Ultrastructure of Chenopodium rubrum L. apices during the effect of fusicoccin and photoperiodic induction

Plant transition from vegetative to reproductive development is associated with ultrastructural changes in stem apices. Those seen in Chenopodium rubrum L. under the influence of fusicoccin in many ways resemble those induced by a short-day treatment favourable to flowering. This suggests that fusicoccin can play a definite (physiological) role in plant development.     

The evolutionary dynamics of grammar acquisition

Grammar is the computational system of language. It is a set of rules that specifies how to construct sentences out of words. Grammar is the basis of the unlimited expressibility of human language. Children acquire the grammar of their native language without formal education simply by hearing a number of sample sentences. Children could not solve this learning task if they did not have some pre-formed expectations. In other words, children have to evaluate the sample sentences and choose one grammar out of a limited set of candidate grammars. The restricted search space and the mechanism which allows to evaluate the sample sentences is called universal grammar. Universal grammar cannot be learned; it must be in place when the learning process starts. In this paper, we design a mathematical theory that places the problem of language acquisition into an evolutionary context. We formulate equations for the population dynamics of communication and grammar learning. We ask how accurate children have to learn the grammar of their parents' language for a population of individuals to evolve and maintain a coherent grammatical system. It turns out that there is a maximum error tolerance for which a predominant grammar is stable. We calculate the maximum size of the search space that is compatible with coherent communication in a population. Thus, we specify the conditions for the evolution of universal grammar.     

Constant brain potentials as neurophysiological markers of autoimmune process]

Neuroimmune interactions in systemic rheumatic diseases were studied. The state of the central nervous system was assessed from the parameters of constant brain potentials, and the state of the immune system, from a complex of immunobiochemical parameters. The highest multiple correlation coefficients were revealed between the immunobiochemical parameters and the parameters of the constant brain potential, which characterize linear and standard deviations of potentials in temporal zones from potentials at other points of recording. The results are discussed in terms of structural and functional integration of the immune and nervous systems.     

Influence of the spacer region between the Shine–Dalgarno box and the start codon for fine-tuning of the translation efficiency in Escherichia coli

Translation efficiency contributes several orders of magnitude difference in the overall yield of exogenous gene expression in bacteria. In diverse bacteria, the translation initiation site, whose sequence is the primary determinant of the translation performance, is comprised of the start codon and the Shine–Dalgarno box located upstream. Here, we have examined how the sequence of a spacer between these main components of the translation initiation site contributes to the yield of synthesized protein. We have created a library of reporter constructs with the randomized spacer region, performed fluorescently activated cell sorting and applied next-generation sequencing analysis (the FlowSeq protocol). As a result, we have identified sequence motifs for the spacer region between the Shine–Dalgarno box and AUG start codon that may modulate the translation efficiency in a 100-fold range.     

Long-distance signal transmission and regulation of photosynthesis in characean cells

Photosynthetic electron transport in an intact cell is finely regulated by the structural flexibility of thylakoid membranes, existence of alternative electron-transport pathways, generation of electrochemical proton gradient, and continuous exchange of ions and metabolites between cell organelles and the cytoplasm. Long-distance interactions underlying reversible transitions of photosynthetic activity between uniform and spatially heterogeneous distributions are of particular interest. Microfluorometric studies of characean cells with the use of saturating light pulses and in combination with electrode micromethods revealed three mechanisms of distant regulation ensuring functional coordination of cell domains and signal transmission over long distances. These include: (1) circulation of electric currents between functionally distinct cell domains, (2) propagation of action potential along the cell length, and (3) continuous cyclical cytoplasmic streaming. This review considers how photosynthetic activity depends on membrane transport of protons and cytoplasmic pH, on ion fluxes associated with the electrical excitation of the plasmalemma, and on the transmission of photoinduced signals with streaming cytoplasm. Because of signal transmission with cytoplasmic flow, dynamic changes in photosynthetic activity can develop far from the point of photostimulus application and with a long delay (up to 100 s) after a light pulse stimulus is extinguished.     

Activity of the autoimmune process during systemic rheumatic diseases and distribution of constant brain potential]

The data obtained upon examination of patients with systemic rheumatic diseases were analyzed by the methods of multiple regression and step-by-step discriminant analysis. Is was shown that the activity of autoimmune process correlates with the parameters of distribution of constant potential level in the brain of each patient, irrespective of diagnosis. The scatter of potential values was the most important predictor of activity. An increase in the activity of the autoimmune process correlated with a decrease in the scatter of potential values at recording points; the cerebral cortex became equipotential.     

High-affinity P2Y2 and low-affinity P2X7 receptor interaction modulates ATP-mediated calcium signaling in murine osteoblasts

The P2 purinergic receptor family implicated in many physiological processes, including neurotransmission, mechanical adaptation and inflammation, consists of ATP-gated non-specific cation channels P2XRs and G-protein coupled receptors P2YRs. Different cells, including bone forming osteoblasts, express multiple P2 receptors; however, how P2X and P2Y receptors interact in generating cellular responses to various doses of [ATP] remains poorly understood. Using primary bone marrow and compact bone derived osteoblasts and BMP2-expressing C2C12 osteoblastic cells, we demonstrated conserved features in the P2-mediated Ca²⁺ responses to ATP, including a transition of Ca²⁺ response signatures from transient at low [ATP] to oscillatory at moderate [ATP], and back to transient at high [ATP], and a non-monotonic changes in the response magnitudes which exhibited two troughs at 10⁻⁴ and 10⁻² M [ATP]. We identified P2Y2 and P2X7 receptors as predominantly contributing to these responses and constructed a mathematical model of P2Y2R-induced inositol trisphosphate (IP₃) mediated Ca²⁺ release coupled to a Markov model of P2X7R dynamics to study this system. Model predictions were validated using parental and CRISPR/Cas9-generated P2Y2 and P2Y7 knockouts in osteoblastic C2C12-BMP cells. Activation of P2Y2 by progressively increasing [ATP] induced a transition from transient to oscillatory to transient Ca²⁺ responses due to the biphasic nature of IP₃Rs and the interaction of SERCA pumps with IP₃Rs. At high [ATP], activation of P2X7R modulated the response magnitudes through an interplay between the biphasic nature of IP₃Rs and the desensitization kinetics of P2X7Rs. Moreover, we found that P2Y2 activity may alter the kinetics of P2X7 towards favouring naïve state activation. Finally, we demonstrated the functional consequences of lacking P2Y2 or P2X7 in osteoblast mechanotransduction. This study thus provides important insights into the biophysical mechanisms underlying ATP-dependent Ca²⁺ response signatures, which are important in mediating bone mechanoadaptation.     

The effect of combined application of quercetin and indralin on postradiation repair of the hematopoietic system in acute radiation sickness

Hybrid F1 mice (CBA × C57Bl/6) were subjected to irradiation at a nonlethal dose of 6.7 Gy that brought on acute radiation sickness. In the experiments performed, we observed the beneficial effect of combined application of quercetin injected 30–60 min prior to irradiation with γ rays and the emergent radioprotector indralin injected after irradiation on development of postradiation repair in hematopoietic tissue. This effect was expressed as accelerated formation of endogenous spleen colonies and recovery of spleen weight and attenuation of leucopenia 12 and 16 days after acute irradiation. Treatment with only quercetin was not radioprotective.