石墨烯对植物的生理毒性效应研究进展

石墨烯是当前研究最热的碳纳米材料,具有独特的理化特性,在各领域广泛应用。随着石墨烯生产和使用量的不断增大,其不可避免地进入到环境中,给生态环境和人类健康带来风险。阐明石墨烯的潜在毒性效应及其作用机制对于客观评价石墨烯的生态环境健康风险具有重要意义。迄今为止,已有诸多研究报道了石墨烯的植物生理毒理效应。研究表明,石墨烯对植物的生理学响应及其生理变化过程存在影响,涉及萌芽、幼苗生长、氧化应激、光合特性、植物激素和代谢过程等,且多呈浓度效应。今后亟需构建一套被广泛认可的植物石墨烯毒性评价体系,为石墨烯的安全生产和使用提供指导。     

中国首批国家公园体制试点的经验与成效、问题与建议

建立国家公园体制是建设生态文明制度的重要内容,是解决我国自然保护地发展过程中存在的重叠设置、多头管理、边界不清、权责不明、保护与发展矛盾突出等问题的重大举措。根据国家统一部署,2020年要设立一批国家公园,分级统一的管理体制基本建立。在跨时2年的资料收集、实地考察基础上,全面总结首批10个国家公园体制试点的经验与成效,梳理试点过程中存在的问题,并提出针对性建议,以期全面展现国家公园体制试点的最新进展,为国家公园深化建设提供参考和依据。结果显示,各试点区基本建立起分级统一的管理体制,创新了运行机制,保护力度持续加强,资金投入不断加大,科研合作不断深化,社会参与逐渐扩大。体制试点产生了明显的生态成效,民生改善初步显现,社会效益充分彰显。但是,仍然存在管理机构级别和类型参差不齐,法律制度不健全,资金保障长效机制未建立,人才队伍建设滞后,保护与发展的矛盾突出,空间范围不合理等问题。建议采取必要措施改进存在的问题,积极推广有效经验,加快健全国家公园体制。     

‘741杨’D2类细胞周期蛋白基因的克隆及功能鉴定

D类细胞周期蛋白(D-type cyclin,CYCD)调控细胞周期G1/S期转变。CYCD与细胞周期蛋白依赖性激酶(cyclin-dependent kinase,CDK)结合形成CYCD/CDK复合物,被激活的CYCD/CDK复合物通过磷酸化下游细胞周期响应因子调控细胞周期有序进行,进而影响植物的生长发育。该研究以‘741杨’为实验材料,成功鉴定得到1个D2类细胞周期蛋白基因(PtoCYCD2;1)。研究表明:(1)实时定量PCR(qRT-PCR)显示,PtoCYCD2;1基因在根、茎、叶、叶柄、树皮和木质部中均有表达,在叶中的相对表达水平最高。(2)亚细胞定位表明PtoCYCD2;1蛋白定位于细胞核。(3)与野生型(Wild-Type poplar,WT)相比,过表达PtoCYCD2;1基因的‘741杨’出现株高降低,茎直径减小,叶片明显下卷的表型。(4)扫描电镜分析(SEM)显示,转基因杨树叶片的上表皮细胞平均面积变小,细胞数量增多;树脂切片结果显示与WT相比,转基因杨树叶片的栅栏组织和海绵组织的细胞间隙疏松。(5)qRT-PCR结果显示,转基因杨树中细胞周期调控基因CDKA;1、CDKB1;1和CDKB2;1的表达水平显著上调,植物成视网膜细胞瘤相关蛋白1(retinoblastoma-related protein1,RBR1)基因、细胞周期蛋白依赖性激酶抑制因子(kip-related protein,KRP)基因的表达水平显著下调。该研究结果为进一步研究木本植物CYCD2基因的功能奠定了基础。     

