Soil organic carbon stocks in estuarine and marine mangrove ecosystems are driven by nutrient colimitation of P and N

Mangroves play an important role in carbon sequestration, but soil organic carbon (SOC) stocks differ between marine and estuarine mangroves, suggesting differing processes and drivers of SOC accumulation. Here, we compared undegraded and degraded marine and estuarine mangroves in a regional approach across the Indonesian archipelago for their SOC stocks and evaluated possible drivers imposed by nutrient limitations along the land‐to‐sea gradients. SOC stocks in natural marine mangroves (271–572 Mg ha^?1 m^?1) were much higher than under estuarine mangroves (100–315 Mg ha^?1 m^?1) with a further decrease caused by degradation to 80–132 Mg ha^?1 m^?1. Soils differed in C/N ratio (marine: 29–64; estuarine: 9–28), δ¹⁵N (marine: ?0.6 to 0.7‰; estuarine: 2.5 to 7.2‰), and plant‐available P (marine: 2.3–6.3 mg kg^?1; estuarine: 0.16–1.8 mg kg^?1). We found N and P supply of sea‐oriented mangroves primarily met by dominating symbiotic N₂ fixation from air and P import from sea, while mangroves on the landward gradient increasingly covered their demand in N and P from allochthonous sources and SOM recycling. Pioneer plants favored by degradation further increased nutrient recycling from soil resulting in smaller SOC stocks in the topsoil. These processes explained the differences in SOC stocks along the land‐to‐sea gradient in each mangrove type as well as the SOC stock differences observed between estuarine and marine mangrove ecosystems. This first large‐scale evaluation of drivers of SOC stocks under mangroves thus suggests a continuum in mangrove functioning across scales and ecotypes and additionally provides viable proxies for carbon stock estimations in PES or REDD schemes.     

S-100 B Concentrations Are a Predictor of Decreased Survival in Patients with Major Trauma,Independently of Head Injury

Background

Major trauma remains one of the principle causes of disability and death throughout the world. There is currently no satisfactory risk assessment to predict mortality in patients with major trauma. The aim of our study is to examine whether S-100 B protein concentrations correlate with injury severity and survival in patients with major trauma, with special emphasis on patients without head injury.

Methods

Our retrospective data analysis comprised adult patients admitted to our emergency department between 1.12. 2008 and 31.12 2010 with a suspected major trauma. S-100 B concentrations were routinely assessed in major trauma patients.

Results

A total of 27.7% (378) of all patients had major trauma. The median ISS was 24.6 (SD 8.4); 16.6% (63/378) of the patients died. S-100 B concentrations correlated overall with the ISS (p<0.0001). Patients who died had significantly higher S-100 B concentrations than survivors (8.2 μg/l versus 2.2 μg/l, p<0.0001). Polytraumatised patients with and without head trauma did not differ significantly with respect to S-100 B concentration (3.2 μg/l (SD 5.3) versus 2.9 μg/l (SD 3.8), respectively, p = 0.63) or with respect to Injury Severity Score (24.8 (SD 8.6) versus 24.2 (SD 8.1), respectively, p = 0.56). S-100 B concentrations correlated negatively with survival (p<0.0001) in all patients and in both subgroups (p = 0.001 and p = 0.006, respectively)

Conclusions

S-100 concentrations on admission correlate positively with greater injury severity and decreased survival in major trauma patients, independently of the presence of a head injury. S-100 B protein levels at admission in patients with major trauma may therefore be used to assess outcome in all polytraumatised patients. These measurements should be subject to further evaluation.     

Tumour necrosis factor activates the mitogen-activated protein kinases p38α and ERK in the synovial membrane in vivo

Tumour necrosis factor (TNF) is considered to be a major factor in chronic synovial inflammation and is an inducer of mitogen-activated protein kinase (MAPK) signalling. In the present study we investigated the ability of TNF to activate MAPKs in the synovial membrane in vivo. We studied human TNF transgenic mice – an in vivo model of TNF-induced arthritis – to examine phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun amino terminal kinase (JNK) and p38MAPKα in the inflamed joints by means of immunoblot and immunohistochemistry. In addition, the effects of systemic blockade of TNF, IL-1 and receptor activator of nuclear factor-κB (RANK) ligand on the activation of MAPKs were assessed. In vivo, overexpression of TNF induced activation of p38MAPKα and ERK in the synovial membrane, whereas activation of JNK was less pronounced and rarely observed on immunohistochemical analysis. Activated p38MAPKα was predominantly found in synovial macrophages, whereas ERK activation was present in both synovial macrophages and fibroblasts. T and B lymphocytes did not exhibit major activation of any of the three MAPKs. Systemic blockade of TNF reduced activation of p38MAPKα and ERK, whereas inhibition of IL-1 only affected p38MAPKα and blockade of RANK ligand did not result in any decrease in MAPK activation in the synovial membrane. These data indicate that TNF preferentially activates p38MAPKα and ERK in synovial membrane exposed to TNF. This not only suggests that targeted inhibition of p38MAPKα and ERK is a feasible strategy for blocking TNF-mediated effects on joints, but it also shows that even currently available methods to block TNF effectively reduce activation of these two MAPKs.     

