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Observable Effects (observable + effects)
Selected AbstractsPhenazines and biosurfactants interact in the biological control of soil-borne diseases caused by Pythium spp.ENVIRONMENTAL MICROBIOLOGY, Issue 3 2008Maaike Perneel Summary In this study, the putative role of phenazines and rhamnolipid-biosurfactants, antagonistic metabolites produced by Pseudomonas aeruginosa PNA1, was tested in the biological control of Pythium splendens on bean (Phaseolus vulgaris L) and Pythium myriotylum on cocoyam (Xanthosoma sagittifolium L Schott). A rhamnolipid-deficient and a phenazine-deficient mutant of PNA1 were used either separately or jointly in plant experiments. When the mutants were applied separately, no disease-suppressive effect was observed, although both mutants still produced one of the antagonistic compounds (phenazines or rhamnolipids). When the mutants were concurrently introduced in the soil, the biocontrol activity was restored to wild-type levels. Bean seeds developed significantly less pre-emergence damping-off caused by P. splendens when treated with a mixture of purified phenazine-1-carboxamide and rhamnolipids than with any of the chemicals alone. When phenazines and rhamnolipids were combined at concentrations that had no observable effects when the metabolites were applied separately, mycelial growth of P. myriotylum was significantly reduced. In addition, microscopic analysis revealed substantial vacuolization and disintegration of Pythium hyphae after incubation in liquid medium amended with both metabolites. Results of this study indicate that phenazines and biosurfactants are acting synergistically in the control of Pythium spp. [source] Accumulation and solubility of metals during leaf litter decomposition in non-polluted and polluted soilEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2009S. Scheid Summary The decomposition of alder (Alnus glutinosa) and poplar (Populus tremula) leaf litter placed in direct contact with non-polluted and metal-polluted soil was investigated over 25 months in a controlled model-ecosystem experiment using the litterbag method. In addition to mass loss, we monitored the total and soluble concentrations of carbon, Cu, Zn, Cd and Pb. Leaves from trees grown on polluted soil had larger initial Zn, Cd and dissolved organic carbon concentrations. Neither the origin of the leaves (from trees grown on non-polluted or polluted soil) nor the placement of the leaves in polluted or unpolluted soil affected the decomposition process. Total metal contents increased in leaves placed on polluted soil over time. The solubility of metals in the leaf litter decreased over time, indicating that leaves acted as a temporary pool for metals from the soil in direct contact with the leaves. The sorbed metals were strongly bound in the litter even after two years of decomposition. The strong binding and thus reduced bioavailability of the metals provides an explanation for why they had no observable effects on litter decomposition. [source] Combined exposure to anti-androgens causes markedly increased frequencies of hypospadias in the ratINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2008S. Christiansen Summary The incidence of hypospadias is increasing in young boys, but it remains unclear whether human exposure to endocrine disrupting chemicals plays a role. Risk assessment is based on estimation of no-observed-adverse-effect levels for single compounds, although humans are exposed to combinations of several anti-androgenic chemicals. In a mixture (MIX) study with three androgen receptor antagonists, vinclozolin, flutamide and procymidone, rats were gavaged during gestation and lactation with several doses of a MIX of the three chemicals or the chemicals alone. External malformations of the male reproductive organs were assessed on PND 47 using a score from 0 to 3 (normal to marked) for hypospadias. Markedly increased frequencies were observed after exposure to a MIX of the three chemicals compared to administration of the three chemicals alone. Anogenital distance at PND 1, nipple retention at PND 13, and dysgenesis score at PND 16 were highly correlated with the occurrence of hypospadias, and MIX effects were seen at doses where each of the individual chemicals caused no observable effects. Therefore, the results indicate that doses of anti-androgens, which appear to induce no hypospadias when judged on their own, may induce a very high frequency of hypospadias when they interact in concert with other anti-androgens. [source] Constructivist Implications of Material Power: Military Engagement and the Socialization of States, 1972,2000INTERNATIONAL STUDIES QUARTERLY, Issue 3 2006CAROL ATKINSON The research presented in this article examines one aspect of state socialization, the extent to which transnational military-to-military interactions have served as an effective mechanism of the democratic political socialization of states. Military organizations are very interesting when we consider avenues by which state socialization might occur because military organizations are an influential part of governments, and members share common beliefs and values as soldiers and officers that transcend borders. Thus, it would seem that a state's military structure is one likely channel whereby politically relevant individuals might learn new ideas and have the capability to reform existing institutional structures. The socialization process described in this study is three level: (1) individuals acquire new ideas; (2) coercion, incentives, and persuasion aid in institutionalizing these ideas in the underlying political structure of the state; and (3) once institutionalized, these new ideas/identity of the state influence the material and ideational structure of international society. Using Cox Proportional Hazard models and an original data set encompassing over 160 states during the years 1972,2000, the analyses find U.S. military-to-military contacts to be positively and systematically associated with liberalizing trends. This finding provides evidence that constructivist mechanisms do have observable effects, and that ideationally based processes play an important role in U.S. national security. [source] Effect of dietary cortisol administration on growth and reproductive success of channel catfishJOURNAL OF FISH BIOLOGY, Issue 3 2004B. C. Small The effect of cortisol administration on reproductive performance was investigated in channel catfish Ictalurus punctatus broodfish. Cortisol was added to a commercial catfish feed by dissolving in ethanol and spraying the feed to yield a dietary concentration of 150 mg kg,1 feed. The cortisol diet and the control (no cortisol) diet were offered at a rate of 1% of biomass to three replicate ponds each containing 28 female and 14 male broodfish, respectively, three times per week for 11 weeks. Spawning began 10 days after the start of the experiment, and continued for 10 weeks. In fish fed cortisol, body mass and the hepato-somatic index were reduced (P , 0·02) and concentrations of plasma cortisol and glucose were significantly higher (P , 0·0003) compared to those of controls. The relative frequency of spawning was similar between the two treatments; however, cortisol-fed channel catfish had an average of 47·1% more spawns than the control-fed fish. On average, there were 25·5 spawns per pond in the treated groups compared to 12·3 spawns per control pond (P = 0·10). No effect was observed on egg production, with individual egg mass, fecundity, and hatching success being similar (P , 0·27) for both treatments. Despite the observed negative effects of cortisol on somatic and hepatic growth, the increased reproductive output coupled with no observable effects on the eggs or hatching success demonstrates that cortisol does not suppress channel catfish reproduction. [source] | ||||||||||