生物入侵机制研究进展

本文从外来种本身的生物学特性,外来种与新栖息地土著种之间的相互作用,群落生物多样性对入侵种的抵抗能力,新栖息地生态环境变化对入侵种的影响等方面综述了近年来有关生物入侵机制的研究进展,并探讨了研究方法的发展和亟待解决的问题,大量的研究表明生物入侵机制是极为多样的,可能没有一般的,通用的机制,阐明生物入侵的机制,对推动生态学理论的发展和控制有害外来种有重要意义。     

分子标记技术在昆虫入侵研究中的应用

遗传变异与种群持续性及其进化潜力密切相关,而生物入侵导致种群遗传变异或遗传多样性的改变为研究自然界中各种生态和进化问题提供了理想模式。分子标记技术是调查种群遗传变异的重要工具,揭示了入侵种的入侵过程和结果,并预测未来的发生情况。本综述归纳了分子标记技术在昆虫入侵机制研究中的应用,以典型的研究个案为例,分别综述了分子标记技术在隐蔽入侵的监测应用,分子标记技术在重构入侵历史研究中的推算方式,分子标记技术在探索种群遗传变异与成功入侵机制方面取得的重要进展,并进一步介绍了高分辨率熔解曲线（high-resolution melting, HRM）分析在昆虫入侵研究中的应用前景。     

肿瘤细胞侵袭研究进展

肿瘤细胞侵袭和转移是癌医学和癌生物学最重要的难题,癌症主要因其肿瘤细胞的侵袭和转移而成为致命的疾病,虽然侵袭和转移的机制仍不清楚,但肿瘤细胞侵袭一直是研究热点,本文就近年来对肿瘤细胞侵袭研究的新进展进行综述,以期为寻找治疗肿瘤的新方案提供参考.     

克氏原螯虾的入侵生态学研究进展

克氏原螯虾(Procambarus clarkii)原产于美国南部和墨西哥北部,是一个著名入侵物种,作为一种水产经济资源物种在世界各地扩散。克氏原螯虾抗逆性强,所具有的广泛生境适应性、生长迅速、高生殖率等特点使它们迅速建立野生种群。近10余年的研究认为,克氏原螯虾通过捕食和资源竞争等机制严重威胁引入地的水生植物、无脊椎动物、两栖类等的生存,显著降低引入地的生物多样性。当前,由于克氏原螯虾的经济价值高,它会借助于人力的作用而继续扩散。为认清和减少克氏原螯虾对引入地的生态影响,应加强以下方面的研究:1)在中国开展克氏原螯虾的生态危害的调查和研究;2)克氏原螯虾种群调节和控制对策研究;3)被入侵地的生态恢复工作。     

Dynamin inhibitor impairs Toxoplasma gondii invasion

The protozoan parasite Toxoplasma gondii infects its host cells through an active mechanism. In this work, we obtained evidence that host cells also play a fundamental role during the infection process. We found that previous incubation of the host cells, but not the parasites, with Dynasore, a small molecule that inhibits dynamin GTPase activity, markedly reduced the penetration of T. gondii tachyzoites into LLC-MK2 cells. In contrast, parasite adhesion to the host cell surface increased, as observed both by light and electron microscopy. Intriguingly, the few parasites internalized by Dynasore-treated cells remained in vacuoles located at the periphery of the cell, in contrast to the perinuclear localization seen in the control.     

