Microspectrophotometry and the photoreceptor of Phycomyces I.
By applying microspectrophotometry to the sporangiophore of Phycomyces blakesleeanus wild-type and the albino car-10(-) type II, absorption spectra were obtained for 1- to 5-day cultures. Spectra in the growing-zone of the wild-type during Stage IVb, taken from 0.1 to 3 mm below the base of the sporangium, show two distinctly different spectra: one is more characteristic of a carotene, the other of a flavin. Combined, these absorption spectra reproduce closely the action spectrum. For the albino car-10(-), which is deficient in carotenes, only the spectrum characteristic of lumichrome or a reduced flavin was found. A c-type cytochrome was isolated from both strains which, if coupled with a flavin, could permit a photoreversible oxidation-reduction system. Birefringent crystals were observed to be aligned in the growing zone in which the photoreceptor is believed to lie. Micro-spectrophotometry of these crystals shows absorption peaks similar to those of riboflavin crystals.
D001718:Birefringence; D002338:Carotenoids / Q000032:analysis*; D003580:Cytochromes / Q000302:isolation & purification; D005415:Flavins / Q000032:analysis*; D005658:Fungi / Q000032:analysis*; D008027:Light; D008854:Microscopy, Electron; D010858:Pigmentation; D012256:Riboflavin / Q000032:analysis; D011984:Sensory Receptor Cells / Q000032:analysis*; D013053:Spectrophotometry; D013170:Spores
D003580:Cytochromes; D005415:Flavins; D002338:Carotenoids; D012256:Riboflavin