Analysis of detergent-resistant membranes in Arabidopsis. Evidence for plasma membrane lipid rafts

The trafficking and function of cell surface proteins in eukaryotic cells may require association with detergent-resistant sphingolipid- and sterol-rich membrane domains. The aim of this work was to obtain evidence for lipid domain phenomena in plant membranes. A protocol to prepare Triton X-100 detergent-resistant membranes (DRMs) was developed using Arabidopsis (Arabidopsis thaliana) callus membranes. A comparative proteomics approach using two-dimensional difference gel electrophoresis and liquid chromatography-tandem mass spectrometry revealed that the DRMs were highly enriched in specific proteins. They included eight glycosylphosphatidylinositol-anchored proteins, several plasma membrane (PM) ATPases, multidrug resistance proteins, and proteins of the stomatin/prohibitin/hypersensitive response family, suggesting that the DRMs originated from PM domains. We also identified a plant homolog of flotillin, a major mammalian DRM protein, suggesting a conserved role for this protein in lipid domain phenomena in eukaryotic cells. Lipid analysis by gas chromatography-mass spectrometry showed that the DRMs had a 4-fold higher sterol-to-protein content than the average for Arabidopsis membranes. The DRMs were also 5-fold increased in sphingolipid-to-protein ratio. Our results indicate that the preparation of DRMs can yield a very specific set of membrane proteins and suggest that the PM contains phytosterol and sphingolipid-rich lipid domains with a specialized protein composition. Our results also suggest a conserved role of lipid modification in targeting proteins to both the intracellular and extracellular leaflet of these domains. The proteins associated with these domains provide important new experimental avenues into understanding plant cell polarity and cell surface processes.     

Basics of Multivariate Analysis in Neuroimaging Data

Multivariate analysis techniques for neuroimaging data have recently received increasing attention as they have many attractive features that cannot be easily realized by the more commonly used univariate, voxel-wise, techniques^1,5,6,7,8,9. Multivariate approaches evaluate correlation/covariance of activation across brain regions, rather than proceeding on a voxel-by-voxel basis. Thus, their results can be more easily interpreted as a signature of neural networks. Univariate approaches, on the other hand, cannot directly address interregional correlation in the brain. Multivariate approaches can also result in greater statistical power when compared with univariate techniques, which are forced to employ very stringent corrections for voxel-wise multiple comparisons. Further, multivariate techniques also lend themselves much better to prospective application of results from the analysis of one dataset to entirely new datasets. Multivariate techniques are thus well placed to provide information about mean differences and correlations with behavior, similarly to univariate approaches, with potentially greater statistical power and better reproducibility checks. In contrast to these advantages is the high barrier of entry to the use of multivariate approaches, preventing more widespread application in the community. To the neuroscientist becoming familiar with multivariate analysis techniques, an initial survey of the field might present a bewildering variety of approaches that, although algorithmically similar, are presented with different emphases, typically by people with mathematics backgrounds. We believe that multivariate analysis techniques have sufficient potential to warrant better dissemination. Researchers should be able to employ them in an informed and accessible manner. The current article is an attempt at a didactic introduction of multivariate techniques for the novice. A conceptual introduction is followed with a very simple application to a diagnostic data set from the Alzheimer s Disease Neuroimaging Initiative (ADNI), clearly demonstrating the superior performance of the multivariate approach.     

