Die Lichtsammelkomplexe der verschiedenen Algenstämme Phylogenetische Vielfalt eukaryotischer Photosyntheseapparate

The energy distribution between the photosystems and light-induced changes in the stoichiometry of system I and II reaction centers in the chlorophyll b-containing alga Mantoniella squamata (Prasinophyceae).

The chlorophyll b-containing alga Mantoniella squamata was analyzed with respect to its capacity to balance the energy distribution from the light-harvesting antenna to photosystem I or photosystem II. It was shown, that this alga is unable to alter the absorption cross section of the two photosystems in terms of short-time regulations (state transitions). The energy absorbed by the LHC, which contains 60% of total photosynthetic pigments, is transferred to both photosystems without any preference. The stoichiometry of the two photosystems is found to be extremely unequal and variable during light adaptation. In high light, the molar ratio of P-680 per P-700 is found to be two, whereas unde…

Ultrastructure and freeze-fracture studies of the thylakoids ofMantoniella squamata (Prasinophyceae)

The ultrastructure and the supramolecular organization of the thylakoids of the small green flagellate,Mantoniella squamata, were examined in thin sections and freeze-fracture preparations. The whole chloroplast is tightly packed with thylakoids, which show a pattern of meandering, branching and/or anastomosing membranes. In freeze-fracture preparations only two fracture-faces can be distinguished: the PF- and the EF-face. The PF-face has a much higher particle density than the EF-face (PF: 4086 particles/μm2; EF: 865 particles/μm2). The EF-face is not as uniform as the PF-face. The areas which are packed with particles probably correspond to closely appressed thylakoid regions or adhesive …

The molecular architecture of the thylakoid membrane from various classes of eukaryotic algae

There is convincing consensus that the photosynthetic apparatus is of prokaryotic origin. The wide variety of algal plastids is mostly assumed to be the result of different endocytological events. Chloroplasts surrounded by two membranes as in rhodophytes and chlorophytes were considered as the association of a prokaryotic symbiont and a eukaryotic host, whereas algae having a chloroplast surrounded with more than two membranes can be delineated from an endocytological event of two eukaryotes (see S. Gibbs in this volume). Since chlorophyll b was neither combined with chlorophyll c nor with phycobiliproteins it was proposed that all present day chloroplasts can be integrated in three lines.…