Of Paleo-Genes and Perch: What if an “Alien” Is Actually a Native?

Documenting whether a biotic taxon is native or alien to an ecosystem has theoretical value for ecological and evolutionary studies, and has practical value because it can potentially identify a taxon as a desirable component of an ecosystem or target it for removal. In some cases, however, such background information is inadequate or unavailable. Here we use paleo-DNA to re-evaluate the historical status of yellow perch in the 6 million acre Adirondack State Park of northern New York. Yellow perch DNA in a 2200-year sediment record reveals a long-term native status for these supposedly alien fish and challenges assumptions that they necessarily exclude native trout from upland lakes. Similar approaches could be applied to other species with uncertain historical distributions and could help to identify unrecognized pockets of biodiversity.     

Blue Native PAGE电泳

在蛋白质组学研究中Blue Native PAGE电泳常用于在非变性条件下分享蛋白质复合物,是研究蛋白质相互作用等的有力工具。本文将对其原理和具体实验操作进行简要介绍。     

How Do Alien Plants Fit in the Space-Phylogeny Matrix?

Recent advances in the field of plant community phylogenetics and invasion phylogenetics are mostly based on plot-level data, which do not take into consideration the spatial arrangement of individual plants within the plot. Here we use within-plot plant coordinates to investigate the link between the physical distance separating plants, and their phylogenetic relatedness. We look at two vegetation types (forest and grassland, similar in species richness and in the proportion of alien invasive plants) in subtropical coastal KwaZulu-Natal, South Africa. The relationship between phylogenetic distance and physical distance is weak in grassland (characterised by higher plant densities and low phylogenetic diversity), and varies substantially in forest vegetation (variable plant density, higher phylogenetic diversity). There is no significant relationship between the proportion of alien plants in the plots and the strength of the physical-phylogenetic distance relationship, suggesting that alien plants are well integrated in the local spatial-phylogenetic landscape.     

A Sea Under Siege – Alien Species in the Mediterranean

Exotic macrophytes, invertebrates and fish are found in most coastal habitats in the Mediterranean Sea. The Mediterranean Sea has been subjected to introductions of non-indigenous species by ship traffic since the opening of interoceanic maritime routes five centuries ago. The Sea, a hub of shipping, is exceptionally susceptible to invaders that arrive in fouling communities or ballast. The Suez Canal has been the largest pathway for the entry of these species: more than 300 Erythrean species – principally molluscs, fish, decapod crustaceans, polychaetes and algae – have become established in the eastern Mediterranean, primarily along the Levantine coasts. Mariculture of nonindigenous shellfish predominates in the northern Mediterranean lagoonar environments. Unrestricted transport of commercially important exotic shellfish has resulted in numerous unintentional introductions of pathogens, parasites and pest species. Some invaders have outcompeted or replaced native species locally, severely reducing biodiversity; some other invaders are so abundant they are exploited commercially. The rate of these biotic invasions has increased in recent decades, and they collectively have significant ecological and economic impacts in the Mediterranean Sea. This revised version was published online in July 2006 with corrections to the Cover Date.     

Alien futures: What is on the horizon for biological invasions?

Aim

To collect and identify the issues that may affect the future global and local management of biological invasions in the next 20–50 years and provide guidance for the prioritization of actions and policies responding to the management challenges of the future.

Location

Global

Methods

We used an open online survey to poll specialists and stakeholders from around the world as to their opinion on the three most important future issues both globally and at their respective local working level.

Results

The 240 respondents identified 629 global issues that we categorized into topics. We summarized the highest rated topics into five broad thematic areas: (1) environmental change, particularly climate change, (2) the spread of species through trade, (3) public awareness, (4) the development of new technologies to enhance management and (5) the need to strengthen policies. The respondents also identified 596 issues at their respective local working levels. Management, early detection, prevention and funding‐related issues all ranked higher than at the global level. Our global audience of practitioners, policymakers and researchers also elicited topics not identified in horizon scanning exercises led by scientists including potential human health impacts, the need for better risk assessments and legislation, the role of human migration and water management.

