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1.
We report in detail two series of chorionic villus cultivation for prenatal chromosomal diagnosis. Chorionic villi were sampled from both first- and second-trimester pregnancies. One hundred cultures were treated with trypsin–EDTA for 2 h and collagenase overnight, (method A) and 100 were treated with trypsin–EDTA for 1 h and collagenase for 2 h (method B). Using short-term enzymatic digestion, the cultivation time was reduced from 14 days to 6 days. Sufficient amounts of metaphases of good quality were present in 93 per cent of primary cultures harvested in situ, whereas enough metaphases of sufficiently good quality were in most cases present only after subcultivation of the cultures using method A. The decrease in cultivation time obtained is probably due to a higher yield of viable cells in monocellular suspension, an increased attachment efficiency, and a more rapid attachment of single cells (within 24 h). 相似文献
2.
Rapid detection of numerical aberrations of chromosomes 13, 18 and 21 in chorionic mesenchymal cells
We have devised and evaluated a rapid screening method for the detection of numerical aberrations of chromosomes13, 18 and 21 in chorionic villus cells. We used non-radioactive in situ hybridization (ISH) with three chromosome-specific probes on overnight-attached mesenchymal cells from chorionic villi. A blind study was performed of 47 karyotypically normal samples, one triploid sample, two samples trisomic for chromosome 21, and two samples from a fetus with putative mosaicism (46/47, +21). All samples were hybridized with the chromosome 18- and 21-specific probes. Thirty samples were additionally hybridized with the chromosome 13-specific probe. The test could be completed within 3-4 days of sampling. In samples disomic with respect to the probed chromosomes, an average of 2 per cent (range 0-9 per cent) had three hybridization signals. By contrast, in the samples trisomic for the probed chromosome(s), 57 per cent (chromosome 13), 51 per cent (chromosome 18), and an average of 74 per cent (55-86 per cent) (chromosome 21) of the nuclei exhibited three signals. In the putative mosaic samples, the number of nuclei with three chromosome 21-specific signals ranged from 41 to 69 per cent. We conclude that this technique rapidly and clearly distinguishes between normal and trisomic/triploid samples, and consequently may be of use in future prenatal diagnosis. 相似文献
3.
The Water Framework Directive (WFD) calls for various modes of public. These participation and involvement. These are judged as key factors to support the successful implementation in terms of attaining a good water status. This paper aims to explore the role of the 'active involvement' of stakeholders for the effective implementation of the WFD regarding the specific problem of reducing agricultural nitrate pollution of groundwater. Our case of reference is the Hase river catchment in northwest Germany, which is a paradigmatic example of an intensive livestock farming region with high nitrate intakes in groundwater. Emphasis is placed on the various forms of involvement that have recently been or will soon be established in northwest Germany at different spatial and administrative scales. We argue that although the WFD refers to whole river basins as the central unit of governance, it is particularly the regional and local scales that will strongly influence the implementation process. We identify different influencing factors and scenario paths, demonstrating both the uncertainties at stake and the range of possible effects that different outcomes of participatory processes will have. These, in turn, are closely linked to the interests, perceptions and strengths of different actors. Identification of critical paths and decision points enables corridors to be mapped out regarding the anticipated success or failure of regional public participation to reduce diffuse agricultural groundwater pollution. 相似文献
4.
Thioarsenates were previously determined as dominant species in geothermal and mineral waters with excess sulfide. Here, we used batch leaching experiments to determine their formation upon weathering or industrial leaching of the arsenic-sulfide minerals orpiment (As2S3) and arsenopyrite (FeAsS) under different pH and oxygen conditions. Under acidic conditions, as expected based on their known kinetic instability at low pH, no thioarsenates formed in either of the two mineral systems. Under neutral to alkaline conditions, orpiment dissolution yielded mono-, di- and trithioarsenate which accounted for up to 43-55% of total arsenic. Thioarsenate formation upon arsenopyrite dissolution was low at neutral (4%) but significant at alkaline pH, especially under suboxic to sulfidic conditions (20-43%, mainly as monothioarsenate). In contrast to orpiment, we postulate that recombination of arsenite and sulfide in solution is of minor importance for monothioarsenate formation during alkaline arsenopyrite dissolution. We propose instead that hydroxyl physisorption lead to formation of As-OH-S surface complexes by transposition of hydroxyl anions to arsenic or iron sites. Concurrently formed ironhydroxides could provide re-sorption sites for the freshly released monothioarsenate. However, sorption experiments with goethite showed slower sorption kinetics of monothioarsenate compared to arsenite, but comparable with arsenate. The discovery that thioarsenates are released by natural weathering and industrial leaching processes and that, once they are released, have a higher mobility than the commonly-investigated species arsenite and arsenate requires future studies to consider them when assessing arsenic release in sulfidic natural or mining-impacted environments. 相似文献
5.
