Population genetics of eight species of Trapezia (Brachyura: Xanthidae), symbionts of corals

Starch-gel electrophoresis was used to study gene-enzyme variation in thirteen populations of eight species of the genus Trapezia from Hawaii, Panamá, and Enewetak Atoll (Marshall Islands). Between 20 and 30 (mean = 27.8) gene-enzyme systems were resolved in each population, with 20 systems in common among all populations. The distribution of electrophenotypes was in agreement with Hardy-Weinberg-Castle expectations, except for T. digitalis, which consistently showed heterozygote deficiencies. Diagnostic loci among color forms support the hypothesis that color forms are distinct species. Low values of genetic distance among species suggest a recent radiation, perhaps during the Pleistocene. Genetic distance between the Hawaiian and Panamanian populations of T. ferruginea did not significantly differ from zero, indicating that the Eastern Pacific population of T. ferruginea has recently immigrated from the central Pacific, and/or that there is gene flow between the two areas. There were diagnostic loci between T. ferruginea and T. formosa from Enewetak and the populations of these species from Hawaii (T. ferruginea only) and Panamá (both species). Therefore, these geographic populations may represent separate species. The level and pattern of genetic variability in Trapezia spp. are in agreement with those observed in most other organisms.     

Improved solid-phase enzyme immunoassay systems in the ppt range for atrazin in fresh water

A solid-phase enzyme immunoassay (EIA) in poylstyrene microtiter-plates was developed for the rapid determination of atrazin in fresh waters. The linear measuring range was between 1 and 2000 p mol atrazin per assay. Atrazin containing aqueous solutions could be directly assayed in a concentration range of 1.1 up to 2200 μg/1 (ppb). The sensitivity of this EIA variant was improved in two ways. Using polystyrene spheres as antibody carriers, a detection limit of 11 ng/1 (ppt) could be reached. If an affinity purified antiserum was applied, detection limits of 11 ng/1 (ppt) in case of microtiter-plates and 0.1 ng/1 (ppt) in case of polystyrene spheres as antibody carriers were obtained. The cross reactivity of other s-triazines in the atrazin EIA was tested.     

Development of a microscale emission factor model for particulate matter for predicting real-time motor vehicle emissions

The U.S. Environmental Protection Agency's National Exposure Research Laboratory is pursuing a project to improve the methodology for modeling human exposure to motor vehicle emissions. The overall project goal is to develop improved methods for modeling the source through the air pathway to human exposure in significant exposure microenvironments. Current particulate matter (PM) emission models, particle emission factor model (used in the United States, except California) and motor vehicle emission factor model (used in California only), are suitable only for county-scale modeling and emission inventories. There is a need to develop a site-specific real-time emission factor model for PM emissions to support human exposure studies near roadways. A microscale emission factor model for predicting site-specific real-time motor vehicle PM (MicroFacPM) emissions for total suspended PM, PM less than 10 microm aerodynamic diameter, and PM less than 2.5 microm aerodynamic diameter has been developed. The algorithm used to calculate emission factors in MicroFacPM is disaggregated, and emission factors are calculated from a real-time fleet, rather than from a fleet-wide average estimated by a vehicle-miles-traveled weighting of the emission factors for different vehicle classes. MicroFacPM requires input information necessary to characterize the site-specific real-time fleet being modeled. Other variables required include average vehicle speed, time and day of the year, ambient temperature, and relative humidity.     

Beurteilung des Ozonrisikos für die Waldregionen Bayerns am Beispiel des Jahres 2002 und des Extremtrockenjahres 2003 auf der Basis der externen Ozonexposition und der internen Ozonaufnahme

