Modulation of membrane fluidity by catalytic hydrogenation affects the chilling susceptibility of the blue‐green alga, Anacystis nidulans

All the changes, i.e. the phase separation temperature of thylakoid lipids, shift in the chilling induced increase of K + permeability and decline in photosynthetic O 2 ‐production, respectively, brought about by temperature acclimation in Anacystis nidulans , can be accomplished by homogeneous catalytic hydrogenation of the fatty acids, as well, using a new water‐soluble Pd(II) complex, hitherto unknown in biological applications. Since the thermo‐adaptation replaced by proper hydrogenation conducted under isothermal condition results in a similar modification of chilling susceptibility, it afforts direct evidence that chilling response is mediated by changing the degree of fatty acid unsaturation in Anacystis nidulans .