Centrosome choreography

Depending on the position of the mitotic spindle, a dividing cell can split evenly or unevenly, lengthwise or down the middle. As a graduate student at the MRC Laboratory of Molecular Biology in Cambridge, England, Anthony Hyman showed how the centrosomes' travels set up the division axis in Caenorhabditis elegans (Hyman and White, 1987).

Hyman was rummaging through the literature when he stumbled across the question of how the cell division axis gets set up. Everyone assumed that the centrosomes determined the positions of the spindle poles, but nobody knew how. His test system was the fertilized worm egg, and the AB and P₁ cells that result from its first cleavage. These cells behave differently from each other. Divisions in the AB lineage are symmetric, and each...