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排序方式: 共有8252条查询结果,搜索用时 15 毫秒
1.
目的:检测JMJD6蛋白在胃癌组织及相应癌旁正常组织中的表达情况,并分析JMJD6蛋白表达与胃癌患者临床病理参数及预后的关系。方法:应用免疫组织化学方法检测JMJD6蛋白在胃癌组织及相应癌旁正常组织中的表达情况,进一步用Kaplan-Meier生存分析、COX比例风险回归模型等统计学方法研究JMJD6表达与胃癌患者临床病理参数及预后的关系。结果:JMJD6在胃癌组织中的表达阳性率显著高于癌旁正常组织(P=0.001);JMJD6在胃癌组织的高表达与肿瘤临床分期(P=0.008)、病理分级(P=0.001)、局部浸润深度(P=0.028)、有无淋巴结转移(P=0.001)等显著相关;Kaplan-Meier生存分析结果表明JMJD6高表达的胃癌患者术后总体生存率显著低于JMJD6低表达的患者(P=0.023)。结论:JMJD6在胃癌的发生发展中可能发挥了癌基因样作用,可能作为胃癌治疗的潜在靶点。 相似文献
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Fish community reassembly after a coral mass mortality: higher trophic groups are subject to increased rates of extinction 下载免费PDF全文
Since Gleason and Clements, our understanding of community dynamics has been influenced by theories emphasising either dispersal or niche assembly as central to community structuring. Determining the relative importance of these processes in structuring real‐world communities remains a challenge. We tracked reef fish community reassembly after a catastrophic coral mortality in a relatively unfished archipelago. We revisited the stochastic model underlying MacArthur and Wilson's Island Biogeography Theory, with a simple extension to account for trophic identity. Colonisation and extinction rates calculated from decadal presence‐absence data based on (1) species neutrality, (2) trophic identity and (3) site‐specificity were used to model post‐disturbance reassembly, and compared with empirical observations. Results indicate that species neutrality holds within trophic guilds, and trophic identity significantly increases overall model performance. Strikingly, extinction rates increased clearly with trophic position, indicating that fish communities may be inherently susceptible to trophic downgrading even without targeted fishing of top predators. 相似文献
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孔雀河下游断流河道的环境特征及物种间关系 总被引:1,自引:0,他引:1
基于孔雀河下游断流河道的环境因子和植被样地数据,采用聚类与CCA排序法,分析了生境的退化特征以及物种间的相互关系,结果表明:1)断流河道退化生境分为绿洲-荒漠过渡类型、轻度荒漠化类型和盐土荒漠化类型。绿洲-荒漠过渡类型地下水位低、盐分含量相对较低,植被盖度相对较高,土壤维持着原砂质壤土,为潜在退化型;轻度荒漠化类型地下水位、土壤质地与含盐量与前者基本相同,土壤未明显退化,但植被盖度低于10%,植物种类与个体数目都较低,属于轻度退化型;盐土荒漠化类型地下水位高、盐分含量高,土壤机械组成中砂粒比重较大、无建群种幸存,属于重度退化型。2)绿洲-荒漠过渡类型总体联结性为显著正联结,正负联结比小于1,生态系统表现为建群种维系物种关系的不稳定状态;轻度荒漠化类型总体联结性为不显著负联结,正负联结比小于1,表现出生态系统进入退化演替的阶段;盐土荒漠化类型总体联结性为显著正联结,正负联结比大于1,表现出重度退化群落的种间平衡状态,物种间以达到稳定共存,其中,真盐生植物对这种平衡的维持起着重要的作用。3)CCA排序表明,绿洲-荒漠过渡类型形成以胡杨为中心的种间正联结,幸存于盐分适中、水分养分相对较高的生境;轻度荒漠化类型,形成以多枝柽柳与刚毛柽柳相互依存的不显著负联结,幸存于土壤养分、水分相对较低的生境;盐土荒漠化类型形成以盐爪爪、盐节木、盐穗木等真盐生植物维系的显著正联结,幸存于土壤贫瘠、地下水位浅、盐分含量高、沙化严重的生境。 相似文献
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Regional distribution patterns can predict the local habitat specialization of arachnids in heterogeneous landscapes of the Atlantic Forest 下载免费PDF全文
Tiago Jordão Porto Ricardo Pinto‐da‐Rocha Pedro Luís Bernardo da Rocha 《Diversity & distributions》2018,24(3):375-386
Aim
This study formally evaluates the ability of three models to use geographical data on species distribution to predict the habitat use patterns of species in heterogeneous landscapes.Location
Species and habitats in the Brazilian Atlantic Rain Forest were investigated.Methods
Based on empirical data on harvestmen and scorpions, we estimated the strength of species association with preferred habitat and classified them as habitat generalists or habitat specialists. We compared these empirical results with predictions made using data on species range size (model 1), species occurrence in biomes (model 2) and species occurrence in habitats within the biomes (model 3).Results
