The effects of temperature and shading on mortality and development rates of Aedes aegypti (Diptera: Culicidae)

Urbanization has caused an increase in favorable habitats for Aedes aegypti (Diptera: Culicidae), given their ability to reproduce in small and often non‐degradable artificial water‐containers. While much work has been done on Ae. aegypti biology and ecology in urban landscapes, the role of shading on immature stages as an independent factor from temperature, and any possible interactions between these factors, remains unexamined. We assessed how temperature and shading affected egg hatch‐rate, larval/pupal mortality, and larval development to adult stage under different factorial temperature (28; 31; 34; 37; 40° C) and shade (0%, 3,100 lux; 40%, 1,860 lux; 75%, 775 lux; 100%, 0 lux) regimes. Hatch‐rate was significantly lower at 37° C (57 %), and no eggs hatched at 40° C. There was no significant effect caused by shading on hatchability. Larval and pupal mortality at 37° C was significantly higher (35%) compared to lower temperature groups, while the effects of shading were emergent at low temperatures. Developmental times from hatching to adult emergence were significantly reduced with increasing temperatures and with greater light exposures. The eco‐physiological response of Ae. aegypti larvae to temperature and light regimes suggest a photosensitivity previously unstudied in this species.     

Habitat Selection by the Spur-thighed Tortoise Testudo graeca in a Multisuccessional Landscape: Implications for Habitat Management

As a result of human activities, natural Mediterranean landscapes (including agro-ecosystems) are characterised by a mosaic-like structure with habitat-patches at different successional stages. These systems have high biodiversity levels and are home to a large number of species protected by European laws whose habitats should be adequately managed. In the present work, we study habitat use from an applied point of view in the spur-thighed tortoise Testudo graeca, an endangered reptile present in semi-arid Mediterranean agro-ecosystems. Results show that, at a landscape scale, the species selects simplified vegetation structures and includes in its home range re-colonisation shrubland and small non-irrigated fields. Within the home range, habitat selection patterns vary and areas with higher vegetation cover and complexity are selected. Detected patterns are discussed in terms of the ecological requirements of the species and with a hierarchical view of resources and conditions. The implications of our findings for habitat management aimed at the conservation of the species are also discussed.     

Role of unfolded state heterogeneity and en-route ruggedness in protein folding kinetics

In order to improve our understanding of the physical bases of protein folding, there is a compelling need for better connections between experimental and computational approaches. This work addresses the role of unfolded state conformational heterogeneity and en-route intermediates, as an aid for planning and interpreting protein folding experiments. The expected kinetics were modeled for different types of energy landscapes, including multiple parallel folding routes, preferential paths dominated by one primary folding route, and distributed paths with a wide spectrum of microscopic folding rate constants. In the presence of one or more preferential routes, conformational exchange among unfolded state populations slows down the observed rates for native protein formation. We find this to be a general phenomenon, taking place even when unfolded conformations interconvert much faster than the "escape" rate constants to folding. Dramatic kinetic deceleration is expected in the presence of an increasing number of folding-incompetent unfolded conformations. This argues for the existence of parallel folding paths involving several folding-competent unfolded conformations, during the early stages of protein folding. Deviations from single-exponential behavior are observed for unfolded conformations exchanging at comparable rates or more slowly than folding events. Analysis of the effect of en-route (on-path) intermediate formation and landscape ruggedness on folding kinetics leads to the following unexpected conclusions: (1) intermediates, which often retard native state formation, may in some cases accelerate folding, and (2) rugged landscapes, usually associated with stretched exponentials, display single-exponential behavior in the presence of late high-friction paths.     

How do biodiversity and conservation values relate to landscape preferences? A case study from the Swiss Alps

The importance of the values underlying different concepts of biodiversity conservation and landscape planning is increasingly recognised, and yet these value judgements of the public and of experts are still poorly understood. Although landscape and conservation management are closely interrelated and measures in one field are likely to have effects on the other, the relationship between biodiversity and conservation values on the one hand, and landscape preferences on the other hand, has been hardly explored so far. This study represents a first attempt to empirically examine this relationship from an integrated perspective, considering philosophical, ecological and economic aspects and using items focused on biodiversity. We used a quantitative survey of the general Swiss population with visualisations of potential landscape developments in the Swiss Alps and items related to biodiversity- and conservation-values. Our research shows that respondents who prefer reforested landscapes tend to be more concerned about the conservation of species, landscapes, and natural processes than people preferring cultural landscapes. Respondents who prefer cultural landscapes are more oriented towards utilitarian values and are overrepresented in mountain areas as compared to the lowlands, thus in areas that are more likely to become the target of conservation measures. Our findings have practical implications for conservation in Switzerland and other mountainous areas, particularly in times of agricultural decline and land abandonment and their associated changes in landscape and biodiversity.     

