BioMEMS for Cell Biology - Introduction to BioMEMS - page 361

FIGURE 6.68 Brain. slice. in. a. microluidic. chip.. (From. A.. J.. Blake,. T.. M.. Pearce,. N.. S.. Rao,. S..
M..Johnson,.and.J..C..Williams,.“Multilayer.PDMS.microluidic.chamber.for.controlling.brain.slice.
microenvironment,”. Lab Chip . 7,. 842-849,. 2007.. Reproduced. with. permission. from. The. Royal.
Society.of.Chemistry.)
uniquely achieved independent control of luids through multiple channels in two separate luid
chambers, one above and one below the slice. Simultaneous electrophysiological recordings
from the edge of the slice while the biochemical environment was modulated were also possible.
6.5.4.3 Caenorhabditis elegans in a Chip
Many neuroscientists interested in studying neuronal networks will contend that even brain
slices are a damaged system, and far too complex—it's better to start with lower organisms that
happen to have a well-deined number of neurons with well-known connectivity, such as the sea
slug Aplysia or the roundworm Caenorhabditis elegans , and that can also be manipulated geneti-
cally. In 2004, the laboratory of Cornelia Bargmann, then at the University of San Francisco
in California (and since 2005 at the Rockefeller University in New York), pioneered the use of
microluidics for chemosensation research as well as the use of microluidics in combination
with C. elegans .
THE ELEGANT WORM
C. elegans is a remarkable, transparent nematode approximately 1 mm
in length. It has become a model organism for molecular biologists, developmental biolo-
gists, and neurobiologists since South African biologist Sydney Brenner irst started study-
ing it in 1974 (which eventually awarded him the Nobel Prize in Physiology or Medicine
in 2002). It remains viable ater repeated cycles of freezing and thawing. In the wild, C.
elegans feeds on bacteria. It is one of the simplest organisms with a nervous system, which
consists of just 302 neurons whose location and synaptic connections are all known. he
developmental fate of every single cell in the adult animal (1031 in male worms and 959 in
hermaphrodites), which is largely invariant from individual to individual, has also been
mapped out. It has not escaped the attention of researchers that a signiicant proportion
of its nervous system is devoted to chemosensation: 32 chemosensory neurons (generally
labeled with three letters: ASA, AWC, ASH, etc.), which penetrate the cuticle to expose
their sensory cilia to the environment.