芍药乙烯受体PlETR1基因过表达载体的构建及烟草转化

芍药是乙烯敏感型花卉,乙烯受体感知并传导乙烯信号,在乙烯信号转导途径中发挥重要作用。芍药PlETR1基因cDNA全长序列已分离,为了鉴定芍药PlETR1基因的功能,本研究基于PlETR1基因和表达载体序列,应用Primer Premier 5.0软件设计了一对特异性PCR引物,采用RT-PCR技术扩增出了PlETR1编码区片段,进一步构建了芍药PlETR1基因过表达载体。基于优化的模式植物烟草的组培体系和筛选出的潮霉素抗性浓度,应用农杆菌介导的叶盘法开展了芍药PlETR1基因转化烟草的研究,对转基因抗性烟草植株进行了PCR检测,结果表明HPT基因和芍药PlETR1基因已导入到烟草基因组中,且芍药PlETR1基因转录表达成功,为下一步鉴定芍药PlETR1基因的功能提供科学依据。     

绵马贯众多糖超声提取工艺优化及抗氧化活性分析

绵马贯众是中国传统常用中药,本研究以温度、时间、超声功率、液料比为影响因子,多糖得率为评价指标,通过响应面法优化超声辅助提取绵马贯众多糖的工艺条件,同时测定其基本理化性质及抗氧化活性。研究结果表明,绵马贯众多糖的最佳提取工艺条件为:温度64℃、时间60 min、超声功率210 W、液料比27 mL/g。此时多糖得率为9.57%,与预测值接近。理化性质分析表明绵马贯众多糖为含少量蛋白的酸性多糖。体外抗氧化研究表明绵马贯众多糖具有很强的DPPH自由基清除活性,IC50值为0.29 mg/mL;较好的羟基自由基清除活性,其IC50值为1.10 mg/mL;对DNA的氧化损伤有显著的保护作用。绵马贯众多糖可以作为一种潜在的抗氧化剂应用于食品和化妆品等领域。     

A non-structural protein encoded by Rice Dwarf Virus targets to the nucleus and chloroplast and inhibits local RNA silencing

RNA silencing is a potent antiviral mechanism in plants and animals. As a counter-defense, many viruses studied to date encode one or more viral suppressors of RNA silencing (VSR). In the latter case, how different VSRs encoded by a virus function in silencing remains to be fully understood. We previously showed that the nonstructural protein Pns10 of a Phytoreovirus, Rice dwarf virus (RDV), functions as a VSR. Here we present evidence that another nonstructural protein, Pns11, also functions as a VSR. While Pns10 was localized in the cytoplasm, Pns11 was localized both in the nucleus and chloroplasts. Pns11 has two bipartite nuclear localization signals (NLSs), which were required for nuclear as well as chloroplastic localization. The NLSs were also required for the silencing activities of Pns11. This is the first report that multiple VSRs encoded by a virus are localized in different subcellular compartments, and that a viral protein can be targeted to both the nucleus and chloroplast. These findings may have broad significance in studying the subcellular targeting of VSRs and other viral proteins in viral-host interactions.

     

Activation of the bitter taste sensor TRPM5 prevents high salt-induced cardiovascular dysfunction

Science China Life Sciences - High salt intake is a known risk factor of cardiovascular diseases. Our recent study demonstrated that long-term high salt intake impairs transient receptor potential...     

Depth‐dependent soil organic carbon dynamics of croplands across the Chengdu Plain of China from the 1980s to the 2010s

Agricultural soils have tremendous potential to sequester soil organic carbon (SOC) and mitigate global climate change. However, agricultural land use has a profound impact on SOC dynamics, and few studies have explored how agricultural land use combined with soil conditions affect SOC changes throughout the soil profile. Based on a paired soil resampling campaign in the 1980s and 2010s, this study investigated the SOC changes of the soil profile caused by agricultural land use and the correlations with parent material and topography across the Chengdu Plain of China. The results showed that the SOC content increased by 3.78 g C/kg in the topsoil (0–20 cm), but decreased in the 20–40 cm and 40–60 cm soil layers by 0.90 and 1.26 g C/kg respectively. SOC increases in topsoil were observed for all types of agricultural land. Afforestation on former agricultural land also caused SOC decreases in the 20–60 cm soil layers, while SOC decreases only occurred in the 40–60 cm soil layer for agricultural land using a traditional crop rotation (i.e. traditional rice–wheat/rapeseed rotation) and with rice–vegetable rotations converted from the traditional rotations. For each agricultural land use, SOC decreases in deep soils only occurred in high relief areas and in soils formed from Q4 (Quaternary Holocene) grey‐brown alluvium and Q4 grey alluvium that had a relatively low soil bulk density and clay content. The results indicated that SOC change caused by agricultural land use was depth dependent and that the effects of agricultural land use on soil profile SOC dynamics varied with soil characteristics and topography. Subsoil SOC decreases were more likely to occur in high relief areas and in soils with low soil bulk density and low clay content.     

Agrobacterium tumefaciens ferritins play an important role in full virulence through regulating iron homeostasis and oxidative stress survival

Ferritins are a large family of iron storage proteins, which are used by bacteria and other organisms to avoid iron toxicity and as a safe iron source in the cytosol. Agrobacterium tumefaciens, a phytopathogen, has two ferritin-encoding genes: atu2771 and atu2477. Atu2771 is annotated as a Bfr-encoding gene (Bacterioferritin, Bfr) and atu2477 as a Dps-encoding gene (D NA binding p rotein from s tarved cells, Dps). Three deletion mutants (Δbfr, Δdps, and bfr-dps double-deletion mutant ΔbdF) of these two ferritin-encoding genes were constructed to investigate the effects of ferritin deficiency on the iron homeostasis, oxidative stress resistance, and pathogenicity of A. tumefaciens. Deficiency of two ferritins affects the growth of A. tumefaciens under iron starvation and excess. When supplied with moderate iron, the growth of A. tumefaciens is not affected by the deficiency of ferritin. Deficiency of ferritin significantly reduces iron accumulation in the cells of A. tumefaciens, but the effect of Bfr deficiency on iron accumulation is severer than Dps deficiency and the double mutant ΔbdF has the least intracellular iron content. All three ferritin-deficient mutants showed a decreased tolerance to 3 mM H₂O₂ in comparison with the wild type. The tumour induced by each of three ferritin-deficient mutants is less than that of the wild type. Complementation reversed the effects of ferritin deficiency on the growth, iron homeostasis, oxidative stress resistance, and tumorigenicity of A. tumefaciens. Therefore, ferritin plays an important role in the pathogenesis of A. tumefaciens through regulating iron homeostasis and oxidative stress survival.