Change of liver metabolism of 1,2-dibromoethane during simultaneous treatment with carbon tetrachloride

The combination of carbon tetrachloride (CCl₄) and 1,2-dibromoethane (DBE) in isolated rat hepatocytes led to a significant potentiation of both lipid peroxidation and of plasma membrane damage observed after a single treatment with CCl₄. Such a synergistic effect appeared to be related to the CCl₄-induced shift of DBE metabolism from the cytosolic conjugation with glutathione towards the microsomal transformation into toxic intermediates. In fact, CCl₄ significantly inactivated hepatocyte total GSH-transferase, i.e. the DBE detoxification pathway. Furthermore, while the microsomal metabolism of CCl₄ was not affected by the simultaneous presence of DBE, the amount of DBE reactive metabolities covalently bound to hepatocyte protein was significantly enhanced in the presence of CCl₄.     

Aphid Herbivory Drives Asymmetry in Carbon for Nutrient Exchange between Plants and an Arbuscular Mycorrhizal Fungus

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Ecological and environmental effects of land use change in rapid urbanization: The case of hangzhou,China

Land use changes sharply under rapid urbanization, yet its ecological and environmental effects are often neglected in land use decisions. Using the case of Hangzhou, China, we analyze the ecological and environmental effects of land use changes, including ecosystem services value (ESV) and carbon emissions, based on Landsat TM images from 1995, 2000, 2005, 2010, and 2014. We found significant ecological and environmental effects of land use changes under rapid urbanization. The value of ecosystem services in Hangzhou decreased from 546.7 million USD in 1995 to 448.97 million USD in 2014, and the ratio of ESV to GDP decreased from 5.8% to 0.6%. The net carbon emissions associated with land use changes increased from 4.26 million tons in 1995 to 15.10 million tons in 2014, mainly due to the increase of built-up land carbon emissions and the decrease of forest land carbon sink. The ESV is unevenly distributed spatially and low ESV spread from the central to the peripheral area. We use scenario analysis to illustrate that economic growth and environmental protection could be coordinated by bringing ecological and environmental effects into land use decisions.     

Effect of Different Carbon and Nitrogen Sources on Clostridium argentinense Toxigenicity in Coculture withPseudomonas mendocina

The effect of different carbon and nitrogen sources on the production of toxin by Clostridium argentinense was examined. The toxin production by C. argentinense in coculture with Pseudomonas mendocina increased in all the cases in relation to that produced by monocultures independent of the nature of the source. Using dextrin as carbon source C. argentinense produced the highest levels of toxin both in monocultures (300 LD₅₀/mL) and in cocultures with P. mendocina (5000 LD₅₀/mL). Experiments run in a microfermenter showed that the slow growth of cocultures associated with the assimilation of dextrin and the pH and Eh profiles favoured the production of toxin. Of the nitrogen sources assayed, corn steep liquor sustained the highest levels of toxin in both monocultures and cocultures with 3 and 2.8 fold increases with respect to that obtained using proteose peptone. The toxin production by C. argentinense cultures and C. argentinense–P. mendocina cocultures was highly dependent on the nature of the carbon and nitrogen sources used in the culture media. Growth of C. argentinense on substrates slowly assimilated stimulated the production of toxin.     

Decreased hydraulic conductance in plants at elevated carbon dioxide

Previous work indicated that long-term exposure to elevated carbon dioxide levels can reduce hydraulic conductance in some species, but the basis of the response was not determined. In this study, hydraulic conductance was measured at concentrations of both 350 and 700 cm³ m^–3 carbon dioxide for plants grown at both concentrations, to determine the reversibility of the response. In Zea mays and Amaranthus hypochondriacus , exposure to the higher carbon dioxide concentration for several hours reduced whole-plant transpiration rate by 22–40%, without any consistent change in leaf water potential, indicating reversible reductions in hydraulic conductance at elevated carbon dioxide levels. Hydraulic conductance in these species grown at both carbon dioxide concentrations responded similarly to measurement concentration of carbon dioxide, indicating that the response was reversible. In Glycine max , which in earlier work had shown a long-term decrease in hydraulic conductance at elevated carbon dioxide levels, and in Abutilon theophrasti , no short-term changes in hydraulic conductance with measurement concentration of carbon dioxide were found, despite lower transpiration rates at elevated carbon dioxide. In G. max and Medicago sativa , growth at high dew-point temperature reduced transpiration rate and decreased hydraulic conductance. The results indicate that both reversible and irreversible decreases in hydraulic conductance can occur at elevated carbon dioxide concentrations, and that both could be responses to reduced transpiration rate, rather than to carbon dioxide concentration itself.