高砷含水层参与腐殖酸-铁矿物转化的关键微生物群落及其对砷迁移转化的影响

【目的】探究不同腐殖酸浓度下参与含砷水铁矿转化的微生物类群组成和丰度变化及对砷释放的影响,预测原位高砷含水层中功能微生物群参与有机质—含砷铁矿物转化过程对砷转化释放的作用。【方法】对河套平原高砷地下水和同深度高砷沉积物中的铁还原功能群落进行富集培养,构建室内厌氧微宇宙体系,将富集菌群分别加入到实验室条件下合成的不同浓度腐殖酸(0、1.5、7、14 mg C/L)-含砷水铁矿体系中,通过体系中砷、铁形态及浓度的变化分析,结合高通量测序技术、X-射线衍射(X-ray diffractometer, XRD),探究不同条件下砷的释放固定和群落的演替。【结果】高砷地下水组(G组)和沉积物组(S组)富集得到的铁还原功能群落具有明显差异,G组中以Aeromonadaceae为特殊优势菌群,而S组中以Shewanellaceae为特殊优势菌群。微宇宙实验结果显示,S组的铁还原量相对较高且速率较快;G组与S组中液相砷形态存在明显差异,整个培养期内G组均以As(Ⅴ)为主,而S组中前期以As(Ⅴ)为主,当反应到达20 d时液相As(Ⅲ)高达3.4μmol/L,推测此时具有砷还原功能的群落占优势地位。当反应...     

Gut microbiome helps honeybee (Apis mellifera) resist the stress of toxic nectar plant (Bidens pilosa) exposure: Evidence for survival and immunity

Honeybee (Apis mellifera) ingestion of toxic nectar plants can threaten their health and survival. However, little is known about how to help honeybees mitigate the effects of toxic nectar plant poisoning. We exposed honeybees to different concentrations of Bidens pilosa flower extracts and found that B. pilosa exposure significantly reduced honeybee survival in a dose-dependent manner. By measuring changes in detoxification and antioxidant enzymes and the gut microbiome, we found that superoxide dismutase, glutathione-S-transferase and carboxylesterase activities were significantly activated with increasing concentrations of B. pilosa and that different concentrations of B. pilosa exposure changed the structure of the honeybee gut microbiome, causing a significant reduction in the abundance of Bartonella (p < 0.001) and an increase in Lactobacillus. Importantly, by using Germ-Free bees, we found that colonization by the gut microbes Bartonella apis and Apilactobacillus kunkeei (original classification as Lactobacillus kunkeei) significantly increased the resistance of honeybees to B. pilosa and significantly upregulated bee-associated immune genes. These results suggest that honeybee detoxification systems possess a level of resistance to the toxic nectar plant B. pilosa and that the gut microbes B. apis and A. kunkeei may augment resistance to B. pilosa stress by improving host immunity.     

The northern corn leaf blight resistance gene Ht1 encodes an nucleotide-binding,leucine-rich repeat immune receptor

Northern corn leaf blight, caused by the fungal pathogen Exserohilum turcicum, is a major disease of maize. The first major locus conferring resistance to E. turcicum race 0, Ht1, was identified over 50 years ago, but the underlying gene has remained unknown. We employed a map-based cloning strategy to identify the Ht1 causal gene, which was found to be a coiled-coil nucleotide-binding, leucine-rich repeat (NLR) gene, which we named PH4GP-Ht1. Transgenic testing confirmed that introducing the native PH4GP-Ht1 sequence to a susceptible maize variety resulted in resistance to E. turcicum race 0. A survey of the maize nested association mapping genomes revealed that susceptible Ht1 alleles had very low to no expression of the gene. Overexpression of the susceptible B73 allele, however, did not result in resistant plants, indicating that sequence variations may underlie the difference between resistant and susceptible phenotypes. Modelling of the PH4GP-Ht1 protein indicated that it has structural homology to the Arabidopsis NLR resistance gene ZAR1, and probably forms a similar homopentamer structure following activation. RNA sequencing data from an infection time course revealed that 1 week after inoculation there was a threefold reduction in fungal biomass in the PH4GP-Ht1 transgenic plants compared to wild-type plants. Furthermore, PH4GP-Ht1 transgenics had significantly more inoculation-responsive differentially expressed genes than wild-type plants, with enrichment seen in genes associated with both defence and photosynthesis. These results demonstrate that the NLR PH4GP-Ht1 is the causal gene underlying Ht1, which represents a different mode of action compared to the previously reported wall-associated kinase northern corn leaf blight resistance gene Htn1/Ht2/Ht3.     

