نتایج جستجو برای: photosystem ii
تعداد نتایج: 581808 فیلتر نتایج به سال:
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.
The activity of Photosystelil II reaction centers increases in the presence of dichlorobenzoquinone (DCBQ) compared to ferricyanide or dimethylbenzoquinone (DMBQ). We demonstrate that enhanced yields from Photosystem II in the presence of DCBQ depend on flash length (temporal distribution). A broad flash with extended decay enhances oxygen yields while a narrow flash without extended decay (300...
Current ambient UV-B levels can significantly depress productivity in aquatic habitats, largely because UV-B inhibits several steps of photosynthesis, including the photooxidation of water catalyzed by photosystem II. We show that upon UV-B exposure the cyanobacterium Synechococcus sp. PCC 7942 rapidly changes the expression of a family of three psbA genes encoding photosystem II D1 proteins. I...
In this study, we report the structural characterization of photosystem II complexes obtained from partially solubilized photosystem II membranes. Direct observation by electron microscopy, within a few minutes after a mild disruption of the membranes with the detergent n-dodecyl-alpha,D-maltoside, revealed the presence of several large supramolecular complexes. Images of these complexes were s...
determination of chlorophyll content and chlorophyll fluorescence has the potential needed to analyze the efficiency of photosynthesis in plants against environmental stresses, especially salinity, and its simplicity facilitates stress evaluation. in order to study the response of different photosynthetic characters to salinity stress at different sugar beet growth stages, two separate experime...
After proper fixation with glutaraldehyde, spinach thylakoids retain both photosystem I and photosystem II activity. The photochemical activity of fixed thylakoids is highly resistant to 1% triton. This indicates that fixed thylakoids may be useful starting material for isolation of functional components which can be related to the original structure of the membrane.
Climate Change Cluster (C3), University of Technology Sydney, Ultimo, NSW, Australia, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, ACT, Australia, 3 Biological Research Centre, Institute of Plant Biology, Hungarian Academy of Sciences, Szeged, Hungary, Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollo...
Photosyntlhesis is presently conceived as a cooperation between 2 photoacts, photosystem I generating a strong reductant and a weak oxidant, photosystem II generating a srong oxidant (yielding O2) and a weak reductant. Coupling between the 2 photosteps presumably occurs between the weak reductant and the weak oxidant, a step possibly generating high energy phosphate. A number of means are avail...
Environmental stresses lower the efficiency of photosynthesis and sometimes cause irreversible damage to plant functions. When spinach thylakoids and Photosystem II membranes were illuminated with excessive visible light (100-1,000 µmol photons m(-1) s(-1)) for 10 min at either 20°C or 30°C, the optimum quantum yield of Photosystem II decreased as the light intensity and temperature increased. ...
The effects of salinity on the primary processes of photosynthesis were studied in the red alga Porphyra perforata. The results show that there are at least three sites in the photosynthetic apparatus of this alga that were affected by increased salinity. The first site, photoactivation and dark-inactivation of electron flow on the reducing side of photosystem I, was completely inhibited at hig...
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