In RNA interference (RNAi), small interfering RNA (siRNA) suppresses the expression of its target mRNA with a perfect complementary sequence. In addition, siRNA also suppresses the expression of ...unintended mRNAs with partially complementary sequences mainly within the siRNA seed region (nucleotides 2-8). This mechanism is highly similar to microRNA (miRNA)-mediated RNA silencing, and known as the siRNA-mediated off-target effect. Previously, we revealed that the off-target effect is induced through stable base-pairing between the siRNA seed region and off-target mRNAs, but not induced through unstable base-pairing. However, in our recent study, we found that the siRNA seed region consists of two functionally different domains: nucleotides 2-5, essential for off-target effects, and nucleotides 6-8, involved in both RNAi and off-target effects. In this study, we investigated the most responsible region for the off-target effect by conducting a comprehensive analysis of the thermodynamic properties of all possible siRNA subregions that involved a machine learning technique using a random sampling procedure. As a result, the thermodynamic stability of nucleotides 2-5 showed the highest positive correlation with the off-target effect, and nucleotides 8-14 showed the most negative correlation. Thus, it is revealed that the siRNA off-target effect is determined by the base-pairing stabilities of two different subregions with opposite effects.
Cereulide-producing Bacillus cereus isolates can cause serious emetic (vomiting) syndrome and even acute lethality. As mobile genetic elements, the exploration of prophages derived from emetic B. ...cereus isolates will help in our understanding of the genetic diversity and evolution of these pathogens. In this study, five temperate phages derived from cereulide-producing B. cereus strains were induced, with four of them undergoing genomic sequencing. Sequencing revealed that they all belong to the Siphoviridae family, but presented in different forms in their hosts. PfNC7401 and PfIS075 have typical icosahedral heads, probably existing alone as phagemids in the host with self-replicating capability in the lysogenic state. PfEFR-4, PfEFR-5, and PfATCC7953 have elongated heads, with the genomes of the former two identified as linear dsDNA, which could be integrated into the host genome during the lysogenic state. Genomic comparison of the four phages with others also derived from emetic B. cereus isolates showed similar genome structures and core genes, thus displaying host spectrum specificity. In addition, phylogenic analysis based on the complete genome and conserved tail fiber proteins of 36 Bacillus species-derived phages confirmed that the phages derived from emetic B. cereus strains were highly similar. Furthermore, one endolysin LysPfEFR-4 was cloned and showed lytic activity against all tested emetic B. cereus strains and cross-lytic activity against some other pathogenic bacteria, implying a potential to control bacterial contamination in the food supply.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Facile alignment control of graphene oxide (GO) particles in aqueous dispersions is a highly useful technique for various potential applications. Aqueous GO dispersions were recently reported to have ...an extremely large Kerr coefficient, which may provide a valuable pathway to the alignment control of GO particles. We investigated the electro-optic responses of GO dispersions in various ionic solutes and with varying ionic concentrations. We found that the addition of NaOH actually improved the electro-optic sensitivity of the GO dispersion, while other ionic additives resulted in desensitization. We experimentally and theoretically elucidated the underlying mechanism of the phenomena. The mechanism is closely related to the acidic nature of the GO dispersion, which is neutralized by the addition of NaOH. The addition of ionic solutes caused only a mild change in the surface conductivity of GO particles, but it brought about a large variation in the bulk solvent conductivity. The electro-optical sensitivity agreed well with the variation in solvent conductivity. Thus, the electro-optic response of GO dispersion was influenced more by the electric properties of solvent rather than by those of the GO particle itself. We also found that the cation-exchange capacity for H+ ions in the electrical double layer is quite high; i.e., H+ ions are not likely to be replaced by other ions.
