New evidence from the fruit fly suggests that the critical life process of cell division is more precisely controlled than previously believed. Chromosome pairing and exchange during cell division are assisted by many tiny chemical "motors," according to an article published in a recent issue of the journal Cell by UC Davis geneticist Scott Hawley, graduate student Katayoun Afshar and UC San Diego colleagues. These results are part of a growing body of evidence showing that chromosomes seem to direct some of the cell-division process, rather than merely riding along as passive cargo as once believed. "This finding of motors along the chromosomal arms has been found in widely divergent organisms," says Hawley, referring to a related report and a review article published in the same issue of Cell, as well as to other recent reports. "This is a general class of proteins that all chromosomes are likely to have." These findings in frogs and fruit flies are believed to be widely applicable because many of the fundamental activities of cells are similar in all animals. The motors, which are located along the lengths of chromosomes, include a protein called "nod" in flies. Similar proteins are likely to exist in humans as well. When cells lack nod, chromosomes fail to line up correctly during cell division, and DNA can be lost. In humans, these lost pieces of DNA cause genetic diseases such as Down's, Turner's and Klinefelter's syndromes. Attached is an illustration of the DNA and motor proteins in action.