DISCOVER Vol. 23 No. 1 (January 2002)
Birthing Amoeba Babies

Microscopic time-lapse images show a midwife amoeba (yellow) disconnecting two daughter cells (blue).
Photograph courtesy of David Biron/Weizmann Institute of Science

Researchers have long observed that Amoebas reproduce through fission, but until this year no one realized the process always stalls, with the two daughter cells apparently frozen together. In March, researchers at the Weizmann Institute of Science in Rehovot, Israel, announced that not only do cells stall in mid-delivery, but they also get help. Other amoebas often make a beeline to the distressed daughters to nudge the two cells apart. "For an amoeba, which doesn't usually display much sense of direction, it was an unexpected behavioral observation, to say the least," says Elisha Moses, a biophysicist who led the research.

Rather than being an isolated case of altruism, this amoebic midwifery turns out to be routine. The distressed cells release a chemical attractant, says Moses, which signals nearby members of the species to come to the rescue. Understanding this fission phenomenon may give researchers an idea of how to deter it. "If there's a way to interfere with this process, then there may be a way to limit their growth rate," says Moses—as well as prevent a lot of human misery. These amoebas cause human dysentery and death among AIDS patients, particularly in the third world.

"You have to look at a slow sequence of events for a long time before you realize what you're seeing," says Moses. But such patience is rare these days. "Everybody has moved on to genetics, which involves slicing and dicing organisms," he says. "Simply watching them under the microscope is out of fashion."
— Curtis Rist