T1N6_22 gene is required for biotic and abiotic stress responses in Arabidopsis

Botrytis cinerea causes severe disease in a wide range of plant species and is difficult to be controlled, resulting in significant economic losses. In this study, T1N6_22, a NAD(P)-binding domain-containing protein in Arabidopsis thaliana, was found to be a positive regulator of the basal defense response, and its loss-of-function mutation resulted in enhanced susceptibility to infection by B. cinerea. In the case of Alternaria brassicae, the t1n6_22 plants exhibited enhanced disease symptoms, suggesting the T1N6_22 was a common host response strategy against these pathogens. Further analyses of 35S: T1N6_22 Arabidopsis plants had shown that complemented transgenic plants were also indistinguishable from wild-type plants in their response to B. cinerea inoculation. To gain insight into the role of the T1N6_22 in the plant defense signaling pathway, we detected the expression of the T1N6_22 in different signaling pathway mutants. Strikingly, t1n6_22 plants had impaired tolerance to salt stress, but drought stress was similar in t1n6_22 and wild-type (WT) plants. These results indicate that T1N6_22 might be involved in tolerance mechanisms to both biotic and abiotic stress response.     

Isolation and characterization of cDNAs encoding Ars2 and Pasha homologues, two components of the RNA interference pathway in Litopenaeus vannamei

The RNA interference (RNAi) is an evolutionarily conserved protective mechanism in eukaryotes against parasitic foreign nucleic acids. Previous studies demonstrated that the RNAi mechanism is important for shrimp antiviral immunity. Here, we report the identification and functional analysis of two key components of the shrimp RNAi activity: Litopenaeus vannamei arsenite resistance gene 2 (LvArs2) and partner of drosha (LvPasha). The full-length cDNA of LvArs2 was 3470 bp, including a 5′ untranslated region (UTR) of 167 bp, a 3′ UTR of 639 bp, and an open reading frame (ORF) of 2664 bp that encoded 887 amino acid residues with an estimated molecular mass of 102.5 kDa. The full-length cDNA of LvPasha was 2654 bp, including a 5′ UTR of 99 bp, a 3′ UTR of 560 bp, and an ORF of 1995 bp that encoded 664 amino acid residues with an estimated molecular mass of 74.2 kDa. Co-immunoprecipitation demonstrated that LvArs2 interacted with L. vannamei Dicer2 (LvDcr2) and LvPasha in Drosophila Schneider 2 (S2) cells, suggesting that LvArs2 may be involved in regulation of the miRNA/siRNA pathways in L.vannamei. Subcellular localization assays demonstrated both LvArs2 and LvPasha proteins mainly presented in the nucleus. After Poly(C-G) stimulation, the expression of LvArs2 was suppressed and expression of LvPasha was enhanced in shrimp gills. These results suggest that LvArs2 and LvPasha may participate in the defense against RNA viruses in crustacea.     

Cutting edge: Evidence for a dynamically driven T cell signaling mechanism

T cells use the αβ TCR to bind peptides presented by MHC proteins (pMHC) on APCs. Formation of a TCR-pMHC complex initiates T cell signaling via a poorly understood process, potentially involving changes in oligomeric state, altered interactions with CD3 subunits, and mechanical stress. These mechanisms could be facilitated by binding-induced changes in the TCR, but the nature and extent of any such alterations are unclear. Using hydrogen/deuterium exchange, we demonstrate that ligation globally rigidifies the TCR, which via entropic and packing effects will promote associations with neighboring proteins and enhance the stability of existing complexes. TCR regions implicated in lateral associations and signaling are particularly affected. Computational modeling demonstrated a high degree of dynamic coupling between the TCR constant and variable domains that is dampened upon ligation. These results raise the possibility that TCR triggering could involve a dynamically driven, allosteric mechanism.     

