Mount Cameroon - ein natürliches Freilandlabor zur systematischen Analyse des Einflusses von Zeit, Niederschlag und Temperatur auf die Pedogenese aus vulkanischen Gesteinen

Die Genese von Böden aus vulkanischen Gesteinen ist nicht nur wegen der spezifischen chemischen und mineralogischen Prozesse besonders interessant; mit Blick darauf, dass diese Böden oft außerordentlich hohe Gehalte an organischem Kohlenstoff (Corg) enthalten, ist sie auch hochrelevant. Die hier vorgestellte Studie zielt auf eine quantitative Analyse des Einflusses der Faktoren Zeit (t), mittlerer Jahresniederschlag (MAP) und Jahresmitteltemperatur (MAT) auf die Pedogenese aus basaltischen Pyroklastika unter feucht-tropischen Bedingungen ab. Mount Cameroon bietet optimale Voraussetzungen dazu, den Einfluss dieser Faktoren auf die Pedogenese unabhängig voneinander zu quantifizieren. Der Einfluss des Faktors t wird an Bodenbildungsstadien auf Basaltströmen unterschiedlichen Alters quantifiziert, vom jüngsten Basaltstrom aus dem Jahr 2000 bis zu einige Tausend Jahre alten Basaltströmen. Der Einfluss des Faktors MAP wird entlang eines MAP-Gradienten von >9000 mm a-1 im Westen (an der Küste) bis 2000 mm a-1 im Osten erfasst, der des Faktors MAT entlang des vertikalen MAT-Gradienten von 26-29 °C am Fuß des Mount Cameroon bis 0 °C auf dem Gipfel in 4095 m ü. NN. Die Pedogenese führt überwiegend zu Silandic Andosols, die sich später zu Nitisols weiterentwickeln. Erste Daten von Böden mit bekannter Faktorenkombination geben Hinweise darauf, wie schnell mit zunehmendem Bodenalter die Fed/Fet-Verhältnisse, die Gehalte an Ton und Corg sowie Sio, Alo und Feo zunehmen. Gesamt- und Tonmineralanalysen stützen die Interpretation dieser Daten im Hinblick auf die Bildung von short-range order minerals. Die Röntgendiffraktogramme zeigen jedoch auch erhebliche Gehalte an Magnetit und Gibbsit an, sodass bei der Interpretation der Feo- und Alo-Werte Vorsicht geboten ist. Die Abnahme der molaren (Ca+Mg+K+Na)/Al- und Si/Al-Verhältnisse aufgrund fortschreitender Verwitterung, Entbasung und Desilifizierung unter dem Einfluss des Faktors t wird ebenso quantifiziert. Diese Indices werden zusätzlich durch die Faktoren MAP und MAT beeinflusst. Mit fortschreitendem Bodenalter sind zudem zunehmende Quarzgehalte in den Böden zu beobachten. Da das Ausgangsgestein quarzfrei ist, ist dies ein Hinweis auf Eintrag von Saharastaub, der für Böden des Mount Cameroon in der Literatur bereits beschrieben wurde. Sowohl die Magnetit- und Gibbsitgehalte als auch der Staubeintrag sind daher bei der Beurteilung der Indices im Hinblick auf fortschreitende Bodenentwicklung zu berücksichtigen

The mobilization and transport of newly fixed carbon are driven by plant water use in an experimental rainforest under drought.

Non-structural carbohydrates (NSCs) are building blocks for biomass and fuel metabolic processes. However, it remains unclear how tropical forests mobilize, export, and transport NSCs to cope with extreme droughts. We combined drought manipulation and ecosystem 13CO2 pulse-labeling in an enclosed rainforest at Biosphere 2, assessed changes in NSCs, and traced newly assimilated carbohydrates in plant species with diverse hydraulic traits and canopy positions. We show that drought caused a depletion of leaf starch reserves and slowed export and transport of newly assimilated carbohydrates below ground. Drought effects were more pronounced in conservative canopy trees with limited supply of new photosynthates and relatively constant water status than in those with continual photosynthetic supply and deteriorated water status. We provide experimental evidence that local utilization, export, and transport of newly assimilated carbon are closely coupled with plant water use in canopy trees. We highlight that these processes are critical for understanding and predicting tree resistance and ecosystem fluxes in tropical forest under drought

Past, present, and future geo-biosphere interactions on the Tibetan Plateau and implications for permafrost