A study on the effects of some laboratory-derived genetic mutations on biofilm formation by Listeria monocytogenes

Biofilms formed by the human pathogen Listeria monocytogenes in food-processing environments can be a potential source of contamination. In this study, we investigated the ability of L. monocytogenes wild type and its laboratory-derived isogenic mutants in cwhA, prfA, agrA, flaA, degU, ami and sigB to adhere to and form biofilms on abiotic surfaces. The results suggest that inactivation of the two component regulatory system degU completely abolished biofilm formation, while inactivation of the flagellar gene flaA, two component response regulator agrA and the autolysin-adhesin gene ami lead to severe impairment of initial attachment and the subsequent development of a mature biofilm by L. monocytogenes. Mutants in the global regulator of virulence prfA and the alternative sigma factor sigB were unaffected and formed biofilms similar to wild type L. monocytogenes.     

Dependence of fluorescence behaviour and other photosystem-II characteristics on the nature of the nitrogen source for the filamentous cyanobacterium Oscillatoria chalybea

The filamentous cyanobacterium Oscillatoria chalybea grows phototrophically on a mineral medium in the presence of either nitrate or ammonium ions as nitrogen source at similar growth rates. In the absence of any combined nitrogen source in the medium the cyanobacterium also grows, although at a reduced growth rate. The steady state rate of oxygen evolution by filaments from these three culture conditions is approximately constant if compared on an equal chlorophyll basis. Qualitative differences, however, emerge, if transient phenomena, e.g. the oxygen gush, are investigated. Only nitrate-and nitrogen-free-grown cultures show an oxygen gush, whereas ammonium sulfate-grown cultures do not show this phenomenon. Fluorescence induction in O. chalybea shows a fast monophasic rise, comparable to the fluorescence rise curves of higher plant chloroplasts in the presence of dithionite. The steady state level of fluorescence in ammonium sulfate-grown cells is up to seven times higher than in nitrate-grown cells when compared on an equal chlorophyll basis. In ammonium sulfate-grown cells, DCMU (N,N-3,4-Dichlorophenyl dimethylurea) causes a further increase in fluorescence level. In nitrate-grown cyanobacteria, however, the effect of DCMU consists of a decrease of the steady state level of fluorescence. In context with earlier research on Anabaena cylindrica, another filamentous cyanobacterium, it appears that the type of the nitrogen source used for growth determines the main location of the DCMU-block in this organism. It thus appears that in O. chalybea the site of DCMU inhibition lies on the oxygen-evolving side of photosystem II, if the organism is grown on nitrate. If grown on ammonium sulfate, no substantial difference of the location of the inhibition site when compared to algae or higher plant chloroplasts is found.Thylakoid preparations of O. chalybea perform the usual Hill reactions with ferricyanide, p-benzoquinone or silicomolybdate as electron acceptors. In each case it is seen that with thylakoids of nitrate-grown cells the steady-state level of fluorescence is lowered by DCMU in the presence of these acceptors, which should be the case, if DCMU inhibits electron transfer on the donor side of photosystem II. According to the literature silicomolybdate accepts electrons mainly before the DCMU-block in higher plant chloroplasts. Hence, in higher plants this reaction is mainly DCMU-insensitive. In thylakoids of O. chalybea, however, the Hill reaction with silicomolybdate is DCMU-sensitive which provides further evidence that the DCMU-block is on the oxygen-evolving side of photosystem II in O. chalybea provided the cells have been grown on nitrate.Abbreviations DCMU N-N-3,4-Dichlorophenyl dimethylurea     

Localization of NADPH-protochlorophyllide reductase in plastids of barley at different greening stages

The localization of protochorophyllide (Pchlide) and of NADPH-protochlorophyllide oxidoreductase (POR, EC 1.6.99.1) within (etio)chloroplasts has been investigated at selected stages of greening of barley seedlings. Pchlide pigment and POR protein contents were evaluated in different plastid membrane fractions by fluorescence spectroscopy and immunoblot analysis using a monospecific polyclonal antibody raised against the purified enzyme. Fluorescence analysis showed the presence of Pchlide in both the envelope and thylakoid membranes. During greening, the Pchlide content, expressed on a total protein basis, decreased in thylakoid membranes, whereas it increased in the envelope membranes. POR proteins were detected mainly in thylakoid membranes at early greening stages. In contrast, the weak amount of POR proteins was associated more specifically with envelope membranes of mature chloroplasts. Whatever the greening stage, thylakoid-bound Pchlide and POR proteins were more abundant in the thylakoid regions which remained unsolubilized after mild Triton treatment used as standard procedure to prepare PS II particles. This suggests the preferential association of Pchlide and POR to the appressed regions of thylakoids. This revised version was published online in June 2006 with corrections to the Cover Date.