Light dependent (35 Klux) chlorophyll bleaching in autotrophically grown Euglena gracilis cells at slightly acidic pH (6.5-5.4) is stimulated by the photosystem II blockers DCMU and DBMIB (both 10(-5) M) as well as by the autooxidizable photosystem I electron acceptor, paraquat (10(-3) M). Chlorophyll photobleaching is accompanied by the formation of thiobarbituric acid -- sensitive material ("...

Using a cotransformation system to identify chloroplast transformants in Chlamydomonas reinhardtii, we converted histidine-195 of the photosystem II reaction center D1 protein to a tyrosine residue. The mutants were characterized by a reduced quantum efficiency for photosynthetic oxygen evolution, which varied in a pH-dependent manner, a reduced capacity to oxidize artificial donors to photosys...

The yield of energy transfer from photosystem II to photosystem I in Porphyridium cruentum varies from a minimum value of about 0.50 when the photosystem II reaction centers are all open to a maximum value between 0.90 and 0.95 when the centers are all closed.

Inhibition of photosynthetic electron transport in isolated chloroplasts by lead salts has been demonstrated. Photosystem I activity, as measured by electron transfer from dichlorophenol indophenol to methylviologen, was not reduced by such treatment. However, photosystem II was inhibited by lead salts when electron flow was measured from water to methylviologen and Hill reaction or by chloroph...

The mechanisms underlying the wavelength dependence of the quantum yield for CO(2) fixation (α) and its acclimation to the growth-light spectrum are quantitatively addressed, combining in vivo physiological and in vitro molecular methods. Cucumber (Cucumis sativus) was grown under an artificial sunlight spectrum, shade light spectrum, and blue light, and the quantum yield for photosystem I (PSI...

S. S. Brody*, D. Simpson**, and M . Rieh* * Dept . Biology, New York University, Washington Square, New Yo rk , N . Y . , 10003, U . S . A . * * Carlsberg Research Laboratory, Gammel Carlsbergvej, Valby, Copenhagen, Denmark Z . Naturforsch. 43c, 577-580 (1988); received March 15, 1988 Photosynthesis, Carotene, High Performance L iqu id Chromatography, Photosystems, PigmentProtein Complex The di...

Physiological and molecular phylogenetic approaches were used to investigate variation among 12 cyanobacterial strains in their tolerance of sulfide, an inhibitor of oxygenic photosynthesis. Cyanobacteria from sulfidic habitats were found to be phylogenetically diverse and exhibited an approximately 50-fold variation in photosystem II performance in the presence of sulfide. Whereas the degree o...

to evaluate the effects of methanol and drought stress on chlorophyll fluorescence parameters, chlorophyll and relative water content in sugar beet, a study was conducted in 2008 in maahdasht (karaj, iran). aqueous solutions of 0 (control), 7, 14, 21, 28, 35% (v/v) methanol with each solution containing 0.2% glycine and a second factor, namely drought stress (irrigation after 70% depletion of a...

Automation in generation of architectural feedback from performance indexes like probability distributions, mean values and variances has been of interest to the researchers from last decade. It is well established that due to the complexity in interpreting the performance indices obtained from performance analysis of software architecture and short time to the market, an automated approach is ...

Developing green propulsion concepts for aviation requires some changes in standard procedures for the preliminary aircraft design. Standard design procedures are not readily applicable to aircraft/rotorcraft that use multiple energy sources; innovative concepts like hybrid propulsion systems require new approaches in weight and performance prediction. In this paper the application of new metho...