关键词： 乳腺肿瘤   7,12-二甲基苯蒽   树鼩   动物模型  

摘要： 目的探讨7,12-二甲基苯蒽(DMBA)诱导树鼩乳腺癌模型的可行性,并比较灌胃和乳腺注射两种给药方式建模的效果。方法将40只树鼩随机分为灌胃组和乳腺注射组,每组20只。灌胃组:用食用植物油溶解的DMBA灌胃1次,15 mg/kg。乳腺注射组:向树鼩腹部一侧乳腺脂肪垫中注射以食用植物油溶解的DMBA,10 mg/kg,共注射3次。在给予DMBA的同时,开始在树鼩大腿外侧肌肉丰厚处注射醋酸甲羟孕酮,100 mg/kg,共注射5次。观察树鼩的成瘤和生存情况,对生成的病变组织行HE染色观察组织学形态,免疫组化染色检测雌激素受体(ER)、孕激素受体(PR)、细胞角蛋白5/6(CK5/6)和人表皮生长因子受体2(HER-2)的表达情况。结果灌胃组死亡10只,存活10只,有4只树鼩成瘤,成瘤率为20.0%(4/20),乳腺癌成模率为10.0%(2/20),成瘤时间为(197.3±15.1)d。乳腺注射组死亡8只,存活12只,有9只树鼩成瘤,成瘤率为45.0%(9/20),乳腺癌成模率为40.0%(8/20),成瘤时间为(71.8±19.0)d。两组死亡率和成瘤率差异无统计学意义(均P>0.05),但乳腺注射组成模率高于灌胃组(P<0.05),成瘤时间短于灌胃组(P<0.01)。灌胃组的病理类型有普通型导管增生、导管内乳头状瘤和导管原位癌。乳腺注射组病理类型有导管内乳头状瘤和导管原位癌。免疫组化染色显示,两组肿瘤组织中ER、PR和CK5/6均有不同程度阳性表达,HER-2阴性表达。结论 DMBA灌胃和乳腺注射两种方法均能成功建立树鼩乳腺癌模型,乳腺脂肪垫注射建模效果优于灌胃建模。

关键词： bamboo cover   farmland abandonment   microsite limitation   selective herbivory   Pleioblastus chino  

摘要： Aims Faunal assemblage alterations due to anthropogenic impacts have changed herbivore-vegetation relationships in various ecosystems,but the influences of small vertebrates on revegetation processes remain *** a peri-urban agricultural landscape in eastern Japan that lacks large ungulates but supports small generalist herbivores,fewer native seedlings have become established in thickets dominated by native dwarf bamboo,Pleioblastus chino(*** Sav.)*** mechanisms limiting tree seedling establishment are *** aim here was to evaluate the influence of interactions among the dwarf bamboo,its litter cover and small vertebrate herbivores on the micro-site conditions governing the establishment of native tree seedlings from different successional stages in an old field in temperate *** First,seedling emergence and survival of seeded Pinus densiflora Siebold et Zucc.,Celtis sinensis Pers.,Aphananthe aspera(Thunb.)Planch.,Quercus serrata Murray,Quercus myrsinifolia Blume and Castanopsis sieboldii(Makino)*** *** Mashiba were observed in a factorial design that accounted for the presence or absence of dwarf bamboo and its litter cover,as well as the exclu-sion or access of small vertebrate fauna,in 2009 and *** identify small vertebrate herbivores that reduced the emergence or survival of tree seedlings in the first experiment,reseeding experi-ments using ***,***,*** and *** were conducted by video trapping in 2011 and video and still-cam-era trapping in *** Findings The abiotic conditions under the dwarf bamboo were lethal to early-to mid-successional ***,***,*** and *** but led to better survival-although spindly growth-of late-succes-sional *** and *** main consumers and the plants they found palatable differed between the bamboo thickets and the intervening *** by mice appeared to have severely limited the emergence of

关键词： biotremology   tropotaxis   directional vibration sensing   communication   mutualism   acacia ants   orientation   social insects   defense behavior  

