Mathematical Biology Seminar: Eldon Emberly

   
In all multicellular organisms one can find examples where a growing tissue divides up until some final fixed cell number ( e.g. in the worm C. elegans there are just 302 neurons). In most of these examples a cell divides asymmetrically where after division the two cells inherit different types or quantities of molecules. Often after asymmetric division the cells receive further extracellular cues that regulate their growth process as well. However, is it possible to find a cell autonomous mechanism that will yield any arbitrary final population size? Here we present a minimal model based on asymmetric division and dilution of a cell-cycle regulator that can generate any final population size that might be needed. We show that within the model there are a variety of growth mechanisms from linear to non-linear that can lead to the same final cell count. Interestingly, when we include noise at division we find that there are special final cell population sizes that can be generated with high confidence that are flanked by population sizes that are less robust to division noise. When we include further noise in the division process we find that these special populations can remain relatively stable and in some cases even improve in their fidelity. The simple model has a rich behaviour which will be discussed.