Discussion
In the anemones exposed to light and feeding treatments, coupling of host and symbiont
cells in the G2 phase of cell division occurred when both partners were fed or both were unfed.
However, feeding only one partner decoupled the growth rates of host and symbiont cells.
This suggests that under conditions where only one partner is able to gain nutrients,
the holobiont does not synchronize its growth to keep densities constant.
Why is this important?
Consistent year-round density of S. muscatinei in A. elegantissima
gastrodermal cells suggests that symbiont densities must be controlled by the holobiont.
Regulation of symbiont density through cell cycle synchrony may be more effective than
simply removing extra symbionts from host gastrodermal cells. Understanding this pattern
of regulation between A. elegantissima and S. muscatinei may help us better understand host-symbiont interactions in other cnidarian-algae symbioses.
