Nov. 26, 2007 One gene for pea pod color generates green pods
while a variant of that gene gives rise to the yellow-pod
phenotype, a feature that helped Gregor Mendel, the 19th century
Austrian priest and scientist, first describe genetic
inheritance. However, many modern-day geneticists are focused on
the strange ability of some genes to be expressed spontaneously
in either of two possible ways. In order to better understand
this phenomenon of epigenetic multistability, a major
complication for Mendelian genetics, scientists at UC San Diego
grew virtual bacterial cells in a computer experiment. They
created a two-phenotype model system programmed to grow in ways
that matched natural growth. In a deceptively simple experiment,
they then recorded the degree to which the two phenotypes varied
over time in individual cells, and then repeated the experiment
over and over. They reported in the Nov. 19 online edition of
Proceedings of the National Academy of Sciences that variability
due to epigenetic multistabilit