关键词： Microarthropods   Earthworms   Collembola   Springtail   Oribatid mites   Mixed stands  

摘要： In the context of sustainable forest management and climate change, increasing tree richness has been proposed as a possible strategy to reach both ecological and productivity goals. This review focuses on the effects of mixed stands and increasing tree richness on soil fauna in temperate forests. Effects on earthworm and microarthropod (Collembola and Oribatid Mites) species diversity and abundance and community structure are examined, and clues to the main factors affecting soil communities in these stands are proposed. Our statistical analyses showed no evidence of any general trend for the effect of mixture either on earthworm or microarthropod diversity or on their abundance. Indeed, positive, negative and nonsignificant effects have all been reported. Nevertheless, the majority of the studies did find that increased tree richness or the introduction of broad-leaves had a positive effect. In addition, our review shows that soil organism abundance and diversity can be strongly affected by the presence of certain tree species and that the soil organism community structure is, in most cases, significantly affected by an increase in. tree richness or by a mixing effect. Litter features appear to be important drivers of soil fauna community composition, while mixture effect seems to have less impact on soil biota. Soil fauna are directly affected by the physical characteristics (microhabitats) and chemical composition (resource quality) of the litter specific to each tree species. Soil communities are then indirectly affected by the subsequent humus characteristics. We conclude our review with some guidelines for forest management and further research. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Fossils   macroevolution   morphological evolution   paleobiology   phylogenetics  

摘要： Morphological cladograms of vertebrates are often inferred from greater numbers of characters describing the skull and teeth than from postcranial characters. This is either because the skull is believed to yield characters with a stronger phylogenetic signal (i.e., contain less homoplasy), because morphological variation therein is more readily atomized, or because craniodental material is more widely available (particularly in the palaeontological case). An analysis of 85 vertebrate datasets published between 2000 and 2013 confirms that craniodental characters are significantly more numerous than postcranial characters, but finds no evidence that levels of homoplasy differ in the two partitions. However, a new partition test, based on tree-to-tree distances (as measured by the Robinson Foulds metric) rather than tree length, reveals that relationships inferred from the partitions are significantly different about one time in three, much more often than expected. Such differences may reflect divergent selective pressures in different body regions, resulting in different localized patterns of homoplasy. Most systematists attempt to sample characters broadly across body regions, but this is not always possible. We conclude that trees inferred largely from either craniodental or postcranial characters in isolation may differ significantly from those that would result from a more holistic approach. We urge the latter.

关键词： Glyphosate   Chlorpyrifos   Dimethoate   Malformation   Propanil  

摘要： The impact of widespread and common environmental factors, such as chemical contaminants, on infectious disease risk in amphibians is particularly important because both chemical contaminants and infectious disease have been implicated in worldwide amphibian declines. Here we report on the lone and combined effects of exposure to parasitic cercariae (larval stage) of the digenetic trematode, Acanthostomum burminis, and four commonly used pesticides (insecticides: chlorpyrifos, dimethoate;herbicides: glyphosate, propanil) at ecologically relevant concentrations on the survival, growth, and development of the common hourglass tree frog, Polypedates cruciger Blyth 1852. There was no evidence of any pesticide-induced mortality on cercariae because all the cercariae successfully penetrated each tadpole host regardless of pesticide treatment. In isolation, both cercarial and pesticide exposure significantly decreased frog survival, development, and growth, and increased developmental malformations, such as scoliosis, kyphosis, and also edema and skin ulcers. The combination of cercariae and pesticides generally posed greater risk to frogs than either factor alone by decreasing survival or growth or increasing time to metamorphosis or malformations. The exception was that lone exposure to chlorpyrifos had higher mortality without than with cercariae. Consistent with mathematical models that suggest that stress should increase the impact of generalist parasites, the weight of the evidence from the field and laboratory suggests that ecologically relevant concentrations of agrochemicals generally increase the threat that trematodes pose to amphibians, highlighting the importance of elucidating interactions between anthropogenic activities and infectious disease in taxa of conservation concern.

