Polarization of yeast cells under different pheromone induction regimens

The yeast Saccharomyces cerevisiae undergoes polarized growth in two
different contexts: budding and pheromone-induced mating. A key difference
between the two processes is that mating polarization occurs in response
to an external stimulus, which can be easily manipulated under laboratory
conditions.  We exploited this property to test the hypothesis
that the underlying polarity circuit is bistable.  To make this
test we used microfluidics to precisely control the temporal profile of
mating pheromone and live-cell imaging to monitor polarization in single
living cells. Files posted here contain single cell polarity time course
data under different pheromone regimens. These data clearly demonstrate
that polarization as a function of pheromone concentration depends on the
history of the system, a behavior that is a hallmark of bistability. The
data also re­veal that polarity is rapidly lost following a sudden loss of
phero­mone.