Biologists discover what causes cells to split

December 28, 2014

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Brett Smith for redOrbit.com Your Universe Online

Biologists have long-wondered what causes a rapidly-growing cell to split: The size it reaches? Or the length of time its been growing?

According to a new report in the journalCurrent Biology, a team of American researchers has finally gotten to the bottom of this mystery.

How cells control their size and maintain stable size distributions is one of the most fundamental, unsolved problems in biology, said study author Suckjoon Jun, an assistant professor of physics and molecular biology at UC San Diego. Even for the bacteriumE. coli, arguably the most extensively studied organism to date, no one has been able to answer this question.

In the study, researchers created a small device to separate and physically adjust individual genetic components.

It turned out that we can use this device to also follow the life history of thousands of individual bacterial cells for hundreds of generations, Jun said. We looked at the growth patterns of the cells very, very carefully, and realized that there is something really special about the way the cells control their size.

In our study, we monitored the growth and division of hundreds of thousands of two kinds of bacterial cells,E. coli andB. subtilis, under a wide range of tightly controlled steady-state growth conditions, he added. This produced statistical samples about three orders of magnitude, or a thousand times better, than those previously available. We could thus pursue an unprecedented level of quantitative analysis.

The scientists discovered through mathematical models that matched up with their experimental results that the development of cells followed growth rules, basically exponential growth founded on a constant rate. Additionally, they discovered that neither cell size nor the time between divisions had anything to do with when the cells split. Instead, to maintain the circulation of several sized cells inside a population, the cells implemented what the scientists termed an extraordinarily simple quantitative principle of cell-size control.

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Biologists discover what causes cells to split