In the Dec. 14, 2004, issue of Current Biology, Leocadia Paliulis and Bruce Nicklas report their progress in understanding how the pairs of chromosomes in each cell manage to balance their adhesion to one another and their release during cell division. Their work was sponsored by the National Institutes of Health. Chromosomes are the tiny fiber structures in the cell that house its genes. They replicate and separate in the process of cell division.
The exquisite management of adhesion properties between newly divided chromosomes, called chromatids, is crucial if the cells are to divide properly. In this process chromatids are drawn apart to separate poles of the dividing cell so that each new "daughter" cell contains a single copy of each. The same basic process operates in normal cell division, called mitosis, as well as the proliferation of sperm and egg cells called meiosis.
"Chromosomes in mitosis and meiosis have to be held together, because otherwise they don't attach to the apparatus called the spindle that distributes them to opposite poles," explained Nicklas, who is a Research Professor of Biology. "If they're held together, then one replicated chromatid can attach to one pole and the other to the opposite pole. But if they are not held together, they attach independently, and often both sister chromatids can go to the same pole rather than to opposite poles. This creates chromosome imbalances that can lead to cancer or chromosomal abnormalities that cause birth defects."