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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