Abrupt drought–flood alternation (T1) is a meteorological disaster that frequently occurs during summer in southern China and the Yangtze river basin, often causing a significant loss of rice ...production. In this study, the response mechanism of yield decline under abrupt drought–flood alternation stress at the panicle differentiation stage was analyzed by looking at the metabolome, proteome as well as yield and physiological and biochemical indexes. The results showed that drought and flood stress caused a decrease in the yield of rice at the panicle differentiation stage, and abrupt drought–flood alternation stress created a synergistic effect for the reduction of yield. The main reason for the decrease of yield per plant under abrupt drought–flood alternation was the decrease of seed setting rate. Compared with CK0 (no drought and no flood), the net photosynthetic rate and soluble sugar content of T1 decreased significantly and its hydrogen peroxidase, superoxide dismutase, peroxidase activity increased significantly. The identified differential metabolites and differentially expressed proteins indicated that photosynthesis metabolism, energy metabolism pathway and reactive oxygen species response have changed strongly under abrupt drought–flood alteration stress, which are factors that leads to the rice grain yield reduction.
Epitaxial alignment of organic liquid crystal (LC) molecules on single‐crystal graphene (SCG), an effective epitaxial molecular assembly template, can be used in alignment‐layer‐free liquid crystal ...displays. However, selectivity among the threefold symmetric easy axes of LCs on graphene is not well understood, which limits its application. Here, sixfold symmetric radial LC domains are demonstrated by dropping an LC droplet on clean SCG, which reveals that the graphene surface does not have an intrinsic preferential direction. Instead, the first contact geometry of the LC molecules determines the direction. Despite its strong anchoring energy on graphene, the LC alignment direction is readily erasable and rewritable, contrary to previous understanding. In addition, the quality of the threefold symmetric alignment is sensitive to alien residue and graphene imperfections, which can be used to detect infinitesimal impurities or structural defects on the graphene. Based on this unique epitaxial behavior of LCs on SCG, an alignment‐layer‐free electro‐optical LC device and LC alignment duplication, which can result in practical graphene‐based flexible LC devices, are realized.
A sixfold symmetric molecular assembly on clean, large, single‐crystal graphene is presented, which directly proves that the molecular‐ordering direction is determined by the first contact direction of the LC molecules on the graphene surface. Epitaxial molecular assembly along one direction is erasable and rewritable to another direction, unlike in previous reports. The findings remedy misleading knowledge regarding epitaxial molecular assembly on graphene.
Pyruvate kinase M2 (PKM2) is an essential regulator of the Warburg effect, but its biological function promoting immune escape of hepatocellular carcinoma (HCC) is unclear.
GEPIA web tool and ...immunohistochemistry (IHC) analysis were employed to evaluate the clinical relevance of PKM2 in HCC patients. Both
CCK-8, colony formation, and transwell assays, and
xenografts were performed to evaluate the malignancy of HCC cells. PKM2 and PD-L1 levels were examined by Western blot, qRT-PCR, and IHC. The role of PKM2 on
immune response was also investigated.
PKM2 was significantly upregulated in HCC and associated with a poor prognosis of HCC patients. Knockdown of PKM2 inhibited
proliferation, migration, and invasion of HCC cells, as well as
tumor growth. Strikingly, PKM2 showed a strong correlation with the expression of immune inhibitory cytokines and lymphocyte infiltration in HCC. The overexpression of PKM2 sensitized HCC to immune checkpoint blockade, which enhanced IFN-γ positive CD8 T cells in HCC mice models.
PKM2 might be a predictor and a potential therapeutic target for immune checkpoint inhibitors in HCC.
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•A novel method for harvesting energy using air bubbles in water.•Higher transducer efficiency than water droplets.•Improvement of harvesting energy using artificially embedded ...surface charges.
Technology to harvest electrical power from waste micro-mechanical energy is increasingly in demand. A promising approach lies in manipulating the electrical double layer on hydrophobic surfaces; however, the underlying mechanism is still unclear. Here, we demonstrate that ascending air bubbles in water can produce electrical power in a mode similar to other systems that use descending water droplets. Although the two systems, which are analogous to electrons and holes in semiconductors, are similar in fundamental principle, their detailed electrification mechanisms are significantly different. In the air bubble system, only the pre-existing charges on the surface are involved. However, electrification in the water droplet system is dominated by triboelectric charges accumulated on the surface over time. An air bubble can produce a maximum of nine times more energy than a water droplet due to its advantages in terms of its geometry, hydrodynamics, and electro-circuitry. We also suggest an innovative approach to improve energy-harvesting efficiency using artificially embedded charges.
