Biomarkers of exposure and effect—interpretation in human risk assessment

The effect of exposure to carcinogenic polycyclic aromatic hydrocarbons adsorbed onto respirable air particles (PM2.5, diameter < 2.5 μm) on DNA adducts and chromosomal aberrations was repeatedly studied in Prague, Czech Republic, in groups of policemen working in the downtown area and in bus drivers. Personal exposure was evaluated using personal samplers during working shifts. DNA adducts were analyzed in lymphocytes by the 32P-postlabeling assay and chromosomal aberrations were analyzed by conventional cytogenetic analysis and fluorescent in situ hybridization (FISH). The impact of environmental pollution on DNA adducts and chromosomal aberrations was studied in a total of 950 subjects. Our results suggest that the environmental exposure of nonsmokers to concentrations higher than 1 ng benzo[a]pyrene/m3 represents a risk of DNA damage, as indicated by an increase in DNA adducts and the genomic frequency of translocations determined by FISH

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nezařazení_neaktivníFirst Faculty of Medicine1. lékařská fakult

Little Cross-Feeding of the Mycorrhizal Networks Shared Between C3-Panicum bisulcatum and C4-Panicum maximum Under Different Temperature Regimes

Common mycorrhizal networks (CMNs) formed by arbuscular mycorrhizal fungi (AMF) interconnect plants of the same and/or different species, redistributing nutrients and draining carbon (C) from the different plant partners at different rates. Here, we conducted a plant co-existence (intercropping) experiment testing the role of AMF in resource sharing and exploitation by simplified plant communities composed of two congeneric grass species (Panicum spp.) with different photosynthetic metabolism types (C3 or C4). The grasses had spatially separated rooting zones, conjoined through a root-free (but AMF-accessible) zone added with 15N-labeled plant (clover) residues. The plants were grown under two different temperature regimes: high temperature (36/32°C day/night) or ambient temperature (25/21°C day/night) applied over 49 days after an initial period of 26 days at ambient temperature. We made use of the distinct C-isotopic composition of the two plant species sharing the same CMN (composed of a synthetic AMF community of five fungal genera) to estimate if the CMN was or was not fed preferentially under the specific environmental conditions by one or the other plant species. Using the C-isotopic composition of AMF-specific fatty acid (C16:1ω5) in roots and in the potting substrate harboring the extraradical AMF hyphae, we found that the C3-Panicum continued feeding the CMN at both temperatures with a significant and invariable share of C resources. This was surprising because the growth of the C3 plants was more susceptible to high temperature than that of the C4 plants and the C3-Panicum alone suppressed abundance of the AMF (particularly Funneliformis sp.) in its roots due to the elevated temperature. Moreover, elevated temperature induced a shift in competition for nitrogen between the two plant species in favor of the C4-Panicum, as demonstrated by significantly lower 15N yields of the C3-Panicum but higher 15N yields of the C4-Panicum at elevated as compared to ambient temperature. Although the development of CMN (particularly of the dominant Rhizophagus and Funneliformis spp.) was somewhat reduced under high temperature, plant P uptake benefits due to AMF inoculation remained well visible under both temperature regimes, though without imminent impact on plant biomass production that actually decreased due to inoculation with AMF

Mutabilis in mutabili: Spatiotemporal dynamics of a truffle colony in soil

The functioning of ectomycorrhizal (ECM) symbioses is closely related to the development of the soil mycelial phase the ECM fungi. The properties and spatiotemporal dynamics of such mycelia in ecosystems is, however, poorly understood. Here we show, using a soil colony of summer truffle (Tuber aestivum) as a model, that an ECM mycelium may only grow and colonize newly-opened soil patches when soil temperatures rise above certain threshold, in this case +10 °C, provided other requirements such as sufficient soil moisture are fulfilled. Extension rates of truffle mycelium in the fields was recorded as >0.3 μm min−1, several-fold greater than that predicted from laboratory cultures. Further, we demonstrated that there was a consistent spatial differentiation in mycelium growth patterns within the fungal colony on a decimeter scale, changing from “diffusion” type of growth at the colony margin to “colony-front” pattern further away from the colony margin. This change was clearly accompanied by shifting structure of soil microbial communities with Terrimonas sp. and another unidentified bacterium correlating with the “colony-front” mycelium growth pattern, and Sphingomonas sp. and Lysobacter brunnescens with the “diffusion” type of mycelium growth. Possible implications of the observed truffle colony differentiation are discussed for processes like fruit-body formation and dispersal of this ECM fungus. Our data indicate that the thallus of T. aestivum has to be considered as a principally variable (“mutabilis”) being in space and time, whose behavior correlates with conditions in ever changing soil environment (“in mutabili”)

Utilization of organic nitrogen by arbuscular mycorrhizal fungi-is there a specific role for protists and ammonia oxidizers?

