My
general area of professional interest is developmental
biology. More specifically I study amphibian development,
focusing particularly on biochemical and molecular
aspects of development. Most of this work is done
with embryos and tadpoles of the oriental fire-bellied
toad, Bombina orientalis.
My current project deals with resorption of the
tail during metamorphosis. As the tadpole is becoming
transformed into a frog, it undergoes many morphological,
physiological, and biochemical changes. Certainly
among the most dramatic of these changes is resorption
of the tail. All of the cells in the tail die
during resorption. Historically it was assumed
that cell death in the tail resembled necrotic
cells death, in which cells lyse. However, recently
it has been recognized that a different kind of
cell death - apoptosis, or programmed cell death
- might contribute significantly to tail resorption.
Apoptotic cell death features orderly dismantling
of the cell, with no lysis. Various components
(including the DNA, the cytoskeleton, and various
intracellular proteins) are degraded within the
cell, and the cell gives off membrane-bound fragments,
which are engulfed by surrounding cells.
Preliminary studies have shown that apoptosis
does contribute to tail resorption. Questions
I am currently asking (and hoping to answer) include:
* To what degree does apoptosis occur at different
times during metamorphosis and at different levels
along the length of the tail?
* Which of the various enzymes (collectively known
as caspases) known to contribute to apoptosis
in various other systems are involved in metamorphosis?
* What are the intracellular targets for the caspases?
* How does the onset of apoptosis relate to external
signals (including elevation in the level of thyroid
hormone) known to contribute to initiation and
regulation of metamorphosis?
As an extension of these studies, I anticipate
that I will begin investigations of contributions
of apoptosis to other developmental events, particularly
ones featuring major remodeling of the organism.
These events include gastrulation in early development
(when a ball consisting of about 10,000 cells
is reorganized into a form in which the three
primary germ layers are established), sculpting
of the paddle at the end of the hind limb bud
into digits, and remodeling of the gut at the
time of metamorphosis.
I invite inquiries from students who might like
to work in my lab and participate in this project.
It is possible to do some of the work during the
academic year. Additionally I anticipate that
every summer (beginning in 2001) I will hire at
least one biology major to work on the project
full time for 10 weeks.
