Somatic segregation and rate of greening after ultraviolet irradiation of Euglena gracilis

Effect of heat shock on the mutagenicity of mutagens and carcinogens in Euglena gracilis

The effect of heat-shock treatment (42 degrees C for 15 min) on the ability of four mutagens and carcinogens to induce hereditary bleaching in Euglena gracilis cells was investigated. All four mutagens (treatment time: 1-24 h) tested after heat shock increased the frequency of bleached mutants of Euglena gracilis.

Diversity of the ribosomal structures in the Euglena gracilis chloroplast genome: description of a mutant with two ribosomal operons and possible mechanism for its production

We studied the bleached mutant of Euglena gracilis Y3BUD producing carotenoids and rich in chloroplast DNA. This mutant which was produced more than twenty years ago segregates permanently, forming 30 to 50% daughter cells without carotenoids and poor in chloroplast DNA. Electron microscopy and mapping with restriction enzymes show the deletion of a complete ribosomal operon out of the three present in the original strain.

Comparative studies of chloroplastic and nuclear DNA repair abilities after ultraviolet irradiation of Euglena gracilis

Studies of nuclear and chloroplastic-DNA repair after ultraviolet irradiation of Euglena gracilis show that photoreactivation is very efficient at both the nuclear and chloroplastic level. Liquid-holding or split-dose experiments and treatment with caffeine reveal, furthermore, that dark-repair is very efficient in nuclear DNA but not in chloroplastic DNA (ctDNA). The possibility of a chloroplastic dark-repair of restricted efficiency is discussed. Determination of chloroplastic DNA content by reassociation kinetics indicates that an important degradation follows UV irradiation during liquid holding in the dark.