The chromophorylated PBLcm domain of the ApcE linker protein in the cyanobacterial phycobilisome (PBS) serves as a bottleneck for Förster resonance energy transfer (FRET) from the PBS to the antennal ...chlorophyll of photosystem II (PS II) and as a redirection point for energy distribution to the orange protein ketocarotenoid (OCP), which is excitonically coupled to the PBLcm chromophore in the process of non-photochemical quenching (NPQ) under high light conditions. The involvement of PBLcm in the quenching process was first directly demonstrated by measuring steady-state fluorescence spectra of cyanobacterial cells at different stages of NPQ development. The time required to transfer energy from the PBLcm to the OCP is several times shorter than the time it takes to transfer energy from the PBLcm to the PS II, ensuring quenching efficiency. The data obtained provide an explanation for the different rates of PBS quenching in vivo and in vitro according to the half ratio of OCP/PBS in the cyanobacterial cell, which is tens of times lower than that realized for an effective NPQ process in solution.
Due to the growing population and consequent pressure of use, agricultural soils must maintain adequate levels of quantity and quality to produce food, fiber, and energy, without falling victim to a ...negative impact on their balance of nutrients, health, or their ability to function ...
The phycobilisome (PBS) is the cyanobacterial antenna complex which transfers absorbed light energy to the photosystem II (PSII), while the excess energy is nonphotochemically quenched by interaction ...of the PBS with the orange carotenoid protein (OCP). Here, the molecular model of the PBS‐PSII‐OCP supercomplex was utilized to assess the resonance energy transfer from PBS to PSII and, using the excitonic theory, the transfer from PBS to OCP. Our estimates show that the effective energy migration from PBS to PSII is realized due to the existence of several transfer pathways from phycobilin chromophores of the PBS to the neighboring antennal chlorophyll molecules of the PSII. At the same time, the single binding site of photoactivated OCP and the PBS is sufficient to realize the quenching.
1. The pedosphere is a part of our natural heritage. Soils should be considered both for their biological and for their geological resources. 2. During the Anthropocene, human activities have ...dramatically changed the land surface and remodified soil cover, resulting in many natural pedotaxa being at risk of extinction. Recently, biogeographers and ecologists recognized that numerous biotaxa should be considered as edaphic endemisms, and as a consequence, in situ soil preservation is important relative to both its biological and geological value. 3. This contribution discusses the similarity and differences between biodiversity and pedodiversity and proposes using pedodiversity as a surrogate measure of above-ground biodiversity and an indicator of below-ground biodiversity. 4. Another objective is to explore the relevance of soil diversity to soil ecology by illustrating how the analysis of pedotaxa and their genetic soil horizons can be applied in conservation biology. To preserve biological and geological heritage inherent to the pedosphere, we propose to design a network of soil reserves. The proposed network could also be an efficient way to preserve soil characteristics and qualities of undisturbed soils that would become benchmarks for soil monitoring programs. 5. Synthesis and applications. The coincidence between patterns of biodiversity and pedodiversity offers a new and unexplored direction for understanding the genesis of biological and non-biological assemblages and the spatial patterns of soils and living organisms. Pedodiversity can be used as a practical surrogate indicator of soil diversity. We provide a pedodiversity framework for the design of a network of soil reserves for the preservation and monitoring of soil biodiversity. This new framework could contribute toward the development of a unified theory of natural diversity and to understanding the role of the pedosphere in the provision of ecosystem services.
The application of pulp and paper mill sludge to agricultural soils is commonly considered as a strategy to improve soil properties, promote plant growth, and reduce the demand for costly chemical ...fertilization. The aim of this study was to evaluate if sodium lignosulfonate (sLS), one of the sludges of pulp production, may affect the biomass production, the respiration (R) and net CO2 assimilation rate (An) at the leaf level, and the content and accumulation of trace elements in the leaves of cucumbers grown under a sufficient nutrient supply or soil nutrient deficit. A pot culture experiment was conducted using sLS application rates of 0, 1.0, 2.5, 5.0, and 10 vol% to sandy loam soil. The decline in nutrient availability caused an increase in the R/An ratio and dramatically depressed biomass accumulation. The leaf Fe, Ni, Cr, Co, Al, and Pb contents were lower under low nutrient availability than under sufficient nutrient supply. Although sLS was not very effective in lessening the negative effect of nutrient deficiency on biomass accumulation, it reduced respiratory carbon losses and cell membrane permeability in the leaves of cucumbers grown under nutrient deficit. The reduction in the toxic level of leaf Mn in seedlings grown under sufficient nutrient availability and the toxic level of leaf Fe under a nutrient deficit might also be considered as a positive effect of the sLS application to sandy soil.
