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1.
Summary The Iguanid lizard Liolaemus tenuis is shown to be a rock and trunk dweller (apparently preferring perches between 0–30 cm height) in a central Chilean locality where it coexists with a single ground-dwelling congener. In its southern distributional ranges L. tenuis is sympatric with another tree-dweller, L. pictus. Habitat shift is demonstrated in this latter case by L. tenuis concentrating on tree trunks, and at modal heights 30–60 cm. Liolaemus pictus occupies lower (apparently more favorable) perches, actively interferring with its congener.  相似文献   

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城市公园是城市生态系统的重要组成部分和城市生物多样性热点地区,具有丰富的声景观资源。由于声景观及声学方法具有信息量大,成本低,低侵入的特点,因此其研究和应用对生态系统健康及监测具有较高价值。声景观研究通过总结生物声的活动或多样性来衡量生物多样性。记录了北京20个城市公园的春季声景观,使用定量方法描述了声景观特征与变化;测试三种了已被证明与生物多样性相关并被广泛使用的声学指数(BIO、ADI、NDSI)与植被群落关系,完成了城市环境中声景观与环境关系的初步探究。研究结果表明:(1)声学指数能够有效表征城市公园声景观信息,具有显著的时间动态特性,能准确反映鸟类黎明合唱等重要生物生态活动;(2)声学强度指数也具有显著的时间动态变化和沿频率梯度的变化,不同的频率区间反映了不同声学群落的活动信息;(3)植被结构尤其是垂直结构对声景观起着重要作用,垂直异质性越大,声学多样性越高。发现支持声景观作为公园植被状况的度量,强调了其作为生物多样性和生态系统健康状况监测方法,用于城市管理和可持续发展的巨大潜力。  相似文献   

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Signaling by bone morphogenetic protein (BMP) receptors is regulated at multiple levels in order to ensure proper interpretation of BMP stimuli in different cellular settings. As with other signaling receptors, regulation of the amount of exposed and signaling-competent BMP receptors at the plasma-membrane is predicted to be a key mechanism in governing their signaling output. Currently, the endocytosis of BMP receptors is thought to resemble that of the structurally related transforming growth factor-β (TGF-β) receptors, as BMP receptors are constitutively internalized (independently of ligand binding), with moderate kinetics, and mostly via clathrin-mediated endocytosis. Also similar to TGF-β receptors, BMP receptors are able to signal from the plasma membrane, while internalization to endosomes may have a signal modulating effect. When at the plasma membrane, BMP receptors localize to different membrane domains including cholesterol rich domains and caveolae, suggesting a complex interplay between membrane distribution and internalization. An additional layer of complexity stems from the putative regulatory influence on the signaling and trafficking of BMP receptors exerted by ligand traps and/or co-receptors. Furthermore, the trafficking and signaling of BMP receptors are subject to alterations in cellular context. For example, genetic diseases involving changes in the expression of auxiliary factors of endocytic pathways hamper retrograde BMP signals in neurons, and perturb the regulation of synapse formation. This review summarizes current understanding of the trafficking of BMP receptors and discusses the role of trafficking in regulation of BMP signals.  相似文献   

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Heterogeneity among individuals influences the life‐history trajectories we observe at the population level because viability selection, selective immigration and emigration processes, and ontogeny change the proportion of individuals with specific trait values with increasing age. Here, we review the two main approaches that have been proposed to account for these processes in life‐history trajectories, contrasting how they quantify ontogeny and selection, and proposing ways to overcome some of their limitations. Nearly all existing approaches to model individual heterogeneity assume either a single normal distribution or a priori known groups of individuals. Ontogenetic processes, however, can vary across individuals through variation in life‐history tactics. We show the usefulness of describing ontogenetic processes by modelling trajectories with a mixture model that focuses on heterogeneity in life‐history tactics. Additionally, most methods examine individual heterogeneity in a single trait, ignoring potential correlations among multiple traits caused by latent common sources of individual heterogeneity. We illustrate the value of using a joint modelling approach to assess the presence of a shared latent correlation and its influence on life‐history trajectories. We contrast the strengths and limitations of different methods for different research questions, and we exemplify the differences among methods using empirical data from long‐term studies of ungulates.  相似文献   

