Comet assay in phytoplankton as biomarker of genotoxic effects of environmental pollution   总被引：2，自引：0，他引：2  

Akcha F  Arzul G  Rousseau S  Bardouil M 《Marine environmental research》2008,66(1):59-61

The alkaline comet assay was tested on different microalgae: the dinoflagellates, Karenia mikimotoi and Alexandrium minutum, and the diatom, Chaetoceros gracilis. The microalgae were exposed during their exponential growth to the model direct genotoxicant, hydrogen peroxide (1h, 5 and 100muM H2O2). Following H2O2 exposure, the comet assay was validated only for K. mikimotoi for which genotoxicity was observed from the lowest tested concentration of 5 microM with a concentration-dependent effect. C. gracilis was too small in size (4 microm) to be correctly analysed. For A. minutum, our lysis buffer was not strong enough to digest the cellulosic thecal plates. For K. mikimotoi, the comet assay was thus applied for the study of the genotoxic effects of different pesticides: epoxiconazole (as Opus formulation), chlorpyriphos-ethyl (as Dursban formulation) and endosulfan at 1, 10 and 100 microg of active substance/L for 24h. Exposure to epoxiconazole in formulation resulted in an increase in the extent of DNA strand breaks at the highest tested concentration icro/L. Endosulfan exposure resulted in DNA damage for K. mikimotoi nuclei. Genotoxicity was observed from 1 microg/L of endosulfan and was not concentration dependent.  相似文献   

The role of water mass dynamics in controlling bacterial abundance and production in the middle Adriatic Sea     

Solić M  Krstulović N  Vilibić I  Kuspilić G  Sestanović S  Santić D  Ordulj M 《Marine environmental research》2008,65(5):388-404

Month-to-month fluctuations in the abundance of bacteria and heterotrophic nanoflagellates (HNF) and bacterial production, as well as various chemical (nutrients, oxygen) and physical (salinity, temperature) parameters were analysed at a station located in the open middle Adriatic Sea during one decade (1997-2006). Being influenced by both coastal waters and open Adriatic circulation in the surface layer, and by the deep Adriatic water masses in the deep layers (100 m), this station is quite suitable for detecting the environmental changes occurring in the open Adriatic Sea with respect to the circulation of its water masses and their long-term changes and anomalies. Multivariate methods were used to identify seasonal and inter-annual changes of the investigated parameters, associating observed changes to the changes in Adriatic water masses and circulation regimes. The analyses showed that bacterial abundance and production were controlled by different water mass dynamics during 1997-2001 compared to 2002-2006 period, particularly noticeable in different seasonal patterns of biological parameters. The interplay between North Adriatic Dense Water (NAdDW) and Levantine Intermediate Water (LIW) resulted in a change in the available nutrients (NAdDW is poor in orthophosphates), and as a consequence different bacterial abundance and production. A few periods were examined in detail, such as 2004, when LIW inflow was particularly strong and was accompanied by an increase of bacterial and HNF abundances, as well as of bacterial production.  相似文献   

GPS精密星历的轨道内插方法比较   总被引：3，自引：1，他引：2  

王磊  罗年学 《地理空间信息》2009,7(5):113-116

在高精度的GPS测量数据处理过程中,获取高精度卫星轨道是重要的环节,内插是获取任意历元的精密轨道信息的重要手段,对拉格朗日插值法、牛顿插值法、Neville逐次线性内插法和切比雪夫插值法的效果做了细致的比较,并在此基础上进一步探讨了短时间外推的效果。  相似文献   

An integrated approach to assess the ecological and chemical status of lakes with HOD/AHOD: a case study of two lakes     