关键词： tree shrew   lung cancer   3-methylcholanthrene   animal model   diethylnitrosamine  

摘要： Animal models play a key role in identifying treatments for various types of cancer, including lung cancer. The aim of the present study was to develop a new animal model for lung cancer induction using tree shrews from the Yunnan region in China. Tree shrews are suitable for a full simulation of human disease because their structure, function and metabolism are adequately close to human. This animal may offer a new experimental animal model to be used in the study of lung cancer. In the present study, 80 healthy tree shrews were distributed in experimental and control groups. Animals in the experimental group received different concentrations of iodized oil suspension of 3-methylcholanthrene (3-MC) and diethylnitrosamine (DEN) while animals in the control groups received saline or lipiodol solvent via endotracheal instillation. In the 3rd, 5th, 7th, 9th and 11th weeks the body weights of the animals were measured and chest X-ray examinations were conducted. Pathological studies on the lung tissues were also performed and the pathological changes occurring in bronchial epithelium in all the groups were examined. Animals in the experimental group gradually lost their body weight. For tree shrews in the blank control and solvent control groups the survival rates were 100 and 80%, respectively while the survival rate for the experimental group was 0%. Results from the chest X-ray conducted on animals in the blank control and solvent control groups revealed no obvious abnormalities while in the experimental group high-density shadow spots within the perfusion sites were observed. Pathological studies performed on these high-density areas confirmed changes in the bronchial epithelium. In the experimental groups we also detected bronchial epithelial atypical hyperplasia, and apparent changes in carcinoma in situ. In conclusion, lung cancer was successfully induced in tree shrews by a one-time endotracheal introduction of iodized oil suspension of 3-MC and DEN.

关键词： breast cancer   tree shrew   animal model   PyMT  

摘要： The tree shrew is becoming an attractive experimental animal model for human breast cancer owing to a closer relationship to primates/humans than rodents. Tree shrews are superior to classical primates because tree shrew are easier to manipulate, maintain and propagate. It is required to establish a high-efficiency tree shrew breast cancer model for etiological research and drug assessment. Our previous studies suggest that 7,12-dimethylbenz(a)anthracene (DMBA) and medroxyprogesterone acetate (MPA) induce breast tumors in tree shrews with a low frequency (<50%) and long latency (similar to 7-month), making these methods less than ideal. We induced mammary tumors in tree shrew (Tupaia belangeri chinensis) by injection of lentivirus expressing the PyMT oncogene into mammary ducts of 22 animals. Most tree shrews developed mammary tumors with a latency of about three weeks, and by 7 weeks all injected tree shrews had developed mammary tumors. Among these, papillary carcinoma is the predominant tumor type. One case showed lymph node and lung metastasis. Interestingly, the expression levels of phosphorylated AKT, ERK and STAT3 were elevated in 41-68% of PyMT-induced mammary tumors, but not all tumors. Finally, we observed that the growth of PyMT-induced tree shrew mammary tumors was significantly inhibited by Cisplatin and Epidoxorubicin. PyMT-induced tree shrew mammary tumor model may be suitable for further breast cancer research and drug development, due to its high efficiency and short latency.

摘要： Plant species richness and the presence of certain influential species (sampling effect) drive the stability and functionality of ecosystems as well as primary production and biomass of consumers. However, little is known about these floristic effects on richness and community composition of soil biota in forest habitats owing to methodological constraints. We developed a DNA metabarcoding approach to identify the major eukaryote groups directly from soil with roughly species-level resolution. Using this method, we examined the effects of tree diversity and individual tree species on soil microbial biomass and taxonomic richness of soil biota in two experimental study systems in Finland and Estonia and accounted for edaphic variables and spatial autocorrelation. Our analyses revealed that the effects of tree diversity and individual species on soil biota are largely context dependent. Multiple regression and structural equation modelling suggested that biomass, soil pH, nutrients and tree species directly affect richness of different taxonomic groups. The community composition of most soil organisms was strongly correlated due to similar response to environmental predictors rather than causal relationships. On a local scale, soil resources and tree species have stronger effect on diversity of soil biota than tree species richness per se.

