EFFECT OF CHROMATIC ADAPTATION OF SPECTRAL PROPERTIES AND ORIENTATIONOF COMPLEXES AND ON ENERGY-TRANSFER IN CYANOBACTERIA TOLYPOTHRIX CELLS EMBEDDED IN SKEW STRETCHED POLY(VINYL ALCOHOL) FILMS

Tolypothrix tenuis cells cultured under white, red and green lights (l ight adapted) were embedded in a polymer film and stretched along two axes forming an angle of 40 degrees (skew deformed samples) or along o ne axis only. In skew samples a high degree of cell orientation was re ached. Unoriented and oriented samples were photographed under fluores cent microscope. Polarized absorption and fluorescence spectra for uni axial and skew film samples were measured. Skew deformation of polymer matrix compared to one axis stretching provides better band resolutio n in polarized spectra of Tolypothrix cells. The efficiency of excitat ion energy transfer from various accessory pigments to fluorescent chl orophyll a from photosystem 1 and 2 for different polarization of exci tation and emission light is discussed. Excitation energy transfer fro m phycocyanin to F740 emitting chlorophyll is equally efficient in the red and green light adapted cells. Carotenoids energy transfer is les s efficient in the red light adapted cells than in the green light one s. This suggests that the energy transfer is going to chlorophyll via phycoerythrin. The orientation of pigments in cells adapted to various colours of light have been compared. Strong influence of pigment orie ntation on excitation energy transfer is shown.,