The initial simulation tested how cell activity would spread through the embryo solely by diffusion. Oscillation indeed found its way across the cell, but disorder took root almost instantly. Cells divided at different speeds, with many left undeveloped by the end of the cycle. As the simulation went on for 200 minutes, the mayhem grew worse. A real embryo would not survive this breakdown, or would at least be left with severe developmental problems, Wingreen said.
Wingreen and McIsaac began to suspect that the calcium wave had a role in keeping the cellular peace. Although known to spark cell cycles, the full purpose of the calcium wave had previously had some shadow of mystery, Wingreen said. But once the team ruled out that cell activity could self-regulate, they knew something else brought order to the developing embryo. The calcium wave -- which spreads across the embryo rapidly following fertilization -- seemed a likely candidate.
The researchers then simulated cell division with fast and slow calcium waves. Slow waves creeping at 1 millimeter every 10 minutes opened the door for havoc. However, when sped up in the simulation to travel a millimeter in four minutes, the calcium wave synchronized cell activity, and the embryo developed normally. The simulation exposed the calcium wave as not only an initiator of embryo development but also a regulator of that activity.
If the calcium wave doubles as a regulator, then it could have other functions. Moreover, other mechanisms that seemingly serve one purpose may also have others. These possible extra duties could be behind other happenings in embryo cells that are not well understood, said Eric Wieschaus, the Squibb Professor of Molecular Biology at Princeton and a 1995 Nobel Prize winner.
"The fact that the system generally doesn't devolve into chaos might mean that embryos have devel
|Contact: Morgan Kelly|