外来种隐蔽入侵： 类型及影响

隐蔽入侵（cryptic invasion）是指在形态上与土著种（或早期建群种）不能或难以区分的外来种在人们未觉察的状态下成功入侵的过程。人们对这类入侵方式往往视而不觉。本文综述了外来种隐蔽入侵的类型以及生态影响。隐蔽入侵的类型主要包括外来姊妹种形式的隐蔽入侵、 不同遗传支系的隐蔽入侵、 不同地理种群的隐蔽入侵以及“返传入”。其中, “返传入”目前还是一种假说。由于这类入侵外来种更容易与土著种（或早期建群种）杂交或基因渗透, 因而可对入侵种自身或土著种产生深远的生态影响。鉴于隐蔽入侵现象的广泛性, 建议进一步加强该方面的研究。     

分子标记技术在入侵生态学研究中的应用

外来入侵物种给农林业生产造成了巨大的经济损失,并威胁生物多样性及人类健康．入侵生态学的研究对于认识外来入侵物种的入侵机制及其可持续控制具有重要意义．分子标记技术为解决入侵生态学研究中的许多基本问题提供了良好的手段．本文综述了该技术在外来入侵物种的鉴定、地理分布、原产地、传播模式、种群遗传变异、杂交及基因渗入等研究中的应用现状,并对其应用前景进行了展望．     

植物入侵机制的主要假说

植物入侵是最严重的全球问题之一,严重破坏生态系统的结构和功能。随着植物入侵现象日益严峻,要控制和解决外来植物入侵问题,了解和掌握植物入侵机制尤为重要。本文概述了植物入侵的多种机制及不同机制间的协同作用,阐述了植物入侵过程中的化感作用、植物-土壤反馈机制、互惠共生关系,以及植物功能性状和表型可塑性对入侵过程的影响,并对多种机制协同与植物入侵轨迹的关系进行综合分析。根据分析结果将外来植物在侵入地的入侵时间轨迹分为引入、定植、建立和侵入4个阶段,把遇到的各种阻碍和促进因素融入其中,提出外来植物入侵曲线图,有助于未来对入侵植物及其影响的研究和管理。对现有的植物入侵研究方法进行分析,提出现阶段研究的不足以及未来的研究方向和目标。     

Plant invasion alters trait composition and diversity across habitats

Increased globalization has accelerated the movement of species around the world. Many of these nonnative species have the potential to profoundly alter ecosystems. The mechanisms underpinning this impact are often poorly understood, and traits are often overlooked when trying to understand and predict the impacts of species invasions on communities. We conducted an observational field experiment in Canada's first National Urban Park, where we collected trait data for seven different functional traits (height, stem width, specific leaf area, leaf percent nitrogen, and leaf percent carbon) across an abundance gradient of the invasive Vincetoxicum rossicum in open meadow and understory habitats. We assessed invasion impacts on communities, and associated mechanisms, by examining three complementary functional trait measures: community‐weighted mean, range of trait values, and species’ distances to the invader in trait space. We found that V. rossicum invasion significantly altered the functional structure of herbaceous plant communities. In both habitats V. rossicum changed the community‐weighted means, causing invaded communities to become increasingly similar in their functional structure. In addition, V. rossicum also reduced the trait ranges for a majority of traits indicating that species are being deterministically excluded in invaded communities. Further, we observed different trends in the meadow and understory habitats: In the understory, resident species that were more similar to V. rossicum in multivariate trait space were excluded more, however this was not the case in the meadow habitat. This suggests that V. rossicum alters communities uniquely in each habitat, in part by creating a filter in which only certain resident species are able to persist. This filtering process causes a nonrandom reduction in species' abundances, which in turn would be expected to alter how the invaded ecosystems function. Using trait‐based frameworks leads to better understanding and prediction of invasion impacts. This novel framework can also be used in restoration practices to understand how invasion impacts communities and to reassemble communities after invasive species management.     

Habitat invasion research: where vegetation science and invasion ecology meet

In the last decade, habitat‐oriented studies of plant invasions, performed at broad scales and using large data sets of vegetation plots, have focused on quantifying the representation of alien species in vegetation or habitat types, identifying factors underlying invasions, and exploring the pools of species available for invasion into particular habitats. In this essay we summarize what we have learned, discuss constraints associated with this kind of data and outline promising research topics to which a macroecological perspective of habitat invasions can contribute. Such topics include, among others: integrating species‐specific information on invasion status, residence time in the region, biological and ecological traits and phylogenetic relationships into habitat invasion research to better capture the context‐dependence of invasions; focusing on the functional role that alien species, relative to natives, play in plant communities; and obtaining insights into the role of pre‐adaptation for invasion by comparing the functional composition of habitat species pools in the native range. There is still a strong geographic bias, with detailed assessments across broader ranges of habitat types in large regions available only from Europe, the United States and New Zealand, which call for extension of this research to other continents.     

