An Assessment of State-and-Transition Models: Perceptions Following Two Decades of Development and Implementation

State-and-transition models (STMs) are being developed for many areas in the United States and represent an important tool for assessing and managing public and private rangelands. Substantial resources have been invested in model development, yet minimal efforts have been made to evaluate the utility of STMs for rangeland assessment and management. We interviewed 47 rangeland professionals, equally divided between managers and researchers, in four ecoregions to determine their perceptions of the purpose, development, and strengths and weaknesses of STMs to assess the status of the STM framework. Our analysis identified three primary perspectives regarding the purpose of STMs: a decision-making tool for land managers, a means to represent the complex dynamics of rangeland ecosystems, and an effective communication tool. These diverse views of STM purposes were associated with differing perspectives concerning model development that identified five major issues in need of further development and refinement: 1) the relative importance of management practices and ecological processes in driving transitions, 2) the criteria used to define thresholds, 3) the appropriate level of model complexity, 4) the respective roles of expert knowledge and ecological data in model development, and 5) processes for model review and revision. We recommend greater dialogue among researchers and managers to further clarify STM terminology and develop standard protocols for model development and validation. Mechanisms are critically needed to assure peer review and revision of existing models so that STMs are continually updated to reflect current understanding of rangeland dynamics.     

Occurrence of Biscogniauxia mediterranea in cork oak stands in Tunisia

Phytoparasitica - Cork oak decline and mortality are increasingly prevalent in the Mediterranean basin. This require particular attention due to the great economic value of this plant species....     

昆明地区瘤大球坚蚧寄生蜂初步研究

 昆明地区瘤大球坚蚧［Eulecaium gigantea (Shinji)］有6种寄生性天敌昆虫,隶属于跳小蜂科和蚜小蜂科,即球蚧花角跳小蜂［Blastothrix sericea (Dalman)］,绵蚧阔柄跳小蜂［Metaphycus pulvinariae (Howard)］,夏威夷食蚧蚜小蜂（Coccophagus hawaiiensis Timberlake）,白蜡虫花翅跳小蜂（Microterys ericeri Ishii）,食蚧蚜小蜂（Coccophagus sp.）① 食蚧蚜小蜂(Coccophagus sp.) ② 前2种寄生蜂在自然情况下的寄生率为88.3%,对瘤大球坚蚧的种群数量有一定的控制作用。     

Quantifying functional connectivity: Experimental evidence for patch-specific resistance in the Natterjack toad (Bufo calamita)

Despite the importance assigned to inter-patch movements in fragmented systems, the structure of landscape between suitable habitat patches, the matrix, is often considered as to be of minor interest, or totally ignored. Consequently, models predicting metapopulation dynamics typically assume that dispersal and movement abilities are independent of the composition of the matrix. The predictions of such models should be invalided if that crucial assumption is unverified. In order to test the hypothesis of a patch-specific resistance, we led an experimental study to assess the matrix effects on the movement ability of juvenile Natterjack toads (Bufo calamita). The movement behaviour of first year toadlets, the dispersal stage in this species, was investigated in an arena experiment. Toadlet mobility was assessed in five landscape components that were mimicked in the lab: sandy soil, road, forest, agricultural field, and pasture. We analysed several movement components including move length, speed, efficiency and turning angle distribution. Our results showed that movement ability was strongly affected by the land cover, even if body size modulated the behavioural responses of toadlets. Performances were the best in the arenas mimicking sand and roads, and the worst in the forest arena, toadlet moves being three to five times less effective in the latter. The mobility was intermediate in the two other arenas. We propose here a new method to quantify functional connectivity, based on quantitative estimates of relative values for resistance of landscape components. This method offers a reliable alternative for resistance value estimates to subjective expert advice or inference from genetic population structure.     

抗菌肽在大肠杆菌中的融合表达策略

抗菌肽抗菌谱广、活性稳定,具有与抗生素不同的抗菌机制,在抑杀病原微生物的同时不易产生耐药性,在免疫调节和抗感染方面具有巨大的发展潜力,能够发展为取代抗生素的新型药剂,在食品、饲料、畜禽养殖等领域也具有重要的应用价值。基因工程技术是降低抗菌肽生产成本的主要方式,其中融合表达在提高抗菌肽产量方面起到了重要作用。综述了抗菌肽在大肠杆菌中融合表达的国内外研究进展,探讨了抗菌肽在大肠杆菌中融合表达的策略,并对高通量融合表达抗菌肽提出了建议。     

Mutations in the DJ-1 gene associated with autosomal recessive early-onset parkinsonism

The DJ-1 gene encodes a ubiquitous, highly conserved protein. Here, we show that DJ-1 mutations are associated with PARK7, a monogenic form of human parkinsonism. The function of the DJ-1 protein remains unknown, but evidence suggests its involvement in the oxidative stress response. Our findings indicate that loss of DJ-1 function leads to neurodegeneration. Elucidating the physiological role of DJ-1 protein may promote understanding of the mechanisms of brain neuronal maintenance and pathogenesis of Parkinson's disease.     

The status of the world's land and marine mammals: diversity, threat, and knowledge

Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action.     

Assembly mechanism of the contractile ring for cytokinesis by fission yeast

Animals and fungi assemble a contractile ring of actin filaments and the motor protein myosin to separate into individual daughter cells during cytokinesis. We used fluorescence microscopy of live fission yeast cells to observe that membrane-bound nodes containing myosin were broadly distributed around the cell equator and assembled into a contractile ring through stochastic motions, after a meshwork of dynamic actin filaments appeared. Analysis of node motions and numerical simulations supported a mechanism whereby transient connections are established when myosins in one node capture and exert force on actin filaments growing from other nodes.     

Radio-telemetry as a tool to define protected areas for seabirds in the marine environment

Although most Manx shearwaters (Puffinus puffinus) in the UK are protected within Special Protection Areas (SPAs) at their breeding colonies, such site-based protection does not currently extend into the marine environment. Manx shearwaters form rafts (dense flocks of birds) on the sea adjacent to their breeding colony from late afternoon onwards, before coming ashore after nightfall. The ecological and protection requirements of Manx shearwaters in the UK would be more completely addressed if existing SPA boundaries were extended into adjacent marine areas to include those used for rafting behaviour. However the spatial extent of rafts has never been assessed accurately. Because rafting behaviour continues after nightfall, radio-telemetry was used to investigate rafting distributions of Manx shearwaters around the three largest UK colonies: Skomer (south-west Wales), Bardsey (north-west Wales) and Rum (north-west Scotland). Totals of 30, 28 and 30 birds were radio-tagged, with 174, 264 and 385 rafting locations estimated for Skomer, Rum and Bardsey, respectively. Kernel contour analysis was used to describe the ‘rafting range’ around each colony. The maximum extent of the 95% kernel contours was used to determine the area which would encompass most rafting birds. The maximum extents of rafting ranges were 4, 6 and 9 km, respectively for Skomer, Rum and Bardsey. We believe this is the first successful illustration of how radio-telemetry data can potentially be used to define protected areas for birds in the marine environment.