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Through their semi-natural and agricultural areas, peri-urban regions are pivotal in providing ecosystem services (ES) to city dwellers. To quantify the ES provided by these areas, it is possible to use ES mapping methods: many ES mapping methods rely on land cover maps, but most maps are coarse compared to the peri-urban scale. Nevertheless, readily-available land use data and methods are often used to map ES at such scales, without contextualisation. As a result, such methods may not be able to capture the diversity that is present in the peri-urban vegetation, which could have consequences for their accuracy and furthermore for urban planning policies.To increase our understanding of the applicability of ES mapping methods in peri-urban regions, we assessed to what degree sites with similar plant composition in the green belt of Paris, France, were also projected to have similar ES bundles. We considered two commonly used ES model types: proxy-based models (here: look-up tables) and phenomenological models. We used 252 sites for which botanical survey data were available and applied the ES models to seven ES relevant in the peri-urban context. A cluster analysis was used to group sites, hence facilitating analyse of the spatial congruence between types of vegetation and bundles of ES.Clustering sites based on plant composition revealed six distinct clusters. Clustering sites based on ES bundles as estimated by phenomenological models and proxy-based models, resulted in four and two clusters, respectively. The proxy-based clustering only highlighted broad-leaved forests as an important ES supply source. The phenomenological model estimates of ES allowed a more nuanced clustering of sites into four different groups. The level of congruence between the different sets of clusters based on plant composition and estimated ES bundles was low. Except for forests, the commonly used ES models tested here were not able to represent the same level of heterogeneity in the peri-urban landscape as was found in the vegetation. Our results demonstrate the need to integrate finer scale approaches and primary data in ES assessments of peri-urban areas.  相似文献   

8.
沙门菌对酸压力的应答及其与毒力的关系   总被引:1,自引:0,他引:1  
沙门菌(Salmonella spp.)作为肠道细菌,必须克服胃中酸性环境,才能进一步入侵宿主肠道上皮细胞。已有的研究表明,沙门菌通过进化出多种应答机制,增强自身在酸性环境下的生存。本文回顾了沙门菌的耐酸特性,阐述了抵御酸压力时的几种应答机理,包括胞内pH的维持、调控酸激蛋白的时序表达以及细胞膜特性的改变。这些研究对人类了解和控制沙门菌的感染具有重要的指导意义。  相似文献   

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The identification of the relationships between different landscape services is important in social–ecological complex systems, especially in areas with intensive human activities. In this paper, Beijing and its peripheral regions are taken as a case study to calculate and map the intensities of five classic landscape services including material production, carbon storage, soil retention, habitat conservation, and population support based on grid maps. Overlap and correlation analyses were used to identify multiple service hotspots and the relationships between landscape services. The results show that (1) landscape services have spatial heterogeneity: high-intensity area of material production and population support is on the southeast plains of this region and high-intensity area of soil retention and habitat conservation is on the northwest; (2) approximately 96.03% of the region can provide at least one type of landscape services, whereas approximately three-quarters of the area provide multiple services, with the multiple service hotspots surrounding Beijing and Tianjin; (3) correlations exist between all pairs of landscape services, but strong correlations (correlation coefficient >0.5 or <−0.5) exist between four pairs, which are soil retention and habitat conservation (0.672), soil retention and population support (−0.613), habitat conservation and population support (−0.540), and material production and population support (0.529); (4) the services can be divided into two trade-off service bundles: the “natural” bundle, which contains carbon storage, soil retention, and habitat conservation, and the “artificial” bundle, which contains material production and population support. Only 4.19% of the area in this region contains these service bundles simultaneously. Finally, an improved understanding of the relationships between services was illustrated, and the importance of such services was highlighted for decision-makers and stakeholders.  相似文献   

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黄土高原植被景观多尺度变化及其与地形的响应关系   总被引:2,自引:0,他引:2  
基于RS和GIS技术,利用黄土高原近30年不同分辨率的归一化植被指数(NDVI),采用基于小波分析的多尺度空间统计学方法,研究不同时期黄土高原植被景观的多尺度变化特征及其与地形的响应关系。结果表明:(1)黄土高原植被景观1982—2011年期间发生了周期性变化。其中,1990年以前为植被恢复阶段,1990—2001年为植被退化阶段,2001年以后为植被恢复阶段。(2)植被景观的空间异质性与数据获取的时间、数据分辨率、空间位置和地形均有关。一方面,植被指数和数据分辨率越高,植被景观的空间异质性就越大,而且沿经度方向植被景观的空间差异性大于纬度方向;另一方面,NDVI的多尺度变化特征与地形因子有不同程度的相关性,表现为:高程地形湿度坡度坡向,这对于今后黄土高原植被景观的合理布局,提高生物多样性,控制水土流失,增强景观的连续性具有特别重要的意义,也可为指导生态环境建设提供基础资料。  相似文献   