石灰碳铵熏蒸联合生物有机肥对香蕉枯萎病和细菌群落的影响

以连续种植的香蕉枯萎病高发病蕉园为试验点,通过实时定量PCR和高通量测序等方法,研究了田间条件下石灰碳铵熏蒸联合生物有机肥施用对香蕉枯萎病的防治效果,以及对土壤细菌群落结构和组成的影响。结果表明: 与不熏蒸施用有机肥(OF)相比,香蕉枯萎病发病率在施用有机肥前使用石灰碳铵进行熏蒸处理(LAOF)和施用生物有机肥前使用石灰碳铵进行熏蒸处理(LABF)中分别降低了13.3%和21.7%,病原菌的拷贝数分别降低了22.4%和33.0%。与OF处理相比,石灰碳铵熏蒸联合不同肥料施用均显著降低了细菌的丰富度和多样性,形成了明显不同的群落结构,且熏蒸对群落组成的差异产生了决定性的影响。LABF的细菌丰富度和多样性均低于其他处理,群落组成也与其他处理存在明显差异。与OF处理相比,熏蒸处理(LAOF和LABF)显著增加了土壤中水恒杆菌、布鲁式菌和漯河杆菌属的相对丰度,且在LABF中的相对丰度均高于LAOF,水恒杆菌和布鲁式菌的相对丰度差异显著。在田间条件下,施用生物有机肥之前使用石灰碳铵进行熏蒸处理能够显著降低病原菌数量,改变土壤细菌群落结构,激发土壤有益微生物,从而减少香蕉枯萎病的发生。     

南京地区早产儿坏死性小肠结肠炎病原体特点和益生菌干预效果及预后影响因素分析

目的探究南京地区早产儿坏死性小肠结肠炎(NEC)的病原体特点,并观察益生菌辅助治疗对患儿血清炎症因子水平的影响,分析影响NEC早产儿预后的因素。方法将2014年5月至2018年12月于东南大学附属中大医院就诊的87例NEC早产儿选为研究对象,分析其病原体特点,观察不同治疗方法对患儿血清炎症因子的影响,并通过Logistic回归分析影响NEC患儿预后的危险因素。结果革兰阴性菌是NEC早产儿的主要致病菌,主要包括肺炎克雷伯菌(25株,27.78%)和大肠埃希菌(21株,23.33%)。肺炎克雷伯菌和大肠埃希菌对美罗培南、亚胺培南/西司他丁、哌拉西林/他唑巴坦、多粘菌素和阿米卡星敏感。益生菌干预后的NEC早产儿血清IL-1β、IL-10、TNF-α水平及TLR4的表达均显著低于常规治疗患儿(均P0.05)。发病前3 d内输血、新生儿窒息、益生菌干预、非营养性吮吸、腹膜炎、败血症、加奶速度、PDA均是影响NEC早产儿预后的相关因素(均P0.05),其中发病前3 d内输血、新生儿窒息、加奶速度、PDA是影响NEC早产儿预后的独立危险因素(均P0.05)。结论革兰阴性菌是NEC早产儿的主要致病菌,益生菌干预可有效降低NEC早产儿血清炎症因子水平。对于NEC早产儿的治疗可选用碳青霉烯类、氨基糖苷类等抗生素,同时需关注影响NEC早产儿预后的独立危险因素。     

6-gingerol protects nucleus pulposus-derived mesenchymal stem cells from oxidative injury by activating autophagy

