The widely expressed Dps proteins, so named after the DNA-binding properties of the first characterized member of the family in Escherichia coli, are considered major players in the bacterial response to stress.
Scope of review
The review describes the distinctive features of the “ferritin-like” ferroxidation reaction, which uses hydrogen peroxide as physiological iron oxidant and therefore permits the concomitant removal of the two reactants that give rise to hydroxyl radicals via Fenton chemistry. It also illustrates the structural elements identified to date that render the interaction of some Dps proteins with DNA possible and outlines briefly the significance of Dps–DNA complex formation and of the Dps interaction with other DNA-binding proteins in relation to the organization of the nucleoid and microbial survival.
General significance
Understanding in molecular terms the distinctive role of Dps proteins in bacterial resistance to general and specific stress conditions.
Major conclusions
The state of the art is that the response to oxidative and peroxide-mediated stress is mediated directly by Dps proteins via their ferritin-like activity. In contrast, the response to other stress conditions derives from the concerted interplay of diverse interactions that Dps proteins may establish with DNA and with other DNA-binding proteins. 相似文献
A review is presented of the techniques currently used in the collection and separation of isolated teeth and bones of fossil vertebrates. These involve the collection and disaggregation of the sediment, its sieving, concentration and sorting of the residue, and curation of the fossils obtained. 相似文献
The analysis of drugs in various biological fluids is an important criterion for the determination of the physiological performance of a drug. After sampling of the biological fluid, the next step in the analytical process is sample preparation. The complexity of biological fluids adds to the challenge of direct determination of the drug by chromatographic analysis, therefore demanding a sample preparation step that is often time-consuming, tedious, and frequently overlooked. However, direct on-line injection methods offer the advantage of reducing sample preparation steps and enabling effective pre-concentration and clean-up of biological fluids. These procedures can be automated and therefore reduce the requirements for handling potentially infectious biomaterial, improve reproducibility, and minimize sample manipulations and potential contamination. The objective of this review is to present an overview of the existing literature with emphasis on advances in automated sample preparation methods for liquid-chromatographic methods. More specifically, this review concentrates on the use of direct injection techniques, such as restricted-access materials, turbulent-flow chromatography and other automated on-line solid-phase extraction (SPE) procedures. It also includes short overviews of emerging automated extraction-phase technologies, such as molecularly imprinted polymers, in-tube solid-phase micro-extraction, and micro-extraction in a packed syringe for a more selective extraction of analytes from complex samples, providing further improvements in the analysis of biological materials. Lastly, the outlook for these methods and potential new applications for these technologies are briefly discussed. 相似文献
The repeated advance and retreat of glaciers during the Pleistocene ice ages have played a major role in shaping the present patterns of genetic variation within and among plant and animal populations of the temperate zone. In Europe, the geographic ranges of many species were confined to a few, mostly southern refugia during periods of full glaciation. Distribution ranges then reexpanded, and uninhabited northern areas were recolonized during the interglacials. These contraction–expansion cycles were repeated at least four times. Paleontological and molecular phylogeographic studies during the last decade have greatly increased our knowledge of refugial areas and postglacial recolonization patterns of European trees, shrubs and Alpine plants since the last glacial maximum about 20,000 years ago. Much less is known yet about non-Alpine herbaceous plants. In the present review, we summarize recent phylogeographic work on halophytic (salt-adapted) plants from coastal and inland habitats in Europe. Major refugial areas for these plants have been identified along the Mediterranean coasts, but some species could also have survived in saline inland localities. In general, recolonization of N and NW Europe occurred in a stepwise fashion along the Atlantic coastline. For a number of species, molecular studies revealed concordant genetic discontinuities on the background of an essentially continuous geographic distribution. Such congruency could be explained by the preferential seed dispersal through sea currents. However, phylogeographic patterns of halophytes also proved to be influenced by other factors like sea-level fluctuations during the Pleistocene, secondary contact between divergent lineages, long-distance dispersal, clonal growth, and special habitat and temperature requirements. 相似文献
Summary. Basic biological processes in which tissue transglutaminase (TG2, tTG) is thought to be important including apoptosis, cell
adhesion and migration, ECM homeostasis and angiogenesis are key stages in the multistage tumour progression cascade. Studies
undertaken with primary tumours and experimental models suggest that TG2 expression and activity in the tumour body and surrounding
matrix generally decreases with tumour progression, favouring matrix destabilisation, but supporting angiogenesis and tumour
invasion. In contrast, in the secondary metastatic tumour TG2 is often highly expressed whereby its potential roles in cell
survival both at the intra- and extracellular level become important. In the following review the underlying molecular basis
for the selection of these different phenotypes in tumour types and the anomaly for the requirement of TG2 is discussed in
