Detection of both the normal and mutant alleles in single cells of individuals heterozygous for the sickle cell mutation—prelude to preimplantation diagnosis

As a preliminary step to preimplantation diagnosis of sickle cell disease in unfertilized eggs or 8-cell embryos of heterozygous parents, we established quality control for detection of the mutant and normal alleles of the beta-haemoglobin gene using single buccal cells. Efficient polymerase chain reaction (PCR) amplification of a 680 base pair sequence of the beta-globin gene spanning the site of the sickle cell mutation was obtained for 79 per cent of single heterozygous cells. In 71 per cent of cases, both alleles were detected. With this current efficiency, we predict that a clinical preimplantation diagnosis at the 8-cell embryo stage could be carried out safely and reliably for a couple at risk of transmitting sickle cell disease to their children.     

Effects of human footprint and biophysical factors on the body-size structure of fished marine species

Marine fisheries in coastal ecosystems in many areas of the world have historically removed large-bodied individuals, potentially impairing ecosystem functioning and the long-term sustainability of fish populations. Reporting on size-based indicators that link to food-web structure can contribute to ecosystem-based management, but the application of these indicators over large (cross-ecosystem) geographical scales has been limited to either fisheries-dependent catch data or diver-based methods restricted to shallow waters (<20 m) that can misrepresent the abundance of large-bodied fished species. We obtained data on the body-size structure of 82 recreationally or commercially targeted marine demersal teleosts from 2904 deployments of baited remote underwater stereo-video (stereo-BRUV). Sampling was at up to 50 m depth and covered approximately 10,000 km of the continental shelf of Australia. Seascape relief, water depth, and human gravity (i.e., a proxy of human impacts) were the strongest predictors of the probability of occurrence of large fishes and the abundance of fishes above the minimum legal size of capture. No-take marine reserves had a positive effect on the abundance of fishes above legal size, although the effect varied across species groups. In contrast, sublegal fishes were best predicted by gradients in sea surface temperature (mean and variance). In areas of low human impact, large fishes were about three times more likely to be encountered and fishes of legal size were approximately five times more abundant. For conspicuous species groups with contrasting habitat, environmental, and biogeographic affinities, abundance of legal-size fishes typically declined as human impact increased. Our large-scale quantitative analyses highlight the combined importance of seascape complexity, regions with low human footprint, and no-take marine reserves in protecting large-bodied fishes across a broad range of species and ecosystem configurations.     

Effects of micro- and mesograzers on intertidal macroalgal recruitment

This study examined the effects of a guild of micrograzing harpacticoid copepods (dominated by two species of Paradactylopodia sp. nov. and one species of Scutellidium sp. nov.) and a mesograzing periwinkle, Afrolittorina praetermissa, on the early recruitment of intertidal macroalgae on a wave-exposed, rocky shore. This is the first study, to our knowledge, to examine the effects of micrograzers (<500 μm) on intertidal macroalgal recruitment. Data showed that microscopic harpacticoid copepods altered the assemblages and reduced the densities of several macroalgal taxa, while A. praetermissa changed the assemblages and reduced both the density and number of macroalgal taxa. Recruitment of encrusting coralline algae was actually higher in copepod inclusions than exclusions, suggesting that copepods may be beneficial to the recruitment of this algal group. These results contribute to the understanding of grazing as a factor causing high mortality of algal recruits, but also highlight the need for more studies that examine the effects of micro- and mesograzers on the distribution and abundance of macroalgae.     

Establishing standards and assessment criteria for ecological instream flow needs in agricultural regions of Canada

Agricultural land use can place heavy demands on regional water resources, strongly influencing the quantity and timing of water flows needed to sustain natural ecosystems. The effects of agricultural practices on streamflow conditions are multifaceted, as they also contribute to the severity of impacts arising from other stressors within the river ecosystem. Thus, river scientists need to determine the quantity of water required to sustain important aquatic ecosystem components and ecological services, to support wise apportionment of water for agricultural use. It is now apparent that arbitrarily defined minimum flows are inadequate for this task because the complex habitat requirements of the biota, which underpin the structure and function of a river ecosystem, are strongly influenced by predictable temporal variations in flow. We present an alternative framework for establishing a first-level, regional ecological instream flow needs standard based on adoption of the Indicators of Hydrologic Alteration/Range of Variability Approach as a broadly applicable hydrological assessment tool, coupling this to the Canadian Ecological Flow Index which assesses ecological responses to hydrological alteration. By explicitly incorporating a new field-based ecological assessment tool for small agricultural streams, we provide a necessary verification of altered hydrology that is broadly applicable within Canada and essential to ensure the continuous feedback between the application of flow management criteria and ecological condition.     

Trisomy 16 detected at chorion villus sampling

Trisomy 16 detected at chorion villus sampling (CVS) may reflect the placental but not the fetal karyotype. We describe a case in which the pregnancy continued until intrauterine death at 37 weeks. Cytogenetic study of two placental samples showed 47, +16 and 46,XX; the fetus was morphologically grossly normal, but fetal tissue culture was unsuccessful. Conservative management may be appropriate when trisomy 16 is detected at CVS and the pregnancy is normal ultransonographically.     

陕西民俗文化旅游资源的保护与开发

陕西民俗文化旅游资源丰富,具有较高的社会价值和旅游价值,但由于政府部门的疏于重视和广大民众认识的浅薄,导致陕西民俗文化旅游资源受到严重的破坏,同时也造成不良风气的大量出现,使这些价值未能得以发挥.针对这一现状,以全国民俗文化的保护和开发为参照,结合陕西民俗文化旅游资源的自身特点,从保护和发展两个方面涉及的具体问题为出发点,就具体的问题提出了具体的建议,希望以此引起各方重视.参5.     

Towards generalised reference condition models for environmental assessment: a case study on rivers in Atlantic Canada

Evaluation of the ecological status of river sites in Canada is supported by building models using the reference condition approach. However, geography, data scarcity and inter-operability constraints have frustrated attempts to monitor national-scale status and trends. This issue is particularly true in Atlantic Canada, where no ecological assessment system is currently available. Here, we present a reference condition model based on the River Invertebrate Prediction and Classification System approach with regional-scale applicability. To achieve this, we used biological monitoring data collected from wadeable streams across Atlantic Canada together with freely available, nationally consistent geographic information system (GIS) environmental data layers. For the first time, we demonstrated that it is possible to use data generated from different studies, even when collected using different sampling methods, to generate a robust predictive model. This model was successfully generated and tested using GIS-based rather than local habitat variables and showed improved performance when compared to a null model. In addition, ecological quality ratio data derived from the model responded to observed stressors in a test dataset. Implications for future large-scale implementation of river biomonitoring using a standardised approach with global application are presented.