Temperature effects on energy metabolism: A dynamic system analysis

Abstract

Q10 factors are widely used as indicators of the magnitude of temperature-induced changes in physicochemical and physiological rates. However, there is a long-standing debate concerning the extent to which Q10 values can be used to derive conclusions about energy metabolism regulatory control. The main point of this disagreement is whether or not it is fair to use concepts derived from molecular theory in the integrative physiological responses of living organisms. We address this debate using a dynamic systems theory, and analyse the behaviour of a model at the organismal level. It is shown that typical Q10 values cannot be used unambiguously to deduce metabolic rate regulatory control. Analytical constraints emerge due to the more formal and precise equation used to compute Q10, derived from a reference system composed from the metabolic rate and the Q10. Such an equation has more than one unknown variable and thus is unsolvable. This problem disappears only if the Q10 is assumed to be a known parameter. Therefore, it is concluded that typical Q10 calculations are inappropriate for addressing questions about the regulatory control of a metabolism unless the Q10 values are considered to be true parameters whose values are known beforehand. We offer mathematical tools to analyse the regulatory control of a metabolism for those who are willing to accept such an assumption.