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1.
Any area that surges ahead as rapidly as this one [clinical ethics] has over the last five years is virtually certain to find that there are many problems which will need to be addressed. There will also be a need for persons working in this field (or studying it) to take some time to reflect on where it is going, as well as to examine some of the possible pitfalls -- both the obvious and the not so obvious -- which lie ahead. The series of papers in this issue of Theoretical Medicine have been written by a group of ethicists who have had a longstanding interest in the field of clinical ethics, and most of whom have spent many years working in the area. While all of the papers focus on the field of clinical ethics, they are very diverse in the topics covered. Some may be viewed as controversial by readers....  相似文献   

2.
The diaspores of the 50 most important maize field weed species (agrestals) in a traditional maize-growing area of south-central Mexico (region of Puebla and Tlaxcala) were analyzed for morphological adaptations to long-distance dispersal. Adaptations to wind-dispersal were absent and to endozoochory were minimal. Most species had no visible adaptations and are presumably transported with mud. However, about one-quarter of the taxa, particularly the tall and dominant ones, relied at least partially on burrs with hooks or awns. The possible vectors for these exo- or epizoochorous species are discussed: the most likely regular dispersers are humans (epianthropochory). Interviews with farmers confirm this conclusion. Using humans as vectors allows the plant to transport relatively large seeds to favorable habitats (directed dispersal). The importance of this relatively rare dispersal adaptation in Mexican maize field weeds leads to questions on the origin and evolution of these agrestals.  相似文献   

3.
Lysosomal involvement in cell death and cancer   总被引:1,自引:0,他引:1  
Lysosomes, with their arsenal of degradative enzymes are increasingly becoming an area of interest in the field of oncology. The changes induced in this compartment upon transformation are numerous and whereas most are viewed as pro-oncogenic the same processes also render cancer cells susceptible to lysosomal death pathways. This review will provide an overview of the pro- and anti-oncogenic potential of this compartment and how these might be exploited for cancer therapy, with special focus on lysosomal death pathways.  相似文献   

4.
The number of European brown hares (Lepus europaeus) has been declining throughout much of Europe since the 1960s. Consequently, many studies have focused on analysing habitat selection of European hares in order to improve the suitability of the habitat for this species. Habitat preferences of European hares are known to be affected by hare density, but most studies have been conducted in agricultural areas where hare densities were medium to high. Finding habitat preferences at high densities is difficult as most available habitats are occupied. In addition, in agricultural areas, field size might influence the hares’ habitat selection because it affects the distribution and availability of certain habitat types. However, most studies relate to areas with large field sizes. In this study, we analysed the habitat preferences of European hares in spring and autumn during the activity period, in the early hours of the night, in an agricultural area with low hare density and small average field size using Chesson’s electivity index. Moreover, we focused on the question whether two different habitat classifications varying in their specificity might cause contradictory results regarding European hares’ habitat preferences. Our results show that in this agricultural area with low hare density, European hares avoided several habitat types which were preferred in other study areas with higher hare densities. Therefore, we assume that hare density has an influence on the species’ habitat selection. In contrast, the small average field size of our study area seemed not to have an effect on hare habitat preference. Furthermore, by pooling habitat types into broader groups, substantial information was lost in some categories. Hence, for some categories, e.g. grassland or agricultural crop land, more detail might be needed than for others, such as urban areas, when analysing hares’ habitat selection. In conclusion, our results imply that studies on habitat preferences have to be conducted in areas with low hare density to be able to gain knowledge on the species’ habitat requirement and hereinafter improve the suitability of the habitat for this species.  相似文献   

5.
为进一步了解武功山地区油脂植物情况,通过野外调查、标本采集鉴定并结合文献的方法,对该区的油脂植物进行统计分析。结果表明武功山地区共有野生油脂植物88科213属383种;形成以樟科、豆科、蔷薇科等为主的优势科类群,以胡椒属、卫矛属、花椒属等为主的优势属类群;生活习性以木本为主。区系地理成分复杂多样,科以热带成分为主,属以温带成分为主,种的地理成分以中国特有分布最多;在分布格局上,垂直方向海拔在400~499 m范围内最多,水平方向以安福县分布油脂植物种类最多。武功山地区含油率超过30%的油脂植物高达116种,体现出该区的油脂植物具有较大的应用开发潜力。  相似文献   

