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991.
Mida Creek (Kenya) comprises mangrove forests and other marine resources that are of economic, ecological, and environmental importance to the local village communities. In total 116 households (100 of which could be used for numerical analysis), which are estimated to correspond to a coverage of ca. 30% of the total Mida Creek population, were interviewed to assess the human reliance on mangrove resources in Mida Creek. The survey indicates that mangroves are a major resource of wood for house construction, fuel wood, charcoal, and boat building. Minor uses of mangrove products include pharmaceutical and medicinal applications, tanning material, and furniture making. Rhizophora mucronata, Ceriops tagal, and Bruguiera gymnorrhiza are the major resources for house construction and fuel wood, while Sonneratia alba and Xylocarpus granatum were reported to be useful for boat building and medicinal uses respectively. The survey further describes harvesting activities and house construction, and reveals species preferences within this one particular use. As a result of depletion of the supply and the banning of mangrove harvesting, the local people are turning to other wood materials and to poaching. In our view, local utilization patterns rather than global usefulness data are required to establish a conservation policy of both mangroves and users’ subsistence requirements.  相似文献   
992.
Glucose serves as the major energy substrate and the main precursor for the synthesis of glycosaminoglycans in chondrocytes. Facilitated glucose transport represents the first rate-limiting step in glucose metabolism. This study examines molecular regulation of facilitated glucose transport in normal human articular chondrocytes by proinflammatory cytokines. IL-1beta and TNF-alpha, and to a lesser degree IL-6, accelerate facilitated glucose transport as measured by [(3)H]2-deoxyglucose uptake. IL-1beta induces an increased expression of glucose transporter (GLUT) 1 mRNA and protein, and GLUT9 mRNA. GLUT3 and GLUT8 mRNA are constitutively expressed in chondrocytes and are not regulated by IL-1beta. GLUT2 and GLUT4 mRNA are not detected in chondrocytes. IL-1beta stimulates GLUT1 protein glycosylation and plasma membrane incorporation. IL-1beta regulation of glucose transport in chondrocytes depends on protein kinase C and p38 signal transduction pathways, and does not require phosphoinositide 3-kinase, extracellular signal-related kinase, or c-Jun N-terminal kinase activation. IL-1beta-accelerated glucose transport in chondrocytes is not mediated by endogenous NO or eicosanoids. These results demonstrate that stimulation of glucose transport represents a component of the chondrocyte response to IL-1beta. Two classes of GLUTs are identified in chondrocytes, constitutively expressed GLUT3 and GLUT8, and the inducible GLUT1 and GLUT9.  相似文献   
993.
994.
Bulk precipitation and throughfall were collected in a wet lowland rainforest in SW Costa Rica on an event basis to allow modelling the contributions of dry deposition and canopy exchange to nutrient inputs and internal cycling of nutrients. Estimates based on bulk precipitation underestimated total atmospheric deposition to tropical rainforests by up to 10-fold ignoring the contributions of dry deposition. Canopy exchange contributed most of the aboveground inputs to the forest soil of Na+, about half for K+, 10% for P and Mg2+ and negligible for N, C and other elements. Tree species composition did not account for the differences found in net throughfall between forest sites, and vegetation structure (plant area index) had only a small effect on net throughfall. Forest regrowth affected net throughfall through reduced soil fertility and differences in leaf traits. Topography most significantly affected net throughfall via increased dry deposition at sites of higher elevation and via soil fertility and increased canopy exchange at down slope sites.  相似文献   
995.
