Quercetin protected against isoniazide‐induced HepG2 cell apoptosis by activating the SIRT1/ERK pathway

Isoniazid (INH) is one of the most commonly used antituberculosis drugs, but its clinical applications have been limited by severe hepatic toxicity. Quercetin (Que), a natural flavonoid, has been proved to have many medicinal properties. This study aimed to clarify the possible protective effects of Que against INH‐induced hepatotoxicity using HepG2 cells. Our results indicated that Que significantly increased cell viability, superoxide dismutase, and GSH levels, while decreased alanine aminotransferase/aspartate aminotransferase levels. Besides, Que significantly abrogated INH‐induced cell apoptosis by upregulating the expression levels of Bcl‐2 and decreasing the levels of Bax, cleaved caspase‐3, and cleaved caspase‐9. Furthermore, Que obviously reversed the inhibition of INH on Sirtuin 1 (SIRT1) expression and extracellular signal‐regulated kinase (ERK) phosphorylation. Next, the SIRT1 inhibitor EX527 blocked the enhancement of Que upon ERK phosphorylation. Notably, EX527 partially abolished the beneficial effects of Que. In brief, our results provided the first evidence that Que protected against INH‐induced HepG2 cells by regulating the SIRT1/ERK pathway.     

中国植物受威胁等级评估系统概述

濒危物种保护是生物多样性保护工作的重要组成部分, 而物种受威胁等级评估则是濒危物种保护的方向指引。经过多年的发展, 物种受威胁等级的评估由定性评估逐渐向定量评估为主、定性评估为辅的方向发展。本文综述了国内植物受威胁等级定量评估系统的研究进展, 同时介绍了国外较为成熟的IUCN红色名录评估系统、CITES评估系统、美国自然保育协会评估系统, 提出未来制定受威胁物种定量评估标准时要兼顾以下方面: (1)等级设置定义要明确、统一且合理; (2)评估标准应该定量化、客观且不冗余; (3)评估系统应该适应不同地理范围, 最好能同时表达出各范围的受威胁等级; (4)评估指标要包含物种动态信息, 能定量分析物种在过去或者未来的变化。此外, 本文认为国内的物种受威胁等级定量评估系统应该形成规范化的大纲, 加大宣传力度, 尽量将理论研究与具体的保护行动结合起来; 同时, 我国还应该采用全球广泛应用的受威胁等级评估系统获取物种受威胁等级, 将国内生物多样性保护工作纳入到全球范围中去。     

Population genetic structure and connectivity of the seagrass Thalassia hemprichii in the Western Indian Ocean is influenced by predominant ocean currents

This study is the first large‐scale genetic population study of a widespread climax species of seagrass, Thalassia hemprichii, in the Western Indian Ocean (WIO). The aim was to understand genetic population structure and connectivity of T. hemprichii in relation to hydrodynamic features. We genotyped 205 individual seagrass shoots from 11 sites across the WIO, spanning over a distance of ~2,700 km, with twelve microsatellite markers. Seagrass shoots were sampled in Kenya, Tanzania (mainland and Zanzibar), Mozambique, and Madagascar: 4–26°S and 33–48°E. We assessed clonality and visualized genetic diversity and genetic population differentiation. We used Bayesian clustering approaches (TESS) to trace spatial ancestry of populations and used directional migration rates (DivMigrate) to identify sources of gene flow. We identified four genetically differentiated groups: (a) samples from the Zanzibar channel; (b) Mozambique; (c) Madagascar; and (d) the east coast of Zanzibar and Kenya. Significant pairwise population genetic differentiation was found among many sites. Isolation by distance was detected for the estimated magnitude of divergence (D_EST), but the three predominant ocean current systems (i.e., East African Coastal Current, North East Madagascar Current, and the South Equatorial Current) also determine genetic connectivity and genetic structure. Directional migration rates indicate that Madagascar acts as an important source population. Overall, clonality was moderate to high with large differences among sampling sites, indicating relatively low, but spatially variable sexual reproduction rates. The strongest genetic break was identified for three sites in the Zanzibar channel. Although isolation by distance is present, this study suggests that the three regionally predominant ocean current systems (i.e., East African Coastal Current, North East Madagascar Current, and the South Equatorial Current) rather than distance determine genetic connectivity and structure of T. hemprichii in the WIO. If the goal is to maintain genetic connectivity of T. hemprichii within the WIO, conservation planning and implementation of marine protection should be considered at the regional scale—across national borders.     