外来种入侵的不确定性动态模拟

外来种的入侵性和生境的可入侵性是研究生物入侵机制的两个关键因素。总结多数学者的研究成果,认为外来种的拓殖率(迁移率或繁殖率)、死亡率及在新生境中的竞争力是衡量外来种能否入侵成功的内在实质。从全新的角度出发,将引入的外来种看作是对原有生态系统的一种干扰,并在此基础上结合Tilman的多物种共存模型提出了外来种干扰模型。模拟发现外来种在入侵时具有明显的不确定性。拓殖率小的外来种在新的生态系统中由于不能适应环境无法成功定殖,被排斥在系统之外;相反,拓殖率足够大的话,外来种由于自身优势具有很强的入侵性,在几年或几十年的时间内就会成功地在新的环境中建立种群并拓殖入侵,影响了当地物种的生存及原有生态系统的稳定。研究还发现,物种入侵也存在一定的不确定性,入侵不一定会一直持续下去,或许在百年或几百年的时间内入侵种会突然灭绝,原生态系统又恢复到原来的水平。     

胃癌侵袭转移相关基因的研究进展

肿瘤的侵袭转移是恶性肿瘤患者死亡的主要原因。目前对胃癌侵袭转移的分子机制尚未查明。胃癌侵袭转移过程中涉及许多特殊基因,包括促进转移的转移基因和控制转移的转移抑制基因。转移基因有：细胞粘附分子(cAM)基因、基质金属蛋白酶(MMPs)基因、肝素酶(heparanase)基因等;转移抑制基因有：nm23、组织基质金属蛋白酶抑制因子(TIMPs)基因等。本文对胃癌侵袭转移相关基因及其产物的结构、功能及其在侵袭转移过程中作用的研究进展作一综述。     

基于分子生物学方法的外来入侵物种入侵历史重构

生物入侵是一个世界性的问题。全球每年因生物入侵造成的损失超过1万亿美元。探究入侵物种在入侵地的入侵历史对了解生物入侵的生物生态学机制、制定阻截及防除措施有重要意义。分子标记方法的兴起和大规模应用打开了入侵生物入侵历史研究的新天地。采用分子标记的方法可鉴定入侵物种的种类、追溯其来源地、回溯其扩散路径、分析扩散模式及探究物种入侵过程中对入侵种群本身的变化及其对生态系统所造成的各种影响。分子标记的应用使得多个入侵物种的入侵历史得以重现。由于分子标记方法重构的入侵历史受采样范围、采用的分子标记的种类及数量等因素的影响,该方法呈现入侵历史是否是真实发生的入侵过程还存在争议。     

Insect invasion sequences: systematic or stochastic?

Abstract. 1. This study examined the invasion sequence of Drosophila species arriving at decomposing strawberries.
2. It was found that the age of fruit affected the likelihood of Drosophila arrival, flies preferring relatively fresh fruit. However, there were no repeatable trends in invasion sequence of Drosophila species, different species responding in a similar manner to changes in fruit age.
3. Although no systematic trends in invasion sequence were observed, species tended to be temporally separated due to stochastic differences in their arrival at the fruit.
4. It is suggested that stochastic, as well as repeatable, temporal separation of species can have an important influence on subsequent community development.     

