Death Comes as an Unrelenting Tide of Destruction, Study Shows

Death sweeps through cells in a swift and unrelenting wave of devastation, scientists investigating cellular self-destruction have discovered.

Researchers watched death propagate through frog egg material in a "trigger wave" that spreads like fire through a forest. They published their findings in the journal Science.

The team put cell material called cytoplasm into test tubes and used fluorescent probes to pinpoint how a form of programmed cell death called apoptosis spreads. They dipped one end of the tube in cell material that had already been through this process, New Scientist explained.

The team had dyed the dead material red to contrast with the bright green dots of the cytoplasm. The green dots vanished much faster than the red material spread through the tube.

Next, scientists zoomed in on an individual frog egg. This time, they observed the cell membrane change color as the egg died.

Apoptosis is important for cell maintenance and the growth of new cells. When the time is right, the tiny biological compartments send out a signal to self-destruct. This alerts certain enzymes called caspases, which rip the cell asunder.

Now scientists know this process is fast but constant, like a wave traveling round the audience at a football game. As part of the cell dies, caspases activate their neighboring enzymes. Death spreads through the cell like a trail of dominos until, finally, all parts of the cell are down.

Death swept through the cells at 30 micrometers per minute—that's less than two inches per day. Although it seems like a snail's pace, in a tiny cell it's actually pretty fast.

"It spreads in this fashion and never slows down, never peters out," James Ferrell, the study author and a professor of chemical and systems biology and of biochemistry at Stanford University, said in a statement. "It doesn't get any lower in amplitude because every step of the way it's generating its own impetus by converting more inactive molecules to active molecules, until apoptosis has spread to every nook and cranny of the cell."

Improving our understanding of cell death is key to medicine, Ferrell explained. "Sometimes our cells die when we really don't want them to—say, in neurodegenerative diseases. And sometimes our cells don't die when we really do want them to—say, in cancer," he said. "If we want to intervene, we need to understand how apoptosis is regulated."

In other cell-related news, researchers recently linked wearing tight underwear to lower sperm count in men. Boxers came on top for both overall count and swimming speed.