Photosynthesis

About: Photosynthesis is a research topic. Over the lifetime, 19789 publications have been published within this topic receiving 895197 citations.

The Photosynthetic Reaction Center from the Purple Bacterium Rhodopseudomonas viridis.

Abstract: The history and methods of membrane protein crystallization are described. The solution of the structure of the photosynthetic reaction center from the bacterium Rhodopseudomonas viridis is described, and the structure of this membrane protein complex is correlated with its function as a light-driven electron pump across the photosynthetic membrane. Conclusions about the structure of the photosystem II reaction center from plants are drawn, and aspects of membrane protein structure are discussed.

Blue light dose–responses of leaf photosynthesis, morphology, and chemical composition of Cucumis sativus grown under different combinations of red and blue light

Abstract: The blue part of the light spectrum has been associated with leaf characteristics which also develop under high irradiances. In this study blue light dose–response curves were made for the photosynthetic properties and related developmental characteristics of cucumber leaves that were grown at an equal irradiance under seven different combinations of red and blue light provided by light-emitting diodes. Only the leaves developed under red light alone (0% blue) displayed dysfunctional photosynthetic operation, characterized by a suboptimal and heterogeneously distributed dark-adapted Fv/Fm, a stomatal conductance unresponsive to irradiance, and a relatively low light-limited quantum yield for CO2 fixation. Only 7% blue light was sufficient to prevent any overt dysfunctional photosynthesis, which can be considered a qualitatively blue light effect. The photosynthetic capacity (Amax) was twice as high for leaves grown at 7% blue compared with 0% blue, and continued to increase with increasing blue percentage during growth measured up to 50% blue. At 100% blue, Amax was lower but photosynthetic functioning was normal. The increase in Amax with blue percentage (0–50%) was associated with an increase in leaf mass per unit leaf area (LMA), nitrogen (N) content per area, chlorophyll (Chl) content per area, and stomatal conductance. Above 15% blue, the parameters Amax, LMA, Chl content, photosynthetic N use efficiency, and the Chl:N ratio had a comparable relationship as reported for leaf responses to irradiance intensity. It is concluded that blue light during growth is qualitatively required for normal photosynthetic functioning and quantitatively mediates leaf responses resembling those to irradiance intensity.

The light-harvesting and protective functions of carotenoids in photosynthetic membranes

Abstract: Siefermann-Harms, D. 1987. The light-harvesting and protective functions of carotenoids in photosynthetic membranes.

Temperature effects on photosynthetic capacity, respiration, and growth rates of bloom-forming cyanobacteria

Abstract: The literature was reviewed to determine the direct temperature effects on photosynthetic capacity (Pmax), specific respiration rate (Rest), and growth rate of bloom‐forming cyanobacteria (Anabaena, Aphanizomenon, Microcystis, Oscillatoria) and to assess the importance of direct tern‐perature effects on cyanobacterial dominance in lakes. This analysis is supported by field studies of Microcystis aeruginosa in a hypertrophic lake. The literature and field data show that Pmax, Rest, and growth rate are temperature‐dependent with optima usually at 25 °C or greater. The four genera varied in their response to low temperatures with Microcystis being most severely limited belw about 15 °C. Oscillatoria tended to tolerate the widest range of temperatures. However, an examination of field data from representative lakes around the world indicated that direct temperature effects were secondary to indirect temperature effects (mixing) and nutrients in determining the dominance of bloom‐forming cyanobacteria...