Mangrove reforestation: greening or grabbing coastal zones and deltas? Case studies in Senegal§

Besides their important contribution to global biodiversity, mangroves provide many services. Nevertheless, due to an increase of human activities and to climate change, in less than 20 years these ecosystems have lost one fifth of their global surface area. In response to this decrease, mangrove reforestation incentives have spread throughout the world. The scientific and societal legitimacy of reforestation actions still remain in question. Focusing on two case studies, the Saloum Delta and Lower Casamance, Senegal, our methodology was mainly based on the analysis of environmental narratives and discourses between 2009 and 2013, and on reforestation campaigns conducted by NGOs. We highlight the complexity of the system of values associated with the mangroves, as well as the positive and negative interactions between the services. Even although the reforestation campaigns were generally successful in terms of reforested surfaces and international visibility, they were poor in terms of biological and cultural diversities and led to spatial injustice. Moreover, the extensive reforestation with a unique mangrove species, Rhizophora mangle, was perceived as means of ‘green grabbing’, and the simultaneous buying of carbon tax by industrial conglomerates induced disempowerment of the local communities. More integrated research programmes must be developed towards the extensive knowledge of the mangroves.     

γδ T Cells Are Required for Pulmonary IL-17A Expression after Ozone Exposure in Mice: Role of TNFα

Ozone is an air pollutant that causes pulmonary symptoms. In mice, ozone exposure causes pulmonary injury and increases bronchoalveolar lavage macrophages and neutrophils. We have shown that IL-17A is important in the recruitment of neutrophils after subacute ozone exposure (0.3 ppm for 24–72 h). We hypothesized that γδ T cells are the main producers of IL-17A after subacute ozone. To explore this hypothesis we exposed wildtype mice and mice deficient in γδ T cells (TCRδ^−/−) to ozone or room air. Ozone-induced increases in BAL macrophages and neutrophils were attenuated in TCRδ^−/− mice. Ozone increased the number of γδ T cells in the lungs and increased pulmonary Il17a mRNA expression and the number of IL-17A⁺ CD45⁺ cells in the lungs and these effects were abolished in TCRδ^−/− mice. Ozone-induced increases in factors downstream of IL-17A signaling, including G-CSF, IL-6, IP-10 and KC were also decreased in TCRδ^−/− versus wildtype mice. Neutralization of IL-17A during ozone exposure in wildtype mice mimicked the effects of γδ T cell deficiency. TNFR2 deficiency and etanercept, a TNFα antagonist, also reduced ozone-induced increases in Il17a mRNA, IL-17A⁺ CD45⁺ cells and BAL G-CSF as well as BAL neutrophils. TNFR2 deficient mice also had decreased ozone-induced increases in Ccl20, a chemoattractant for IL-17A⁺ γδ T cells. Il17a mRNA and IL-17A⁺ γδ T cells were also lower in obese Cpe^fat versus lean WT mice exposed to subacute ozone, consistent with the reduced neutrophil recruitment observed in the obese mice. Taken together, our data indicate that pulmonary inflammation induced by subacute ozone requires γδ T cells and TNFα-dependent recruitment of IL-17A⁺ γδ T cells to the lung.     

Influence of biomass production and detachment forces on biofilm structures in a biofilm airlift suspension reactor

The influence of process conditions (substrate loading rate and detachment force) on the structure of biofilms grown on basalt particles in a Biofilm Airlift Suspension (BAS) reactor was studied. The structure of the biofilms (density, surface shape, and thickness) and microbial characteristics (biomass yield) were investigated at substrate loading rates of 5, 10, 15, and 20 kg COD/m3. day with basalt concentrations of 60 g/L, 150 g/L, and 250 g/L. The basalt concentration determines the number of biofilm particles in steady state, which is the main determining factor for the biofilm detachment in these systems. In total, 12 experimental runs were performed. A high biofilm density (up to 67 g/L) and a high biomass concentration was observed at high detachment forces. The higher biomass content is associated with a lower biomass substrate loading rate and therefore with a lower biomass yield (from 0.4 down to 0.12 gbiomass/gacetate). Contrary to general beliefs, the observed biomass detachment decreased with increasing detachment force. In addition, smoother (fewer protuberances), denser and thinner compact biofilms were obtained when the biomass surface production rate decreased and/or the detachment force increased. These observations confirmed a hypothesis, postulated earlier by Van Loosdrecht et al. (1995b), that the balance between biofilm substrate surface loading (proportional to biomass surface production rate, when biomass yield is constant) and detachment force determines the biofilm structure. When detachment forces are relatively high only a patchy biofilm will develop, whereas at low detachment forces, the biofilm becomes highly heterogeneous with many pores and protuberances. With the right balance, smooth, dense and stable biofilms can be obtained. Copyright 1998 John Wiley & Sons, Inc.     

Oligomerization of the Mg2+-transport proteins Alr1p and Alr2p in yeast plasma membrane

Alr1p is an integral plasma membrane protein essential for uptake of Mg(2+) into yeast cells. Homologs of Alr1p are restricted to fungi and some protozoa. Alr1-type proteins are distant relatives of the mitochondrial and bacterial Mg(2+)-transport proteins, Mrs2p and CorA, respectively, with which they have two adjacent TM domains and a short Mg(2+) signature motif in common. The yeast genome encodes a close homolog of Alr1p, named Alr2p. Both proteins are shown here to be present in the plasma membrane. Alr2p contributes poorly to Mg(2+) uptake. Substitution of a single arginine with a glutamic acid residue in the loop connecting the two TM domains at the cell surface greatly improves its function. Both proteins are shown to form homo-oligomers as well as hetero-oligomers. Wild-type Alr2p and mutant Alr1 proteins can have dominant-negative effects on wild-type Alr1p activity, presumably through oligomerization of low-function with full-function proteins. Chemical cross-linking indicates the presence of Alr1 oligomers, and split-ubiquitin assays reveal Alr1p-Alr1p, Alr2p-Alr2p, and Alr1p-Alr2p interactions. These assays also show that both the N-terminus and C-terminus of Alr1p and Alr2p are exposed to the inner side of the plasma membrane.     

Studies on the cytochrome P-450 product complexes formed during the metabolism of N,N-dimethylaniline

The oxidative metabolism of N,N-dimethylaniline by partially solubilized cytochrome P-450 from rabbit liver was found to be associated with the formation of a 424- and 448-nm product adduct of the hemoprotein. From the effects of temperature, hydrogen ion concentration, n-octylamine, extraction of the enzyme preparations with organic solvents and pretreatment of the animals with inducers of drug metabolism on both the formation of the spectral species and the enzymic C- and N-oxidation of N,N-dimethylaniline it is concluded that the 424-nm spectral change is generated from an intermediate in the C-oxidation reaction, whereas formation of the 448-nm spectral perturbation is the result of binding to cytochrome P-450 of a metabolite arising from N-oxidation of the arylamine; N-dealkylation of the parent amine is not a obligatory intermediary step in 448-nm complex formation.The 448-nm ferrohemochrome is supposed to be formed through coordination of the N-oxidized intermediate via the oxygen atom. This type of interaction appears to require considerably stronger thermal activation as compared with the 424-nm complex. The 448-nm product adduct of cytochrome P-450 is unstable in the ferric state or in the presence of sodium dithionite.