Alkaline pH is one of the most important problems of our aquatic habitat. We used Stigonematalean native cyanobacterium Fischerella sp. FS 18 as our model strain, andstudied it under different alkaline pHs (7, 9 and rarely 11) under two different – short and long- time treatments (24 and 96 hours after inoculation). Spectroscopic results showed that both alkalinity and time affected growth rate...

Genes of the HSP70 chaperone family are induced by light. In Chlamydomonas reinhardtii, the induction of HSP70 (70 kDa heat shock protein) chaperones by light results in a partial protection of photosystem II against damage by photoinhibitory conditions. Underexpression of a chloroplast-localized HSP70 protein caused an increased sensitivity of photosystem II to light. Overexpression of this pr...

The protein composition o f Chlamydomonas reinhardii thylakoids in the molecular weight range of 3 2 -3 5 kDa was studied. The thylakoids were labelled with 32P—Pj in vivo using Prstarved cell cultures, solubilized with SDS and separated by polyacrylam ide gradient gel electrophoresis. The following differentiation of proteins could be accomplished: two proteins were phosphorylated, which were ...

In the red alga Porphyra perforata, the level of chlorophyll fluorescence in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) decreased during illumination of the thallus. The results showed that: (a) this decay was related to the photooxidative activity of photosystem I; (b) Q, the primary electron acceptor of photosystem II, became oxidized during the decay of the fluorescence; ...

To understand whether fusions of thylakoid membranes from the parental chloroplasts occurred during zygote formation in Chlamydomonas reinhardtii, we performed an ultrastructural analysis of the zygotes produced by crossing mutants lacking photosystem I or II protein complexes, in the absence of de novo chloroplast protein synthesis. Thylakoid membranes from each parent could be distinguished o...

Cyanobacterin is a secondary metabolite produced by the cyanobacterium (blue-green alga) Scytonema hofmanni. The compound had previously been isolated and chemically characterized. It was shown to inhibit the growth of algae at a concentration of approximately 5 micromolar. Cyanobacterin also inhibited the growth of angiosperms, including the aquatic, Lemna, and terrestrial species such as corn...

Photosynthetic thylakoid membranes in plants contain highly folded membrane layers enriched in photosystem II, which uses light energy to oxidize water and produce oxygen. The sunlight also causes quantitative phosphorylation of major photosystem II proteins. Analysis of the Arabidopsis thaliana stn7xstn8 double mutant deficient in thylakoid protein kinases STN7 and STN8 revealed light-independ...

The variable fluorescence yield of photosystem II is dependent on the redox state of the fluorescence quencher molecule or the primary electron acceptor of the system. We have carried out redox titrations of fluorescence yield of a photochemically active photosystem-II reaction-center particle and have measured the redox potential of the photosystem-II primary acceptor.During reductive titratio...

Jutta Thiemann and W olfgang Barz Institut für Biochemie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität, Hindenburgplatz 55, D-48143 Münster, Bundesrepublik Deutschland Dedicated to Professor Rolf Wiermann on the occasion o f his 60th birthday Z. Naturforsch. 49c, 791-801 (1994); received May 30/July 11, 1994 Chenopodium rubrum, Photoautotrophic Cell Cultures, Herbicide Resi...