PHOTOSYNTHETIC CHARACTERISTICS OF TEMPERATURE-SENSITIVE HIGH FLUORESCENCE MUTANTS OF THE BLUE-GREEN-ALGA, SYNECHOCOCCUS-CEDRORUM

A preliminary characterization of 8 temperature-sensitive, high-fluorescent mutants of the blue-green alga Synechococcus cedrorum is presented. The mutants can be placed into three broad classes based primarily on fluorescence induction kinetics. Class 1 mutants have an increased variable fluorescence, grow less than 50% as fast as wild-type, but show few other photosyntetically-related changes. Mutants in class 2 are morphological growth mutants. They divide very poorly at 40°C, but are similar to the wild-type in pigment composition and fluorescence kinetics. Class 3 is composed of mutants that are characterized by very high fluorescence and a smaller relative proportion of variable fluorescence. Mutants in this class have perturbed photosynthetic rates and variations in the low temperature fluorescence spectra. One of these mutants is also a distinct temperature-sensitive pigment mutation and has a high phycocyanin to chlorophyll ration when grown at 40°C. All of the mutants display specific alterations in their membrane protein composition when grown at the high temperature. © 1979.