BACKGROUNDTo date, there has been no effective treatment for intervertebral disc degeneration (IDD). Nucleus pulposus-derived mesenchymal stem cells (NPMSCs) showed encouraging results in IDD treatment, but the overexpression of reactive oxygen species (ROS) impaired the endogenous repair abilities of NPMSCs. 6-gingerol (6-GIN) is an antioxidant and anti-inflammatory reagent that might protect NPMSCs from injury.AIMTo investigate the effect of 6-GIN on NPMSCs under oxidative conditions and the potential mechanism.METHODSThe cholecystokinin-8 assay was used to evaluate the cytotoxicity of hydrogen peroxide and the protective effects of 6-GIN. ROS levels were measured by 2´7´-dichlorofluorescin diacetate analysis. Matrix metalloproteinase (MMP) was detected by the tetraethylbenzimidazolylcarbocyanine iodide assay. TUNEL assay and Annexin V/PI double-staining were used to determine the apoptosis rate. Additionally, autophagy-related proteins (Beclin-1, LC-3, and p62), apoptosis-associated proteins (Bcl-2, Bax, and caspase-3), and PI3K/Akt signaling pathway-related proteins (PI3K and Akt) were evaluated by Western blot analysis. Autophagosomes were detected by transmission electron microscopy in NPMSCs. LC-3 was also detected by immunofluorescence. The mRNA expression of collagen II and aggrecan was evaluated by real-time polymerase chain reaction (RT-PCR), and the changes in collagen II and MMP-13 expression were verified through an immunofluorescence assay.RESULTS6-GIN exhibited protective effects against hydrogen peroxide-induced injury in NPMSCs, decreased hydrogen peroxide-induced intracellular ROS levels, and inhibited cell apoptosis. 6-GIN could increase Bcl-2 expression and decrease Bax and caspase-3 expression. The MMP, Annexin V-FITC/PI flow cytometry and TUNEL assay results further confirmed that 6-GIN treatment significantly inhibited NPMSC apoptosis induced by hydrogen peroxide. 6-GIN treatment promoted extracellular matrix (ECM) expression by reducing the oxidative stress injury-induced increase in MMP-13 expression. 6-GIN activated autophagy by increasing the expression of autophagy-related markers (Beclin-1 and LC-3) and decreasing the expression of p62. Autophagosomes were visualized by transmission electron microscopy. Pretreatment with 3-MA and BAF further confirmed that 6-GIN-mediated stimulation of autophagy did not reduce autophagosome turnover but increased autophagic flux. The PI3K/Akt pathway was also found to be activated by 6-GIN. 6-GIN inhibited NPMSC apoptosis and ECM degeneration, in which autophagy and the PI3K/Akt pathway were involved.CONCLUSION6-GIN efficiently decreases ROS levels, attenuates hydrogen peroxide-induced NPMSCs apoptosis, and protects the ECM from degeneration. 6-GIN is a promising candidate for treating IDD.     

An undiscovered facet of hydraulic redistribution driven by evaporation—a study from a Populus tomentosa plantation

Maintaining the activity and function of the shallow root system of plants is essential for withstanding drought stress, but the associated mechanism is poorly understood. By investigating sap flow in 14 lateral roots (LRs) randomly selected from trees of a Chinese white poplar (Populus tomentosa) plantation receiving three levels of irrigation, an unknown root water transport mode of simultaneous daytime bi-directional water flow was discovered. This mode existed in five LRs confined to the surface soil without attached sinker roots. In the longer term, the bi-directional water flow was correlated with the soil water content. However, within the day, it was associated with transpiration. Our data demonstrated that bi-directional root sap flow occurred during the day, and was driven by evaporative demand, further suggesting the existence of circumferential water movement in the LR xylem. We named this phenomenon evaporation-driven hydraulic redistribution (EDHR). A soil-root water transport model was proposed to encapsulate this water movement mode. EDHR may be a crucial drought-tolerance mechanism that allows plants to maintain shallow root survival and activity by promoting root water recharge under extremely dry conditions.     

Exogenous spermidine enhances Epichloë endophyte-induced tolerance to NaCl stress in wild barley (Hordeum brevisubulatum)

Plant and Soil - We investigated morphological variations in podzols caused by changes in soil porosity and permeability upon the growth of large tree-roots in a tropical barrier island (Ilha...     

PGAM5: A crucial role in mitochondrial dynamics and programmed cell death

In response to mitochondrial damage, mitochondria activate mitochondrial dynamics to maintain normal functions, and an imbalance in mitochondrial dynamics triggers multiple programmed cell death processes. Recent studies have shown that phosphoglycerate mutase 5 (PGAM5) is associated with mitochondrial damage. PGAM5 activates mitochondrial biogenesis and mitophagy to promote a cellular compensatory response when mitochondria are mildly damaged, whereas severe damage to mitochondria leads to PGAM5 inducing excessive mitochondria fission, disruption to mitochondrial movement, and amplification of apoptosis, necroptosis and mitophagic death signals, which eventually evoke cell death. PGAM5 functions mainly through protein-protein interactions and specific Ser/Thr/His protein phosphatase activity. PGAM5 is also regulated by mitochondrial proteases. Detection of PGAM5 and its interacting protein partners should enable a more accurate evaluation of mitochondrial damage and a more precise method for the diagnosis and treatment of diseases.