Main conclusions

The topic areas identified in this horizon scan provide guidance where future policy priorities for invasive alien species should be set. First, to reduce the magnitude and speed of environmental change and its impacts on biological invasions; second, to restrict the movement of potentially invasive alien species via trade; third, to raise awareness with the general public and empower them to act; and finally, to invest in innovative technologies that can detect and mitigate adverse impacts of introduced species.

     

Pioneer Hi-Bred购进Native Plants的RFLP项目

Pioneer公司(Des Moines,IA)已从Native Plants Inc.(NPI)(Salt Lake City,UT)购得其限制性片段长度多态性(RFLP)项目.NPI原先是单纯的植物生物技术公司.此番交易使其业务范围漂移到植物衍生的杀虫剂.未公布交易的详细条款. 这种RFLP技术(有时被称为指印分析),被用来定位并标记特异的植物基因.通过这一途径,育种者可以根据RFLP探针的出现来确定植物的性状,而不必进行费时的筛选.在植物育种工作者眼中,这项技术是改进传统植物育利工作、鉴别专利性材料以及追踪重要遗传性状的关键技术.     

Do Native Parasitic Plants Cause More Damage to Exotic Invasive Hosts Than Native Non-Invasive Hosts? An Implication for Biocontrol

Field studies have shown that native, parasitic plants grow vigorously on invasive plants and can cause more damage to invasive plants than native plants. However, no empirical test has been conducted and the mechanism is still unknown. We conducted a completely randomized greenhouse experiment using 3 congeneric pairs of exotic, invasive and native, non-invasive herbaceous plant species to quantify the damage caused by parasitic plants to hosts and its correlation with the hosts' growth rate and resource use efficiency. The biomass of the parasitic plants on exotic, invasive hosts was significantly higher than on congeneric native, non-invasive hosts. Parasites caused more damage to exotic, invasive hosts than to congeneric, native, non-invasive hosts. The damage caused by parasites to hosts was significantly positively correlated with the biomass of parasitic plants. The damage of parasites to hosts was significantly positively correlated with the relative growth rate and the resource use efficiency of its host plants. It may be the mechanism by which parasitic plants grow more vigorously on invasive hosts and cause more damage to exotic, invasive hosts than to native, non-invasive hosts. These results suggest a potential biological control effect of native, parasitic plants on invasive species by reducing the dominance of invasive species in the invaded community.     

Alien eggs in duck nests: brood parasitism or a help from Grandma?

Intraspecific brood parasitism (IBP) is a remarkable phenomenon by which parasitic females can increase their reproductive output by laying eggs in conspecific females' nests in addition to incubating eggs in their own nest. Kin selection could explain the tolerance, or even the selective advantage, of IBP, but different models of IBP based on game theory yield contradicting predictions. Our analyses of seven polymorphic autosomal microsatellites in two eider duck colonies indicate that relatedness between host and parasitizing females is significantly higher than the background relatedness within the colony. This result is unlikely to be a by-product of relatives nesting in close vicinity, as nest distance and genetic identity are not correlated. For eider females that had been ring-marked during the decades prior to our study, our analyses indicate that (i) the average age of parasitized females is higher than the age of nonparasitized females, (ii) the percentage of nests with alien eggs increases with the age of nesting females, (iii) the level of IBP increases with the host females' age, and (iv) the number of own eggs in the nest of parasitized females significantly decreases with age. IBP may allow those older females unable to produce as many eggs as they can incubate to gain indirect fitness without impairing their direct fitness: genetically related females specialize in their energy allocation, with young females producing more eggs than they can incubate and entrusting these to their older relatives. Intraspecific brood parasitism in ducks may constitute cooperation among generations of closely related females.     

Native N-glycopeptide thioester synthesis through N→S acyl transfer

Peptide thioesters are important tools for the total synthesis of proteins using native chemical ligation (NCL). Preparation of glycopeptide thioesters, that enable the assembly of homogeneously glycosylated proteins, is complicated by the perceived fragile nature of the sugar moiety. Herein, we demonstrate the compatibility of thioester formation via N→S acyl transfer with native N-glycopeptides and report observations that will aid in their preparation.     

Evidence of Native α-Synuclein Conformers in the Human Brain

α-Synuclein aggregation is central to the pathogenesis of several brain disorders. However, the native conformations and functions of this protein in the human brain are not precisely known. The native state of α-synuclein was probed by gel filtration coupled with native gradient gel separation, an array of antibodies with non-overlapping epitopes, and mass spectrometry. The existence of metastable conformers and stable monomer was revealed in the human brain.     

