Compositional homeostasis of the dinoflagellate Protoceratium reticulatum grown at three different pCO2.

In the CO2-richer world that awaits us, the impact of elevated pCO2 on the allocation of resources in phytoplankton may have profound repercussions on the physiology of the microalgae and on the ecology of the ecosystems of which they are part. We studied the overall physiology and cell composition of the potentially toxic dinoflagellate Protoceratium reticulatum subjected to a medium-term increase of CO2. The physiological responses investigated were growth rates, cell size, photosynthetic and respiratory rates, and key enzyme activities.

Homeostasis of cell composition during prolonged darkness.

The chemical composition of organisms in relation to their environmental resource availability is an area of intense research activity. We studied the changes in cell composition of the cyanobacterium Phormidium autumnale in response to prolonged darkness. Cells allocated their internal resources in a homeostatic manner, oxidizing all the three major cellular constituents in a proportional way.