Inhibitory role of bone marrow mesenchymal stem cells-derived exosome in non-small-cell lung cancer: microRNA-30b-5p,EZH2 and PI3K/AKT pathway

Exosomal microRNA (miRNA) exerts potential roles in non-small-cell lung cancer (NSCLC). The current study elucidated the role of miR-30b-5p shuttled by bone marrow mesenchymal stem cells (BMSCs)-derived exosomes in treating NSCLC. Bioinformatics analysis was performed with NSCLC-related miRNA microarray GSE169587 and mRNA data GSE74706 obtained for collection of the differentially expressed miRNAs and mRNAs. The relationship between miR-30b-5p and EZH2 was predicted and confirmed. Exosomes were isolated from BMSCs and identified. BMSCs-derived exosomes overexpressing miR-30b-5p were used to establish subcutaneous tumorigenesis models to study the effects of miR-30b-5p, EZH2 and PI3K/AKT signalling pathway on tumour growth. A total of 86 BMSC-exo-miRNAs were differentially expressed in NSCLC. Bioinfomatics analysis found that BMSC-exo-miR-30b-5p could regulate NSCLC progression by targeting EZH2, which was verified by in vitro cell experiments. Besides, the target genes of miR-30b-5p were enriched in PI3K/AKT signalling pathway. Animal experiments validated that BMSC-exo-miR-30b-5p promoted NSCLC cell apoptosis and prevented tumorigenesis in nude mice via EZH2/PI3K/AKT axis. Collectively, the inhibitory role of BMSC-derived exosomes-loaded miR-30b-5p in NSCLC was achieved through blocking the EZH2/PI3K/AKT axis.     

采伐剩余物管理对杉木人工林土壤nosZ型反硝化细菌群落多样性的影响

反硝化细菌是土壤氧化亚氮(N₂O)排放的关键因子。以杉木人工林为研究对象,设置4种采伐剩余物处理方式(RF:对照;RB:火烧;MT:粉碎;NR:移除),采用高通量测序技术,以nosZ为标记基因,测定了自2018年9月—2020年9月,2年期间土壤nosZ型反硝化细菌群落的组成和丰度。研究结果显示,4种采伐剩余物处理中的土壤nosZ型反硝化细菌90%以上来自变形菌门,优势菌属包括固氮螺菌属、中慢生根瘤菌属、动胶菌属、伯克霍尔德菌属、嗜酸菌属、慢生根瘤菌属、假单胞菌属、固氮弧菌属以及无色杆菌属;样本间差异物种的显著性分析表明,在处理完成半年时,火烧相较于对照于β-变形菌纲水平显著增加了nosZ基因丰度;在处理完成一年时,火烧分别于红螺菌目、红螺菌科、固氮螺菌属水平显著高于粉碎;粉碎相较于移除在处理完成一年时,于γ-变形菌纲和产碱菌科水平显著增加了nosZ基因丰度;在处理完成两年时,粉碎处理的nosZ基因丰度在变形菌门水平显著高于对照和火烧。α多样性数据显示,处理完成一年时,粉碎处理相较于对照和移除显著增加了Shannon和Simpson指数;处理完成两年时,粉碎和火烧...     

高原湖泊流域国土空间生态修复优先区诊断及修复研究

高原湖泊流域是高原地区人类活动的重要载体,兼具高生态价值和高脆弱性的特点。随着高原湖泊流域城市化和工业化发展加速,湖泊面积萎缩,污染加剧,流域生态环境受损严重,引发了一系列生态环境问题,如水土流失、水污染、湿地退化、生境质量下降等。亟需开展生态修复以平衡经济发展与生态环境保护之间关系,而基于整体保护与系统治理思维诊断并修复生态修复优先区,是科学有序推进国土空间生态保护与修复的重要抓手。基于此,研究以高原湖泊流域典型代表滇池流域为例,利用人类足迹和景观生态风险模型定量评估生态系统所受负向干扰,以最小累积阻力模型和电路理论构建流域生态网络;提取生态网络受负向干扰较高的关键区域为生态修复优先区并提出针对性修复措施。研究表明：(1)滇池流域人类干扰和生态风险整体较高,人类干扰整体呈核心—边缘递减的圈层式分布,中高生态风险占据了绝大部分区域。人类交通网络大幅扩展了人类干扰和生态风险的强度和深度;(2)区域生态网络呈典型湖泊生态网络特点,38条生态廊道呈放射状或环状分布,连通湖区、山区两大生态空间内共23块生态源地,保障区域生态安全;(3)研究共提取生态源地修复优先区73.83km²     

