virtually overnight. The trick that allows this to occur is their
potential for rapid growth. Under ideal conditions, they can
increase in size 10,000 times in just ten days.
This fast growth is what draws Champlin's interest. He looks at the
molecular regulation of development in insects. Insect
metamorphosis is controlled by a steroid hormone that stimulates
cell division. As the caterpillar undergoes rapid growth, cells that
will make adult structures such as the wings are quiet. Late in the
caterpillar's life, the steroid appears in the blood and gives these
cells the signal they need to begin growing.
"We use insect metamorphosis in my lab as a model to understand
how steroid hormones control development," Champlin explains.
Each cell that responds to the steroid contains a receptor that
communicates the signal from the hormone to the cell. These
receptors are similar to those in humans that respond to steroids
and several other hormones that play critical roles in development.
These receptors are players, Champlin says, in the
"metamorphosis" of humans that occurs during puberty and also
during fetal development. Cancers often occur in tissues, such as
the breast or prostate, whose growth is normally controlled by
these steroid hormones and their receptors. The work in
Champlin's laboratory is basic research; he's trying to understand
how these receptors function under normal circumstance. But his
work may shed light on how cell-growth can go awry, as in cancer
and in fetal development leading to birth defects.
The same steroid that regulates the cell growth of insects also
drives behavioral changes. The steroid prompts this non-native
caterpillar to stop eating, burrow into the ground, and pupate,
growing a shell in which it can survive the winter in Maine
underground. Analysis of the role of hormones has led to research
on how to exploit insect hormones as pesticides. So maybe
Champlin and the student researchers who help him can find a way
to give backyard tomato growers a break.
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