The antioxidant balance, photochemical activity of photosystem II (PSII), and photosynthetic pigment content, as well as the expression of genes involved in the light signalling of callus lines of
...Eutrema salsugineum
plants (earlier
Thellungiella salsuginea
) under different spectral light compositions were studied. Growth of callus in red light (RL, maximum 660 nm), in contrast to blue light (BL, maximum 450 nm), resulted in a lower H
2
O
2
content and thiobarbituric acid reactive substances (TBARS). The BL increased the activities of key antioxidant enzymes in comparison with the white light (WL) and RL and demonstrated the minimum level of PSII photochemical activity. The activities of catalase (CAT) and peroxidase (POD) had the highest values in BL, which, along with the increased H
2
O
2
and TBARS content, indicate a higher level of oxidative stress in the cells. The expression levels of the main chloroplast protein genes of PSII (
PSBA
and
PSBD
), the NADPH-dependent oxidase gene of the plasma membrane (
RbohD
), the protochlorophyllide oxidoreductase genes (
POR B, C
) involved in the biosynthesis of chlorophyll, and the key photoreceptor signalling genes (
CIB1, CRY2, PhyB, PhyA
, and
PIF3
) were determined. Possible mechanisms of light quality effects on the physiological parameters of callus cells are discussed.
The scattering of dark matter (DM) particles with sub-GeV masses off nuclei is difficult to detect using liquid xenon-based DM search instruments because the energy transfer during nuclear recoils is ...smaller than the typical detector threshold. However, the tree-level DM-nucleus scattering diagram can be accompanied by simultaneous emission of a Bremsstrahlung photon or a so-called "Migdal" electron. These provide an electron recoil component to the experimental signature at higher energies than the corresponding nuclear recoil. The presence of this signature allows liquid xenon detectors to use both the scintillation and the ionization signals in the analysis where the nuclear recoil signal would not be otherwise visible. In this work, we report constraints on spin-independent DM-nucleon scattering for DM particles with masses of 0.4-5 GeV/c$^2$ using 1.4$\times10^4$ kg$\cdot$day of search exposure from the 2013 data from the Large Underground Xenon (LUX) experiment for four different classes of mediators. Finally, this analysis extends the reach of liquid xenon-based DM search instruments to lower DM masses than has been achieved previously.
In a recent computational study, we revealed some mechanistic aspects of TRPV1 (transient receptor potential channel 1) thermal activation and gating and proposed a set of probable functionally ...important residues — “hot spots” that have not been characterized experimentally yet. In this work, we analyzed TRPV1 point mutants G643A, I679A + A680G, and K688G/P combining molecular modeling, biochemistry, and electrophysiology. The substitution G643A reduced maximal conductivity that resulted in a normal response to moderate stimuli, but a relatively weak response to more intensive activation. I679A + A680G channel was severely toxic for oocytes most probably due to abnormally increased basal activity of the channel (“always open” gates). The replacement K688G presumably facilitated movements of TRP domain and disturbed its coupling to the pore, thus leading to spontaneous activation and enhanced desensitization of the channel. Finally, mutation K688P was suggested to impair TRP domain directed movement, and the mutated channel showed ~100-fold less sensitivity to the capsaicin, enhanced desensitization and weaker activation by the heat. Our results provide a better understanding of TRPV1 thermal and capsaicin-induced activation and gating. These observations provide a structural basis for understanding some aspects of TRPV1 channel functioning and depict potentially pathogenic mutations.
BeKm‐1 is a peptide toxin from scorpion venom that blocks the pore of the potassium channel hERG (Kv11.1) in the human heart. Although individual protein structures have been resolved, the structure ...of the complex between hERG and BeKm‐1 is unknown. Here, we used molecular dynamics and ensemble docking, guided by previous double‐mutant cycle analysis data, to obtain an in silico model of the hERG–BeKm‐1 complex. Adding to the previous mutagenesis study of BeKm‐1, our model uncovers the key role of residue Arg20, which forms three interactions (a salt bridge and hydrogen bonds) with the channel vestibule simultaneously. Replacement of this residue even by lysine weakens the interactions significantly. In accordance, the recombinantly produced BeKm‐1R20K mutant exhibited dramatically decreased activity on hERG. Our model may be useful for future drug design attempts.
Using computational methods, we constructed a model of the cardiac ion channel hERG in complex with BeKm‐1, a scorpion toxin. We identified the crucial role of the toxin residue Arg20 and validated it by in silico and in vitro mutagenesis. The BeKm‐1R20K mutant showed dramatically reduced activity, suggesting the significance of Arg20 for channel binding. Our model aids future drug design attempts.
The condensation of aryl methyl ketones with diethyl oxalate in the presence of metallic sodium or sodium hydride gave sodium 4-aryl-1-ethoxy-1,4-dioxobut-2-en-2-olates, and metal exchange of the ...latter with magnesium(II), zinc(II), cobalt(II), and copper(II) salts afforded the corresponding metal bis(4-aryl-1-ethoxy-1-oxobutane-2,4-dionates). The obtained complexes were tested for antibacterial activity against gram-positive and gram-negative bacteria by the agar diffusion method.
The aim of this work is to study equipment utilization of an enterprise. To examine the random order arrivals and random output, we use the supply and demand model, in which demand is equipment ...utilization and supply is product output. There are no restrictions on the type of value, deterministic or random, and on the form of the distribution function of demand and/or supply. The initial data are integer random supply and demand with arbitrary distribution functions. The output parameters of the model are supported and unsupported demand, and unused supply. These parameters are also integer random variables for which the model allows obtaining their functional characteristics. We show that the conventional deterministic approach to calculating the quantity of equipment as a ratio of the average product demand to the average machine capacity leads to both equipment downtime and consumer unsupported demand. We solve this problem for the enterprise manufacturing temperature sensors. When two pieces of equipment are used to produce a certain type of sensors under study, the average unsupported demand is about 12% of the average monthly order and varies from 17 to 112 (non-produced) sensors. Only five months a year the order is fully executed within a month; the equipment is fully utilized for 7-8 months a year. The model allows calculating not only the average values of parameters, but also their distribution functions.
We revise the process of muon pair production by high-energy muons in rock using the recently published cross-section. The three-dimensional Monte Carlo code MUSIC has been used to obtain the ...characteristics of the muon bundles initiated via this process. We have compared them with those of conventional muon bundles initiated in the atmosphere and shown that large underground detectors, capable of collecting hundreds of thousands of multiple muon events, can discriminate statistically muon induced bundles from conventional ones. However, we find that the enhancement of the measured muon decoherence function over that predicted at small distances, recently reported by the MACRO experiment, cannot be explained by the effect of muon pair production alone, unless its cross-section is underestimated by a factor of 3.
PDF