Different responses of avian feeding guilds to spatial and environmental factors across an elevation gradient in the central Himalaya

Although elevational patterns of species richness have been well documented, how the drivers of richness gradients vary across ecological guilds has rarely been reported. Here, we examined the effects of spatial factors (area and mid‐domain effect; MDE) and environmental factors, including metrics of climate, productivity, and plant species richness on the richness of breeding birds across different ecological guilds defined by diet and foraging strategy. We surveyed 12 elevation bands at intervals of 300 m between 1,800 and 5,400 m a.s.l using line‐transect methods throughout the wet season in the central Himalaya, China. Multiple regression models and hierarchical partitioning were used to assess the relative importance of spatial and environmental factors on overall bird richness and guild richness (i.e., the richness of species within each guild). Our results showed that richness for all birds and most guilds displayed hump‐shaped elevational trends, which peaked at an elevation of 3,300–3,600 m, although richness of ground‐feeding birds peaked at a higher elevation band (4,200–4,500 m). The Normalized Difference Vegetation Index (NDVI)—an index of primary productivity—and habitat heterogeneity were important factors in explaining overall bird richness as well as that of insectivores and omnivores, with geometric constraints (i.e., the MDE) of secondary importance. Granivore richness was not related to primary production but rather to open habitats (granivores were negatively influenced by habitat heterogeneity), where seeds might be abundant. Our findings provide direct evidence that the richness–environment relationship is often guild‐specific. Taken together, our study highlights the importance of considering how the effects of environmental and spatial factors on patterns of species richness may differ across ecological guilds, potentially leading to a deeper understanding of elevational diversity gradients and their implications for biodiversity conservation.     

Arbuscular mycorrhizal fungi protect a subtropical tree species exposed to simulated acid rain by accelerating photosynthetic ability,antioxidant enzymes and osmolyte accumulation

丛枝菌根真菌对其宿主光合能力、抗氧化酶和渗透物质积累的促进作用 及其抗酸雨机制的探讨 酸雨在中国南方发生频繁,对亚热带树种生长具有明显抑制作用。以往研究表明,丛枝菌根真菌(AM真菌)可以缓解酸雨对宿主植物的胁迫效应。榉树(Zelkova serrata)为中国南方主要经济树种之一,其如何与共生AM真菌协同、增强其抗酸雨胁迫的能力是本项研究所要探讨的关键科学问题。通过温室控制实验,将榉树幼苗随机接受4个水平的AM真菌接种处理(接种灭菌菌种;单独接种Rhizophagus intraradices;单独接种Diversispora versiformis;接种这两种菌种的混合菌种)和3个pH水平(pH2.5、pH4.0和pH5.6)的硫酸型酸雨和硝酸型酸雨处理组成的12个处理组合,同时测定其生长、光合性能、抗氧化酶、渗透调节和土壤酶的响应格局。研究发现酸雨处理显著降低了非菌根榉树幼苗的总干重、总叶绿素含量、叶片净光合速率和可溶性蛋白的含量;接种AM真菌,特别是接种混合菌种,显著提高了强酸胁迫下榉树幼苗的总干重、光合性能、丙二醛、过氧化物酶、超氧化物歧化酶、可溶性蛋白和根系酸性磷酸酶活性。此外,菌根效应依赖于AM真菌的种类和酸胁迫的梯度。本研究 结果表明,AM真菌对榉树幼苗抗酸胁迫的调控作用主要源于调节宿主植株光合能力、抗氧化酶和渗透物质的积累。榉树与其共生AM真菌在应对酸胁迫上协同机制的解析为该树种在中国南方酸雨区的栽培提供理论基础、具有重要的实践指导意义。     

Secular trends in childhood obesity in Denmark during 50 years in relation to economic growth

