Degreening of the unicellular alga Euglena gracilis: thylakoid composition, room temperature fluorescence spectra and chloroplast morphology

摘要: Thylakoid dismantling is one of the most relevant processes occurring when chloroplasts are converted to non-photosynthetically active plastids. The process well characterised in senescing leaves, but other systems could present different features. In this study, thylakoid has been analysed dividing cells unicellular alga, Euglena gracilis, cultured darkness. Changes photosynthetic pigments and abundance LHC PSII core proteins (D2 CP43) showed that: (i) during 0-24 h interval, decline LHCII was faster than that core; (ii) 24-48 were strongly degraded nearly same extent; (iii) 48-72 declined markedly, while maintained. These changes accompanied by variations room temperature fluorescence emission spectra recorded from single living with a microspectrofluorimeter (excitation, 436 nm; range 620-780 nm). Emission 700-715 nm proposed derive LHCI-II assemblages; at 678 relative matched degradation phases. Overall, results suggest that, degreening E. somewhat associated senescence, because early loss LHCII. Moreover, it disruption correct stoichiometry alters energy transfer photosystems destabilises membrane appression leading destacking observed using transmission electron microscopy.