relation to the complex events of tumour progression. 相似文献
The conservation of Spotted Owl (Strix occidentalis) populations has been one of the most controversial and visible issues in United States conservation history. Coincident
with declines in Spotted Owl populations over the last three decades has been the invasion of Barred Owls (Strix varia) throughout the range of the Northern Spotted Owl (S. o. caurina) and into the range of the California Spotted Owl (S. o. occidentalis). This invasion has confused the reasons behind recent Spotted Owl declines because anecdotal and correlative information
strongly suggests that Barred Owls are a new factor influencing the declines. There is great uncertainty about all aspects
of the invasion, and this has sparked discussion about appropriate management and research responses regarding the effects
of this invasion on Spotted Owls. We present a set of possible responses to address the issue, and we discuss the relative
merits of these with regard to their efficacy given the current state of knowledge. We recommend that research specifically
aimed at learning more about the interspecific relationships of these two owls throughout the range of sympatry should begin
immediately. Approaches that seem unlikely to be useful in the short-term either because they do not facilitate knowledge
acquisition, are relatively costly, or would be technically less feasible, should not be considered viable at this time. We
believe the consequences of the invasion are potentially dire for the Spotted Owl and that research and management actions,
including the use of adaptive management, are required to inform the near- and long-term decision-making process for conservation
of Spotted Owls. 相似文献
Falls in the hospital setting are a major health problem due to their high prevalence and their physical, functional, psychological or economic consequences. Since 1990s, different fall risk assessment scales have been developed to detect high-risk patients, which are also applied in the hospital setting. The aim of this review is to analyse the validity of different scales for assessing fall risk in adults in the hospital setting, especially in elderly patients. Following a literature search in April 2021, 36 primary studies were found that analysed the validity of the Downton, Morse, Hendrich II, Stratify and Tinetti scales. Meta-analyses of sensitivity and specificity showed a high heterogeneity that does not allow recommending a specific tool that can be considered as standard in acute inpatients. 相似文献
Fundulus heteroclitus, the mummichog or Atlantic killifish, is the dominant small-bodied fish species of the east coast estuaries and salt marshes of Canada and the USA, where it is present as two subspecies, the northern F. h. macrolepidotus and the southern F. h. heteroclitus. Recently identified as the premier teleost model in environmental biology, the species has long been of value in understanding evolved tolerance to toxicants and more lately in adding to our knowledge about reproductive effects of environmental endocrine disruptors. The body of literature on F. heteroclitus ovarian physiology and reproduction, from both field and laboratory studies, provides the foundation for present work focused on understanding the reproductive effects and modes of action of environmental toxicants. In this paper, we review the environmental and endocrine factors controlling ovarian and reproductive cycling in F. heteroclitus, noting specifics related to field and laboratory studies on the two subspecies as well as key research gaps compared to other fish species. We also summarize recent development of methodologies to study the effects of environmental contaminants on endocrine signalling and egg production in F. heteroclitus. Continued efforts to progress both our fundamental understanding of reproductive physiology in mummichog, coupled with studies focused on the modes of action of environmental contaminants, have high potential to further develop this teleost model. While the model may presently lag behind those based on other species of fish, the unique biochemical and physiological adaptations which allow F. heteroclitus to adapt to changing environmental and toxic conditions provide a valuable experimental system for comparative physiologists, ecotoxicologists and evolutionary biologists. 相似文献
The World Health Organization (WHO) has a commitment to helping Member States achieve safe, sustainable and health-enhancing human environments, protected from biological, chemical and physical agents. The latter includes advising on the health impact of electromagnetic fields (EMFs) and radiation.
The results of the WHO/ICNIRP/NRPB workshop on static magnetic fields, published in this volume, provide a valuable and much needed contribution to the health risk assessment of exposure to static electric and magnetic fields, which is currently being coordinated by the WHO's International EMF Project. This WHO health risk assessment will be published as an environmental health criteria (EHC) monograph in early 2005.
This paper briefly gives an overview of the process of developing the WHO static fields EHC monograph, the criteria applied to studies that could contribute to the EHC, along with the ‘weight-of-evidence’ approach to health risk assessment. In addition, there is an increasing awareness of the need to account for uncertainty in the science database. This is traditionally addressed by further research, and the EMF project addresses these needs through the development of a ‘research agenda’. However, research programmes may take several years to complete, and the long latency associated with diseases such as cancer in people may also preclude a rapid outcome in some studies. The issue of current uncertainty is being addressed by the WHO EMF project through the development of a ‘precautionary framework’ in which precautionary measures will be applied to policy recommendations. 相似文献