Native parasitic plants: Biological control for plant invasions?

Plant invasions cause biodiversity loss and degradation in ecosystems worldwide. The invasive species involved may be introduced, or native invaders, and controlling them is a major global challenge. Here, we highlight an emerging role for native parasitic plants in suppressing invasive species, thus aiding in restoration of affected habitats. Compelling empirical evidence is provided by three study systems located in Central Europe, southern Australia and eastern China. Further cases of parasitism of invasive plants have been recorded across five continents. We propose including the interactions between parasitic and invasive plants into the theoretical framework of the biotic resistance hypothesis concerning generalist interactions between invaders and native biota. Among parasitic plants, numerous root hemiparasites, mistletoes and parasitic vines show low host specificity and exert substantial negative effects on their hosts. These parasitic plants may interfere with key traits of invaders such as symbiotic nitrogen fixation or clonal propagation which provide them with competitive advantage over native species. We contend that some parasitic plants may present a cost‐effective environmentally sustainable component of invasion management schemes. Therefore, we encourage exploration of this potential and the development of methods for practical applications in ecological restoration and nature conservation.     

Alien plant species distribution in the European Alps: influence of species’ climatic requirements

The paper provides the first estimate of the role of abiotic and anthropogenic variables driving both alien plant species richness and composition covering the whole region of the European Alps. To establish and spread in a new area, alien plants must be able to tolerate the prevailing climatic conditions. We therefore tested the hypothesis that climatic requirements modified by bioclimatic origin and elevational distribution influence the distribution of alien plants in the Alps. Despite most alien plant species showing a relatively restricted distribution in the Alps, some regions, however, were already more strongly invaded. Most of these species were adapted to warmer conditions, probably constrained by climatic factors. Environmental heterogeneity was the most important predictor of alien plant species richness, followed by anthropogenic disturbance. Due to the political/artificial delineation of the administrative districts in the Alps (i.e., ignoring ecological conditions) we did not find a direct influence of climatic constraints on alien distribution. Anyway, northern Holarctic alien species showed a broader climatic tolerance and the capability to grow across a wide environmental range. Our results also reveal a strong influence of human pressure on warmer tropical species, despite their low adaptability to anthropogenic habitats. To this aim, managers would profit from early warnings to prevent future invasions. Considering bioclimatic origin, our study can aid in identifying potentially invasive species in a more regional setting.     

Competition Experiments on Alien Weeds with Crops: Lessons for Measuring Plant Invasion Impact?

Can we quantify the impact of invasive species? Here we use the per-plant competitiveness of alien weeds on crops as a model of invasive species impact in general. We reviewed 97 weed–crop competition experiments in 32 papers that included 30 alien weed and 14 crop species. The majority (68.92%) were randomised block designs where the alien weed had been either added (additive experiments) or removed (removal experiments). We propose using the relative competition index to estimate the effect of alien species in all systems, specifying in each case the density and proportion of alien and native plants essayed. We found that the impact of the weed cannot be considered independently of the crop and, thus, we should be cautious in ranking weed species according to their competition effect. A similar situation can be postulated for alien plants interfering with native species. Invaded communities are not random assemblages, and researchers tend to study the most competitive alien plants. We also found that the effect of the weed on crop yield depends on the duration of the interference and the life-history stage of the weed–crop system at which the interaction takes place. We were not able to conduct a more rigorous comparative analysis of the impacts, such as a meta-analysis. To do this would require some measure of the variation of the competition effect such as standard deviation or standard error, which we found are almost never reported.     

Mass Mortality of Adult Male Subantarctic Fur Seals: Are Alien Mice the Culprits?

Background

Mass mortalities of marine mammals due to infectious agents are increasingly reported. However, in contrast to previous die-offs, which were indiscriminate with respect to sex and age, here we report a land-based mass mortality of Subantarctic fur seals with apparent exclusivity to adult males. An infectious agent with a male-predilection is the most plausible explanation for this die-off. Although pathogens with gender-biased transmission and pathologies are unusual, rodents are known sources of male-biased infectious agents and the invasive Mus musculus house mouse, occurs in seal rookeries.