This article proposes a new phase compensation technique to expand the operating bandwidth of an asymmetric Doherty power amplifier (ADPA). Its operation principle is to increase the solution space ...of network parameters, thereby contributing to the broadband solvability of network parameters. The article provides a general method for solving network parameters in theory and numerical solutions for each network parameter. To verify the theory, a simple current source model simulates the load modulation process. The results show that this new compensation technique has consistent performance with the load modulation process of traditional ADPA at a similar parameter solution region. This technique can greatly expand the applicability of the network and allow for a more flexible design of ADPA. Furthermore, this theory was validated by designing a broadband ADPA of 1.7-2.7-GHz. The experimental results show that the saturation output power range is 46.9 dBm-48.5 dBm, with a saturation gain between 6 dB-9.3 dB and a corresponding saturation efficiency of 44%-69%. The efficiency is between 37%-65% at 6 dB back-off and 44%-52% at 9 dB back-off.
Melamine quaternary ammonium salt (MQAS), a novel flame‐retardant intercalation modifier, was used to prepare the flame‐retardant organic montmorillonite (FOSM), and which was added to SBR by a ...two‐roll mixing and molding process to prepared the SBR/FOSM composites. The synergistic flame‐retardant effects of sodium‐based montmorillonite (MMT) and MQAS were investigated by the various methods. The LOI value of SBR was only 19.1%, and FOSM‐4 increased the LOI value of SBR to 24.3%. The cone calorimetry test showed that compared with SBR, the total heat release and the peak heat release rate of SBR/FOSM were reduced by 81.39% and 86.08%, respectively. The analysis of MMT after modification showed that the grafting rate of MQAS was about 10% and the interlayer spacing of MMT was enlarged by about 20%. The synergy of MQAS and MMT not only effectively solves the violent droplet of pure SBR combustion, but also avoids the curling problem of only adding MMT. The char morphology and TG‐FTIR showed that FOSM had dual flame‐retardancy in the condensed phase and the gas phase. The synergistic flame‐retardant effect of phosphorus‐free flame‐retardant modifier and MMT will open up new possibilities for flame‐retardant elastomer composites.
Melamine quaternary ammonium salt (MQAS) was Intercalated into montmorillonite (MMT) as a flame retardant modifier in Butadiene Styrene Rubber(SBR). Together, MQAS acted as flame retardantsby absorbing heat and MMT could prevent heat penetration to the SBR. Therefore, the synergistic flame‐retardant effect of phosphorus‐free flame‐retardant modifier and MMT will open up new possibilities for flame‐retardant elastomer composites.
An outbreak of clusters of viral pneumonia due to a novel coronavirus (2019-nCoV/SARS-CoV-2) happened in Wuhan, Hubei Province in China in December 2019. Since the outbreak, several groups reported ...estimated
of Coronavirus Disease 2019 (COVID-19) and generated valuable prediction for the early phase of this outbreak. After implementation of strict prevention and control measures in China, new estimation is needed. An infectious disease dynamics SEIR (Susceptible, Exposed, Infectious, and Removed) model was applied to estimate the epidemic trend in Wuhan, China under two assumptions of
. In the first assumption,
was assumed to maintain over 1. The estimated number of infections would continue to increase throughout February without any indication of dropping with
= 1.9, 2.6, or 3.1. The number of infections would reach 11,044, 70,258, and 227,989, respectively, by 29 February 2020. In the second assumption,
was assumed to gradually decrease at different phases from high level of transmission (
= 3.1, 2.6, and 1.9) to below 1 (
= 0.9 or 0.5) owing to increasingly implemented public health intervention. Several phases were divided by the dates when various levels of prevention and control measures were taken in effect in Wuhan. The estimated number of infections would reach the peak in late February, which is 58,077-84,520 or 55,869-81,393. Whether or not the peak of the number of infections would occur in February 2020 may be an important index for evaluating the sufficiency of the current measures taken in China. Regardless of the occurrence of the peak, the currently strict measures in Wuhan should be continuously implemented and necessary strict public health measures should be applied in other locations in China with high number of COVID-19 cases, in order to reduce
to an ideal level and control the infection.
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