6.
神农架川金丝猴栖息地植物区系特征及食物资源研究   总被引:1,自引:0,他引:1  
2008年春季我国南方特大冰雪灾害,给受灾林区的森林生态系统及野生动物造成了巨大影响。神农架是川金丝猴分布的最东端,也是重灾区之一。该文基于灾前两年的实地调查资料,对神农架川金丝猴栖息地植物区系进行分析,以期为灾后生物多样性的检测评估及川金丝猴栖息地恢复建设提供依据。实地调查发现,川金丝猴栖息地内木本植物共有255种,隶属44科105属,其中乔木23科51属129种,灌木22科49属113种,木质藤本7科9属13种;据统计在栖息地内共有31科58属85种川金丝猴的食源植物。该区植物区系中温带分布性质的属占优势,有58个,占属数的56.30%;热带分布性质的属有22个,东亚和中国特有分布成分共有23个属,分别占属数的21.36%和22.33%;显示了该区地处亚热带与温带的过度性质。还统计了栖息地食源植物区系谱,分析了该区域食源植物特点。  相似文献   

7.
Biomarker research is a rapidly advancing field in medicine. Recent advances in genomic, genetic, epigenetic, neuroscientific, proteomic, and metabolomic knowledge and technologies have opened the way to thriving research. In the most general sense, a biomarker refers to any useful characteristic that can be measured and used as an indicator of a normal biologic process, a pathogenic process, or a pharmacologic response to a therapeutic agent. Despite the extensive resources concentrated on this area, there are very few biomarkers currently available that qualify and are satisfactorily validated for mental disorders, and there is still a major lack of biomarkers for typifying neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. This article provides an overview of this field of research and focuses on recent advances in biomarker research in Alzheimer's disease and Parkinson's disease.  相似文献   

8.
新疆准噶尔盆地北缘第三纪地层   总被引:20,自引:12,他引:8  
童永生  齐陶等 《古脊椎动物学报》1990,28(1):59-70,001,T002
根据脊椎动物化石的发现,订正了乌伦古河北岸的地层时代:乌伦古河组为晚白垩世,索索泉组为晚渐新世,哈拉玛盖组为中中新世。在三个泉地区恢复使用了依希白拉组,时代为中始新世。  相似文献   

9.
Broadening the application of evolutionarily based genetic pest management   总被引:1,自引:0,他引:1  
Insect- and tick-vectored diseases such as malaria, dengue fever, and Lyme disease cause human suffering, and current approaches for prevention are not adequate. Invasive plants and animals such as Scotch broom, zebra mussels, and gypsy moths continue to cause environmental damage and economic losses in agriculture and forestry. Rodents transmit diseases and cause major pre- and postharvest losses, especially in less affluent countries. Each of these problems might benefit from the developing field of Genetic Pest Management that is conceptually based on principles of evolutionary biology. This article briefly describes the history of this field, new molecular tools in this field, and potential applications of those tools. There will be a need for evolutionary biologists to interact with researchers and practitioners in a variety of other fields to determine the most appropriate targets for genetic pest management, the most appropriate methods for specific targets, and the potential of natural selection to diminish the effectiveness of genetic pest management. In addition to producing environmentally sustainable pest management solutions, research efforts in this area could lead to new insights about the evolution of selfish genetic elements in natural systems and will provide students with the opportunity to develop a more sophisticated understanding of the role of evolutionary biology in solving societal problems.  相似文献   

10.
Achievements and challenges of sialic acid research   总被引:17,自引:0,他引:17  
Sialic acids are one of the most important molecules of life, since they occupy the terminal position on macromolecules and cell membranes and are involved in many biological and pathological phenomena. The structures of sialic acids, comprising a family of over 40 neuraminic acid derivatives, have been elucidated. However, many aspects of the regulation of their metabolism at the enzyme and gene levels, as well as of their functions remain mysterious. Sialic acids play a dual role, not only are they indispensable for the protection to and adaptation of life, but are also utilised by life-threatening infectious microorganisms. In this article the present state of knowledge in sialobiology, with an emphasis on my personal experience in this research area, is outlined including a discussion of necessary future work in this fascinating field of cell biology.  相似文献   

11.
Bioremediation of metals and radionuclides has had many field tests, demonstrations, and full-scale implementations in recent years. Field research in this area has occurred for many different metals and radionuclides using a wide array of strategies. These strategies can be generally characterized in six major categories: biotransformation, bioaccumulation/bisorption, biodegradation of chelators, volatilization, treatment trains, and natural attenuation. For all field applications there are a number of critical biogeochemical issues that most be addressed for the successful field application. Monitoring and characterization parameters that are enabling to bioremediation of metals and radionuclides are presented here. For each of the strategies a case study is presented to demonstrate a field application that uses this strategy.  相似文献   