11.
《HOMO》2014,65(2):155-160
Anthropometry in dance and aesthetic sports has been shown to play an important role in selection and performance criteria. The aim of the present study was to examine variations in somatotype and anthropometry in three different competitive dance styles: DanceSport Standard, Latin American and Ten Dance. Anthropometry and somatotype data were collected from thirty couples competing in Standard (n = 24 individuals), Latin American (n = 14) and Ten Dance (n = 22) styles. A single tester (ISAK Level 1) carried out all anthropometric measurements using the Heath-Carter protocol and somatotypes were calculated using the Heath-Carter's decimal equations. Results indicated that the mean somatotype for the male dancers was 2.4–3.9–3.2, whilst for females it was 2.7–2.7–3.5. Factorial analysis reported Standard dancers scored significantly higher for ectomorphy, sitting height and arm span than Latin dancers (p < 0.05). Correlation analysis with the Standard dancer's International Ranking highlighted moderate positive correlation with mesomorphy (r = 0.434, p < 0.05) and negative correlation with ectomorphy (r = −0.546, p < 0.001). The findings of this study show that somatotypes differ among DanceSport participants by dance style. Compared with other aesthetic sports, male and female dancers were less mesomorphic and more ectomorphic. Standard dancers tend to be more ectomorphic with greater height, longer arm span and greater sitting height compared with Latin American dancers. Although Standard dancers were ectomorphic, those dancers who had higher mesomorphic ranking had higher places in the dancers’ international ranking.  相似文献   

12.
It is well-known that mitochondrial DNA (mtDNA) can escape to intracellular or extracellular compartments under different stress conditions, yet understanding their escape mechanisms remains a challenge. Although Bax/Bak pores and VDAC oligomers are the strongest possibilities, other mechanisms may be involved. For example, mitochondria permeability transition, altered mitophagy, and mitochondrial dynamics are associated with intracellular mtDNA escape, while extracellular traps and extracellular vesicles can participate in extracellular mtDNA escape. The evidence suggests that mtDNA escape is a complex event with more than one mechanism involved. In addition, once the mtDNA is outside the mitochondria, the effects can be complex. Different danger signal sensors recognize the mtDNA as a damage-associated molecular pattern, triggering an innate immune inflammatory response that can be observed in multiple metabolic diseases characterized by chronic inflammation, including autoimmune diseases, diabetes, cancer, and cardiovascular disorders. For these reasons, we will review the most recent evidence regarding mtDNA escape mechanisms and their impact on different metabolic diseases.  相似文献   

13.
以黄淮麦区优良品种矮抗58、周麦18、豫麦49、百农418为研究对象,采用田间试验与实验室分析相结合的方法,对不同小麦品种在不同生育时期的抗倒伏性状进行研究.结果表明: 茎秆机械强度在开花期至花后20 d处于较高水平,在花后30 d明显下降;倒伏指数在开花期最小,花后30 d最大,其余两个时期处于中间水平.相关分析表明,开花期机械强度与重心高度呈显著负相关,与纤维素、木质素含量呈显著正相关,倒伏指数与节长、株高、重心高度呈显著正相关,与纤维素、木质素含量呈显著负相关;花后10 d和花后20 d机械强度与节长、株高、重心高度呈显著负相关,与茎粗、纤维素、半纤维素、木质素含量呈显著正相关,倒伏指数这段时期正好与之相反;花后30 d机械强度与株高、重心高度呈显著负相关,倒伏指数与株高、重心高度呈显著正相关,与木质素含量呈显著负相关.因此,明确各个生育时期与抗倒性相关的茎秆特性,可为黄淮麦区高产抗倒性品种的选育提供依据.  相似文献   

