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1.
Ectomycorrhizal fungi: A new source of atmospheric methyl halides?   总被引:1,自引:1,他引:1  
Incomplete source budgets for methyl halides – compounds that release inorganic chlorine and bromine radicals which, in turn, catalyze atmospheric ozone depletion – limit our ability to predict the fate of the stratospheric ozone layer. We report here the first measured emissions of methyl chloride, methyl bromide, and methyl iodide from ectomycorrhizal fungi. We grew nine fungal isolates on growth media containing halide concentrations similar to those found in soils and plant tissues. The observed range of emissions was 0.003–65 μg methyl chloride, 0.001–3 μg methyl bromide, and 0.02–12 μg methyl iodide g?1 dry weight fungi day?1. Species varied in production rates of methyl chloride vs. methyl bromide vs. methyl iodide. Cenococcum geophilum, a widespread ectomycorrhizal fungus, was further tested to investigate the effects of halide substrate concentration in growth media. Emissions from this species increased linearly with increasing concentrations of both bromide and iodide. In addition, a subset of four fungi was studied with two media concentrations each of chloride, bromide, and iodide (0.2 or 20 mm ). These fungi had similar responses to halide concentration, despite 1000‐fold differences in baseline emission rates between isolates. Finally, high chloride concentrations (20 mm ) in media did not appear to inhibit emissions of methyl bromide or methyl iodide. Overall, ectomycorrhizal fungi might be an important source of methyl halides to the atmosphere, and substrate concentrations and community composition may influence production levels in ecosystems.  相似文献   

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In the highly competitive environment of contemporary pharmaceutical research, natural products provide a unique element of molecular diversity and biological functionality which is indispensable for drug discovery. The emergence of strategies to deliver drug leads from natural products within the same time frame as synthetic chemical screening has eliminated a major limitation of the past. At a more functional level, the application of molecular genetics techniques has permitted the manipulation of biosynthetic pathways for the generation of novel chemical species as well as rendering hitherto uncultivatable microorganisms accessible for secondary metabolite generation. These developments augur well for an industry confronted with the challenge of finding lead compounds directed at the plethora of new targets arising from genomics projects. The exploitation of structural chemical databases comprising a wide variety of chemotypes, in conjunction with databases on target genes and proteins, will facilitate the creation of new chemical entities through computational molecular modelling for pharmacological evaluation.  相似文献   

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The technologies used in histopathology are changing as a consequence of the current revolutionary progress in several areas of biology. It is likely that general cancer management will improve because of the impact of molecular techniques and immunohistochemistry on tumor diagnosis and classification and on the determination of prognosis and response to therapy. Moreover, as therapies are starting to be modelled after the distinctive molecular characteristics of a specific tumor, the availability of molecular tests to all patients will become a matter of great importance.  相似文献   

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Francisella tularensis is one of the most infectious bacterial pathogens known and is the causative agent of the zoonotic disease tularemia. In spite of the importance of this pathogen little is known about its virulence mechanisms. However, it is clear that the bacterium is an intracellular pathogen, replicating mainly in macrophages, with replication in amoebae also having been reported. The genome sequence of a high virulence strain of F. tularensis is close to completion and when available, will stimulate further research into virulence mechanisms.  相似文献   

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Disease, through the ages, has been considered as a 'visitation' from afar to the body or as 'disequilibrium' of an internal order. In practical terms, these two concepts of disease have generated a nosology, that is a classification of disease states. Genetics, in its dazzling recent advances, has opened another conceptual framework: disease is an individual event, inasmuch as our growing understanding of the genetic 'terrain' makes all subjects true individuals. Hence, it is time to abandon the old conceptual dichotomy for a Hegelian synthesis: there are no diseases (either as visitation or disequilibrium) only diseased individuals.  相似文献   

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Genetics has played only a modest role in drug discovery, but new technologies will radically change this. Whole genome sequencing will identify new drug discovery targets, and emerging methods for the determination of gene function will increase the ability to select robust targets. Detection of single nucleotide polymorphisms and common polymorphisms will enhance the investigation of polygenic diseases and the use of genetics in drug development. Oligonucleotide arraying technologies will allow analysis of gene expression patterns in novel ways.  相似文献   

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Females of Dinarmus basalis, a solitary ectoparasitoid, strongly avoid superparasitising hosts bearing eggs which are 20 or more hours old. Our objective was to determine the mechanism by which the factors inducing host discrimination and such an oviposition deterring effect act, and the origin of the deterrent. This study showed that the information is carried by the parasitised host. It is acquired by a transfer of molecules from the wasp egg onto the host and it requires contact between egg and host for at least 4 h. The factors transferred do not, as commonly reported in other species, come from the female's genital apparatus but from the live egg itself. Consequently, the D. basalis egg directly participates in the success of parasitism by releasing factors which elicit the oviposition host deterring effect. The originality and the ecological importance of these results are discussed.  相似文献   

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The crystal structure of PfPK5, a cyclin-dependent kinase from Plasmodium falciparum, is the first CDK structure determined from a nonhuman source and represents a potential new target for anti-malarial drug development.  相似文献   