多效性基因Ghd7调控水稻剑叶面积

光合作用是植物的唯一能量来源,剑叶是水稻开花后进行光合作用的主要部位。Ghd7是一个多效性产量基因,能显著提高水稻产量。为了研究Ghd7对水稻剑叶形态的遗传效应,文章利用一个包含190个家系的BC2F2群体对水稻剑叶长度(FLL)、剑叶宽(FLW)和剑叶面积(FLA)进行QTL定位分析。在BC2F2群体,FLL、FLW和FLA性状表型值均显示为双峰分布,符合孟德尔单基因分离比,并均与每穗实粒数呈现显著正相关。在第7染色体上RM3859和C39分子标记间定位到FLL、FLW和FLA的QTL,分别解释变异的73.3%、62.3%和71.8%,均与Ghd7共分离。以珍汕97为轮回亲本,特青和明恢63分别为供体亲本,获得两个Ghd7近等基因系NIL(MH63)和NIL(TQ),FLL、FLW和FLA表型值均比珍汕97显著提高。另外,超表达Ghd7的合江19转基因植株的FLL、FLW和FLA表型值分别比合江19增加了8.9 cm、0.5 cm和17.8 cm2。这些结果表明Ghd7对调控剑叶面积起重要作用。     

Studies of the Activity of Peroxidase‐Like DNAzyme by Modifying 3′‐ or 5′‐End of Aptamers

In the presence of hemin and under appropriate conditions, some modalities of G‐quadruplexes can form a peroxidase‐like DNAzyme that has been widely used in biology. Structure? function studies on the DNAzyme revealed that its catalytic ability may be dependent on the unimolecular parallel G‐quadruplex. In this report, we present the preliminary investigation on the relationship between the structure and function of DNAzymes through a terminal oligo modification in G‐quadruplex sequences by adding different lengths of oligo‐dT to the 3′‐ or 5′‐end of the aptamers. The results suggested that adding dT_n to the 5′‐end of the DNA sequence of the enzyme improved the ability of hemin to bind with DNA, but the addition of dT_n to the 3′‐end decreased the binding ability of hemin for DNA. The increased stability of the assembled DNAzyme would lead to more favorable binding between the enzyme and substrate (H₂O₂), facilitating higher peroxidase activity; on the contrary, with lower stability of the DNAzyme complex, we observed reduced peroxidase activity.     

Studies of the activity of peroxidase-like DNAzyme by modifying 3'- or 5'-end of aptamers

In the presence of hemin and under appropriate conditions, some modalities of G-quadruplexes can form a peroxidase-like DNAzyme that has been widely used in biology. Structure-function studies on the DNAzyme revealed that its catalytic ability may be dependent on the unimolecular parallel G-quadruplex. In this report, we present the preliminary investigation on the relationship between the structure and function of DNAzymes through a terminal oligo modification in G-quadruplex sequences by adding different lengths of oligo-dT to the 3'- or 5'-end of the aptamers. The results suggested that adding dT(n) to the 5'-end of the DNA sequence of the enzyme improved the ability of hemin to bind with DNA, but the addition of dT(n) to the 3'-end decreased the binding ability of hemin for DNA. The increased stability of the assembled DNAzyme would lead to more favorable binding between the enzyme and substrate (H(2) O(2)), facilitating higher peroxidase activity; on the contrary, with lower stability of the DNAzyme complex, we observed reduced peroxidase activity.     

Molecular Design of Interfacial Modifiers for Polymer‐Inorganic Hybrid Solar Cells

The heterojunction of poly(3‐hexylthiophene) (P3HT) and TiO₂ in hybrid solar cells is systematically engineered with four cyanoacrylic acid‐containing conjugated molecules with various lowest unoccupied molecular orbital (LUMO) levels, WL‐1 to WL‐4, which are prepared by the formylation of thiophene derivatives in a Vilsmeier–Haack reaction, followed by treatment with cyanoacetic acid. The optical characteristics, redox properties, and intrinsic dipole moments of these interfacial modifiers (IMs) are examined using UV‐vis spectrophotometry, cyclic voltammetry, and density functional theory calculations. Using cyanoacrylic acid as a terminal anchoring group in IMs increases the electron affinity in regions close to the titania surface and forms a molecular dipole that is orientated away from the TiO₂ surface, enabling both open‐circuit voltage (V_OC) and short‐circuit current density to be increased simultaneously. Photovoltaic measurements demonstrate that V_OC increases with the dipole moment of IMs along the molecular backbone. Moreover, the external quantum efficiency (EQE) spectra display a bimodal distribution, revealing that both IMs and P3HT contribute to the photocurrent. The EQE at 570 nm is identified as characteristic of P3HT. More importantly, the LUMO of the IMs decisively determines the dissociation efficiency of P3HT excitons. The device based on P3HT/WL‐4/TiO₂ exhibits the highest power conversion efficiency of 2.87%.     

