Decreased protein nitration in macrophages that overexpress indoleamine 2, 3-dioxygenase

The activity of indoleamine 2, 3-dioxygenase (IDO; E.C. 1.13.11.42) catalyzes the oxidative cleavage of tryptophan to form kynurenine. IDO activity consumes superoxide anions; therefore, we postulated that over-expression of IDO might mitigate superoxide-anion dependent, oxidative modification of cellular proteins in vitro. We prepared and characterized RAW 264.7 macrophages that were stably transfected with either an IDO expression vector or the control (empty) vector. We detected IDO mRNA, protein, and enzyme activity in the IDO-transfected macrophages, but not in the macrophages transfected with the empty vector. To generate superoxide anions in situ, we treated the IDO-and control-transfected cultures with xanthine or hypoxanthine, and then used ELISA methods to quantitate the relative levels of oxidatively modified proteins in total cell lysates. The levels of protein carbonyls were similar in IDO-transfected and vector-transfected macrophages; however, protein nitration was significantly less in IDO-transfected cells compared to control transfectants. In addition, steady-state levels of superoxide anions were significantly lower in the IDO-transfected cultures compared with control transfectants. Our results are consistent with the concept that, besides degrading tryptophan, IDO activity may protect cells from oxidative damage.     

Impacts of climate change on stream benthic diatoms—a nation-wide perspective of reference conditions

Hydrobiologia - Consequences of anthropogenic climate change directly affect freshwater ecosystems and their aquatic biological communities. Diatoms are amongst the most sensitive organisms to...     

Interplay between vitamin E and phosphorus availability in the control of longevity in Arabidopsis thaliana

Background and Aims Vitamin E helps to control the cellular redox state by reacting with singlet oxygen and preventing the propagation of lipid peroxidation in thylakoid membranes. Both plant ageing and phosphorus deficiency can trigger accumulation of reactive oxygen species, leading to damage to the photosynthetic apparatus. This study investigates how phosphorus availability and vitamin E interact in the control of plant longevity in the short-lived annual Arabidopsis thaliana.Methods The responses of tocopherol cyclase (VTE1)- and γ-tocopherol methyltransferase (VTE4)-null mutants to various levels of phosphorus availability was compared with that of wild-type plants. Longevity (time from germination to rosette death) and the time taken to pass through different developmental stages were determined, and measurements were taken of photosynthetic efficiency, pigment concentration, lipid peroxidation, vitamin E content and jasmonate content.Key Results The vte1 mutant showed accelerated senescence under control conditions, excess phosphorus and mild phosphorus deficiency, suggesting a delaying, protective effect of α-tocopherol during plant senescence. However, under severe phosphorus deficiency the lack of α-tocopherol paradoxically increased longevity in the vte1 mutant, while senescence was accelerated in wild-type plants. Reduced photoprotection in vitamin E-deficient mutants led to increased levels of defence chemicals (as indicated by jasmonate levels) under severe phosphorus starvation in the vte4 mutant and under excess phosphorus and mild phosphorus starvation in the vte1 mutant, indicating a trade-off between the capacity for photoprotection and the activation of chemical defences (jasmonate accumulation).Conclusions Vitamin E increases plant longevity under control conditions and mild phosphorus starvation, but accelerates senescence under severe phosphorus limitation. Complex interactions are revealed between phosphorus availability, vitamin E and the potential to synthesize jasmonates, suggesting a trade-off between photoprotection and the activation of chemical defences in the plants.     

The peculiar heme pocket of the 2/2 hemoglobin of cold-adapted Pseudoalteromonas haloplanktis TAC125

The genome of the cold-adapted bacterium Pseudoalteromonas haloplanktis TAC125 contains multiple genes encoding three distinct monomeric hemoglobins exhibiting a 2/2 ??-helical fold. In the present work, one of these hemoglobins is studied by resonance Raman, electronic absorption and electronic paramagnetic resonance spectroscopies, kinetic measurements, and different bioinformatic approaches. It is the first cold-adapted bacterial hemoglobin to be characterized. The results indicate that this protein belongs to the 2/2 hemoglobin family, Group II, characterized by the presence of a tryptophanyl residue on the bottom of the heme distal pocket in position G8 and two tyrosyl residues (TyrCD1 and TyrB10). However, unlike other bacterial hemoglobins, the ferric state, in addition to the aquo hexacoordinated high-spin form, shows multiple hexacoordinated low-spin forms, where either TyrCD1 or TyrB10 can likely coordinate the iron. This is the first example in which both TyrCD1 and TyrB10 are proposed to be the residues that are alternatively involved in heme hexacoordination by endogenous ligands.     

Tree age influences on the development of edible ectomycorrhizal fungi sporocarps in Pinus sylvestris stands

The study of factors influencing the production and development of wild edible mushroom sporocarps is extremely important in the characterization of the fungi life cycle. The main objective of this work is to determine how tree age influences the speed of sporocarp growth of edible ectomycorrhizal fungi Boletus edulis and Lactarius deliciosus in a Pinus sylvestris stand. This study is based on information recorded on a weekly basis every autumn between 1995 and 2008 in a set of permanent plots in Spain. Sporocarps are collected weekly, and as a result, specimens may not have reached their maximum size. The study area is a monospecific P. sylvestris stand. Three age classes were considered: under 30 years, between 31 and 70 years, and over 70 years. Sporocarps of B. edulis and L. deliciosus grow faster in the first age class stands than in the other two, and in the second age class stands, sporocarps are more than 50% smaller. The average weight of the picked B. edulis sporocarps clearly varies in the three age classes considered, with its maximum in the first age class (127 g and 6.8 cm cap diameter), minimum in the second age class (68 g and 4.7 cm cap diameter), and showing a relative maximum in the third (79 g and 4.3 cm cap diameter). L. deliciosus sporocarps are on average larger in the first age class (48 g and 7.4 cm cap diameter), decreasing in the second (20 g and 5.8 cm cap diameter) and also in the third (21 g and 5.3 cm cap diameter). The results show the influence of tree age in speed of sporocarp growth for the two ectomycorrhizal species.     

Assessment of regional and local biodiversity in tropical and subtropical coastal habitats in the East African Marine Ecoregion

The transboundary networks of Marine Protected Areas (MPAs) project, TRANSMAP, assessed local turnover and regional biodiversity across the East African Marine Ecoregion, where inter-governmental co-operation has been working to connect local MPAs. The benthic fauna in the three most dominant habitats on this coastline??beaches, mangroves and seagrasses??were studied in two Regions (Northern Region, 10?C13°S; Southern Region, 25?C28°S). Meiofaunal taxa were used as the model faunal group owing to their diversity and abundance across habitat types and environmental conditions. Meiofaunal abundance averaged 2,500 individuals 10 cm^?2 and was generally higher in mangrove and seagrass sediments than on the beaches, and was significantly different between habitats × Regions. In total, 18 taxa were recorded with highest diversity in the beach samples. Diversity indices and assemblage structure were significantly different between habitats, but also Regions. Specific granulometric 1?? size classes, shore-height and number of rain days were the factors most significantly correlating with the observed assemblage patterns. Additionally, the size of a MPA and latitude (which correlated with MPA age, but not number of rain days), were the factors fitting best with meiofaunal assemblage patterns across the beaches, the habitat for which the most comprehensive data were generated. Sample diversity was higher in the Southern Region, and although within- and across-habitats diversity were similar across the Regions, the two Regions appeared to provide complementary habitats and supported different assemblages. Within the Regions, beaches (the only habitat for which more than one location was sampled) were significantly different between Locations, supporting the establishment of multiple protected locations of the same habitat within each transboundary MPA.