Background, aim, and scope Increasing background concentrations of ground-level tropospheric ozone and more frequent and prolonged summer drought incidences due to climate change are supposed to increase the stress on Bavarian forests. For such scenarios growth reduction and yield losses are predicted. Sustainable forest management in Bavaria aims to significantly increase the proportion of beech (Fagus sylvatica L.) because of its broad ecological amplitude. In our regional study different approaches for calculating ozone impact were used to estimate the risks for Bavarian forests in the average climatic, rather moist year 2002 and the extremely dry year 2003.Materials and methods Measurements were conducted for eleven forest ecosystem sites and two forest research sites representing typical Bavarian forest stands under different climatic conditions and situated in different altitudes. For risk assessment currently used approaches were applied either based on the calculation of the cumulative ozone exposure (external dose; MPOC maximal permitted ozone concentration; critical level AOT40_phen? accumulated ozone exposure over a threshold of 40 nl [O₃] l^–1, for the effective phenolgy of beech) or based on the calculation of the phytomedically relevant ozone flux into the stomata (internal dose, critical level AF_st>1,6, accumulated stomatal flux above a flux threshold of 1.6 nmol O₃?m^–2 PLA; PLA = projected leaf area). For calculations continuously recorded ozone concentrations and meteorological and phenological data from nearby rural open field background measuring stations from the national air pollution control and from forested sites were used. Additionally ozone induced leaf symptoms were assessed.Results The exposure-based indices AOT40_phen and MPOC as well as the flux-based index AF_st>1.6suggest that Bavarian forests are at risk from O₃ during a rather moist average year concerning climate conditions (2002) as well as in an extreme dry year (2003). Thus, growth reductions of 5?% are predicted when thresholds are exceeded. Threshold exceedance occurred in both years at all plots, mostly already at the beginning of the growing season and often even many times over. Ozone induced leaf symptoms could be detected only on a few plots in a very slight occurrence.Discussion The results for the applied critical level indices differed depending on climatic conditions during the growing seasons: Regarding exposure-based indices, the highest degree of threshold exceedance occurred in the dry year of 2003 at all plots; the flux-based approach indicated the highest stomatal ozone uptake and thus an increased risk at moist sites or during humid years, whereas the risk was decreasing at dry sites with prolonged water limitation. Hence, soil and accordingly plant water availability was the decisive factor for the flux-modelled internal ozone uptake via stomata. Drought and increased ozone impact can generate synergistic, but also antagonistic effects for forest trees. At water limited rather dry forest sites restricted transpiration and thus production, but concurrently lower ozone uptake and reduced risk for damage can be expected.Conclusions, recommendations, and perspectives For realistic site-specific risk assessment in forest stands the determination of the internal ozone dose via modeling flux based internal stomatal ozone uptake is more appropriate than the calculation of the external ozone dose. The predicted 5?% growth reductions are in discrepancy with the frequently observed increment increase during the last decades in forest stands. Comprehensive and significant statistical verification for ozone induced forest growth reduction as well as the systematic validation of thresholds for ozone in the field is still lacking. However, a multiplicity of different specific new and retrospective growth analysis data should allow closing the gap. Moreover, the determination of canopy transpiration with sap flow measurements is a novel approach to provide cause-effect related, site specific results for the effective internal ozone dose as well as for canopy water supply and consecutively for regional risk estimation. A further future objective is the refinement of O₃ flux modelling by further consideration of soil/water budget characteristics and the above mentioned improved estimations of crown and canopy transpiration. Further, the introduction of threshold ranges for forest trees in view of their specific regional climatic conditions and their validation in real forest stands is necessary for developing meaningful ozone risk predictions for forests.     

Nitrogen Turnover and Nitrate Leaching after Bark Beetle Attack in Mountainous Spruce Stands of the Bavarian Forest National Park

More than 85% of the mountainous spruce forest of the Bavarian Forest National Park died after bark beetle attack during the last decade. The elemental budget of intact stands and of different stages after the dieback was investigated. N-fluxes in throughfall of intact stands were lower (12–16 kg ha^-1 a^-1) than in an earlier study in an intact mountainous spruce stand in the Bavarian Forest National Park and were reduced in the first years after the dieback (3–5 kg N ha^-1 a^-1). Nitrate-N fluxes by seepage water of intact stands at 40 cm depth, which is below the main rooting zone, were moderate (5–9 kg ha^-1 a^-1). After the dieback of the stands, NH₄ ⁺ concentrations were increased in humus efflux as were NO₃ ^- concentrations in mineral soil. Due to the relatively high precipitation, dilution of the elemental concentrations in seepage was considerable.Therefore, NO₃ ^- concentrations were usually below the level of drinking water (806 μmol NO₃ ^- L^-1), with lowest concentrations after the snowmelt and highest in autumn. Nitrate concentrations were elevated from the first year until the 7th year after the dieback. Total NO₃ ^--N losses by seepage until the 7th year after the dieback equalled 543 kg N ha^-1. Aluminium fluxesafter the dieback were enhanced in the mineral soil from 55 to 503 mmol_c m^-2 a^-1 (average of 8 yr), K⁺ fluxes from 8 to 37 mmol_c m^-2 a^-1, and Mg²⁺ fluxes from 13 to 35 mmol_c m^-2 a^-1. The consequences for the nutritional status of the ecosystem, the hydrosphere, and forest management are discussed in the paper.     

Enrichment of fetal cells from maternal blood by high gradient magnetic cell sorting (double MACS) for PCR-based genetic analysis

For simple and effective isolation of fetal cells from peripheral maternal blood, we combined depletion of maternal cells and enrichment of fetal cells by high-gradient magnetic cell separation (MACS). First CD45⁺ and CD14⁺ cells were depleted from maternal peripheral blood mononuclear cells by MACS. From the depleted fraction, CD71⁺ erythroid cells were enriched up to 80 per cent by MACS. This ‘double-MACS’ procedure yielded an average depletion rate of 780-fold and an average enrichment rate of 500-fold, with approximate recovery rates of 40–55 per cent. For paternity testing, cells from unseparated blood and the various fractions were analysed for polymorphism of the HLA-DQ-A1 locus and D1S80 locus by the polymerase chain reaction (PCR). In CD45⁻/CD71⁺ sorted cells from maternal blood, but not in unfractionated cells from maternal blood or CD45⁻/CD14⁻ cells, paternal alleles could be detected. In the CD45⁻/CD71⁺ fraction, the relative frequency of paternal alleles compared with maternal alleles ranged from 1 in 20 to 1 in 200 (determined by titration and depending on the quality of separation and biological variation). In 7 out of 11 cases, between weeks 12 and 25 of gestation, we could identify paternal alleles by PCR, either HLA-DQ-A1 or D1S80. This double-MACS procedure is simple, fast, efficient, and reliable for non-invasive prenatal diagnosis.