摘要： Living in the African savanna is dangerous, especially for plants. Many plants therefore engage in mutualism with ants, in which plants provide food and shelter in exchange for protection against herbivores. Ants become alarmed when the plant takes on some sort of damage. They immediately emerge from their plant shelter and aggressively defend the plant. Mammalian herbivores can have devastating effects on trees by browsing, breaking tree branches, stripping bark, and pushing over entire trees. However, mutualistic ants substantially reduce the amount of damage. To efficiently protect the tree, ants need to rapidly react together when the tree is under attack. Here, we show that the acacia ant Crematogaster mimosae defends its host tree by exploiting plant-borne vibrations caused by browsers feeding on the tree. Experiments with controlled vibrations show that ants discriminate browser-induced vibrations from those induced by wind, become alarmed, and patrol on the branches. Browser-induced vibrations serve as a long-distance alarm cue. The vibrations propagate through the whole acacia tree and trigger ants' defensive behavior, even on the other side of the tree. Furthermore, the ants make use of tropotactic directional vibration sensing to orient to the attacked part of the tree and fight back the attacker.

关键词： Acacia   Fever tree   Woodland   Land management   Disturbance   Crown cover   Ground cover  

摘要： Losses of acacia woodlands have been reported throughout eastern and southern Africa. Of particular concern is the loss of fever tree (Vachellia xanthophloea) woodlands along the riparian areas of lakes which may result in the loss of important terrestrial and aquatic ecosystem services. For example, the Lake Naivasha basin in Kenya has endured considerable population growth and associated changes in land management with potential consequences for fever tree woodlands. This study assessed how fever tree woodland integrity differed with varying degrees of human and wildlife disturbances among surrounding land use management types. A field survey of fever tree woodlands suggest that land management types influenced degrees of human and wildlife disturbances, with settlement areas having significantly more human disturbance and conservation areas having significantly more wildlife disturbance. Furthermore, while land management type did not significantly influence the stem sizes of fever trees, it did influence the condition of woodland crown and ground covers. Settlement areas with high human disturbance were correlated with healthier crown covers (a possible artifact of the removal of dead or dying crown for fuelwood) while conservation areas with high wildlife disturbance were correlated with less healthy crown covers in smaller trees (< 45 cm diameter at breast height) that were not killed but stunted by wildlife browsing. Settlement areas were dominated by more but less diverse ground cover while conservation areas were correlated with less but more diverse ground cover. While fever trees show resilience to multiple disturbances, the early warning of changes to the woodlands imply that the future of the fever tree woodlands is at risk and that limits to the encroachment of land management activities into the fever tree woodlands should be established.

关键词： 树鼩   肿瘤   动物模型  

摘要： 肿瘤是困扰人类健康的一大顽疾,构建合适的动物模型是研究肿瘤发生发展及治疗预防的重要手段,但是理想的非人灵长类动物受到资源稀缺、伦理审查严格等诸多限制,传统的啮齿类动物因为明显的种属界限而较难在整体水平模拟人类肿瘤疾病。新兴的一种与灵长类有亲缘关系的小型实验动物——树鼩,不仅在系统发育和生理、生化及解剖学等生物学特性方面有着独特优势,其某些自发性肿瘤也与人类肿瘤具有更高的相似性。目前以树鼩自发性肿瘤特点为基础,已经成功通过各种方式诱导出树鼩肝癌、乳腺癌、肺癌及胶质母细胞瘤,但总体上来说对树鼩作为人类肿瘤疾病动物模型的探索仍然较少,研究深度有待加强,未来需要更多的科研人员加入来充分挖掘其潜力。

关键词： NATURE   ECOLOGY   NONFICTION  

关键词： 树鼩   实验动物   质量控制   标准  

摘要： 树鼩在新陈代谢、生理机能、大体解剖和基因组等方面与人类具有相似性,已被广泛应用于医学和生物学研究领域。作为一种极具价值和科学研究需求的实验动物新资源,标准化质量控制已经成为树鼩使用中亟待解决的技术瓶颈和研究发展的必然趋势。本文对树鼩质量控制团体标准进行归纳总结和分析说明,加强标准的宣传推广和贯彻实施,为树鼩实验动物标准化质量控制及国家标准的制订提供参考依据,最终促进树鼩推广应用和产业化发展。

关键词： Acari   Collembola   Forest ecosystem   Litter traits   Plant-soil interaction   Predator-prey interaction  