The objective of the study was to evaluate the use of targeted multiplex Nanopore MinION amplicon re-sequencing of key Candida spp. from blood culture bottles to identify azole and echinocandin resistance associated SNPs. Targeted PCR amplification of azole (ERG11 and ERG3) and echinocandin (FKS) resistance-associated loci was performed on positive blood culture media. Sequencing was performed using MinION nanopore device with R9.4.1 Flow Cells. Twenty-eight spiked blood cultures (ATCC strains and clinical isolates) and 12 prospectively collected positive blood cultures with candidaemia were included. Isolate species included Candida albicans, Candida glabrata, Candida krusei, Candida parapsilosis, Candida tropicalis and Candida auris. SNPs that were identified on ERG and FKS genes using Snippy tool and CLC Genomic Workbench were correlated with phenotypic testing by broth microdilution (YeastOne™ Sensititre). Illumina whole-genome-sequencing and Sanger-sequencing were also performed as confirmatory testing of the mutations identified from nanopore sequencing data. There was a perfect agreement of the resistance-associated mutations detected by MinION-nanopore-sequencing compared to phenotypic testing for acquired resistance (16 with azole resistance; 3 with echinocandin resistance), and perfect concordance of the nanopore sequence mutations to Illumina and Sanger data. Mutations with no known association with phenotypic drug resistance and novel mutations were also detected.  相似文献   
996.
997.
998.
The vast majority of flowering plants rely solely on insects for pollination. A number of pathogens have evolved mechanisms to exploit these close associations and use pollinators as vectors of infective propagules. Factors that affect pollinator movements and successful pollination may in turn also influence successful transmission of fungal spores. Here we investigate the effect of host density and the frequency of diseased Oxalis lanata individuals infected by the anther-smut fungus, Thecaphora capensis, on the likelihood of receiving pollen and fungal spores. Specifically, we determined the numbers of spores and pollen grains deposited on stigmatic surfaces of selected flowers under natural and standardized conditions where host density and disease frequency varied. The effect of host flower density and diseased flower frequency on pollen and spore transfer was variable under natural conditions and these factors interacted significantly. However, an increase in host density and disease frequency significantly influenced pollen and spore deposits under standardized conditions. The effect of host density was, however, not linear and an optimal flower density for pollen and fungal spore transmission was found. Similar to other systems of vector-borne disease, the transmission of anther-smut of Oxalis lanata is more frequency-dependent than density-dependent. This study represents a first step towards understanding the disease transmission process of T. capensis on Oxalis and lays the foundation for future comparative studies between this and other systems to develop and test general hypotheses of disease dynamics in vector-borne disease transmission systems.  相似文献   
999.
Degeneracy of antibody specificity   总被引:2,自引:0,他引:2  
Evidence was obtained, by direct binding assays (radioimmunoassays) and by inhibition of binding assays, that after immunization some of the antibody molecules produced are degenerate in that they bind not only the immunizing antigen, but also unrelated ligands. It can be concluded that the exquisite specificity of the immune response is not necessarily a property of any given antibody molecule but is, at least to some extent, due to the summation of specificities held in common by the population of antibody molecules produced during the response.  相似文献   
1000.
In the development of the horseshoe crab, Limulus polyphemus, the fertilized egg undergoes a complicated cleavage (Stages 1–3) resulting in blastoderm formation (Stage 4). Stage 1 involves intralecithal cleavage and consists of nine discrete surface modifications (events) which have been briefly described with light microscopy by Brown and Barnum ('83). Since in Stage 1 the cortical reaction (events 1–4) has already been examined with ultrastructural methods, the objectives of the present study were to examine with scanning electron microscopy: (1) the first two of three intermittent granulations (events 5 and 7), and (2) the associated events characterized by smooth surfaces (events 4, 6, and 8). The first granulation occurs 2 1/2 to 3 hours after fertilization (22°C) and lasts approximately 1 1/2 hours. The second granulation appears approximately 5 hours after fertilization and lasts about 3 hours. The dynamic changes that occur during the two granulations involve the transformation of a smooth appearing embryonic surface, liberally coated with microvilli, into a granule-dominated surface on which microvilli are greatly reduced in number. Also of considerable interest are the numerous projections which begin to appear on the surface near the end of the second granulation (event 7) and dominate the surface of the following smooth step stage (event 8). Hypotheses on the significance of these dynamic changes and surface modifications involve relationships to the cell cycle, possible mechanisms for membrane storage, and secretory function.  相似文献   
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