关键词： 树鼩   非肥胖型非酒精性脂肪肝   胆固醇   发病机理   脂蛋白脂酶   动物模型  

摘要： 非酒精性脂肪肝病(non-alcoholic fatty liver disease，NAFLD)是由酒精之外的其他因素导致的肝脏中以脂肪积累为主要特征的临床病理综合征，高能量食物（尤其是高脂高胆固醇食物）的过多摄入和多坐少动等都是它的诱发因素。目前其正在逐渐成为一个严重的公共健康问题，在西方发达国家，大约有20-30％的人患有非酒精性脂肪肝，而在中国，也有12-24％的人承受同样的疾病折磨。\n 一般而言，患有非酒精性脂肪肝的患者同时也伴有肥胖、高血糖、高血脂、胰岛素抵抗甚至2型糖尿病等代谢综合征(metabolic syndrome)的症状，对于这一类非酒精性脂肪肝已经建立了诸多的动物模型来供人们研究，尽管目前对其发病机理了解的不是很透彻，但还是取得了一些进展;但是，另一方面，在亚太地区，一些非酒精性脂肪肝患者(15-21％)却并没有表现出肥胖和糖尿病症状，因此被称为是非肥胖型非酒精性脂肪肝(non-obese NAFLD)，遗憾的是，目前并没有十分理想的动物模型可用来对其开展研究，这也导致我们对这种非肥胖型非酒精性脂肪肝的发病机理知之甚少。\n 树鼩(tree shrew)是一种小型哺乳动物，它在生物分类学上的位置介于啮齿类和灵长类之间，其进化地位比啮齿类更为高级。正因为如此，树鼩不断被应用于生物学研究领域，包括神经生物学、病毒学（乙型和丙型肝炎病毒等）、行为学（应激和抑郁等）、癌症和代谢性疾病等方面的研究。然而树鼩能否被用来研究非酒精性脂肪肝还不得而知。\n 为了回答上述问题，在本研究中，首先，我们用不同高热量食物的组合（如高糖、高脂、高糖高脂以及高脂高胆固醇等）来对树鼩（Tupaia belangeri chinensis）进行食物诱导。结果发现，诱导之后，各组树鼩表现出不同程度的肝功能受损，同时伴随有高脂血症，但血糖并未呈现明显变化。进一步通过组织切片检查其肝脏组织发现，所有树鼩都出现肝脏脂肪积累，这意味着我们成功诱导了树鼩脂肪肝。但令人惊奇的是，和对照组树鼩相比，这些脂肪肝树鼩的体重并没有增加，而且在皮下和腹腔等处也没有脂肪组织的出现，说明它们没有形成肥胖。因此，我们认为树鼩可以作为一种较好的研究非肥胖型非酒精性脂肪肝的动物模型。\n 接着，我们用高脂高胆固醇食物进一步研究发现，树鼩不仅能够形成非酒精性脂肪肝的早期阶段（单纯性脂肪肝），还能够出现脂肪性肝炎和纤维化，也就是说树鼩能够完整模拟非酒精性脂肪肝的发病过程，并且模拟这一过程需要的时间只有小鼠模型的三分之一。同时，在发病机理方面，经过对脂代谢基因的筛选，我们发现肝脏脂蛋白脂酶(lipoprotein lipase，LPL)在高脂高胆固醇诱导下高表达，而将LPL抑制之后，动物水平上，高脂高胆固醇导致的脂肪肝症状得到了明显的恢复;细胞水平上，氧化型LDL引起的树鼩肝脏原代细胞内的脂肪积累现象也得到了显著改善。因此我们的研究结果说明，LPL在高脂高胆固醇诱导的树鼩非肥胖型非酒精性脂肪肝发病过程中起着关键作用。\n 此外，在上述基础上，为了探究肝脏LPL的高表达到底是高脂和高胆固醇的共同作用诱导的、还是单独的胆固醇诱导的以及这其中蕴藏着怎样的调控机制等问题，我们在小鼠上设计了单独不同浓度的胆固醇诱导以及不同浓度的胆固醇与高脂组合诱导的实验并做了肝脏转录组检测，结果显示，单独的一定浓度胆固醇就可以诱导肝脏LPL的高表达。然而，由于转录组数据分析还在进行之中，因此关于这其中的调控机理还需要等待转录组数据的分析结果和实验验证来回答。

关键词： Freedom from animal disease   Absence of disease   Swine   Aujeszky's disease   Scenario tree modelling   OIE  