摘要： Plant litter decomposition is an essential process of ecosystem functioning, driven by a complex soil food web. The identity and density of the predators, as well as the quality and quantity of litter, could conjointly affect the strength of trophic interactions within a soil food web. Pine and oak are dominant tree species in temperate and Mediterranean forests and, although they exhibit distinct litter characteristics, no previous study attempted to decipher how these two litters can affect a litter-based multi-trophic system with varying predator density. Using a microcosm experiment, we aimed at understanding how different densities of a predatory Acari (Stratiolaelaps scimitus) and two Mediterranean litter species (Quercus pubescens and Pinus halepensis) may impact the demographic parameters of the predatory Acari, its Collembola prey (Folsomia candida) and the fungal biomass associated with litter. We did not observe any interactive effect of litter identity and predator density on both predator and prey demographic parameters. Survival and fecundity rates of the predator and its prey decreased at high predator density. However, demographic parameters of the predator and its prey were differentially affected by litter identity, with greater prey demographic parameters in Quercus litter and, in the opposite, greater predator demographic parameters in Pinus litter, probably due to differences in physical characteristics providing more or less refuge for the prey. We also observed a higher increase in fungal biomass in Pinus compared to Quercus litter, i.e. the litter with the fungivorous Collembola abundance reduced by the predatory Acari. Litter identity could thus strongly regulate these tri-trophic interactions (Fungi - fungivorous Collembola - predatory Acari) in forest ecosystems. Finally, the implications of our findings could be important as the distribution area of oak and pine forests may be altered in response to climate change with then potentially st

关键词： LenStar   Ultrasonography   Ocular axial dimensions   Refractive indices   Tree shrews  

摘要： We describe an analysis strategy to obtain ultrasonography-matched axial dimensions of small animal eyes using the LenStar biometer. The LenStar optical low-coherence reflectometer is an attractive device for animal research due to its high precision, non-invasiveness, and the ability to measure the axial dimensions of cornea, anterior chamber, lens, vitreous chamber, and axial length. However, this optical biometer was designed for clinical applications in human eyes and its internal analysis provides inaccurate values when used on small eyes due to species-dependent differences in refractive indices and relative axial dimensions. The LenStar uses a near infrared light source to measure optical path lengths (OPLs) that are converted by the LenStar's EyeSuite software into geometrical lengths (GLs) based on the refractive indices and axial dimensions of the human eye. We present a strategy that extracts the OPLs, determines refractive indices specific for the small animal eye of interest and then calculates corrected GLs. The refractive indices are obtained by matching the LenStar values to ultrasonography values in the same eyes. As compared to ultrasounography, we found that the internal calculations of the LenStar underestimate the axial dimensions of all ocular compartments of the tree shrew eye: anterior segment depth by 6.17 +/- 4.50%, lens thickness by 1.37 +/- 3.06%, vitreous chamber depth by 29.23 +/- 2.35%, and axial length by 10.62 +/- 1.75%. Using tree shrew-specific refractive indices, the axial dimensions closely matched those measured by ultrasonography for each compartment. Our analysis strategy can be easily translated to other species by obtaining a similar paired data set using ultrasonography and LenStar, and applying our step by step procedures.

关键词： culling   fire management   fire-grazing interaction   grazing   herbivore driven system   Kruger National Park   protected area   rewilding  

摘要： Fire and herbivory are competitive processes in grassy ecosystems as they both consume above-ground biomass. Despite this interaction between fire and grazing, herbivore and fire management plans in conservation areas are usually perceived, and hence managed, independently. This study aims to demonstrate the importance of acknowledging and integrating the interdependence between herbivore and fire management. We compare average proportional area burnt during years when large-scale culling kept herbivore biomass within a narrow range within the Kruger National Park, South Africa, against subsequent years of no culling when herbivore densities increased to effectively double the biomass. Furthermore, to improve our mechanistic understanding, we utilize natural gradients in rainfall (north to south) and grazing (distance from rivers) to test a conceptual model of how herbivory influences fire occurrence under different rainfall regimes. Fires were more prevalent during the culling period than thereafter, and the fire suppression effect of increasing grazing biomass was most pronounced in areas closer to rivers (50% reduction within 1 km of rivers). The "grazer effect" (i.e. difference between % area burnt between low and high grazer biomass years) seems to be more pronounced in arid landscapes than in semiarid landscapes, which in turn is more pronounced than in the mesic landscapes. Despite elephants being mixed feeders, elephant density influences fire occurrence more than the density of buffaloes or hippopotami. Synthesis and applications: Herbivore and fire management actions should be integrated, as events that influence herbivore densities go on to influence fire occurrence in subsequent years. In areas with 400-600 mm MAP it is particularly important because changes in herbivore numbers-due to drought, predation, disease, or human interventions-can result in switches between fire- and herbivore-dominated systems, with cascading consequences for biodiversity and