Central role for ATP in determining some aspects of animal and plant cell behaviour

Abstract

Light, temperature and pressure all act to influence both intracellular ATP levels and cytoplasmic viscosity. Decrease of temperature decreases cytoplasmic viscosity and increases ATP level. Increase in pressure (at least at high hydrostatic pressures) similarly acts to increase ATP level and to decrease viscosity. In both cases, cellular rounding and impaired adhesion is observed. The effect of light is more complex. Whereas, low light intensity decreases ATP in both animal and plant cells and tissues; in plants, high irradiance tends to increase ATP, possibly through the intervention of photosynthesis beyond the compensation point. Again, high ATP is associated with decrease in viscosity. In all examples studies, an inverse correlation can be adduced between increase of ATP level and decrease of cytoplasmic viscosity. Moreover, a similar correlation can be established by the use of narcotics and anaesthetics, which also increase ATP level and decrease cytoplasmic viscosity. It is suggested that many cellular phenomena which are reflected in the behaviour of the whole organism depend on, and directly respond to fluctuations of intracellular ATP, and it is in this manner that the cell and organism transduces parameters of state. In this category may be included aspects of morphogenesis, cell division and cell adhesion; and possibly other phenomena such as irritability, dormancy and melanophoric response. On the basis of these results and on experimental evidence, it is suggested that the underlying rhythm of circadian clocks is that of ATP (and other nucleoside phosphates) at a cellular level and that the common basis of the interaction of light and temperature as “Zeitgeber” or phasing agents depends on this community of action.