An open-top chamber study with filtered and non-filtered air to evaluate the effects of air pollutants on crops

Four non-filtered and four charcoal-filtered open-top chambers were employed to determine the effects of ambient levels of gaseous air pollutants at Braunschweig, FRG, on growth and yield of potted plants of winter and spring barley. During the exposure period (November 1985-August 1986) monthly mean values of gaseous air pollutants (microg m(-3)) ranged between 34 and 127 for SO(2), 34 and 52 for NO(2) and 12 and 33 for O(3) in winter (November-March), and 16 to 26 for SO(2), 20 to 33 for NO(2) and 42 to 53 for O(3) in spring-summer (April-August). Monthly 2% percentile values for these gases reached (microg m (-3)) 561 for SO(2), 140 for NO(2) and 170 for O(3). The filtering efficiencies of the charcoal filters used averaged 60% for SO(2), 50% for NO(2) and 70% for O(3). All plants of winter barley from the unchambered plot were killed by severe frost periods in winter, 1986. Little frost damage occurred on plants grown in the chambers. Air filtration resulted in higher numbers of plants of winter barley per pot, i.e. a higher number of individuals per area, and a higher dry weight of whole plants and ears compared to the non-filtered atmosphere. In the experiments with spring barley, fresh and dry weight of whole plants were lower and dry weight of leaves were higher in the filtered open-top chambers. These effects could not be observed at all harvests which were carried out during the growing season. Grain yield and sulphur content of the leaves of both barley cultivars were not affected by the air filtration. Production of biomass of spring barley grown in ambient air was higher than of that grown in open-top chambers.     

Seasonal dynamics of freshwater pathogens as measured by microarray at Lake Sapanca,a drinking water source in the north-eastern part of Turkey

Monitoring drinking water quality is an important public health issue. Two objectives from the 4 years, six nations, EU Project μAqua were to develop hierarchically specific probes to detect and quantify pathogens in drinking water using a PCR-free microarray platform and to design a standardised water sampling program from different sources in Europe to obtain sufficient material for downstream analysis. Our phylochip contains barcodes (probes) that specifically identify freshwater pathogens that are human health risks in a taxonomic hierarchical fashion such that if species is present, the entire taxonomic hierarchy (genus, family, order, phylum, kingdom) leading to it must also be present, which avoids false positives. Molecular tools are more rapid, accurate and reliable than traditional methods, which means faster mitigation strategies with less harm to humans and the community. We present microarray results for the presence of freshwater pathogens from a Turkish lake used drinking water and inferred cyanobacterial cell equivalents from samples concentrated from 40 into 1 L in 45 min using hollow fibre filters. In two companion studies from the same samples, cyanobacterial toxins were analysed using chemical methods and those dates with highest toxin values also had highest cell equivalents as inferred from this microarray study.     

Influence of Riffle and Snag Habitat Specific Sampling on Stream Macroinvertebrate Assemblage Measures in Bioassessment

Stream macroinvertebrate communities vary naturally among types of habitats where they are sampled, which affects the results of environmental assessment. We analyzed macroinvertebrates collected from riffle and snag habitats to evaluate influences of habitat-specific sampling on taxon occurrence, assemblage measures, and biotic indices. We found considerably more macroinvertebrate taxa unique to snags (143 taxa) than to riffles (75 taxa), and the numbers of taxa found in both riffles and snags (149 taxa) were similar to that found in snags. About 64% of the 47 macroinvertebrate measures we tested differed significantly between riffles and snags. Eighty percent intercepts of regressions between biotic indices and urban or agricultural land uses differed significantly between riffles and snags. The Hilsenhoff biotic index calculated from snag samples explained 69% of the variance of riffle samples and classified 66% of the sites into the same stream health group as the riffle samples. However, four multimetric indices for snag samples explained less than 50% of the variance of riffle samples and classified less than 50% of the sites into the same health group as the riffle samples. We concluded that macroinvertebrate indices developed for riffle/run habitat should not be used for snag samples to assess stream impairment. We recommend developing an index of biotic integrity specifically for snags and using snags as an alternate sampling substrate for streams that naturally lack riffles.     

