Formation of regulatory patterns during signal propagation in a Mammalian cellular network

We developed a model of 545 components (nodes) and 1259 interactions representing signaling pathways and cellular machines in the hippocampal CA1 neuron. Using graph theory methods, we analyzed ligand-induced signal flow through the system. Specification of input and output nodes allowed us to identify functional modules. Networking resulted in the emergence of regulatory motifs, such as positive and negative feedback and feedforward loops, that process information. Key regulators of plasticity were highly connected nodes required for the formation of regulatory motifs, indicating the potential importance of such motifs in determining cellular choices between homeostasis and plasticity.     

Interaction of biological nitrogen fixation with sowing nitrogen fertilization on common bean in the two seasons of cultivation in Brazil

Sowing nitrogen (N) fertilization can limit biological nitrogen fixation (BNF) reducing common bean yield. The aim of this study was to evaluate the effect of sowing N fertilization plus inoculation on the growth and yield of plants in the two seasons of cultivation in Brazil. In the dry season, N fertilization and inoculation promoted a greater shoot dry weight and higher pod number and yield than only inoculated. In contrast, in the rainy season, this treatment promoted no increase in shoot dry weight and yield compared with the inoculated alone. The number of nodules was greater for the inoculated alone treatment, but nodule weight was not affected by N fertilization in either season. Therefore, sowing N fertilization and inoculation can be an agronomic practice to achieve a higher common bean yield in the dry season, while in the rainy season, the inoculation without N fertilization can support a high yield at a lower cost.     

Forms of Cu (II), Zn (II), and Pb (II) compounds in technogenically transformed soils adjacent to the Karabashmed copper smelter

Purpose

The aim was to study Cu (II), Zn (II), and Pb (II) forms in technogenically transformed soils adjacent to the Karabashmed copper smelter.

Materials and methods

Studies were performed in the plume zone of the Karabash smelter and in the floodplains of Ryzhii Brook and Sak-Egla River. Geomorphological and geochemical migration processes prevail in technogenic landscapes. The differentiation of landscape-geochemical conditions plays the dominant role, which determines the localization of metals. The total Mn, Cr, Ni, Cu, Zn, Pb, Cd, and As contents and the macroelement compositions of soils were determined by X-ray fluorescence. The composition of Cu, Pb, and Zn compounds in soils was determined by the Tessier sequential fractionation. The determination of the geochemical fractions of heavy metals in soils is a key issue in the study of their mobility. The metals were fractionated into the following five fractions: exchangeable, bound to carbonates, bound to Fe and Mn oxides, bound to organic matter, and residual fractions.

Results and discussion

It is shown that the total Zn and As contents in the 0- to 5-cm layer of soils on monitoring plots exceed their lithosphere clarks in hundreds of times, and the total Cu, Pb, and Cr contents exceed their lithosphere clarks in tens of times. Factors and processes controlling the distribution and transport of Cu, Pb, and Zn forms in soils were determined. According to landscape-geochemical differentiation, the eluvial (automorphic) catena (plot T4) takes the main technogenic load of dust fallouts from the Karabash copper smelter. The accumulation of material brought from above and the geochemical precipitation of discharges from tailings dumps occur in superaqual catenas (plots T1, T2, and T3). In the technogenically transformed soils, the basic stabilizers of the mobility of Cu is organic matter, for Pb it is Fe-Mn (hydro) oxides, and for Zn - it is clay minerals.

Conclusions

The distributions of Cu, Zn, and Pb forms in the studied technogenically transformed soils are due to a number of factors: First, these are the composition of technogenic pollutants contaminating ecosystems and the time during which the contamination occurred, and second, this is the combination of physicochemical properties controlling the buffer properties of the polydisperse system of soils and parent materials.

     

Mineral nitrogen impairs the biological nitrogen fixation in soybean of determinate and indeterminate growth types

Soybean (Glycine max Merrill) crop production in Brazil relies mainly on biological nitrogen fixation (BNF) for nitrogen (N) supply. Recent adoption of indeterminate growth-type genotypes has raised doubts on the need for supplemental mineral N that might negatively affect the BNF. We assessed the effects of mineral N on BNF attributes of soybean genotypes grown in central and southern Brazil. Genotypes were inoculated with Bradyrhizobium sp. and/or received mineral N in three sets of experiments. In the first set, two genotypes received increasing rates of mineral N in nutrient solution, which consistently reduced the BNF. In the second set, mineral N applied at sowing and/or topdressing reduced nodulation and ureides-N in determinate and indeterminate growth-type genotypes. In the third set, mineral N applied at R5.3 stage, foliar or as topdressing, did not increase grain yield in four field experiments. Mineral N impaired BNF irrespective of the growth type and had no effect on grain yield.