黑土长期施肥及养分循环再利用的作物产量及土壤肥力质量变化Ⅲ.土壤养分收支

许了1985－1999年试验期间各模拟施肥模型的作物移出养分量和施肥输入养分量,结果表明,施用N肥可加剧土壤P收支赤字,而施用N,P肥则加剧土壤K收支赤字,实验展示了我国在20世纪70年代大面积贫P土壤和80年代大面积缺K土壤出现的原因,保持养分循环再利用可缓解土壤养分收支赤字,但不能满足丰产作物的养分需求,在保持养分循环利用基础上根据土壤肥力适当施用化肥,可满足丰产作物的养分需求和平衡土壤养分收支,不致发生大量过剩N进入环境。     

Brain-derived neurotrophic factor regulates LYN kinase–mediated myosin light chain kinase activation to modulate nonmuscle myosin II activity in hippocampal neurons

Myosins belong to a large superfamily of actin-dependent molecular motors. Nonmuscle myosin II (NM II) is involved in the morphology and function of neurons, but little is known about how NM II activity is regulated. Brain-derived neurotrophic factor (BDNF) is a prevalent neurotrophic factor in the brain that encourages growth and differentiation of neurons and synapses. In this study, we report that BDNF upregulates the phosphorylation of myosin regulatory light chain (MLC2), to increases the activity of NM II. The role of BDNF on modulating the phosphorylation of MLC2 was validated by using Western blotting in primary cultured hippocampal neurons. This result was confirmed by injecting BDNF into the dorsal hippocampus of mice and detecting the phosphorylation level of MLC2 by Western blotting. We further perform coimmunoprecipitation assay to confirm that this process depends on the activation of the LYN kinase through binding with tyrosine kinase receptor B, the receptor of BDNF, in a kinase activity-dependent manner. LYN kinase subsequently phosphorylates MLCK, further promoting the phosphorylation of MLC2. Taken together, our results suggest a new molecular mechanism by which BDNF regulates MLC2 activity, which provides a new perspective for further understanding the functional regulation of NM II in the nervous system.     

地卷属地衣1中国新记录种——栗色地卷(新拟)

本研究以采集于河北省小五台山自然保护区地卷属地衣为试验材料,通过形态解剖学、地衣次生代谢产物和nrDNA的ITS分子系统学分析,对地卷属地衣进行鉴定,发现小五台山分布地卷属1中国地衣新记录种——栗色地卷（新拟）(Peltigera castanea Goward, Goffinet & Mi?dl.)。该种的识别特征为：地衣体上表面灰褐色至暗褐色,中部稍具光泽;裂片顶端边缘稍具绒毛;粉芽颗粒状,褐色,并聚集成不规则圆形;下表面脉纹扁平,淡白色、淡褐色至淡黑色;假根密集,束状、丛生,上部呈柔毛状。     

P2Y<Subscript>12</Subscript> receptor upregulation in satellite glial cells is involved in neuropathic pain induced by HIV glycoprotein 120 and 2′,3′-dideoxycytidine

The direct neurotoxicity of HIV and neurotoxicity of combination antiretroviral therapy medications both contribute to the development of neuropathic pain. Activation of satellite glial cells (SGCs) in the dorsal root ganglia (DRG) plays a crucial role in mechanical and thermal hyperalgesia. The P2Y₁₂ receptor expressed in SGCs of the DRG is involved in pain transmission. In this study, we explored the role of the P2Y₁₂ receptor in neuropathic pain induced by HIV envelope glycoprotein 120 (gp120) combined with ddC (2′,3′-dideoxycytidine). A rat model of gp120+ddC-induced neuropathic pain was used. Peripheral nerve exposure to HIV-gp120+ddC increased mechanical and thermal hyperalgesia in gp120+ddC-treated model rats. The gp120+ddC treatment increased expression of P2Y₁₂ receptor mRNA and protein in DRG SGCs. In primary cultured DRG SGCs treated with gp120+ddC, the levels of [Ca²⁺]_i activated by the P2Y₁₂ receptor agonist 2-(Methylthio) adenosine 5′-diphosphate trisodium salt (2-MeSADP) were significantly increased. P2Y₁₂ receptor shRNA treatment inhibited 2-MeSADP-induced [Ca²⁺]_i in primary cultured DRG SGCs treated with gp120+ddC. Intrathecal treatment with a shRNA against P2Y₁₂ receptor in DRG SGCs reduced the release of pro-inflammatory cytokines, decreased phosphorylation of p38 MAPK in the DRG of gp120+ddC-treated rats. Thus, downregulating the P2Y₁₂ receptor relieved mechanical and thermal hyperalgesia in gp120+ddC-treated rats.     

