Influence of forest degradation on tree diversity in a forest-savannah transition in Eastern Ivory Coast

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Assessing atmospheric particulate matter distribution based on Saturation Isothermal Remanent Magnetization of herbaceous and tree leaves in a tropical urban environment

Particulate matter (PM) emissions, and the associated human health risks, are likely to continue increasing in urban environments of developing countries like Abidjan (Ivory Cost). This study evaluated the potential of leaves of several herbaceous and tree species as bioindicators of urban particulate matter pollution, and its variation over different land use classes, in a tropical area. Four species well distributed (presence frequencies >90%) over all land use classes, easy to harvest and whose leaves are wide enough to be easily scanned were selected, i.e. Amaranthus spinosus (Amaranthaceae), Eleusine indica (Poaceae), Panicum maximum (Poaceae) and Ficus benjamina (Moraceae). Leaf sampling of these species was carried out at 3 distances from the road and at 3 height levels. Traffic density was also noted and finally biomagnetic parameters of these leaves were determined. Results showed that Saturation Isothermal Remanent Magnetization (SIRM) of leaves was at least 4 times higher (27.5×10-6A) in the vicinity of main roads and industrial areas than in parks and residential areas. The main potential sources of PM pollution were motor vehicles and industries. The slightly hairy leaves of the herbaceous plant A. spinosus and the waxy leaves of the tree F. benjamina showed the highest SIRM (25×10-6A). Leaf SIRM increased with distance to road (R2>0.40) and declined with sampling height (R2=0.17). The distance between 0 and 5m from the road seemed to be the most vulnerable in terms of PM pollution. This study has showed that leaf SIRM of herbaceous and tree species can be used to assess PM exposure in tropical urban environments. © 2013 Elsevier B.V.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Electron transport pathways in isolated chromoplasts from Narcissus pseudonarcissus L

International audienceDuring daffodilflower development,chloroplasts differentiate into photosynthetically inactive chromoplasts, which have lostfunctional photosynthetic reaction centers. Chromoplasts exhibit a respiratory activity reducing oxygen to water and generating ATP. Immunoblots revealed the presence of the plastid terminal oxidase(PTOX), the NAD(P)H dehydrogenase (NDH) complex, the cytochrome b6fcomplex, ATP synthase and several isoforms of ferredoxin-NADP+oxidoreductase (FNR) and of ferredoxin (Fd). Fluorescence spectroscopy allowed the detection of chlorophyll a in the cytochrome b6fcomplex. Here we characterize the electron transport pathway of chromorespiration by using specific inhibitors forthe NDH complex, the cytochrome b6fcomplex, FNR and redox-inactive Fd in which the iron was replaced by gallium. Our data suggest anelectron flowvia twoseparatepathways, both reducing plastoquinone and using PTOX as oxidase. The first oxidizes NADPH via FNR, Fd,and cytochrome bh of the cytochrome b6fcomplex and does not result in the pumpingofprotons across the membrane. In the second,electron transport takes place via the NDH complex using preferentially NADH but also NADPH as electron donor. FNR and Fd are not involved in this pathway. The NDH-complex is responsible for the generation of the proton gradient. We propose a new model for chromorespiration which may also be relevant for the understanding of chlororespiration and for the characterization of the electron input from Fd to the cytochrome b6fcomplex during cyclic electron transport in chloroplasts