We used 1,278 records of eight harvestman and two scorpion species that had specific determination and enough sampling numbers to allow safe identification of habitat specialization. We observed the following: (1) the extension of species occurrence did not influence the strength of species–habitat association (estimated by IndVal), which led us to reject model 1; (2) species habitat specialization derived from occurrences in biomes was 60% coincident with the classification derived from empirical data. This value is not different enough from the value expected by chance for these data, which also led us to reject model 2; and (3) species classification derived from secondary data about the habitats used had a significant coincidence of 80% with the empirical classification, which led us to accept model 3.Main conclusions
For correct classification of species habitat specialization using secondary distributional data, we recommend that future studies consider using the most accurate information available on the habitats used by species. Especially for megadiverse and understudied groups, information about habitats used is not easy to obtain, so it is important for researchers and institutions to register and disseminate this information, which could support many other studies.9.
Stallion semen quality depends on major histocompatibility complex matching to teaser mare 下载免费PDF全文
E. Jeannerat E. Marti C. Berney F. Janett H. Bollwein H. Sieme C. Wedekind 《Molecular ecology》2018,27(4):1025-1035
The major histocompatibility complex (MHC) has repeatedly been found to influence mate choice of vertebrates, with MHC‐dissimilar mates typically being preferred over MHC‐similar mates. We used horses (Equus caballus) to test whether MHC matching also affects male investment into ejaculates after short exposure to a female. Semen characteristics varied much among stallions. Controlling for this variance with a full‐factorial within‐subject experimental design, we found that a short exposure to an MHC‐dissimilar mare enhanced male plasma testosterone and led to ejaculates with elevated sperm numbers as compared to exposure to an MHC‐similar mare. Sperm velocity seemed not affected by the treatment. Overall genetic similarity between stallions and mares (determined from polymorphic microsatellites on 20 different chromosomes) played no significant role here. The MHC type of the teaser mare also affected characteristics of cold‐stored sperm after 24 and 48 hr. As expected from ejaculate economics, sperm viability was elevated after exposure to an MHC‐dissimilar mare. However, oxidative stress and the percentage of sperm with a high DNA fragmentation were mostly increased after exposure to an MHC‐dissimilar mare, depending also on whether the teaser mare was in oestrous or not. We conclude that males can quickly adjust ejaculate quality relative to a female's MHC, and that this male reaction to the social environment can also affect important characteristics of cold‐stored semen. 相似文献
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A unified framework to model the potential and realized distributions of invasive species within the invaded range 下载免费PDF全文
Tarek Hattab Carol X. Garzón‐López Michael Ewald Sandra Skowronek Raf Aerts Hélène Horen Boris Brasseur Emilie Gallet‐Moron Fabien Spicher Guillaume Decocq Hannes Feilhauer Olivier Honnay Pieter Kempeneers Sebastian Schmidtlein Ben Somers Ruben Van De Kerchove Duccio Rocchini Jonathan Lenoir 《Diversity & distributions》2017,23(7):806-819