Nighttime sap flow of Acacia mangium and its implications for nighttime transpiration and stem water storage

Aims Nighttime sap flow of trees may indicate transpiration and/or recharge of stem water storage at night. This paper deals with the water use of Acacia mangium at night in the hilly lands of subtropical South China. Our primary goal was to reveal and understand the nature of nighttime sap flow and its functional significance.Methods Granier's thermal dissipation method was used to determine the nighttime sap flux of A. mangium. Gas exchange system was used to estimate nighttime leaf transpiration and stomatal conductance of studied trees.Important findings Nighttime sap flow was substantial and showed seasonal variation similar to the patterns of daytime sap flow in A. mangium. Mean nighttime sap flow was higher in the less precipitation year of 2004 (1122.4 mm) than in the more precipitation year of 2005 (1342.5 mm) since more daytime transpiration and low soil water availability in the relatively dry 2004 can be the cause of more nighttime sap flow. Although vapor pressure deficit and air temperature were significantly correlated with nighttime sap flow, they could only explain a small fraction of the variance in nighttime sap flow. The total accumulated water loss (E L) by transpiration of canopy leaves was only ~2.6–8.5% of the total nighttime sap flow (E t) during the nights of July 17–18 and 18–19, 2006. Therefore, it is likely that the nighttime sap flow was mainly used for refilling water in the trunk. The stem diameter at breast height, basal area and sapwood area explained much more variance of nighttime water recharge than environmental factors and other tree form features, such as tree height, stem length below the branch, and canopy size. The contribution of nighttime water recharge to the total transpiration ranged from 14.7 to 30.3% depending on different DBH class and was considerably higher in the dry season compared to the wet season.     

秦岭南坡陕西洋县辖区哺乳动物物种多样性的空间分布格局

物种多样性的空间分布格局一直是生态学和生物地理学研究的一个热点问题。山地生态系统的生境异质性和物种多样性高, 适合研究物种多样性空间分布格局及其相关机制。2016年11月至2017年11月, 本研究选取秦岭南坡陕西洋县辖区作为研究区域, 采用样线法、红外相机法和笼捕/夹捕法, 系统分析了8目21科48种哺乳动物物种多样性的空间分布格局。研究结果发现秦岭南坡洋县辖区哺乳动物物种丰富度的空间分布格局大致是中南部低, 北部和东部高; 物种多样性指数大致是中南部和北部低, 东部高。啮齿类动物和非啮齿类动物的空间分布格局存在差异。哺乳动物物种丰富度和多样性指数的垂直分布格局都符合中峰模式, 但啮齿类动物和非啮齿类动物间存在差异。最优线性模型结果表明, 研究地区哺乳动物物种多样性的空间分布格局受到多种环境因素的共同影响。其中, 年均温与物种多样性的相关性最强, 在6个最优线性模型中贡献都是最大。综上, 秦岭南坡洋县辖区中高海拔区域的物种多样性较高, 应加强对中高海拔地区的保护, 以维系该区域较高的生物多样性。     

底栖生物影响下的潮滩微地貌演化数值模拟

潮滩是海岸带湿地的主要类型之一,其中分布的底栖生物对生态环境具有重要的调节作用。潮滩底栖微藻、泥沙与水动力之间存在相互作用,影响潮滩微地貌形态,明晰底栖生物对潮滩微地貌的演化机制至关重要。以黄河三角洲潮滩湿地为研究区,通过构建潮滩微地貌动力模型,探究底栖生物对微地貌格局演化的作用机制,分析底栖生物对微地貌系统稳定性的影响。结果表明(1)底栖微藻生长与泥沙扩散、水流再分配过程交互作用驱动下,潮滩上可形成底栖微藻覆盖的高丘与积水洼地交替分布的规则性微地貌斑图;(2)微地貌斑图的形成提高了潮滩生态系统初级生产力和泥沙淤积高度;(3)底栖微藻与泥沙、水流的交互作用使得潮滩微地貌系统对侵蚀扰动呈现非线性响应行为,系统存在临界点,且在一定侵蚀率范围内存在双稳态;(4)黄河口泥螺入侵使得微地貌系统抵抗侵蚀扰动能力减小,且系统稳定性随泥螺生物量的增加而降低。     