Organic carbon (OC) accumulation in soil mitigates greenhouse gases emission and improves soil health. We aimed to quantify the dynamics of OC stock in soils and to justify technologies that allow ...annual increasing OC stock in the arable soil layer by 4‰. We based the study on a field experiment established in 1936 in the 9-field crop rotation with a fallow on Chernozem in European Russia. The RothC version 26.3 was used for the reproducing and forecasting OC dynamics. In all fertilizer applications at FYM background, there was a decrease in the OC stock with preferable loss of active OC, except the period 1964–1971 with 2–5‰ annual OC increase. The model estimated the annual C input necessary to maintain OC stock as 1900 kg·ha−1. For increasing OC stocks by 4‰ per year, one should raise input to 2400 kg·ha−1. The simulation was made for 2016–2090 using climate scenarios RCP4.5 and RCP8.5. Crop rotation without fallowing provided an initial increase of 3‰ and 6‰ of stocks in the RCP8.5 and RCP4.5 scenarios accordingly, followed by a loss in accumulated OC. Simulation demonstrates difficulties to increase OC concentration in Chernozems under intensive farming and potential capacity to rise OC stock through yield management.
Phycobilisome (PBS) is a giant water-soluble photosynthetic antenna transferring the energy of absorbed light mainly to the photosystem II (PSII) in cyanobacteria. Under the low light conditions, ...PBSs and PSII dimers form coupled rows where each PBS is attached to the cytoplasmic surface of PSII dimer, and PBSs come into contact with their face surfaces (state 1). The model structure of the PBS core that we have developed earlier by comparison and combination of different fine allophycocyanin crystals, as reported in Zlenko et al. (Photosynth Res 130(1):347–356,
2016b
), provides a natural way of the PBS core face-to-face stacking. According to our model, the structure of the protein–protein contact between the neighboring PBS cores in the rows is the same as the contact between the APC hexamers inside the PBS core. As a result, the rates of energy transfer between the cores can occur, and the row of PBS cores acts as an integral PBS “supercore” providing energy transfer between the individual PBS cores. The PBS cores row pitch in our elaborated model (12.4 nm) is very close to the PSII dimers row pitch obtained by the electron microscopy (12.2 nm) that allowed to unite a model of the PBS cores row with a model of the PSII dimers row. Analyzing the resulting model, we have determined the most probable locations of ApcD and ApcE terminal emitter subunits inside the bottom PBS core cylinders and also revealed the chlorophyll molecules of PSII gathering energy from the PBS.
The phycobilisome (PBS) is a major light-harvesting complex in cyanobacteria and red algae. To obtain the detailed structure of the hemidiscoidal PBS core composed of allophycocyanin (APC) and minor ...polypeptide components, we analyzed all nine available 3D structures of APCs from different photosynthetic species and found several variants of crystal packing that potentially correspond to PBS core organization. Combination of face-to-face APC trimer crystal packing with back-to-back APC hexamer packing suggests two variants of the tricylindrical PBS core. To choose one of these structures, a computational model of the PBS core complex and photosystem II (PSII) dimer with minimized distance between the terminal PBS emitters and neighboring antenna chlorophylls was built. In the selected model, the distance between two types of pigments does not exceed 37 Å corresponding to the Förster mechanism of energy transfer. We also propose a model of PBS and photosystem I (PSI) monomer interaction showing a possibility of supercomplex formation and direct energy transfer from the PBS to PSI.
Arable Chernozems with high SOC contents have the potential to be significant sources of GHGs, and climate change is likely to increase SOC losses, making the issue of carbon sequestration in this ...region even more important. The prospect of maintaining SOC stock or increasing it by 4‰ annually under planned management practice modifications for the period up to 2090 was evaluated using a long-term experiment on Haplic Chernozem in the Rostov Region, Russia. In this study, we used the RothC model to evaluate SOC dynamics for three treatments with mineral and organic fertilization under two adaptation scenarios vs. business-as-usual scenarios, as well as under two climate change scenarios. The correction of crop rotation and the application of organic fertilizers at high rates are essential tools for maintaining and increasing SOC stocks. These methods can maintain SOC stock at the level of 84–87 Mg∙ha−1 until the middle of the 21st century, as the first half of the century is considered to be the most promising period for the introduction of adaptation measures for the additional accumulation of SOC on Chernozems. Part of the additional accumulated SOC is expected to be lost before 2090.
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