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Oligomerization state and pigment contents of algal light-harvesting proteins
MALINOVÁ, Kateřina
Light-harvesting antennas (LHCs) from four microalgae species (diatom Phaeodactylum tricornutum, haptophyte Emiliania huxleyi, and two eustigmatophytes Nannochloropsis oceanica and Trachydiscus minutus) were studied. LHCs were extracted and purified using sucrose gradient ultracentrifugation and ion-exchange chromatography. Oligomerization states of LHCs were assessed using two independent methods - CN-PAGE and size-exclusion chromatography. Effects of the purification on LHC pigment composition was assessed using HPLC.
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Cirkadiální hodiny se neúčastní načasování buněčného dělení v řase Chlamydomonas reinhardtii
Vítová, Milada ; Bišová, Kateřina ; Hendrychová, Jana ; Čížková, Mária ; Zachleder, Vilém
To determine whether the circadian clock functions in control the entry of algal cells into the cell cycle, we have tested the green alga Chlamydomonas reinhardtii in a wide range of growth conditions both light intensity and temperature. We monitored the course of the cell cycles in asynchronous as well as in synchronized cultures. The cultures were grown either at the continuous light or at alternating light/dark periods. The length of the cell cycle was monitored also at different temperatures and in “circadian” mutant. We have evidenced that the length of the cell cycle corresponding to circadian times can be attained only under relatively narrow range of growth conditions and even in this case the “circadian time” is a result of given growth conditions and not of any circadian gating. These results suggest that the intrinsic circadian clock does not play any role in timing of the cell cycle division in the green alga Chlamydomonas
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Xantofylový cyklus u rostlin a zelených řas: jeho role ve fotosyntetickém aparátu
Masojídek, Jiří ; Kopecký, Jiří ; Koblížek, Michal ; Torzillo, G.
Light-induced conversion of violaxanthin to zeaxanthin, the so-called xanthophyll cycle serves as a major, short-term light acclimation mechanism in higher plants. The role of xanthophylls in thermal dissipation of surplus excitation energy was deduced from the linear relationship between zeaxanthin formation and the magnitude of nonphotochemical quenching. We have studied the role of the xanthophyll cycle in the adaptation of several species of green algae (Chlorella, Scenedesmus, Haematococcus, Chlorococcum, Spongiochloris) to high irradiance. The xanthophyll cycle was found functional in all tested organisms; however its contribution to nonphotochemical quenching is not as significant as in higher plants. We assume that algae rely on other dissipation mechanism(s), which operate along with the xanthophyll cycle-dependent quenching
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