NSG/SENSE Worksop: Beginning of life
Title: Quantitative steps in the evolution of metabolic organization
Speaker: S. A. L. M. Kooijman
Date: 2005/10/24
Place: VU Amsterdam

    The Dynamic Energy Budget (DEB) theory quantifies the metabolic
    organisation of organisms on the basis of mechanistically inspired
    assumptions. I discuss a scenario for how various elements of this
    theory, such as maintenance, storage, development and life stages
    could have evolved since the beginning of life. The combination of
    homeostasis and maintenance induced the development of reserves
    and that subsequent increases in the maintenance costs came with
    increases of the reserve capacity. The DEB theory specifies
    reserve dynamics on the basis of the requirements of weak
    homeostasis and partitionability. I will present a new mechanism
    for this dynamics which considers an inhibition of growth such
    that homeostasis is most effective and the processes of
    mobilization of reserve and the allocation its products becomes
    independent of each other. Osmotic problems can play a role in
    this inhibition. The monomerisation machinery of the polymers in
    reserve, the resulting monomers, and problably most if not all
    polymerization machinery is part of the reserve in the overall
    dynamics of the cell. The plasticity of membranes is here
    recognized as a mayor step in metabolic evolution; it allowed
    e.g. phagocytosis, which is much more efficient to digest
    live-derived particles, compared to the excretion of digestive
    enzymes.