长江下游平原区乡村景观的结构、管理和土壤有机碳研究

通过实地研究主要位于宜兴市域的区域乡村景观代表性样方,评价并阐明了人口密集的长江下游平原区乡村景观的结构,土地管理与土壤有机碳储量的关系。景观绘图是基于1m分辨率的IKONOS影像并采用生态立地分类及绘图标准,通过直接解译和实地检验对边界清晰的均质景观缀块进行分类和绘图;依据区域权重分层取样设计方法,在生态立地斑块中随机设定取样点进行土壤和淤泥取样;利用区域权重系数进行区域土地利用/覆被和土壤有机碳储量评价计算。结果表明:在2.13×106hm2的长江下游平原区乡村景观面积范围内,0~30cm土壤有机碳储量为76.97Tg。该区域土地利用/覆被的主要类型为水田,水产养殖,非渗漏性建筑用地,旱地1年生作物和水浇地多年生作物,这5种类型的面积百分数和土壤有机碳储量百分数分别为83%和85%。其中平原稻田面积为0.89×106hm2,占总面积的42%;其0~30cm土壤有机碳储量高达36.60Tg,占总储量的48%。通过区域分层取样和小尺度景观斑块的区域权重推绎分析,揭示了人口密集的乡村景观中土地利用/覆被方式对当地和区域土壤有机碳的影响模式。这种在小尺度下对土地管理调查,土壤有机碳和其它生态特征研究的方法明显优于传统的基于30~1000m分辨率遥感影像的土地覆被研究和基于土壤类型的区域土壤有机碳储量评价方法。     

乡村旅游地生态文化传统与生态环境建设的互动效应——以云南石林县彝族阿着底村为例

乡村生态旅游是适合我国国情的生态旅游形式,也是一项可持续发展的朝阳产业。乡村旅游地的生态文化传统与生态环境建设之间有一种互动机制。本文以云南石林县阿着底彝族村寨的密枝林文化传统与乡村旅游产业的互动效应为例,探讨了文化传统对乡村森林资源及生物多样性保护的意义,强调通过加强村民生态教育、加强村规民约建设、发展生态循环经济,使互动效应永续发展。     

Regional and local variation in tallgrass prairie remnants of Iowa and eastern Nebraska

Tallgrass prairie vegetation, persisting as numerous small relics scattered across central North America, exhibits a complex pattern of community structure and composition. We sampled vegetation from 11 prairie preserves in Iowa and eastern Nebraska spanning three physiographic regions and a wide variety of upland habitats. Numerical classification and partitioned ordination revealed a complex pattern of both local and geographical variation in the vegetation. The primary coenocline is a complex topographic-moisture gradient. Secondary factors influencing the vegetation include subsoil permeability, chorological differences, and local peculiarities of stand history and dynamics. Local patterns of interaction between the primary and secondary environmental factors vary among Quaternary landscapes resulting in regional vegetation complexity.Nomenclature follows Gleason (1952) except for the grasses which follow Pohl (1966).Supported by the National Science Foundation (No. GU 2795 and GU 3373), The Nature Conservancy, and the Iowa State Advisory Board for Preserves. We thank T. L. Roberts, S. Taylor, and S. Lundquist for help with field work, and R. K. Peet, A. T. Harrison, and J. K. White for advice, comments, and criticisms.     

Evolution of model proteins on a foldability landscape

We model the evolution of simple lattice proteins as a random walk in a fitness landscape, where the fitness represents the ability of the protein to fold. At higher selective pressure, the evolutionary trajectories are confined to neutral networks where the native structure is conserved and the dynamics are non self-averaging and nonexponential. The optimizability of the corresponding native structure has a strong effect on the size of these neutral networks and thus on the nature of the evolutionary process. Proteins 29:461–466, 1997. © 1997 Wiley-Liss, Inc.     

Role of long interspersed nuclear element-1 in the regulation of chromatin landscapes and genome dynamics

LINE-1 retrotransposon, the most active mobile element of the human genome, is subject to tight regulatory control. Stressful environments and disease modify the recruitment of regulatory proteins leading to unregulated activation of LINE-1. The activation of LINE-1 influences genome dynamics through altered chromatin landscapes, insertion mutations, deletions, and modulation of cellular plasticity. To date, LINE-1 retrotransposition has been linked to various cancer types and may in fact underwrite the genetic basis of various other forms of chronic human illness. The occurrence of LINE-1 polymorphisms in the human population may define inter-individual differences in susceptibility to disease. This review is written in honor of Dr Peter Stambrook, a friend and colleague who carried out highly impactful cancer research over many years of professional practice. Dr Stambrook devoted considerable energy to helping others live up to their full potential and to navigate the complexities of professional life. He was an inspirational leader, a strong advocate, a kind mentor, a vocal supporter and cheerleader, and yes, a hard critic and tough friend when needed. His passionate stand on issues, his witty sense of humor, and his love for humanity have left a huge mark in our lives. We hope that that the knowledge summarized here will advance our understanding of the role of LINE-1 in cancer biology and expedite the development of innovative cancer diagnostics and treatments in the ways that Dr Stambrook himself had so passionately envisioned.     

Exploring the energy landscapes of molecular recognition by a genetic algorithm: Analysis of the requirements for robust docking of HIV-1 protease and FKBP-12 complexes

Energy landscapes of molecular recognition are explored by performing “semi-rigid” docking of FK-506 and rapamycin with the Fukisawa binding protein (FKBP-12), and flexible docking simulations of the Ro-31-8959 and AG-1284 inhibitors with HIV-1 protease by a genetic algorithm. The requirements of a molecular recognition model to meet thermodynamic and kinetic criteria of ligand-protein docking simultaneously are investigated using a family of simple molecular recognition energy functions. The critical factor that determines the success rate in predicting the structure of ligand-protein complexes is found to be the roughness of the binding energy landscape, in accordance with a minimal frustration principle. The results suggest that further progress in structure prediction of ligand-protein complexes can be achieved by designing molecular recognition energy functions that generate binding landscapes with reduced frustration. © 1996 Wiley-Liss, Inc.