Lenvatinib for effectively treating antiangiogenic drug-resistant nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) clinical trials show that antiangiogenic drugs (AADs) fail to achieve the expected efficacy, and combining AAD with chemoradiotherapy does not show superiority over chemoradiotherapy alone. Accumulating evidence suggests the intrinsic AAD resistance in NPC patients with poorly understood molecular mechanisms. Here, we describe NPC-specific FGF-2 expression-triggered, VEGF-independent angiogenesis as a mechanism of AAD resistance. Angiogenic factors screening between AAD-sensitive cancer type and AAD-resistant NPC showed high FGF-2 expression in NPC in both xenograft models and clinical samples. Mechanistically, the FGF-2-FGFR1-MYC axis drove endothelial cell survival and proliferation as an alternative to VEGF-VEGFR2-MYC signaling. Genetic knockdown of FGF-2 in NPC tumor cells reduced tumor angiogenesis, enhanced AAD sensitivity, and reduced pulmonary metastasis. Moreover, lenvatinib, an FDA recently approved multi-kinase inhibitor targeting both VEGFR2 and FGFR1, effectively inhibits the tumor vasculature, and exhibited robust anti-tumor effects in NPC-bearing nude mice and humanized mice compared with an agent equivalent to bevacizumab. These findings provide mechanistic insights on FGF-2 signaling in the modulation of VEGF pathway activation in the NPC microenvironment and propose an effective NPC-targeted therapy by using a clinically available drug.Subject terms: Tumour angiogenesis, Head and neck cancer, Targeted therapies     

贵阳地区蝉花微生态系统中细菌种群结构与功能

【目的】探索自然生态下蝉花内菌核、菌膜和环境细菌群落结构、功能及其相互关系。【方法】对细菌16S rRNA扩增片段进行高通量测序,分析贵阳市大将山和贵阳森林公园的蝉花内菌核、菌膜及其生境土壤的细菌群落组成、多样性及潜在功能。【结果】蝉花内菌核样本共检测到细菌562个属,菌膜样本521个属,菌际土样本578个属。两地的各组样本细菌群落结构相似,内菌核样本中假单胞菌属Pseudomonas、沙雷氏菌属Serratia占优势地位;菌膜样本中假单胞菌属和氨基杆菌属Aminobacter占优势;土壤样本以未分类的酸杆菌纲Acidobacteria和黄杆菌科Xanthobacteraceae为优势属。Venn图分析显示,菌际土样本包括了菌膜样本的大多数属,内菌核样本拥有较多的特有属,如沃尔巴克氏体属Wolbachia和立克次氏体Rickettsia等。PICRUSt功能预测结果显示,共计24个基因功能家族,主要与物质能量的代谢运输、细胞的行为发生及调控等功能相关。【结论】蝉花及其微生境中细菌具有丰富多样性,它们的潜在功能可能与营养物质的新陈代谢有关,对蝉花的个体生长发育有重要作用。研究结果对蝉花虫...     

市售畜禽肉产CTX-M酶大肠杆菌的流行病学调查

【目的】调查市售畜禽肉类中大肠杆菌的耐药状况和bla_CTX-M基因的流行病学特征。【方法】采集广州市不同区域零售市场和超市畜禽肉类样品进行大肠杆菌的分离,通过基因phoA扩增和测序进行大肠杆菌鉴定,采用琼脂扩散法和微量肉汤稀释法测定药物敏感性,通过PCR扩增检测bla_CTX-M基因,对bla_CTX-M阳性大肠杆菌进行全基因组测序。【结果】从323份市售畜禽肉样品中分离获得大肠杆菌241株;药物敏感性结果表明大肠杆菌对氨苄西林(63.07%)、多西环素(47.72%)和复方新诺明(43.15%)耐药率较高;bla_CTX-M基因检出率为3.32%(n=8),其中4株携带bla_CTX-M-14,3株携带bla_CTX-M-65,1株携带bla_CTX-M-55;8株产CTX-M大肠杆菌可分为4种不同的ST型,且携带多种耐药基因和毒力基因。【结论】市售畜禽肉中大肠杆菌污染严重。产CTX-M酶大肠杆菌均为多重耐药菌株,且bla_CTX-M<...     

冬季郑州市12个常绿树种的光合特性及滞尘能力

为筛选出北方城市冬季生态效益突出的常绿树种,以缓解大气CO2和粉尘颗粒物污染,并为这些树种的园林应用提供科学支持,该文选取郑州市园林绿化应用广泛的12个常绿树种,利用LI-6400便携式光合测定仪和洗脱-质量差值法,并对其光合特性及滞尘能力进行测定,计算出其光合参数[叶片的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度...     

Is it necessary for screening irregular antibodies of blood donors?