Serdar G?NCü  Erdem ALBEK 《中国海洋湖沼学报》2019,37(1):146-159

The thermal strati?cation of the lakes impedes the transfer of atmospheric oxygen into the lower layers of the lake. In lakes which are af fected by diverse anthropogenic in?uences, the increasing organic matter amounts lead to a sharp decrease in hypolimnetic oxygen amounts, aided by thermal strati?cation,and anaerobic conditions arise. The determination of hypolimnetic oxygen demand(HOD) and areal hypolimnetic oxygen demand(AHOD) and their monitoring represent an integrated approach to investigate the oxygenation of lakes, the nutrient conditions, and the physicochemical dynamics. In this study, two lakes dif fering by size and af fected by dif ferent anthropogenic sources, are investigated in this respect. At?rst, bathymetric studies were conducted to determine the depth, surface area, and volume relationships.Then, based on monitoring studies conducted in 2013 and 2014, the thermal strati?cation dynamics and layer properties were established using the relative thermal resistance to mixing(RTRM) index based on temperature and density pro?les. Following this, the oxygen depletion rates were determined by oxygen and temperature pro?ling in the hypolimnion. For the years of 2013 and 2014, the AHOD values for the Borabey Pond which is far from anthropogenic in?uences, were found to be 0.848 and 0.569 g O 2/(m·d), respectively.The AHOD values for the Porsuk Reservoir which was overburdened for years by industrial and domestic pollution were found to be 4.263 and 5.099 g O 2/(m·d), larger than its counterpart by almost sevenfold. The HOD and AHOD monitoring can be considered to a valuable tool for assessing the ecological and chemical status of lakes within Annex 5 of the Water Framework Directive and as an integrated approach to assess and monitor the status of lakes.  相似文献   

三疣梭子蟹几丁质酶基因(PtCht6)的克隆及其在免疫中的功能分析     

宋柳  吕建建  王磊  孙东方  刘萍 《海洋与湖沼》2019,50(5):1080-1090

几丁质酶(chitinase)在甲壳动物的蜕皮、消化和免疫等很多生物学过程中发挥重要功能,为深入探讨几丁质酶的免疫防御机制,本实验利用RACE技术克隆了三疣梭子蟹(Portunus trituberculatus)PtCht6基因。该基因cDNA全长2736bp,开放阅读框(ORF)2103bp,编码700个氨基酸,具有几丁质酶GH18家族典型特征。利用实时荧光定量技术分析PtCht6在三疣梭子蟹不同组织、不同蜕皮阶段、不同病原感染以及低盐胁迫(11)下的表达特征,结果显示:PtCht6在各组织中均有表达且在肝胰腺中的表达量最高;在不同蜕皮时期的肝胰腺中,其表达量由蜕皮后期(A/B)、蜕皮间期(C)、蜕皮前期(D)依次递减(P0.05);人工感染WSSV和副溶血弧菌后.PtCht6的表达量在肝胰腺中分别于12h、72h达到最大值,在血细胞中均于12h达到最大值,且相较于对照组,整体显著上调表达(P0.05);低盐胁迫能够显著抑制该基因的表达,最高抑制73倍(P0.05)。同时发现,低盐环境下感染WSSV后,该基因达到峰值的时间明显延迟(至少延迟12h.P0.05)。该研究结果预示PtCht6作为免疫因子参与三疣梭子蟹的病原防御,且低盐胁迫在一定程度上抑制了该基因的免疫功能。  相似文献   