Identifying Biotic Integrity and Water Chemistry Relations in Nonwadeable Rivers of Wisconsin: Toward the Development of Nutrient Criteria

We sampled 41 sites on 34 nonwadeable rivers that represent the types of rivers in Wisconsin, and the kinds and intensities of nutrient and other anthropogenic stressors upon each river type. Sites covered much of United States Environmental Protection Agency national nutrient ecoregions VII—Mostly Glaciated Dairy Region, and VIII—Nutrient Poor, Largely Glaciated upper Midwest. Fish, macroinvertebrates, and three categories of environmental variables including nutrients, other water chemistry, and watershed features were collected using standard protocols. We summarized fish assemblages by index of biotic integrity (IBI) and its 10 component measures, and macroinvertebrates by 2 organic pollution tolerance and 12 proportional richness measures. All biotic and environmental variables represented a wide range of conditions, with biotic measures ranging from poor to excellent status, despite nutrient concentrations being consistently higher than reference concentrations reported for the regions. Regression tree analyses of nutrients on a suite of biotic measures identified breakpoints in total phosphorus (~0.06 mg/l) and total nitrogen (~0.64 mg/l) concentrations at which biotic assemblages were consistently impaired. Redundancy analyses (RDA) were used to identify the most important variables within each of the three environmental variable categories, which were then used to determine the relative influence of each variable category on the biota. Nutrient measures, suspended chlorophyll a, water clarity, and watershed land cover type (forest or row-crop agriculture) were the most important variables and they explained significant amounts of variation within the macroinvertebrate (R ² = 60.6%) and fish (R ² = 43.6%) assemblages. The environmental variables selected in the macroinvertebrate model were correlated to such an extent that partial RDA analyses could not attribute variation explained to individual environmental categories, assigning 89% of the explained variation to interactions among the categories. In contrast, partial RDA attributed much of the explained variation to the nutrient (25%) and other water chemistry (38%) categories for the fish model. Our analyses suggest that it would be beneficial to develop criteria based upon a suite of biotic and nutrient variables simultaneously to deem waters as not meeting their designated uses.     

Determination of selected pharmaceuticals and caffeine in sewage and seawater from Tromsø/Norway with emphasis on ibuprofen and its metabolites

Selected pharmaceuticals, among them analgesics, ss-blockers and anti-depressants as well as caffeine, the anti-bacterial triclosan and the insect repellent N,N-diethyl-3-toluamide (DEET) were determined in different sewage samples (sewage treatment plants, hospital effluents) from Troms?/Norway and in seawater from Troms?-Sound, into which the sewage is discharged. While caffeine, triclosan, ibuprofen and its major metabolites hydroxy- and carboxy-ibuprofen were present in all sewage samples, additional pharmaceuticals were observed in sewage containing hospital effluents. Concentrations were in the range of 20-293 microg/l (caffeine), 0.2-2.4 microg/l (triclosan) and 0.1-20 microg/l (sum ibuprofen + metabolites). In seawater, only caffeine (7-87 ng/l), DEET (0.4-13 ng/l) and ibuprofen + metabolites (sum concentration < LOQ-7.7 ng/l) were detected. Ibuprofen and its metabolites hydroxy- and carboxy-ibuprofen were quantified individually by use of the respective reference compounds. Relative amounts of the three compounds were determined in different types of water showing characteristic patterns, with hydroxy-ibuprofen being the major component in sewage whereas carboxy-ibuprofen was dominant in seawater samples. The patterns which were compared to those observed in similar samples from Germany indicated different transformation behaviour under limnic and marine conditions.     

Effects of open-top chamber fumigations with ozone on three fungal leaf diseases of wheat and the mycoflora of the phyllosphere

Spring wheat (Triticum aestivum L. cv. Turbo) was exposed in open-top chambers to six different ozone levels (8-h daily means from 12.4 to 122 microg m(-3)), to non-filtered air and to chamberless field conditions for 31 days from seedling stage through ear emergence. Powdery mildew (Erysiphe graminis DC. f.sp. tritici Marchal) which developed during the exposure period was significantly enhanced from 0.3/0.6% (two chamber replicates), 1.2/2.1%, 0.9/2.2% in charcoal-filtered air (CF) to 1.5/1.6%, 3.7/4.3%, 4.4/4.6% at the highest level of ozone, on the flag leaf, second and third leaf position, respectively. Post-exposure inoculation with Septoria nodorum Berk. led to increases of disease severity on the flag leaf from 40.9/43.6% in CF to 66.3/70.6% at the highest ozone concentration and on the ears from 15.7/16.5% to 26.3/26.6%. In the same comparison, severity of spot blotch following inoculation with Bipolaris sorokiniana (Sacc.) Shoem. (syn. Helminthosporium sativum Pamm., King et Bakke) was increased on the flag leaf from 3.6/8.9% to 12.3/23.4%. The three diseases examined correlated significantly with the ozone treatments in fumigated chambers. Disease severity was enhanced even on undamaged plant tissue (flag leaves). Infections of the two facultative pathogens on lower leaf positions started only in part from visible ozone lesions, mildew did not start from such lesions. No significant effects of ozone in the chambers on the saprobial colonization of the phyllosphere were detected, whereas there were marked differences in this respect between plants from the field and the chambers. At the highest ozone treatment, contents of chlorophyll a and carotenoids on the second leaf position declined significantly, which was associated with symptoms of premature senescence. Senescing effects of ozone are therefore assumed to be one major factor in predisposing wheat for necrotrophic leaf pathogens. Surprisingly, injurious and predisposing effects of ozone were completely absent in chambers supplied with non-filtered air containing ambient ozone at doses equivalent to those in CF + ozone chambers. Evidently, biological effects of ozone in pure air and in ambient air may differ markedly.     

