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Fascinating cellular world of the flatworm


Narrator: This is Science Today. One of the most basic laws of biology is being challenged by the discovery of a tiny flatworm with an unusual way of reproducing. Researchers at the University of California, San Francisco recently discovered this flatworm as the only known animal that lacks centrosomes — a crucial component for organized cell division.

Marshall: Basically, you've got an organism that has no centrosome but it's an animal just like any other animal and it's hard to put your finger on anything that's different about it.

Narrator: Study leader Wallace Marshall thinks that the missing centrosome has something to do with the way these worms regenerate and reproduce — called blastomere anarchy. Basically, this means that instead of highly organized cell division, the new cells of the embryo are randomly oriented instead.

Marshall: They point all different directions and then the daughter cells that are born just move around and the whole embryo is a seething mass of cells that are moving at random. And way later in development they figure out what their fates will be. So we think that the reason they've lost centrosomes is because they've switched to a totally different method of embryogenesis that doesn't require oriented cell divisions. It's wild.

Narrator:       For Science Today, I'm Larissa Branin.