|Okay, so that didnt
happen. But she did, and does, have a passionate and rather unusual
fascination for the order Araneae. Unusual, at least, for most two-legged
creatures, who would rather have the smallest possible quantity of
spiders in their vicinity.
Ive always loved them, Chaw says now, in the glass
and slimy-critter-filled confines of the research lab of professor
Steve Black, her teacher, guide, and fellow scientist. I guess
its because my older brother was terrified of spiders, so I
had a tool to use!
The Reed junior still makes her arachnid-amour pay off: her developmental
biology independent project and her senior thesis will explore an
area of spider development that no other scientists have studied.
And that, of course, is the great strength of the Reed-style independent
project, in the biology department or anywhere on campus: the undergraduate
student has the opportunity to do real, meaningful science that would
be the stuff of graduate school at most colleges and universities.
The independent project was, for me, really intense, Chaw
says. I loved it. It was student-driven, and thats the
way I learn best. I got to work closely with Steve [Black], which
was great, and the project led directly to discovering what I want
to do for my thesis. It was a lot of hard work, but I was just so
excited to study spiders! Bear in mind that this is a woman
whose eyes light up when she explains that if people and spiders
were proportionate in size, wed be dead!
Spiders are, of course, extraordinary creatures, somewhere between
miniature space aliens and eight-legged cans of insecticide. Some
stalk and hunt like leopards, and most spin webs far stronger, fiber
for fiber, than steel. They wear their skeletons on the outside like
knights in armor. They drift long distances on the wind, carried by
elegant strands of silk. A few produce toxins that can injure or kill
you; most simply keep the local insect population at bay. Right now
there are more of them in your house than you would believe.
And, it turns out, from a developmental
biology perspective, spiders do something that no other animal does:
a little trick called germ band inversion.
The end product of very early embryonic development is the production
of the germ band, meaning that the part of the embryo that is going
to make the central nervous system and muscles appears at one end
of the egg as an elongated bandthe germ of these
critical organ systems. Then it gets strange. In spider embryos,
the germ band splits down the middle, each half migrates around
the horn, as it were, and both halves end up on the other side of
the spherical egg. Go figure. The two halves rejoin, connect and
fuse into the definitive germ band, forming the little
leggies and all the rest. To the casual, non-spider observer, it
seems like a completely unnecessary and complicating bit of developmental
business. Chaw would love to find out how it happens.
In one of her two independent projects (in the other, she ran wolf
spiders through a maze) Chaw attempted to learn if a gene important
to fly development and segmentation had a similar pattern of expression
in spiders, as the two species likely have a common ancestor. The
findings? One, that you need a lot of time and patience to do good
science; and two, that spider eggs are not very cooperative.
Among their many mind-bending capabilities, you see, spiders lay
eggs that have an inner and outer shell, layers of wax and protein
designed to let gases pass in and out, but not liquid. It took Chaw
months of systematic work to figure out the chemical conditions
that would allow her to see the cells and their contents.
one has studied the mechanisms underlying this dramatic and complex
movement of cells, says Black. Crystal hopes to learn
whether the motive force for this morphogenesis comes from the germ
band cells themselves or from the other cells in the embryo. For
example, other cells could attach and pull apart the germ band.
Its a fascinating, original study.
One that the very independent Chaw will continue soon, right after
she finishes rampaging across campus, attacking defenseless Reedies
with her eight hideous feet and giant spider jaws. Or not.