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Flatworms defy fundamental rule of biology


Narrator:       This is Science Today. Inside each of your cells is a microscopic structure called a centrosome, which acts like a hub, organizing the cell's internal structure and playing an essential role in cell division. Every animal ever studied, from humans all the way down to insects, have centrosomes in their cells. That is ... until now. Researchers at the University of California, San Francisco, recently discovered a tiny, freshwater flatworm that defies this seemingly fundamental rule of biology.

Marshall:         They look different than every other animal and they don't have a centrosome there, they don't even have centrioles there; they just have some kind of a blob that we don't know what it is.

Narrator:       Wallace Marshall, a biochemistry professor who led the flatworm research, said that when they didn't see centrosomes with an electron microscope, they turned to genetics to try to solve the mystery.

Marshall:         We found that there are two critical genes that in all other animals are necessary for building a centrosome, that are missing from the genome of planarians, so they've apparently just ditched it.

Narrator:       Marshall believes this finding implies that centrosomes may not be as essential for basic cell biology as previously thought. For Science Today, I'm Larissa Branin.