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Marine Protected Areas (MPA) can be powerful coastal management tools with several specific goals, although there is debate concerning their effectiveness. There is no consensus regarding the ideal size of MPAs, and actually there is some evidence that perhaps size is not as critical as other specific factors in determining their success in terms of populations’ protection and ecological functions conservation. On the other hand, depending on the objectives, zones with different classification regimes in terms of rules and uses might enable the maintenance of the intended uses.At this light, we examined the case of the small (605 002 m2) rocky shore area of Avencas, near Lisbon, on the Atlantic western Coast of Portugal, which was classified as Biophysical Interest Zone (ZIBA) in 1998, due to its exceptional intertidal biodiversity, after what its protection status became controversial, leading to conflicts with the local population and incompliance with extant regulations. From 2010 efforts were carried out by local authorities to reclassify Avencas as Marine Protected Area, which was achieved in 2016.Monitoring intertidal communities in a MPA and adjacent areas is an effective and low-cost procedure to evaluate the evolution of the biodiversity of rocky shores. Therefore, antedating the creation of the new MPA, assessments of the ZIBA biodiversity were conducted from January 2013 to December 2015 on a monthly basis. This timeline was selected as a function of a change in visitors’ behavior induced from 2013 by several management and outreach initiatives, which increased in a certain extent the user’s compliance with regulations.A positive evolution was expected for density and/or species diversity of the different groups analysed (flora, sessile fauna and mobile fauna) in this three years period. However, a very strong storm occurred in 2014 produced a significant impact and changed large areas of the Avencas rocky shore. As a consequence, results did not display a recognizable recovery pattern of the intertidal communities, and following that extreme event are not even consistent with a hypothesized enhanced recovery capability of the ecosystem in a protected area. This suggests that longer data series are necessary to obtain more robust data regarding natural variability, since alterations caused by extreme events are always likely to occur. Additionally, results illustrate that indeed size matters because it influences the MPA openness, expressed as the ratio of periphery to area, and therefore its susceptibility to external driving forces. Such considerations must be taken into account in any management plan, which in this case should encompass an increase in the intertidal protected area, a new conditioned small-scale fishing regime, and an adequate monitoring programme to evaluate the effectiveness of the new management scheme.  相似文献   

16.
In the context of global warming, this study aimed to assess the effect of temperature and irradiance on the macroalgal Taonia atomaria holobiont dynamics. We developed an experimental set-up using aquaria supplied by natural seawater with three temperatures combined with three irradiances. The holobiont response was monitored over 14 days using a multi-omics approach coupling algal surface metabolomics and metabarcoding. Both temperature and irradiance appeared to shape the microbiota and the surface metabolome, but with a distinct temporality. Epibacterial community first changed according to temperature, and later in relation to irradiance, while the opposite occurred for the surface metabolome. An increased temperature revealed a decreasing richness of the epiphytic community together with an increase of several bacterial taxa. Irradiance changes appeared to quickly impact surface metabolites production linked with the algal host photosynthesis (e.g. mannitol, fucoxanthin, dimethylsulfoniopropionate), which was hypothesized to explain modifications of the structure of the epiphytic community. Algal host may also directly adapt its surface metabolome to changing temperature with time (e.g. lipids content) and also in response to changing microbiota (e.g. chemical defences). Finally, this study brought new insights highlighting complex direct and indirect responses of seaweeds and their associated microbiota under changing environments.  相似文献   

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An integrated soil vacuum extraction/ biofiltration system has been designed and installed at a gasoline‐contaminated leaking underground storage tank (LUST) site in southern Delaware. The system remediates contaminated moisture entrained in the air stream, employs automatic water level controls in the filters, and achieves maximum vapor extraction and VOC destruction efficiency with an optimum power input. In addition, the valving and piping layout allows the sequence of air flow through the filters to be reversed at given time intervals, which minimizes biofouling, thereby increasing efficiency by decreasing system backpressure. This integrated system achieves VOC destruction rates of up to 69%. The modular design allows for easy mobilization, setup, and demobilization at LUST sites throughout Delaware.  相似文献   

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This study was undertaken to evaluate the effect of galanthamine, a new cholinesterase inhibitor on cognitive performances in 84 patients with various apoE genotype and Alzheimer's disease (AD) during the six-month treatment. The diagnosis of AD was made on the basis of NINCDS/ADRDN criteria. ApoE4 genotype was determined by PCR procedure. The cognitive performance was assessed MMSE at baseline and six months later. The difference among the groups was statistically analyzed by ANOVA model and Pearson's chi2-test. The MMSE at baseline in all completes was 18.0 +/- 3.73, whereas the mean value of MMSE after 6 months was 16.4 +/- 5.61 indicating significant deterioration (p < 0.01). Of the 84 patients, 14 (169%) were apoE4 homozygous, 41 (49%) were heterozygous, whereas 29 (35%) were apoE4 negative. The significant number of responders was observed among apoE4 homozygous patients (71%; chi2 = 6.89; p = 0.032). The subgroup of apoE4 homozygous patients with AD in its mild to moderate stage may be considered as responders to galanthamine.  相似文献   

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Mendel's work in hybridization is ipso facto a study in inheritance. He is explicit in his interest to formulate universal generalizations, and at least in the case of the independent segregation of traits, he formulated his conclusions in the form of a law. Mendel did not discern, however, the inheritance of traits from that of the potential for traits. Choosing to study discrete non-overlapping traits, this did not hamper his efforts.  相似文献   

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