Objective: Our aim was to examine whether secular trends in childhood overweight and obesity during five decades could be explained by economic growth. Research Methods and Procedures: Annual measurements of height and weight were available for all children born between 1930 and 1983 attending primary school in the Copenhagen Municipality: 165,389 boys and 163,609 girls from the age of 7 through 13 years. After computerization, we calculated BMI (kg/m²) and estimated the prevalence of overweight and obesity, according to international age‐ and gender‐specific criteria, by year of birth and of measurement, and separately by each age group and gender. Economic growth was indicated by the Gross National Product and the overall consumption per capita, adjusted for inflation. Results: The prevalence of overweight occurred in phases: an increase from 1930 until the 1950s, followed by a plateau period between the 1950s and the 1960s and a steep increase thereafter. This pattern was apparent across all age groups and in both genders. Obesity trends showed a similar phase pattern; the prevalence remained relatively stable from 1930 until the 1940s, increased until the mid‐1950s, followed by a plateau until 1965, and thereafter a second steep increase. Obesity trends were similar among boys across all age groups, although only among girls from 11 to 13 years of age. In both genders, increments were most pronounced in the upper BMI percentiles. After stagnation until 1947, the economic growth indicators showed a steady increase; i.e., after the first increase started in overweight and obesity, whether analyzed by year of birth or year of measurement, there were no indications of phases in the rise thereafter. Discussion: Prevalence of overweight and obesity among Danish children rose in phases, which were not paralleled by trends in economic growth. The macroeconomic growth indicators seem inappropriate as proxies for the environmental exposures that have elicited the obesity epidemic.     

A kinetic approach to the dependence of dissimilatory metal reduction by Shewanella oneidensis MR-1 on the outer membrane cytochromes c OmcA and OmcB

The Gram-negative bacterium Shewanella oneidensis MR-1 shows a remarkably versatile anaerobic respiratory metabolism. One of its hallmarks is its ability to grow and survive through the reduction of metallic compounds. Among other proteins, outer membrane decaheme cytochromes c OmcA and OmcB have been identified as key players in metal reduction. In fact, both of these cytochromes have been proposed to be terminal Fe(III) and Mn(IV) reductases, although their role in the reduction of other metals is less well understood. To obtain more insight into this, we constructed and analyzed omcA, omcB and omcA/omcB insertion mutants of S. oneidensis MR-1. Anaerobic growth on Fe(III), V(V), Se(VI) and U(VI) revealed a requirement for both OmcA and OmcB in Fe(III) reduction, a redundant function in V(V) reduction, and no apparent involvement in Se(VI) and U(VI) reduction. Growth of the omcB(-) mutant on Fe(III) was more affected than growth of the omcA(-) mutant, suggesting OmcB to be the principal Fe(III) reductase. This result was corroborated through the examination of whole cell kinetics of OmcA- and OmcB-dependent Fe(III)-nitrilotriacetic acid reduction, showing that OmcB is approximately 11.5 and approximately 6.3 times faster than OmcA at saturating and low nonsaturating concentrations of Fe(III)-nitrilotriacetic acid, respectively, whereas the omcA(-) omcB(-) double mutant was devoid of Fe(III)-nitrilotriacetic acid reduction activity. These experiments reveal, for the first time, that OmcA and OmcB are the sole terminal Fe(III) reductases present in S. oneidensis MR-1. Kinetic inhibition experiments further revealed vanadate (V(2)O(5)) to be a competitive and mixed-type inhibitor of OmcA and OmcB, respectively, showing similar affinities relative to Fe(III)-nitrilotriacetic acid. Neither sodium selenate nor uranyl acetate were found to inhibit OmcA- and OmcB-dependent Fe(III)-nitrilotriacetic acid reduction. Taken together with our growth experiments, this suggests that proteins other than OmcA and OmcB play key roles in anaerobic Se(VI) and U(VI) respiration.     

贵州省典型汞铊矿区周边农田土壤跳虫群落特征

大量的采矿活动导致矿区周边土壤重金属污染, 严重危害土壤生物安全。汞、铊等重金属元素毒性强, 相关污染的土壤生态风险鲜有研究。跳虫作为土壤环境变化指示生物, 能很好地反映土壤质量的健康状况。本研究以贵州省某汞铊矿区周边的农田土壤为研究对象, 按离矿区距离和作物类型设置4个采样区, 每个采样区种植2种作物, 每种作物农田设置3个样方。研究土壤跳虫群落结构和多样性及其影响因子。结果表明, 调查区内跳虫平均密度为12,000 ind./m²; 采样区距离矿区越近, 土壤重金属污染程度越大, 综合污染指数越高, 跳虫种数、密度、多样性和丰富度指数均呈先增加再降低的趋势; 环境因子分析表明重金属显著影响跳虫群落结构: Folsomides americanus、Isotomiella minor和Protaphorura encarpatus数量与汞、铊和砷含量呈负相关。高有机质含量能缓解重金属对土壤跳虫的影响, 但作物类型(玉米与薏仁)对土壤跳虫群落结构的影响无显著差异。本研究结果表明土壤有机质或能反向调节重金属污染对土壤跳虫群落的影响。