140kaBP以来南海西南部上升流影响区沉积记录及其古海洋环境变化   总被引：1，自引：0，他引：1  

邹杨浩  冉莉华  Martin G Wiesner  刘飞  梁文  陈建芳  刘连文 《海洋地质与第四纪地质》2019,39(2):123-133

对南海西南部现代上升流区沉积物柱样BIS-187-61孔有机碳、生物蛋白石、碳酸盐等各沉积组分进行了详细的分析,试图探讨末次间冰期(MIS 5)以来南海西南部夏季上升流影响区沉积过程及其所反映的海洋环境变化过程。研究结果发现,140kaBP以来该孔沉积记录期总体表现为:碳酸盐百分含量冰期低间冰期高,主要受周边陆源物质输入稀释的控制,为典型的"大西洋型碳酸盐旋回",有机碳、生物蛋白石、碳酸钙以及陆源沉积物的堆积速率均在MIS 2期、MIS 4期和MIS 5e期出现高值。其中,MIS 2期和MIS 4期生源和陆源沉积堆积速率增加可能与冰期时冬季风增强及海平面下降导致陆源营养物质输入增加对初级生产力的刺激有关,也可能与陆源物质输入增加对海洋生源颗粒物输出的压载作用增强有关。而MIS 5e期南海海平面高度与现代相仿,间冰期较强的夏季风引起的越南沿岸上升流增强是导致该时段本研究区域表层初级生产力增强,沉积物总堆积速率及各组分堆积速率都相应增加的主要原因。  相似文献   

高分辨率光学遥感场景分类的深度度量学习方法   总被引：1，自引：1，他引：0  

叶利华  王磊  张文文  李永刚  王赠凯 《测绘学报》2019,48(6):698-707

针对高分辨率光学遥感影像场景具有同类型内部差异大、不同类型间相似度高导致部分场景识别困难的问题,本文提出了一种深度度量学习方法。首先在深度学习模型的特征输出层上为每类预设聚类中心,其次基于欧氏距离方法设计均值中心度量损失项,最后联合交叉熵损失项以及权重与偏置正则项构成模型的损失函数。该方法的目标是在特征空间上使同类型特征聚集并扩大类型间的距离以提高分类准确率。试验结果表明,本文方法有效地提升了分类准确率。在RSSCN7、UC Merced和NWPU-RESISC45数据集上,与现有方法相比,分类准确率分别提高了1.46%、1.09%和2.51%。  相似文献   

卢氏局打好“组合拳”保障扶贫攻坚用地     

王磊 《资源导刊(河南)》2018,(2)

正脱贫攻坚战打响以来,卢氏县国土资源局充分发挥部门职责,立足脱贫攻坚工作需求,在用好用活土地政策方面狠下功夫,主动对接,靠前服务,打好组合拳,全力保障全县脱贫攻坚用地需求。2017年,累计上报新增建设用地91.27公顷,申报城乡建设用地增减挂钩批次2个。其中,拆旧区总面积53.15公顷,建新区总面积52.71公顷,在全县脱贫攻坚项目用地上实现了"应保尽保"。  相似文献   

Challenges in the Detection and Attribution of Northern Hemisphere Surface Temperature Trends Since 1850     

Ronan Connolly  Willie Soon  Michael Connolly  Sallie Baliunas  Johan Berglund  C. J. Butler  Rodolfo Gustavo Cionco  Ana G. Elias  Valery M. Fedorov  Hermann Harde  Gregory W. Henry  Douglas V. Hoyt  Ole Humlum  David R. Legates  Nicola Scafetta  Jan-Erik Solheim  László Szarka  Víctor M. Velasco Herrera  Hong Yan  Weijia Zhang 《天文和天体物理学研究(英文版)》2023,(10):369-388

Since 2007, the Intergovernmental Panel on Climate Change(IPCC) has heavily relied on the comparison between global climate model hindcasts and global surface temperature(ST) estimates for concluding that post-1950s global warming is mostly human-caused. In Connolly et al., we cautioned that this approach to the detection and attribution of climate change was highly dependent on the choice of Total Solar Irradiance(TSI) and ST data sets.We compiled 16 TSI and five ST data sets and found by alter...  相似文献   

Effect of Matching Algorithm and Profile Shape on Pulsar Pulse Time of Arrival Uncertainties     

J.Wang  J.P.W.Verbiest  G.M.Shaifullah  J.P.Yuan 《天文和天体物理学研究(英文版)》2023,(12):232-243

For high-precision pulsar timing analysis and low-frequency gravitational wave detection, it is essential to accurately determine pulsar pulse times of arrival(ToAs) and associated uncertainties. To measure the ToAs and their uncertainties, various cross-correlation-based techniques can be employed. We develop methodologies to investigate the impact of the template-matching method, profile shape, signal-to-noise ratio of both template and observation on ToA uncertainties. These methodologies are...  相似文献