The effects of NONRATT021972 lncRNA siRNA on PC12 neuronal injury mediated by P2X<Subscript>7</Subscript> receptor after exposure to oxygen-glucose deprivation

Adenosine triphosphate (ATP) participates in signal transmission by acting on P2X receptors, and the P2X₇ receptor is involved in the pathophysiological changes of ischemic injury. The PC12 cell line is a popular model system to study sympathetic neuronal function. Long noncoding RNAs (lncRNAs) are highly expressed in the nervous system and serve as regulatory RNAs. In this study, the effects of NONRATT021972 lncRNA siRNA on P2X₇-mediated PC12 neuronal injury after exposure to oxygen-glucose deprivation (OGD) were investigated. Our results showed that the viability of PC12 cells cultured with OGD or the P2X₇ agonist BzATP was significantly decreased. Treatment with NONRATT021972 siRNA reversed the decreased viability of PC12 cells under OGD conditions. The upregulated P2X₇ mRNA and protein levels in PC12 cells under OGD conditions or BzATP treatment were significantly decreased when pretreated with NONRATT021972 siRNA. Moreover, NONRATT021972 siRNA treatment effectively suppressed the increase in [Ca²⁺]_i induced by OGD or P2X₇ agonists (ATP or BzATP) in PC12 cells. Therefore, treatment with NONRATT021972 siRNA may decrease sympathetic neuronal injury induced by ischemia.     

Dynamically probing ATP‐dependent RNA helicase A‐assisted RNA structure conversion using single molecule fluorescence resonance energy transfer

RNA helicase A (RHA) as a member of DExH‐box subgroup of helicase superfamily II, participates in diverse biological processes involved in RNA metabolism in organisms, and these RNA‐mediated biological processes rely on RNA structure conversion. However, how RHA regulate the RNA structure conversion was still unknown. In order to unveil the mechanism of RNA structure conversion mediated by RHA, single molecule fluorescence resonance energy transfer was adopted to in our assay, and substrates RNA were from internal ribosome entry site of foot‐and‐mouth disease virus genome. We first found that the RNA structure conversion by RHA against thermodynamic equilibrium in vitro, and the process of dsRNA YZ converted to dsRNA XY through a tripartite intermediate state. In addition, the rate of the RNA structure conversion and the distribution of dsRNA YZ and XY were affected by ATP concentrations. Our study provides real‐time insight into ATP‐dependent RHA‐assisted RNA structure conversion at the single molecule level, the mechanism displayed by RHA may help in understand how RHA contributes to many biological functions, and the basic mechanistic features illustrated in our work also underlay more complex protein‐assisted RNA structure conversions.     

黑土长期施肥及养分循环再利用的作物产量及土壤肥力质量变化Ⅰ.作物产量

在一丰P黑土(Olsen P25.8mg·kg^-1)上进行13年中长期田间试验的结果表明,氮肥平均增产率为275%,年增产粮食(大豆、玉米、小麦混合)724kg·hm^-2,1kgN增产粮食9.4kg;磷肥前期增产不明显,13年平均增产率为7%,年增产粮食241kg·hm^-2,1kgP增产粮食12.7kg.每年施用循环回田猪圈肥(以处理区收获产品的80%喂猪、垫圈经堆制而成),粮食平均年增产量在不施化肥、施N、施NP基础上,分别为268、258、255kg·hm^-2,相应的增产率为9.8%、7.6%和7.0%.试验期间循环回田猪圈肥的增产效果有逐渐增长趋势,表明存在着猪圈肥残效的叠加效应.