Secondary invasion: When invasion success is contingent on other invaders altering the properties of recipient ecosystems

Positive interactions between exotic species may increase ecosystem‐level impacts and potentially facilitate the entry and spread of other exotic species. Invader‐facilitated invasion success—”secondary invasion”—is a key conceptual aspect of the well‐known invasional meltdown hypothesis, but remains poorly defined and empirically underexplored. Drawing from heuristic models and published empirical studies, we explore this form of “secondary invasion” and discuss the phenomenon within the recognized conceptual framework of the determinants of invasion success. The term “secondary invasion” has been used haphazardly in the literature to refer to multiple invasion phenomena, most of which have other more accepted titles. Our usage of the term secondary invasion is akin to “invader‐facilitated invasion,” which we define as the phenomenon in which the invasion success of one exotic species is contingent on the presence, influence, and impacts of one or more other exotic species. We present case studies of secondary invasion whereby primary invaders facilitate the entry or establishment of exotic species into communities where they were previously excluded from becoming invasive. Our synthesis, discussion, and conceptual framework of this type of secondary invasion provides a useful reference to better explain how invasive species can alter key properties of recipient ecosystems that can ultimately determine the invasion success of other species. This study increases our appreciation for complex interactions following invasion and highlights the impacts of invasive species themselves as possible determinants of invasion success. We anticipate that highlighting “secondary invasion” in this way will enable studies reporting similar phenomena to be identified and linked through consistent terminology.     

Factors governing rate of invasion: a natural experiment using Argentine ants

Predicting the success of biological invasions is a major goal of invasion biology. Determining the causes of invasions, however, can be difficult, owing to the complexity and spatio-temporal heterogeneity of the invasion process. The purpose of this study was to assess factors influencing rate of invasion for the Argentine ant (Linepithema humile), a widespread invasive species. The rate of invasion for 20 independent Argentine ant populations was measured over 4 years in riparian woodlands in the lower Sacramento River Valley of northern California. A priori predictors of rate of invasion included stream flow (a measure of abiotic suitability), disturbance, and native ant richness. In addition, baits were used to estimate the abundance of Argentine ants and native ants at the 20 sites. A multiple regression model accounted for nearly half of the variation in mean rate of invasion (R ² = 0.46), but stream flow was the only significant factor in this analysis. Argentine ants spread, on average, 16 m year⁻¹ at sites with permanent stream flow and retreated, on average, −6 m year⁻¹ at sites with intermittent stream flow. Rate of invasion was independent of both disturbance and native ant richness. Argentine ants recruited to more baits in higher numbers in invaded areas than did native ants in uninvaded areas. In addition, rate of invasion was positively correlated with the proportion of baits recruited to by native ants in uninvaded areas. Together, these findings suggest that abiotic suitability is of paramount importance in determining rate of invasion for the Argentine ant. Received: 16 September 1997 / Accepted: 8 February 1998     

Dual roles of E-cadherin in prostate cancer invasion

The role(s) of E-cadherin in tumor progression, invasion, and metastasis remains somewhat enigmatic. In order to investigate various aspects of E-cadherin biological activity, particularly in prostate cancer progression, our laboratory cloned unique subpopulations of the heterogeneous DU145 human prostatic carcinoma cell line and characterized their distinct biological functions. The data revealed that the highly invasive, fibroblastic-like subpopulation of DU145 cells (designated DU145-F) expressed less than 0.1-fold of E-cadherin protein when compared to the parental DU145 or the poorly invasive DU145 cells (designated DU145-E). Experimental disruption of E-cadherin function stimulated migration and invasion of DU145-E and other E-cadherin-positive prostate cancer cell lines, but did not affect the fibroblastic-like DU145-F subpopulation. Within the medium of parental DU145 cells, the presence of an 80 kDa E-cadherin fragment was detected. Subsequent functional analyses revealed the stimulatory effect of this fragment on the migratory and invasive capability of E-cadherin-positive cells. These results suggest that E-cadherin plays an important role in regulating the invasive potential of prostate cancer cells through an unique paracrine mechanism.