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Recent observations have shown that increases in climate change‐related coral mortality cause changes in shallow coral reef community structure through phase shifts to alternative taxa. As a result, sponges have emerged as a potential candidate taxon to become a “winner,” and therefore a numerically and functionally dominant member of many coral reef communities. But, in order for this to occur, there must be sufficient trophic resources to support larger populations of these active filter‐feeding organisms. Globally, climate change is causing an increase in sea surface temperatures (SSTs) and a decrease in salinity, which can lead to an intensification in the stratification of shallow nearshore waters (0–200 m), that affects both the mixed layer depth (MLD) and the strength and duration of internal waves. Specifically, climate change‐driven increases in SSTs for tropical waters are predicted to cause increased stratification, and more stabilized surface waters. This causes a shallowing of the MLD which prevents nutrients from reaching the euphotic zone, and is predicted to decrease net primary production (NPP) up to 20% by the end of the century. Lower NPP would subsequently affect multiple trophic levels, including shallow benthic filter‐feeding communities, as the coupling between water column productivity and the benthos weakens. We argue here that sponge populations may actually be constrained, rather than promoted, by climate change due to decreases in their primary trophic resources, caused by bottom‐up forcing, secondary to physical changes in the water column (i.e., stratification and changes in the MLD resulting in lower nutrients and NPP). As a result, we predict sponge‐dominated tropical reefs will be rare, or short‐lived, if they occur at all into the future in the Anthropocene.  相似文献   

13.
Utilizing genome sequence data from bacterial and fungal pathogens for the discovery of new antimicrobial agents has received considerable attention, both practical and critical, from the pharmaceutical and biotechnological communities. Although no new drugs derived from genomics-based discovery have been reported to be in a development pipeline, the utilization of genomics has revolutionized many aspects of drug discovery. The application, utility, opportunity, and challenges afforded by many of these new approaches are discussed.  相似文献   

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Systems that have yet to stand the test of time carry imperfections that need to be skillfully addressed with the least amount of authoritarianism as possible. The communication and transmission of knowledge that we hold dear are essential pillars to social progress. As such, it is necessary to analyze with the greatest scientific objectivity the applications arising from the deep revolution rooted in the total sequencing of the human genome which affects all aspects of our societies. This extraordinary advance in human knowledge and the resulting technological achievements should not lend themselves to the fears or fantasies often fueled by those who criticize all scientific progress calling into question the most established dogmas. Certain supposedly scholarly analyses of the health situation with which we are currently confronted worldwide are a perfect illustration of this unfortunate trend. It is undeniable that the progress of molecular genetics has opened up a wide range of applications in many fields, affecting the well-being of humans, their mental and physical health. The apparent universal and individual interest for the most advanced genetic profile analyzing technologies is a testimony to this strong common desire to better understand one’s genetic heritage and to control their usage. Despite this movement, little attention is given to the recent advances in genetics applied to essential aspects of the social life of individuals through their inter-personal interactions. It is particularly distressing that the contributions of molecular biology and genetics to the daily well-being of individuals have not yet allowed open-access non-medical genetic testing to gain the recognition it deserves and are still viewed as recreational applications. Through an analysis of the cross influences that genetic biotechnologies have had since the beginning of the century in the fields of nutrition and cosmetics, we have tried to project ourselves into the near future which should witness major behavioral and social upheavals.  相似文献   

16.
The environmental distribution of non-obligate orchid mycorrhizal (OM) symbionts belonging to the ‘rhizoctonia’ complex remains elusive. Some of these fungi, indeed, are undetectable in soil outside the host rhizosphere. A manipulation experiment was performed to assess the importance of neighbouring non-orchid plants and soil as possible reservoirs of OM fungi for Spiranthes spiralis, a widespread photosynthetic European terrestrial orchid species. Fungi of S. spiralis roots were identified by DNA metabarcoding before and 4 months after the removal of the surrounding vegetation and soil. Although such a treatment significantly affected fungal colonization of newly-formed orchid roots, most OM fungi were consistently associated with the host roots. Frequency patterns in differently aged roots suggest that these fungi colonize new orchid roots from either older roots or other parts of the same plant, which may thus represent an environmental source for the subsequent establishment of the OM symbiosis.  相似文献   

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Lycopene, an efficient antioxidant and singlet oxygen quencher, is mainly delivered within the human diet out of tomatoes and tomato products. Processing liberates this carotenoid from complexes with proteins and thus makes it more bioavailable. Rosehip, a wild fruit which is used more often recently to produce mark, jams and juices, showed remarkable contents of lycopene (12.9–35.2 mg/100 g) with an unexpected isomer pattern.  相似文献   

18.
A new source of endothelial progenitor cells--vascular biology redefined?   总被引:3,自引:0,他引:3  
The initial discovery of endothelial progenitor cells (EPCs) in tandem with emerging concepts in stem cell biology has generated enormous interest and excitement in fields as diverse as tissue engineering, regenerative medicine, and tumor and vascular biology. A recent paper by Ingram et al. identifies a complete hierarchy of EPCs in the vessel wall, providing a new framework for classification of cells supporting endopoiesis akin to that previously established for hematopoiesis. This could have fundamental implications for our understanding of the role of the endothelium and, more specifically, the role of EPC interfacing with the vessel wall in health and disease.  相似文献   

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