12.
The challenge of crystallizing proteins has led to a significant amount of research in understanding protein self-association and assembly. Arguably the most influential finding in this field in the past decade has been that weakly attractive protein interactions, characterized in terms of the osmotic second virial coefficient, correlate with solution conditions that are conducive to crystallization. Recent work in this area has focused on the development of more efficient techniques for measuring the second virial coefficient, as traditional characterization methods suffer from poor efficiency in terms of time and protein consumption. The resulting measurements have provided new insights into patterns of protein interactions and their relation to protein phase behavior.  相似文献   

13.
AX Santos  H Riezman 《FEBS letters》2012,586(18):2858-2867
Lipids are essential eukaryotic cellular constituents. Lipid metabolism has a strong impact on cell physiology, and despite good progress in this area, many important basic questions remain unanswered concerning the functional diversity of lipid species and on the mechanisms that cells employ to sense and adjust their lipid composition. Combining convenient experimental tractability, a large degree of conservation of metabolic pathways with other eukaryotes and the relative simplicity of its genome, proteome and lipidome, yeast represents the most advantageous model organism for studying lipid homeostasis and function. In this review we will focus on the importance of yeast as a model organism and some of the innovative advantages for the lipid research field.  相似文献   

14.
Human impacts on the species-area relationship in reef fish assemblages   总被引:2,自引:0,他引:2  
The relationship between species richness and area is one of the oldest, most recognized patterns in ecology. Here we provide empirical evidence for strong impacts of fisheries exploitation on the slope of the species–area relationship (SAR). Using comparative field surveys of fish on protected and exploited reefs in three oceans and the Mediterranean Sea, we show that exploitation consistently depresses the slope of the SAR for both power-law and exponential models. The magnitude of change appears to be proportional to fishing intensity. Results are independent of taxonomic resolution and robust across coral and rocky reefs, sampling protocols and statistical methods. Changes in species richness, relative abundance and patch occupancy all appear to contribute to this pattern. We conclude that exploitation pressure impacts the fundamental scaling of biodiversity as well as the species richness and spatial distribution patterns of reef fish. We propose that species–area curves can be sensitive indicators of community-level changes in biodiversity, and may be useful in quantifying the human imprint on reef biodiversity, and potentially elsewhere.  相似文献   

15.
Therapeutic enzymes are one of the most promising applications of this century in the field of pharmaceutics. Biocatalyst properties can be improved by enzyme immobilization on nano-objects, thereby increasing stability and reusability and also enhancing the targeting to specific tissues and cells. Therapeutic biocatalyst–nanodevice complexes will provide new tools for the diagnosis and treatment of old and newly emerging pathologies. Among the advantages of this approach are the wide span and diverse range of possible materials and biocatalysts that promise to make the matrix–enzyme combination a unique modality for therapeutic delivery. This review focuses on the most significant techniques and nanomaterials used for enzyme immobilization such as metallic superparamagnetic, silica, and polymeric and single-enzyme nanoparticles. Finally, a review of the application of these nanodevices to different pathologies and modes of administration is presented. In short, since therapeutic enzymes constitute a highly promising alternative for treating a variety of pathologies more effectively, this review is aimed at providing the comprehensive summary needed to understand and improve this burgeoning area.  相似文献   

16.
This review considers the Russian scientific literature on the influence of weak static and of low-frequency alternating magnetic fields on biological systems. The review covers the most interesting works and the main lines of investigation during the period 1900 to the present. Shown here are the historical roots, beginning with the ideas of V. Vernadsky and A. Chizhevsky, which led in the field of Russian biology to an increasing interest in magnetic fields, based on an intimate connection between solar activity and life on the Earth, and which determined the peculiar development of Russian magnetobiology. The variety of studies on the effects of magnetic storms and extremely low-frequency, periodic variations of the geomagnetic field on human beings and animals as well as on social phenomena are described. The diverse experiments involving artificial laboratory magnetic fields acting on different biological entities under different conditions are also considered. A series of theoretical advances are reviewed that have paved the way for a step-by-step understanding of the mechanisms of magnetic field effects on biological systems. The predominantly unfavorable influence of magnetic fields on living beings is shown, but the cases of favorable influence of magnetic fields on human beings and lower animals are demonstrated as well. The majority of Russian investigations in this area of science has been unknown among the non-Russian speaking audience for many reasons, primarily because of a language barrier. Therefore, it is hoped that this review may be of interest to the international scientific community.  相似文献   