摘要： "Freedom from animal disease" is an ambiguous concept that may have a different meaning in trade and science. For trade alone, there are different levels of freedom from OIE listed diseases. A country can: be recognized by OIE to be "officially free";self-declare freedom, with no official recognition by the OIE;or report animal disease as absent (no occurrence) in six-monthly reports. In science, we apply scenario tree models to calculate the probability of a population being free from disease at a given prevalence to provide evidence of freedom from animal disease. Here, we link science with application by describing how a scenario tree model may contribute to a country's claim of freedom from animal disease. We combine the idea of a standardized presentation of scenario tree models for disease freedom and having a similar model for two different animal diseases to suggest that a simple generic model may help veterinary authorities to build and evaluate scenario tree models for disease freedom. Here, we aim to develop a generic scenario tree model for disease freedom that is: animal species specific, population specific, and has a simple structure. The specific objectives were: to explore the levels of freedom described in the OIE Terrestrial Animal Health Code;to describe how scenario tree models may contribute to a country's claim of freedom from animal disease;and to present a generic swine scenario tree model for disease freedom in Canada's domestic (commercial) swine applied to Aujeszky's disease (AD). In particular, to explore how historical survey data, and data mining may affect the probability of freedom and to explore different sampling strategies. Finally, to frame the generic scenario tree model in the context of Canada's claim of freedom from AD. We found that scenario tree models are useful to support a country's claim of freedom either as "recognized officially free" or as part of a self-declaration but the models should not stand alone in a claim. T

关键词： TREE populations   FORESTS & forestry   HERBIVORES   SEEDLINGS   TREE growth   FOREST canopies   TROPICS  

摘要： The Janzen-Connell hypothesis proposes that specialized herbivores maintain high numbers of tree species in tropical forests by restricting adult recruitment so that host populations remain at low densities. We tested this prediction for the large timber tree species, Swietenia macrophylla, whose seeds and seedlings are preyed upon by small mammals and a host-specific moth caterpillar Steniscadia poliophaea, respectively. At a primary forest site, experimental seed additions to gaps - canopy-disturbed areas that enhance seedling growth into saplings - over three years revealed lower survival and seedling recruitment closer to conspecific trees and in higher basal area neighborhoods, as well as reduced subsequent seedling survival and height growth. When we included these Janzen-Connell effects in a spatially explicit individual-based population model, the caterpillar's impact was critical to limiting Swietenia's adult tree density, with a >10-fold reduction estimated at 300 years. Our research demonstrates the crucial but oft-ignored linkage between Janzen-Connell effects on offspring and population-level consequences for a long-lived, potentially dominant tree species.

关键词： SAVANNA plants   PLANT growth   LEGUMES   PLANT diversity   PLANT physiology   PLANT defenses  

摘要： Herbivory contributes substantially to plant functional diversity and in ways that move far beyond direct defence trait patterns, as effective growth strategies under herbivory require modification of multiple functional traits that are indirectly related to defence. In order to understand how herbivory has shaped plant functional diversity, we need to consider the physiology and architecture of the herbivores and how this constrains effective defence strategies. Here we consider herbivory by mammals in savanna communities that range from semi-arid to humid conditions. We posited that the saplings of savanna trees can be grouped into two contrasting defence strategies against mammals, namely architectural defence versus low nutrient defence. We provide a mechanistic explanation for these different strategies based on the fact that plants are under competing selection pressures to limit herbivore damage and outcompete neighbouring plants. Plant competitiveness depends on growth rate, itself a function of leaf mass fraction (LMF) and leaf nitrogen per unit mass (N-m). Architectural defence against vertebrates (which includes spinescence) limits herbivore access to plant leaf materials, and partly depends on leaf-size reduction, thereby compromising LMF. Low nutrient defence requires that leaf material is of insufficient nutrient value to support vertebrate metabolic requirements, which depends on low N-m. Thus there is an enforced tradeoff between LMF and N-m, leading to distinct trait suites for each defence strategy. We demonstrate this tradeoff by showing that numerous traits can be distinguished between 28 spinescent (architectural defenders) and non-spinescent (low nutrient defenders) Fabaceae tree species from savannas, where mammalian herbivory is an important constraint on plant growth. Distributions of the strategies along an LMF-N-m tradeoff further provides a predictive and parsimonious explanation for the uneven distribution of spinescent and non-spinescen