Polyploidy is defined as when a living creature, usually a plant or insect, has more than two, or diploid, sets of chromosomes – for example, it can have a triploid (three) or tetraploid (four) sets of chromosomes. Sometimes polyploidy can occur in tissues of otherwise diploid animals, including people, in which tissues of the muscle, placenta, and liver produce large polyploid cells.
An international team of scientists, including geneticist Bruce Edgar, PhD of the University of Heidelberg, Germany and Robert J. Duronio, PhD, professor of biology and genetics at the University of North Carolina at Chapel Hill (UNC), may have pinpointed the underlying mechanism for cell polyploidy. They noted that many organisms achieve this growth by increasing cell size rather than number. Drosophila melanogaster, or the laboratory fruit fly, enter a specialized cell cycle called an endocycle, which ultimately results in cell polyploidy. The researchers studied the Drosophila endocycle by mathematically modeling “the behavior of molecules known to control this special type of cell cycle and the progression to polyploidy” and then making predictions about the regulation of these molecules, which they then tested in fruit flies.
The results in their original research article abstract showed that the cyclical manner in which genes were turned on and off led cells to continue in the endocycle and become polyploid, and that one specific mutation of the mechanism disrupted this process. Duronio noted that further research may allow scientists to someday manipulate cells into becoming polyploid, which may be crucial to liver regeneration, for example, since polyploidy in the human liver may be important to its functions. Personally, I believe that this type of research is valuable since organs like the liver are necessary to survival in vertebrates, prone to disease because of its role in supporting most other organs in the body, and cannot be regenerated to its original form even though its function can be restored.