To explore the necessity of electronic crossmatching applied to irregular antibodies from blood donors, to ensure blood transfusion safety. Irregular antibody screening was performed on blood samples collected in the Dongguan Blood Center from Apr 17, 2014 to Dec 31, 2017. Primary screening was performed on the Sanquin automatic blood group analyzer by the microcolumn gel method (Sanquin). The positive samples were analyzed again using the salt medium method, polybrene method and micro-column gel method (Diana) for the second screening. If the second screening was positive, it was used to determine irregular antibody specificity (using panel cells) and any irregular antibody titer was detected. A total of 208,004 samples were detected, of which 316 were positive (316/208,004; 0.152%). Among them, 120 alloantibodies (120/135,139; 0.088%) were detected in male donors, which was much lower than in female donors (173/72,865; 0.237%) (P<0.01). A total of 16 kinds of known irregular antibodies and 40 cases of unknown antibody specificity were detected, with 119 cases of IgG type and 197 cases of IgM type, at the ratio of 1.65:1. In female donors, the frequencies of anti-D, anti-E, anti-M and anti-Le^a were significantly higher than in male donors (P<0.01). In married couples, the frequencies of anti-D and anti-E were significantly higher than those unmarried (P<0.05). In minority nationalities, the frequency of anti-M was significantly higher than in the Han nationality (P<0.05). In non-Guangdong donors, the frequencies of anti-D and anti-Le^a were significantly higher than in Guangdong donors. 87.02% of irregular antibody positive donors’ antibody titers were lower than “++”, which was deemed as no serious hazard for clinical transfusion. The study suggests that it is unnecessary to screen for irregular antibodies in blood donors. Male donors from Guangdong may not be required to undergo screening for irregular antibodies, and anti-D and anti-E only identification is also not required to be detected in female donors.     

Single-Atom Immobilization Boosting Oxygen Redox Kinetics of High-Entropy Perovskite Oxide Toward High-Performance Lithium-Oxygen Batteries

Understanding and modulating the unique electronic interaction between single-metal atoms and high entropy compounds are of great significance to enable their high-efficiency oxygen electrocatalysis for aprotic lithium-oxygen (Li-O₂) batteries. Herein, a novel bi-functional electrocatalyst is for the first time created by immobilizing single-atom ruthenium (Ru) on lanthanum-based high entropy perovskite oxide La(Mn_0.2Co_0.2Fe_0.2Ni_0.2Cr_0.2)O₃ (Ru@HEPO), which demonstrates high activity and stability in Li-O₂ batteries. The heteronuclear coordination between single-atom Ru and HEPO facilitates fast electron transfer from Ru to HEPO by establishing Ru-O-M (M stands for Mn, Co, Fe, Ni) bridges, which well redistributes electrons within the Ru@HEPO hence significantly improving its interfacial charge transfer kinetics and electrocatalytic activity. Additionally, the strong electron coupling between Ru and Mn atoms enhances the hybridization between Mn 3d and O 2p orbitals, which promotes the inherent affinity of Ru@HEPO toward the LiO₂ intermediate, thereby reducing the reaction energy barrier of the oxygen electrode. As a result, the Ru@HEPO-based Li-O₂ batteries deliver remarkable electrochemical performances, such as high energy efficiency (87.3% at 100 mA g⁻¹), excellent rate capability (low overpotential of 0.52 V at 100 mA g⁻¹) and durable cyclability (345 cycles at 300 mA g⁻¹). This work opens up a promising avenue for the development of high entropy-based electrocatalysts for Li-O₂ batteries by precisely tailoring the electronic distributions at an atomic scale.     

Construction of a cross-species cell landscape at single-cell level

Individual cells are basic units of life. Despite extensive efforts to characterize the cellular heterogeneity of different organisms, cross-species comparisons of landscape dynamics have not been achieved. Here, we applied single-cell RNA sequencing (scRNA-seq) to map organism-level cell landscapes at multiple life stages for mice, zebrafish and Drosophila. By integrating the comprehensive dataset of > 2.6 million single cells, we constructed a cross-species cell landscape and identified signatures and common pathways that changed throughout the life span. We identified structural inflammation and mitochondrial dysfunction as the most common hallmarks of organism aging, and found that pharmacological activation of mitochondrial metabolism alleviated aging phenotypes in mice. The cross-species cell landscape with other published datasets were stored in an integrated online portal—Cell Landscape. Our work provides a valuable resource for studying lineage development, maturation and aging.