Response of cellular antioxidants to ozone in wheat flag leaves at different stages of plant development

The effect of ozone (O3) on growth, yield and foliar antioxidants of spring wheat (Triticum aestivum L. cv. Turbo) was investigated in 1990 and 1991 in Braunschweig, Germany. Plants were grown full-season in pots in open-top chambers ventilated with charcoal-filtered (CF) air to which one or two levels of O3 were added. Mean 8 h day(-1) (10.00-18.00 h) O3 concentrations in the CF and CF + O3 treatments were 5.9, 61.2 and 92.5 nl litre(-1) in 1990, and 4.7 and 86.4 nl litre(-1) in 1991. Plants that received the high O3 level showed symptoms of premature senescence of the oldest leaves and yield reductions in both growing seasons. The contents of ascorbate and glutathione and the enzyme activities of ascorbate peroxidase and glutathione reductase were measured in symptomless flag leaves in weekly intervals before and after the beginning of anthesis. Leaf age had a significant effect on all antioxidants investigated. The O3 exposures of about 90 nl litre(-1) increased the activity of ascorbate peroxidase and the concentration of glutathione, but there were no pollutant effects on ascorbate content and glutathione reductase activity. Measurements of the antioxidant levels throughout one day showed no clear indications of diurnal changes in the antioxidative capacity in wheat flag leaves. The results are discussed in relation to the role of antioxidants in O3 detoxification.     

Phylogeography of Australia’s king brown snake (Pseudechis australis) reveals Pliocene divergence and Pleistocene dispersal of a top predator

King brown snakes or mulga snakes (Pseudechis australis) are the largest and among the most dangerous and wide-ranging venomous snakes in Australia and New Guinea. They occur in diverse habitats, are important predators, and exhibit considerable morphological variation. We infer the relationships and historical biogeography of P. australis based on phylogenetic analysis of 1,249 base pairs from the mitochondrial cytochrome b, NADH dehydrogenase subunit 4 and three adjacent tRNA genes using Bayesian, maximum-likelihood, and maximum-parsimony methods. All methods reveal deep phylogenetic structure with four strongly supported clades comprising snakes from New Guinea (I), localities all over Australia (II), the Kimberleys of Western Australia (III), and north-central Australia (IV), suggesting a much more ancient radiation than previously believed. This conclusion is robust to different molecular clock estimations indicating divergence in Pliocene or Late Miocene, after landbridge dispersal to New Guinea had occurred. While members of clades I, III and IV are medium-sized, slender snakes, those of clade II attain large sizes and a robust build, rendering them top predators in their ecosystems. Genetic differentiation within clade II is low and haplotype distribution largely incongruent with geography or colour morphs, suggesting Pleistocene dispersal and recent ecomorph evolution. Significant haplotype diversity exists in clades III and IV, implying that clade IV comprises two species. Members of clade II are broadly sympatric with members of both northern Australian clades. Thus, our data support the recognition of at least five species from within P. australis (auct.) under various criteria. We discuss biogeographical, ecological and medical implications of our findings.Electronic Supplementary Material  Supplementary material is available in the online version of this article at     

Musterbildung bei Drosophila

Drosophila proved an excellent system to study molecular processes in establishing the body pattern of an embryo. Genes which are active during oogenesis provide localized cues which regulate a cascade of zygotic genes that determines the developmental fate of the blastoderm cells along the longitudinal axis of the embryo.     

On the distribution of particulate metals,chlorophyll and seston in the Baltic Sea

During the end of the phytoplankton spring bloom, about 100 water samples were taken at 23 stations in the Baltic Sea. The samples were analyzed for particulate Cu, Fe, Zn, Cd, and Pb by atomic absorption as well as for chlorophyll and seston. Further subsamples were counted with an inverted microscope, and phytoplankton carbon content was calculated. The hydrographical-biological state of the Baltic Sea during spring is described. Two different water masses could be differentiated and these were separated by the halocline. The concentrations of particulate metals are in accordance with those published by other authors. No significant differences could be calculated between mean values of particulate metal concentrations in the two water bodies. Correlations between particulate metal concentrations and chlorophyll, seston, phytoplankton carbon and cell-count were calculated for both photic layer and deeper waters. Significant correlations were found only in the photic layer. The importance of standing crop for metal accumulation in seston is discussed.