The review is devoted to the outstanding contributions to the path of carbon in photosynthesis by Professor Emeritus Andrew A. Benson, on the occasion of his death at the age of 97, on January 16, 2015. Benson is the legendary co-discoverer of the photosynthetic reductive pentose phosphate cycle, known to every student of photosynthesis as the Benson-Bassham-Calvin cycle. This pathway evolved into the dominant assimilation mechanism for atmospheric carbon into metabolites. The fundamental ecological and biochemical optimization and evolutionary stability of this mechanism unfolded elegantly in Benson’s hands, as he was the first to recognize the building blocks for the synthesis of essential organic compounds that satisfy the energetic needs and demands of most life forms. Photosynthetic carbon metabolism together with other energy and oxidative reactions and secondary biosynthetic processes are critical for the formation of organic matter; and, thereby, the Benson-Bassham-Calvin cycle ensures maintenance of the biosphere., K. Biel, I. Fomina., and Obsahuje bibliografii
The macrozoobenthos in saline pools at dumps in a former coal mining area was studied over a period of two years. Due to specific environmental conditions these pools are unique in the Czech Republic. Extremely high values of salinity (up to 11‰) along with a low concentration of dissolved phosphorus (0.01-0.1 mg.l-1) are typical of some of the water in this area. The pools were grouped into three categories based on their conductivity values and treated using cow dung, municipal wastewater treatment sludge and inorganic NPK (nitrogen-phosphorus-potassium) fertilizer at doses recommended for carp ponds. The application of fertilizer had a positive effect on the density and biomass of all the groups in the macrozoobenthos. The highest and the lowest increases in macrozoobenthos biomass were recorded after the application of NPK and cow dung, respectively. However, the application of fertilizer had no effect on the diversity of macrozoobenthos. Chironomus aprilinus, recorded in the Czech Republic for the first time, inhabited all pools with conductivity ranges of between 5,000-16,000 µS.cm-1. The density of C. aprilinus larvae increased with increasing salinity reaching a maximum of about 17,083 ind.m-2 (biomass - 82 g.m-2). Analysis of C. aprilinus phenology revealed a bivoltine pattern with the summer generation of larvae reaching a maximum in June-July and the overwintering generation in October to November., Josef Matěna, Iva Šínová, Jakub Brom, Kateřina Novotná., and Obsahuje bibliografii
Benzoxazolin-2-(3H)-one (BOA) has been tested in many plants species, but not in soybean (Glycine max). Thus, a hydroponic experiment was conducted to assess the effects of BOA on soybean photosynthesis. BOA reduced net photosynthetic rate, stomatal conductance, and effective quantum yield of PSII photochemistry without affecting intercellular CO2 concentration or maximal quantum yield of PSII photochemistry. Results revealed that the reduced stomatal conductance restricted entry of CO2 into substomatal spaces, thus limiting CO2 assimilation. No change found in intercellular CO2 concentration and reduced effective quantum yield of PSII photochemistry revealed that CO2 was not efficiently consumed by the plants. Our data indicated that the effects of BOA on soybean photosynthesis occurred due to the reduced stomatal conductance and decreased efficiency of carbon assimilation. The accumulation of BOA in soybean leaves reinforced these findings. and Obsahuje bibliografii
Betaglucans are highly conserved structural polysacharids in the cell walls of bacteria, cyanobacteria, algae, seaweed, yeast, fungi, lichens, and some plants, particularly grain. They belong to a group of active natural substances commonly called biological response modifiers (BRM) and play a role as potent immune response stimulators in all multicellular animals. Their effects against infectious diseases and in cancer therapy have been described in many experimental research studies and human case histories but their functional mechanisms have not yet been fully elucidated. and Petr Šíma.
Leaf gas-exchange responses to shadefleck-sunfleck and sun-cloud transitions were determined for in situ Cycas micronesica K.D. Hill plants on the island of Guam to add cycads to the published gymnosperm data. Sequential sunfleck-shadefleck transitions indicated understory leaves primed rapidly but open field leaves primed slowly. Time needed to reach 90% induction of net CO2 assimilation (PN) was 2.9 min for understory leaves and 13.9 min for open field leaves. Leaf responses to sun-cloud transitions exhibited minimal adjustment of stomatal conductance, so PN rapidly returned to precloud values following cloud-sun transitions. Results indicate bi-directional leaf acclimation behavior enables mature C. micronesica trees to thrive in deep understory conditions in some habitats and as emergent canopy trees in other habitats. These data are the first nonconifer gymnosperm data; the speed of gas-exchange responses to rapid light transitions was similar to some of the most rapid angiosperm species described in the literature., T. E. Marler., and Obsahuje bibliografii