Arbuscular mycorrhizal (AM) fungi can significantly contribute to plant nitrogen (N) uptake from complex organic sources, most likely in concert with activity of soil saprotrophs and other microbes releasing and transforming the N bound in organic forms. Here, we tested whether AM fungus (Rhizophagus irregularis) extraradical hyphal networks showed any preferences towards certain forms of organic N (chitin of fungal or crustacean origin, DNA, clover biomass, or albumin) administered in spatially discrete patches, and how the presence of AM fungal hyphae affected other microbes. By direct N-15 labeling, we also quantified the flux of N to the plants (Andropogon gerardii) through the AM fungal hyphae from fungal chitin and from clover biomass. The AM fungal hyphae colonized patches supplemented with organic N sources significantly more than those receiving only mineral nutrients, organic carbon in form of cellulose, or nothing. Mycorrhizal plants grew 6.4-fold larger and accumulated, on average, 20.3-fold more N-15 originating from the labeled organic sources than their nonmycorrhizal counterparts. Whereas the abundance of microbes (bacteria, fungi, or Acanthamoeba sp.) in the different patches was primarily driven by patch quality, we noted a consistent suppression of the microbial abundances by the presence of AM fungal hyphae. This suppression was particularly strong for ammonia oxidizing bacteria. Our results indicate that AM fungi successfully competed with the other microbes for free ammonium ions and suggest an important role for the notoriously understudied soil protists to play in recycling organic N from soil to plants via AM fungal hyphae

Presentation_1.PDF

<p>Common mycorrhizal networks (CMNs) formed by arbuscular mycorrhizal fungi (AMF) interconnect plants of the same and/or different species, redistributing nutrients and draining carbon (C) from the different plant partners at different rates. Here, we conducted a plant co-existence (intercropping) experiment testing the role of AMF in resource sharing and exploitation by simplified plant communities composed of two congeneric grass species (Panicum spp.) with different photosynthetic metabolism types (C₃ or C₄). The grasses had spatially separated rooting zones, conjoined through a root-free (but AMF-accessible) zone added with ¹⁵N-labeled plant (clover) residues. The plants were grown under two different temperature regimes: high temperature (36/32°C day/night) or ambient temperature (25/21°C day/night) applied over 49 days after an initial period of 26 days at ambient temperature. We made use of the distinct C-isotopic composition of the two plant species sharing the same CMN (composed of a synthetic AMF community of five fungal genera) to estimate if the CMN was or was not fed preferentially under the specific environmental conditions by one or the other plant species. Using the C-isotopic composition of AMF-specific fatty acid (C16:1ω5) in roots and in the potting substrate harboring the extraradical AMF hyphae, we found that the C₃-Panicum continued feeding the CMN at both temperatures with a significant and invariable share of C resources. This was surprising because the growth of the C₃ plants was more susceptible to high temperature than that of the C₄ plants and the C₃-Panicum alone suppressed abundance of the AMF (particularly Funneliformis sp.) in its roots due to the elevated temperature. Moreover, elevated temperature induced a shift in competition for nitrogen between the two plant species in favor of the C₄-Panicum, as demonstrated by significantly lower ¹⁵N yields of the C₃-Panicum but higher ¹⁵N yields of the C₄-Panicum at elevated as compared to ambient temperature. Although the development of CMN (particularly of the dominant Rhizophagus and Funneliformis spp.) was somewhat reduced under high temperature, plant P uptake benefits due to AMF inoculation remained well visible under both temperature regimes, though without imminent impact on plant biomass production that actually decreased due to inoculation with AMF.</p

Cytogenetic effects in children and mothers exposed to air pollution assessed by the frequency of micronuclei and fluorescence in situ hybridization (FISH): A family pilot study in the Czech Republic

