Key questions for biologists interested in cells are:
When a rapidly-growing cell divides into two smaller cells, what triggers the split?
Is it the size the growing cell eventually reaches?
Or is the real trigger the time period over which the cell keeps growing ever larger?
To roll this into one big question: how do cells control their size and maintain stable size distributions? The reason for the great interest is because some researchers think that identifying the mechanism for cell division would provide answers to the escalating processes of cell division that can lead to cancer.
A new research project has gone some way to providing answers to this. The research group has turned to bacteria for the answer. Cell division is the process by which a parent cell divides into two or more daughter cells. Bacteria undergo a type of vegetative cell division known as binary fission. Here their genetic material is segregated equally into two daughter cells.
For the study, researchers developed a micro-size device to isolate and then physically manipulate individual genetic materials. The device enabled researchers to track the development of thousands of individual bacterial cells for hundreds of generations. The main focus was on Escherichia coli.
The research group discovered a growth law. With this exponential cell growth is based on a constant rate. It was also discovered that cell size and the time between cell divisions was not related to when the cells divided. Instead, to ensure that the distribution of different sized cells within a population remained constant; cells follow a model of cell-size control. This means that cells do not sense space or time; alternatively, they add a constant size irrespective of their birth size. It is this so-termed ‘adder’ principle that automatically ensures stability of size distributions.
The findings have been published in the journal Current Biology. The paper is titled “Cell-Size Control and Homeostasis in Bacteria.”