Methodology/ Principal Findings

Molecular screening for male-biased pathogens in this potential rodent reservoir host revealed the absence of Cardiovirus and Leptospirosis genomes in heart and kidney samples, respectively, but identified a novel Streptococcus species with 30% prevalence in mouse kidneys.

Conclusions/ Significance

Inter-species transmission through environmental contamination with this novel bacterium, whose congenerics display male-bias and have links to infirmity in seals and terrestrial mammals (including humans), highlights the need to further evaluate disease risks posed by alien invasive mice to native species, on this and other islands.     

Native and alien invasive plants: more of the same?

We compare the ecological and habitat characteristics of alien and native vascular plants which have recently expanded in range m England, Scotland, the Republic of Ireland and the Netherlands In the great majority of respects, expanding aliens and natives are functionally indistinguishable However, there are a few consistent differences aliens are more likely than natives to be clonal, polycarpic perennials with erect, leafy stems, and to have transient seed banks We discuss these trends m the context of the difficulties faced by aliens in invading mostly closed plant communities in relatively cool, damp climates Our results are consistent with some predictions of the attributes of'ideal'invaders, but contradict others We argue that the ecological attributes of successful alien invaders are strongly habitat-dependent     

The βγ-crystallins: Native state stability and pathways to aggregation

The βγ-crystallins are among the most stable and long-lived proteins in the human body. With increasing age, however, they transform to high molecular weight light-scattering aggregates, resulting in cataracts. This occurs despite the presence in the lens of high concentrations of the a-crystallin chaperones. Aggregation of crystallins can be induced in vitro by a variety of stresses, including acidic pH, ultraviolet light, oxidative damage, heating or freezing, and specific amino acid substitutions. Accumulating evidence points to the existence of specific biochemical pathways of protein: protein interaction and polymerization. We review the methods used for studying crystallin stability and aggregation and discuss the sometimes counterintuitive relationships between factors that favor native state stability and those that favor non-native aggregation. We discuss the behavior of βγ-crystallins in mixtures and their chaperone ability; the consequences of missense mutations and covalent damage to the side-chains; and the evolutionary strategies that have shaped these proteins. Efforts are ongoing to reveal the nature of cataractous crystallin aggregates and understand the mechanisms of aggregation in the context of key models of protein polymerization: amyloid, native-state, and domain-swapped. Such mechanistic understanding is likely to be of value for the development of therapeutic interventions and draw attention to unanswered questions about the relationship between a protein’s native state stability and its transformation to an aggregated state.     

Introduction of Alien Host–parasite Complexes in a Natural Environment and the Symbiota Concept

When a species is introduced in a new territory its parasites may also follow, thus forming a sort of biotic unit. We propose the term symbiota to indicate this host–parasite complex. This concept is at the basis of the present research in which 11 species of alien and native freshwater fish were collected by electrofishing in the Po river area (Northern Italy). The alien host fish Ictalurus melas and Silurus glanis were parasitized by only one monogenean species each. Lepomis gibbosus, of North American origin, hosted four monogeneans and Carassius carassius three. All these parasites should be considered as alien species, except those collected from C. carassius that should be considered in part natives and in part aliens.     

优化的Native PAGE蛋白回收方法在AFM中的应用

原子力显微镜(AFM)可以在生理条件下获得生物大分子的自然结构信息而不需要进行图像处理。虽然对含有大小范围不一的异质样品成像可以得到几纳米的分辨率,但是具有更高的亚纳米级分辨率的图像仅可以从含有单一亚基数目的高度均一的蛋白复合物获得。在重组蛋白的制备中这种蛋白复合物经常不存在,尤其是对于膜蛋白则更具有挑战性。本研究中,研究者以一种熟知的膜成孔蛋白复合物Perfringolysin O(PFO)作为模型系统,研制出一种方法来分离含有单一亚基数目的复合物,并用于随后在液相的AFM成像。具体而言,研究人员通过非变性聚丙烯酰胺凝胶电泳(Native PAGE)分离出该复合物中特定大小的蛋白成分,然后提取时采用一种新方法使结构完整保持。预计这种方法不仅对更多其他蛋白的高分辨率AFM研究有效用,而且在基于单分子方法和生物技术应用的研究上有更普遍的用途。