By means of environmental education, teachers are supposed to intervene in pupils’ awareness and concern of environmental
issues. Teachers’ environmental attitudes, however, have rarely been studied. We analysed 367 German pre- and in-service teachers’
environmental attitudes for their structure and socio-economic correlates within the frame of a European project. Thus, we
retrieved for adults the two-dimensional model of ecological values (2-MEV) presented for adolescents by Bogner and Wiseman
(Sci Educ Int 15(1):27–48, 2004). For the two domains, Preservation and Utilisation, the psychometric structure was confirmed and discriminative correlations
with age, gender and teaching subject were unveiled. Further research is needed to deduce the implications for teaching practice. 相似文献
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7.
Thirty-six polychlorinated biphenylols (OH-PCBs) congeners were characterized in Fulmar (Fulmarus glacialis) eggs collected from the Faroe Islands. The seven most abundant congeners were quantified in 19 samples, and the sigmaOH-PCB concentrations ranged between 0.92 and 4.0 ng g(-1) fresh weight (f.w.). These eggs constitute a part of the traditional diet for at least a part of the population on the Faroe Islands and may contribute to the high levels of these contaminants found in the blood of pregnant Faroese women. Because the metabolites are present in the nonhatched fulmar egg, it is concluded that the OH-PCBs are transferred to the egg before laying. High levels, 3300-18,000 ng g(-1) l.w., of sigmapolychlorinated biphenyls (PCB) were determined in the fulmar eggs, which are a considerable source for human exposure. The high PCB levels are a source for metabolic formation of hydroxylated PCBs. 相似文献
8.
Morphological plasticity is a striking characteristic of plants in natural communities. In the context of foraging behavior particularly, root plasticity has been documented for numerous species. Root plasticity is known to mitigate competitive interactions by reducing the overlap of the individuals' rhizospheres. But despite its obvious effect on resource acquisition, plasticity has been generally neglected in previous empirical and theoretical studies estimating interaction intensity among plants. In this study, we developed a semi-mechanistic model that addresses this shortcoming by introducing the idea of compensatory growth into the classical-zone-of influence (ZOI) and field-of-neighborhood (FON) approaches. The model parameters describing the belowground plastic sphere of influence (PSI) were parameterized using data from an accompanying field experiment. Measurements of the uptake of a stable nutrient analogue at distinct distances to the neighboring plants showed that the study species responded plastically to belowground competition by avoiding overlap of individuals' rhizospheres. An unexpected finding was that the sphere of influence of the study species Bromus hordeaceus could be best described by a unimodal function of distance to the plant's center and not with a continuously decreasing function as commonly assumed. We employed the parameterized model to investigate the interplay between plasticity and two other important factors determining the intensity of competitive interactions: overall plant density and the distribution of individuals in space. The simulation results confirm that the reduction of competition intensity due to morphological plasticity strongly depends on the spatial structure of the competitive environment. We advocate the use of semi-mechanistic simulations that explicitly consider morphological plasticity to improve our mechanistic understanding of plant interactions. 相似文献
9.
Claudia Pahl-Wostl Georg Holtz Britta Kastens Christian Knieper 《Environmental Science & Policy》2010,13(7):571-581
This paper presents the Management and Transition Framework (MTF), an interdisciplinary conceptual and methodological framework supporting the analysis of water systems, management processes and multi-level governance regimes. It serves to improve the scientific understanding of system properties and to give practical guidance for the implementation of transition processes towards more adaptive systems. Doing so requires a systemic perspective to embrace complexity and the wealth of interactions characterizing resource governance regimes. The MTF supports and provides guidance for an interdisciplinary approach in the social sciences and across the social–natural science interface.The framework integrates a range of concepts to develop a more coherent understanding of the complexity of water management regimes. Specific emphasis is given to adaptive capacity and learning processes. However, the MTF is not linked to one specific theory but provides a language that can be tailored to specific research questions and different theoretical approaches. The structured yet flexible approach is a condition for developing shared databases that allow comparative analyses over a wider range of case studies. The MTF does not promote panaceas but a diagnostic approach supporting context sensitive analysis without being case specific and thus not directly transferable. 相似文献
10.
Maternal cell contamination was assessed in 18 macroscopically blood-stained amniotic fluid samples from male fetuses. The samples were analysed by double-target fluorescent in situ hybridization (ISH) with Y and X chromosome-specific probes. The only sample with an aberrant karyotype (47, XY, +18) was also analysed by hybridization with a chromosome 18-specific probe. An interpretation of extensive maternal cell contamination was made in two samples, one of which was the sample with trisomy 18. ISH with the chromosome 18-specific probe on this latter sample showed that the sensitivity of the ISH method for chromosome enumeration of uncultured amniotic fluid samples may be reduced in bloodstained samples. It was calculated that by using ISH for chromosome enumeration of the two extensively contaminated samples, a case of trisomy 21 might have been overlooked in both samples, while a case of trisomy 18 might only have been overlooked in one of the samples. It is concluded that ISH should not be used for chromosome enumeration of uncultured amniotic fluid samples that are macroscopically blood-stained without further technical developments. 相似文献