Cells can divide by polar relaxation or equatorial stimulation, using one as a backup if the other fails, according to PLoS Biology article.

Researchers from Oregon State University report that cells can divide by any of the two mechanisms that have previously been proposed to be mutually exclusive. They believe that their findings end nearly 50 years of debate about how chromosomes in a cell replicate and then divide into two cells.

The OSU team discovered that in the same cell type, cells could divide either by polar relaxation or equatorial stimulation. They suggest that cells thus have a backup system that can work if the other approach fails.

“Researchers have been debating cell cleavage ever since the cell was discovered, with two basic models proposed around 1960 of how a contractile ring pulls together and allows a single cell to split into two,” points out Dahong Zhang, Ph.D. associate professor of zoology.

Some investigators propose that the equator contracts, while others said that the poles relaxed to allow this contraction and division. These theories came to be known as equatorial stimulation and polar relaxation, respectively.

The problem with deciphering which theory was right stemmed from a lack of technology, according to Zhang. “Until now there was no decisive way to manipulate the cytoskeleton, such as the microtubules and filaments that are involved, and see what was happening as it occurred.”

To address this issue, Zhang developed new instrumentation that uses microneedles and enhanced imaging techniques. The technology allows direct manipulation of the cytoskeleton while capturing the results of contractile ring formation. By labeling cells and moving microtubules around while still being able to see them and their impact on microfilaments, the investigators were able to selectively inhibit one mechanism of cell division or the other.

The study results will appear in PLoS Biology.


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