泥河湾盆地发现短喙象化石

本文记述泥河湾盆地河北蔚县两个地点发现的化石,它们被鉴定为短喙象类的?Anancus和Pentalopodon两个属。     

Investigations of interaction mechanism and conformational variation of serum albumin affected by artemisinin and dihydroartemisinin

In this work, binding interactions of artemisinin (ART) and dihydroartemisinin (DHA) with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated thoroughly to illustrate the conformational variation of serum albumin. Experimental results indicated that ART and DHA bound strongly with the site I of serum albumins via hydrogen bond (H-bond) and van der Waals force and subsequently statically quenched the intrinsic fluorescence of serum albumins through concentration-dependent manner. The quenching abilities of two drugs on the intrinsic fluorescence of HSA were much higher than the quenching abilities of two drugs on the intrinsic fluorescence of BSA. Both ART and DHA, especially DHA, caused the conformational variation of serum albumins and reduced the α-helix structure content of serum albumins. DHA with hydrophilic hydroxyl group bound with HSA more strongly, suggesting the important roles of the chemical polarity and the hydrophilicity during the binding interactions of two drugs with serum albumins. These results reveal the molecular understanding of binding interactions between ART derivatives and serum albumins, providing vital information for the future application of ART derivatives in biological and clinical areas.     

放养鲢鱼(Hypophthalmichys molitrix C et V)对水库围隔浮游生物群落的影响

本文研究在水库围隔实验生态系统中鲢鱼对浮游生物群落的影响。结果表明,放养鲢鱼后,浮游动物生物量、浮游植物生物量、叶绿素a和浮游植物毛产量分别下降了58.7％、63.6％、52.5％和65.0％;透明度、浮游植物群落多样性指数分别提高了18.2％、32.5％;铜绿微囊藻数量减少了90.6％“水华”得到明显抑制。但小型绿藻(<20μm)数量未出现显著变化,因而其在藻类生物量中所占比例反而提高了82.3％。围隔内可被鲢鱼滤食的大型藻类(硅藻、甲藻、隐藻和绿藻(>20μm))占藻类生物量的85.8％,因此鲢鱼的存在能明显限制浮游植物的生物量。此外,放养鲢鱼还显著降低了水体中的COD,TP,DO和pH值,这表明鲢鱼对水质有净化作用。     

Rhizosphere effect of nanoscale zero-valent iron on mycorrhiza-dependent maize assimilation

Rhizosphere effect of nanoscale zero-valent iron (nZVI) is crucial but little reported. Maize seeds were dressed with four nZVI concentrations (0, 1.0, 1.5, 2 g kg⁻¹) and inoculated with arbuscular mycorrhizal fungus (AMF) (Funneliformis mosseae). The SEM images illuminated that excessive nZVI particles (2 g kg⁻¹) were agglomerated on the surface of hyphae and spore, causing severe deformation and inactivation of AMF symbionts and thereafter inhibiting water uptake in maize seedlings. This restrained the scavenging effects of enzymatic (superoxide dismutase, peroxidase) and non-enzymatic compounds (proline & malondialdehyde) on ROS, and leaf photoreduction activity and gas exchange ability (p < 0.05). Interestingly, the inoculation with AMF effectively alleviated above negative effects. In contrast, appropriate dose of nZVI, that is, ≤1.5 g kg⁻¹, can be evenly distributed on the hyphae surface and form the ordered symbionts with AMF. This help massively to enhance hyphae growth and water and nutrient uptake. The enhanced mycorrhizal infection turned to promote rhizosphere symbiont activity and leaf Rubisco and Rubisco activase activity. Light compensation point was massively lowered, which increased photosynthetic carbon supply for AMF symbionts. Particularly, such priming effects were evidently enhanced by drought stress. Our findings provided a novel insight into functional role of nZVI in agriculture and AMF-led green production.