A family pilot study was conducted in the Czech Republic to test the hypothesis that exposure to air pollution with particulate matter (PM) in children results in detectable effects indicated by a number of biomarkers of exposure and early effects. The frequency of micronuclei (MN) in peripheral blood lymphocytes (PBLs) was analysed to assess the cytogenetic effects in children and mothers living in two different areas. From each area two groups of children from a total of 24 families (mean age: 6.0 ± 0.6 and 9.0 ± 1.2 years) in a total of 47 children and 19 mothers (mean age: 33.6 ± 3.9 years) participated. Chromosome aberrations determined with fluorescence in situ hybridization (FISH) painting for chromosomes 1 and 4 were analysed in 39 children and 20 parents. Teplice, a mining district, in Northern Bohemia was selected for the analyses of the effects in a population exposed to high levels of air pollution, especially during winter, and compared with a population from the rural area of Prachatice in Southern Bohemia. Significant higher frequencies of MN were found in the younger children living in the Teplice area as compared with those living in the Prachatice area (7.0 ± 2.3‰ versus 4.9 ± 2.0‰, p = 0.04). Higher levels of MN were also measured in the older children and the mothers from the Teplice area (9.2 ± 3.7‰ versus 6.6 ± 4.4‰) and (12.6 ± 3.4‰ versus 10.1 ± 4.0‰). The increased MN frequency may be associated with elevated carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) concentration of the PM2.5 measured in the ambient Teplice air, but other factors like genotoxic compounds from the diet or protective effect of micronutrients, which was not addressed in this pilot study, may also differ between the two areas. MN frequencies were found to increase with age in children. Lower MN frequency was found in boys as compared to girls. The result of the FISH analyses showed a low number of individuals with detectable levels of aberrations and no significant increases in genomic frequency of stable chromosome exchanges (FG/100) were found in children or parents from the Teplice area in comparison with those from the Prachatice area. The family pilot study indicates that MN is a valuable and sensitive biomarker for early biological effect in children and adults living in two different areas characterised with significant exposure differences in c-PAHs concentrations during winter. © 2006 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Znečištění ovzduší a ochrana zdraví

Závěry řešení: 1. Byla vyhodnocena úroveň modelové pražské populace (městských strážníků) karcinogenním polycyklickým aromatickým uhlovodíkům, která je závislá na sezónních vlivech se zvýšenou expozicí v průběhu zimních měsíců. 2. Expozice karcinogenním PAU je nutno považovat za zvýšené genotoxické riziko, jak bylo prokázáno zvýšenou úrovní DNA aduktů, chromosomových aberací konvenční cytrogenetickou metodou, metodou FISH a oxidací proteinů. 3. Na základě provedené studie pro potřeby systematického biomonitoringu genotoxických účinků komplexních směsí znečišťujících atmosféru považujeme jako vhodné biomarkery stanovení DNA aduktů metodu 32P-postlabeling, využití cytogenetické analýzy konvenční metodou, fluorescence in situ hybridizace s pomocí barvicích sond (FISH), hodnocení oxidačního poškození proteinů a hodnocení rozdílné vnímavosti jedinců s rozdílnou distribucí genotypů (genetický polymorfismus) i hladin vitaminů a lipidů. 4. Studium geneticky podmíněné vnímavosti k účinkům PAU naznačuje význam kombinance metabolických genotypů CY1A1-Msp I s GSTM1 a CYP1A1-Ile/Val s GSTM1. 5. Studium vlivů hladin vitaminů na rozsah genotoxických účinků PAU je ve stadiu hodnocení. Zatím byl prokázán pozitivní vliv vitaminu A na DNA adukty. 6. Při hodnocení podílu oxidativního poškození na indukci genotoxických změn bylo zjištěno, že kometový test není vhodnou metodou pro podobný typ studií. Za vhodnější je považována metoda stanovení oxidativního poškození proteinů. 7. Pro hodnocení zdravotních rizik je opakovaně prokazována nutnost monitorování karcinogenních PAU a využití těchto poznatků pro hodnocení rizika jak pro těhotné ženy a děti, tak i jedince pracující v prostředí se zvýšenou expozicí (jako např. městští strážníci v Praze). 8. V okrese Teplice se pokračovalo ve sledování průběhu a výsledků těhotenství ve vztahu ke kvalitě ovzduší. Získávané poznatky jsou dnes mezinárodně využívány i v materiálech WHO. 9. Byl navržen postup hodnocení genotoxicity komplexních směsí organických látek z ovzduší in vitro

Znečištění ovzduší a ochrana zdraví

Cílem projektu je stanovit rizika expozice nízkým hladinám komplexních směsí látek přítomných ve znečištěném ovzduší, hodnocení dlouhodobých účinků znečištění v Praze a v Teplicích. Vyhodnotit následky kombinovaného působení biologicky aktivních látek ve vztahu ke genotypu a se zřetelem k životnímu stylu validovat biomarkery zátěže lidské populace polutanty z ovzduší. Odhadnout podíl hlavních zdrojů na této zátěži a vypracovat systém interpretace získávaných dat. Projekt bude metodicky navazovat na Program Teplice I a II a "Program znečištění ovzduší a zdraví". Pro zajištění cíle byly řešeny 3 projekty: Projekt 1 Hodnocení projevů genotoxicity ovzduší u environmentálně exponovaných osob, Projekt 2 Dopady znečištění ovzduší na výsledky těhotenství, Projekt 3 Studium mechanismů působení komplexních směsí organických látek z ovzduší v buněčných systémech in vitro