Ref ID : 4427
Paul Nicolas, Philippe Heizmann, and Victor Nigon; [Les differents phenotypes de mutants non photosynthetiques (photo-) chez Euglena gracilis; frequence de formation par irradiation ultraviolette]. C.R.Acad.Sc.Paris 294:145-148, 1982
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In Euglena gracilis, pigment-less mutants appear spontaneously with a frequency of about 2-5x10E-3. Ultraviolet-irradiation increases the proportion of chlorophyll-less colonies to an upper limit where green colonies represent 4x10E-4 of surviving ones. This limit might indicate the occurrence of processes involving repair of the chloroplastic DNA. Most of the photosynthetic-deficient (phot-) mutants induced by ultraviolet irradiation are characterized by the presence of a reduced number of chloroplast DNA molecules showing deletions ((phi-) class). Most of the (phi-) mutants present the phenotype (phi-) (chlo-) (car-), where neither chlorophyll nor carotenoids are obvious; the (phi-) (chlo-) (car+) mutants, devoid of chlorophyll but containing carotenoids, are obtained among the (phi-) strains with a frequency lower than 10E-3. The (photo-) mutants which belong to the (cp-) class are characterized by the maintenance of a great number of chloroplastic DNA molecules, where large deletions are absent; their occurrence after ultraviolet irradiation is low.