Overview of mathematical approaches used to model bacterial chemotaxis I: the single cell

Mathematical modeling of bacterial chemotaxis systems has been influential and insightful in helping to understand experimental observations. We provide here a comprehensive overview of the range of mathematical approaches used for modeling, within a single bacterium, chemotactic processes caused by changes to external gradients in its environment. Specific areas of the bacterial system which have been studied and modeled are discussed in detail, including the modeling of adaptation in response to attractant gradients, the intracellular phosphorylation cascade, membrane receptor clustering, and spatial modeling of intracellular protein signal transduction. The importance of producing robust models that address adaptation, gain, and sensitivity are also discussed. This review highlights that while mathematical modeling has aided in understanding bacterial chemotaxis on the individual cell scale and guiding experimental design, no single model succeeds in robustly describing all of the basic elements of the cell. We conclude by discussing the importance of this and the future of modeling in this area.

Overview of mathematical approaches used to model bacterial chemotaxis II: bacterial populations

We review the application of mathematical modeling to understanding the behavior of populations of chemotactic bacteria. The application of continuum mathematical models, in particular generalized Keller-Segel models, is discussed along with attempts to incorporate the microscale (individual) behavior on the macroscale, modeling the interaction between different species of bacteria, the interaction of bacteria with their environment, and methods used to obtain experimentally verified parameter values. We allude briefly to the role of modeling pattern formation in understanding collective behavior within bacterial populations. Various aspects of each model are discussed and areas for possible future research are postulated.

Making ecological science policy relevant: issues of scale and disciplinary integration

In this paper, we ask why so much ecological scientific research does not have a greater policy impact in the UK. We argue that there are two potentially important and related reasons for this failing. First, much current ecological science is not being conducted at a scale that is readily meaningful to policy-makers. Second, to make much of this research policy-relevant requires collaborative interdisciplinary research between ecologists and social scientists. However, the challenge of undertaking useful interdisciplinary research only re-emphasises the problems of scale: ecologists and social scientists traditionally frame their research questions at different scales and consider different facets of natural resource management, setting different objectives and using different language. We argue that if applied ecological research is to have greater impact in informing environmental policy, much greater attention needs to be given to the scale of the research efforts as well as to the interaction with social scientists. Such an approach requires an adjustment in existing research and funding infrastructures.

Educational and psychosocial programmes for adolescents with diabetes: approaches, outcomes and cost-effectiveness

Diabetes incurs heavy personal and health system costs. Self-management is required if complications are to be avoided. Adolescents face particular challenges as they learn to take responsibility for their diabetes. A systematic review of educational and psychosocial programmes for adolescents with diabetes was undertaken. This aimed to: identify and categorise the types of programmes that have been evaluated; assess the cost-effectiveness of interventions; identify areas where further research is required. Sixty-two papers were identified and Subjected to a narrative review. Generic programmes focus on knowledge/skills, psychosocial issues, and behaviour/self-management. They result in modest improvements across a range of outcomes but improvements are often not sustained, suggesting a need for continuous support, possibly integrated into normal care. In-hospital education at diagnosis confers few advantages over home treatment. The greatest returns may be obtained by targeting poorly controlled individuals. Few studies addressed resourcing issues and robust cost-effectiveness appraisals are required to identify interventions that generate the greatest returns on expenditure. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Modern approaches to floristics and their impact on the region of SW Asia

Attitudes to floristics have changed considerably during the past few decades as a result of increasing and often more focused consumer demands, heightened awareness of the threats to biodiversity, information flow and overload, and the application of electronic and web-based techniques to information handling and processing. This paper will examine these concerns in relation to our floristic knowledge and needs in the region of SW Asia. Particular reference will be made to the experience gained from the Euro+Med PlantBase project for the preparation of an electronic plant-information system for Europe and the Mediterranean, with a single core list of accepted plant names and synonyms, based on consensus taxonomy agreed by a specialist network. The many challenges Ð scientific, technical and organisational Ð that it has presented will be discussed as well as the problems of handling nontaxonomic information from fields such as conservation, karyology, biosystematics and mapping. The question of regional cooperation and the sharing of efforts and resources will also be raised and attention drawn to the recent planning workshop held in Rabat (May 2002) for establishing a technical cooperation network for taxonomic capacity building in North Africa as a possible model for the SW Asia region.

Managing threatened species: the ecological toolbox, evolutionary theory and declining-population paradigm

1. The management of threatened species is an important practical way in which conservationists can intervene in the extinction process and reduce the loss of biodiversity. Understanding the causes of population declines (past, present and future) is pivotal to designing effective practical management. This is the declining-population paradigm identified by Caughley. 2. There are three broad classes of ecological tool used by conservationists to guide management decisions for threatened species: statistical models of habitat use, demographic models and behaviour-based models. Each of these is described here, illustrated with a case study and evaluated critically in terms of its practical application. 3. These tools are fundamentally different. Statistical models of habitat use and demographic models both use descriptions of patterns in abundance and demography, in relation to a range of factors, to inform management decisions. In contrast, behaviour-based models describe the evolutionary processes underlying these patterns, and derive such patterns from the strategies employed by individuals when competing for resources under a specific set of environmental conditions. 4. Statistical models of habitat use and demographic models have been used successfully to make management recommendations for declining populations. To do this, assumptions are made about population growth or vital rates that will apply when environmental conditions are restored, based on either past data collected under favourable environmental conditions or estimates of these parameters when the agent of decline is removed. As a result, they can only be used to make reliable quantitative predictions about future environments when a comparable environment has been experienced by the population of interest in the past. 5. Many future changes in the environment driven by management will not have been experienced by a population in the past. Under these circumstances, vital rates and their relationship with population density will change in the future in a way that is not predictable from past patterns. Reliable quantitative predictions about population-level responses then need to be based on an explicit consideration of the evolutionary processes operating at the individual level. 6. Synthesis and applications. It is argued that evolutionary theory underpins Caughley's declining-population paradigm, and that it needs to become much more widely used within mainstream conservation biology. This will help conservationists examine critically the reliability of the tools they have traditionally used to aid management decision-making. It will also give them access to alternative tools, particularly when predictions are required for changes in the environment that have not been experienced by a population in the past.

The assessment of enriched apoplastic extracts using proteomic approaches

In plant tissues the extracellular environment or apoplast, incorporating the cell wall, is a highly dynamic compartment with a role in many important plant processes including defence, development, signalling and assimilate partitioning. Soluble apoplast proteins from Arabidopsis thaliana, Triticum aestivum and Oryza sativa were separated by two-dimensional electrophoresis. The molecular weights and isoelectric points for the dominant proteins were established prior to excision, sequencing and identification by matrix-assisted laser-desorption ionisation time of flight mass spectrometry (MALDI - TOF MS). From the selected spots, 23 proteins from O. sativa and 25 proteins from A. thaliana were sequenced, of which nine identifications were made in O. sativa (39%) and 14 in A. thaliana (56%). This analysis revealed that: (i) patterns of proteins revealed by two-dimensional electrophoresis were different for each species indicating that speciation could occur at the level of the apoplast, (ii) of the proteins characterised many belonged to diverse families reflecting the multiple functions of the apoplast and (iii), a large number of the apoplast proteins could not be identified indicating that the majority of extracellular proteins are yet to be assigned. The principal proteins identified in the aqueous matrix of the apoplast were involved in defence, i.e. germin-like proteins or glucanases, and cell expansion, i.e. β-D-glucan glucohydrolases. This study has demonstrated that proteomic analysis can be used to resolve the apoplastic protein complement and to identify adaptive changes induced by environmental effectors.