Assessing the Impact of Iron-based Nanoparticles on pH,Dissolved Organic Carbon,and Nutrient Availability in Soils

With the ongoing commercialization of nanotechnology products, the increasing use of engineered nanoparticles (NPs) could lead potentially to environmental risks. This study investigated the dynamic influences of three iron-based NPs (Fe⁰, Fe₃O₄, and Fe₂O₃) applied into a red soil (RS) and a Wushan soil (WS) with different application rates (2 to 6 g kg^?1) on soil physicochemical properties such as pH, dissolved organic carbon (DOC), available ammonium nitrogen (NH₄ ⁺-N), available phosphorus (AP), and enzymatic activities. The results showed that the addition of Fe⁰ NPs increased DOC and available NH₄ ⁺-N, but significantly decreased AP, while Fe₃O₄ and Fe₂O₃ NPs slightly reduced soil pH in both soils and significantly declined available NH₄ ⁺-N in the WS and AP in the RS. No significant difference was observed between the effects of Fe₃O₄ and Fe₂O₃ NPs on soil properties except AP in the RS. All iron-based NPs decreased the activities of urease and acid phosphatase in both soils. The effects on soil physicochemical properties, especially available NH₄ ⁺-N and AP induced by iron-based NPs, varied greatly with soil types. These results implied that cautions should be paid for the environmental application of iron-based NPs, especially iron oxide NPs in soils.     

Direct observation of mammalian cell growth and size regulation

We introduce a microfluidic system for simultaneously measuring single-cell mass and cell cycle progression over multiple generations. We use this system to obtain over 1,000 h of growth data from mouse lymphoblast and pro-B-cell lymphoid cell lines. Cell lineage analysis revealed a decrease in the growth rate variability at the G1-S phase transition, which suggests the presence of a growth rate threshold for maintaining size homeostasis.     

PA from an H5N1 highly pathogenic avian influenza virus activates viral transcription and replication and induces apoptosis and interferon expression at an early stage of infection

ABSTRACT: BACKGROUND: Although gene exchange is not likely to occur freely, reassortment between the H5N1 highlypathogenic avian influenza virus (HPAIV) and currently circulating human viruses is aserious concern. The PA polymerase subunit of H5N1 HPAIV was recently reported toactivate the influenza replicon activity. METHODS: The replicon activities of PR8 and WSN strains (H1N1) of influenza containing PA fromHPAIV A/Cambodia/P0322095/2005 (H5N1) and the activity of the chimeric RNApolymerase were analyzed. A reassortant WSN virus containing the H5N1 Cambodia PA (CPA)was then reconstituted and its growth in cells and pathogenicity in mice examined. Theinterferon promoter, TUNEL, and caspase 3, 8, and 9 activities of C-PA-infected cells werecompared with those of WSN-infected cells. RESULTS: The activity of the chimeric RNA polymerase was slightly higher than that of WSN, and CPAreplicated better than WSN in cells. However, the multi-step growth of C-PA and itspathogenicity in mice were lower than those of WSN. The interferon promoter, TUNEL, andcaspase 3, 8, and 9 activities were strongly induced in early infection in C-PA-infected cellsbut not in WSN-infected cells. CONCLUSIONS: Apoptosis and interferon were strongly induced early in C-PA infection, which protected theuninfected cells from expansion of viral infection. In this case, these classical host-virusinteractions contributed to the attenuation of this strongly replicating virus.