17.
The Flooding Pampa (FP) is the most important area for cattle breeding in Argentina. In this region, persistence and yield of typical forage legumes are strongly limited by soil salinity and alkalinity, which affect around 30% of the total area. Instead, naturalized Lotus tenuis is the main forage legume in this region. Rhizobial strains currently used for inoculating L. tenuis in the FP are exotic or native from non-saline soils of this region, their taxonomic identity being unknown. Assuming that rhizobia native from the most restrictive environments are well adapted to adverse conditions, the use of such isolates could improve the productivity of L. tenuis in the FP. Hence, the goal of this study was to evaluate the symbiotic efficiency of selected L. tenuis rhizobia native from the FP, as compared with strains currently used for field inoculation of this legume. Under non-stressing conditions, the symbiotic performance of native strains of FP exceeded those ones currently used for L. tenuis. Moreover, the symbiotic performance of the native strain ML103 was considerably high under salt stress, compared with strains currently used as inoculants. Analysis of 16S rRNA gene sequencing revealed that unclassified rhizobia currently used for field inoculation of L. tenuis and native strains grouped with the genus Mesorhizobium. As a whole, results obtained demonstrate that soils of the FP are a source of efficient and diverse rhizobia that could be used as a sustainable agronomic tool to formulate inoculants that improve forage yield of L. tenuis in this region.  相似文献   

18.
The dietary preference of badgers Meles meles (Linnaeus, 1758) for earthworms and other food resources has been widely discussed. In the Mediterranean area, rabbits Oryctolagus cuniculus, fruits (mainly olives Olea europaea) and arthropods are the most important foods. We describe badger dietary habits in a xeric Mediterranean area, comparing use and availability of olives and rabbits. Our results indicated that olives and rabbits are the predominant resources consumed, however we did not detect any evidence of specialisation when we compared consumption versus field availability. In the case of olives we found that their consumption is reduced when juvenile rabbits or figs Ficus carica are widely available, which is evidence against any specialisation in this resource. Figs appear to be a key food item for badgers; they were consumed in large amounts when available. Badgers in this xeric area can be viewed as generalist or facultative specialists, using the most profitable resource when available but shifting its preferences to other less profitable food resources when availability of other primary food resource are reduced. Our results also indicated the high suitability of some human agricultural uses (eg fruit orchards) for this species, especially in the otherwise harsh Mediterranean environments.  相似文献   

19.
Analytic Hierarchy Process (AHP) and Analytic Network Process (ANP) are helpful multi-criteria methods used by the decision-makers to prioritize the ecosystem services provided to humankind by a natural area. Despite being the most common in this field, as it is the easiest and quickest method, AHP simplifies reality by distributing criteria as a hierarchy. As many ecosystem services are firmly connected, this simplification can alter the results owing to the inherent subjectivity of the decision-makers' judgments when completing the required pairwise comparisons. In contrast, ANP considers the relationships among criteria, drawing a complex network that can help in reducing subjectivity and uncertainty. This study aims to compare how both the methods deal with these possible biases. This study prioritizes the ecosystem services provided by a farming area in an internationally recognized wetland with various interconnected services. The case study was conducted in a rice field area raised in the Guadalquivir marshes located within the Doñana Biosphere Reserve in Spain. After applying both methodologies, the results conclude that AHP considerably overestimates the most abstract services. Generally, decision-makers overvalue cultural services as they are socially more visible than others, and in AHP, they are not compared directly with other elements. Additionally, when a problem impacts the production and many people are affected, AHP also magnifies its importance because it is in the limelight. Therefore, ANP is an efficient method when a study requires higher accuracy and coexists with intangible assets despite the benefits and drawbacks of each multi-criteria method.  相似文献   

20.
Ditchweed ( Cannabis sativa L.) is widely distributed in the Chu Valley of southeast Kazakhstan and is difficult to control using conventional chemical or mechanical control. Thus, plant pathogens were investigated as potential biocontrol agents. Fusarium oxysporum was isolated from symptomatic C. sativa plants from this area. Twenty-five of the isolated strains of F. oxysporum were pathogenic and host-specific to C. sativa in greenhouse studies. These strains of F. oxysporum f. sp. cannabis were further evaluated as mycoherbicides for control of ditchweed in natural field infestations. Twelve strains showed field control of C. sativa , and the most virulent strain elicited wilt symptoms within 2 weeks of inoculation of field plants. Three different mycoherbicide formulations were evaluated. A birch sawdust formulation was the most effective carrier in the field. Food based formulations were heavily predated by birds, rodents and insects.  相似文献   

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