ИСТИНА

Reconstitution of rhodopsin activity in blind (carotenoid-less) Chlamydomonas mutants by exogenous retinal was studied by the light-gradient method of photoelectric measurements in cell suspension Dark-grown mutant cells exhibited no photoelectric responses to flashes of actinic light, but within a few minutes after the addition of all-trans retinal (5.10-9-10-6 M) to the cell suspension both photoreceptor potential and regenerative response were registered. Photoreceptor potential in retinal-reconstituted mutant cells resembled that measured in wild type cells concerning the value of threshold fluence, action spectrum (maximum at 500 nm) and sensitivity to hydroxylamine bleaching. Restoration of normal phototactic behavior in retinal-reconstituted mutant cells was shown by measuring photoelectric responses under weak orienting background illumination. Photoelectric responses in retinal-reconstituted mutant cells measured in experimental cuvette with electrodes positioned in the horizontal plane had the opposite sign comparing with wild type cells which can be explained by the -lens effecr of practically transparent cell bodies of blind mutants. With electrodes positioned in the vertical plane the same result could be observed only in medium with increased viscosity preventing gravitactic orientation of the cells.