This manuscript resulted from a Workshop in 2019 at the Senckenberg Research Institute and Natural History Museum Frankfurt, Germany, supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA20100300). J. Liu also thanks the support of the Henan Provincial Key Laboratory of Hydrosphere and Watershed Water Security. T. Ehlers thanks the California Institute of Technology Moore Distinguished Scholar Program for support in completing this manuscript during a sabbatical. J. Liu and T. Bolch thank the support from the Strategic Priority Research Program of the Chinese Academy of Sciences (grants no. XDA20060402, XDA20100300). We thank the German Science Foundation (DFG) for support of the TiP (Tibetan Plateau: Formation-Climate-Ecoystems) priority research program (SPP-1372) for initiating the collaborations that led to this manuscript.Interactions between the atmosphere, biosphere, cryosphere, hydrosphere, and geosphere are most active in the critical zone, a region extending from the tops of trees to the top of unweathered bedrock. Changes in one or more of these spheres can result in a cascade of changes throughout the system in ways that are often poorly understood. Here we investigate how past and present climate change have impacted permafrost, hydrology, and ecosystems on the Tibetan Plateau. We do this by compiling existing climate, hydrologic, cryosphere, biosphere, and geologic studies documenting change over decadal to glacial-interglacial timescales and longer. Our emphasis is on showing present-day trends in environmental change and how plateau ecosystems have largely flourished under warmer and wetter periods in the geologic past. We identify two future pathways that could lead to either a favorable greening or unfavorable degradation and desiccation of plateau ecosystems. Both paths are plausible given the available evidence. We contend that the key to which pathway future generations experience lies in what, if any, human intervention measures are implemented. We conclude with suggested management strategies that can be implemented to facilitate a future greening of the Tibetan Plateau.Publisher PDFPeer reviewe

Initial Steps of Thermal Decomposition of Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate Crystals from Quantum Mechanics

Dihydroxylammonium 5,5?-bistetrazole-1,1?-diolate (TKX-50) is a recently synthesized energetic material (EM) with most promising performance, including high energy content, high density, low sensitivity, and low toxicity. TKX-50 forms an ionic crystal in which the unit cell contains two bistetrazole dianions {c-((NO)N3C)-[c-(CN3(NO)], formal charge of ?2} and four hydroxylammonium (NH3OH)+ cations (formal charge of +1). We report here quantum mechanics (QM)-based reaction studies to determine the atomistic reaction mechanisms for the initial decompositions of this system. First we carried out molecular dynamics simulations on the periodic TKX-50 crystal using forces from density functional based tight binding calculations (DFTB-MD), which finds that the chemistry is initiated by proton transfer from the cation to the dianion. Continuous heating of this periodic system leads eventually to dissociation of the protonated or diprotonated bistetrazole to release N2 and N2O. To refine the mechanisms observed in the periodic DFTB-MD, we carried out finite cluster quantum mechanics studies (B3LYP) for the unimolecular decomposition of the bistetrazole. We find that for the bistetrazole dianion, the reaction barrier for release of N2 is 45.1 kcal/mol, while release of N2O is 72.2 kcal/mol. However, transferring one proton to the bistetrazole dianion decreases the reaction barriers to 37.2 kcal/mol for N2 release and 59.5 kcal/mol for N2O release. Thus, we predict that the initial decompositions in TKX-50 lead to N2 release, which in turn provides the energy to drive further decompositions. On the basis of this mechanism, we suggest changes to make the system less sensitive while retaining the large energy release. This may help improve the synthesis strategy of developing high nitrogen explosives with further improved performance

Foodborne norovirus outbreak: the role of an asymptomatic food handler

Background: In July 2005 an outbreak of acute gastroenteritis occurred on a residential summer camp in the province of Barcelona (northeast of Spain). Forty-four people were affected among residents and employees. All of them had in common a meal at lunch time on 13 July (paella, round of beef and fruit). The aim of this study was to investigate a foodborne norovirus outbreak that occurred in the residential summer camp and in which the implication of a food handler was demonstrated by laboratory tests. Methods: A retrospective cohort study was designed. Personal or telephone interview was carried out to collect demographic, clinical and microbiological data of the exposed people, as well as food consumption in the suspected lunch. Food handlers of the mentioned summer camp were interviewed. Ten stool samples were requested from symptomatic exposed residents and the three food handlers that prepared the suspected food. Stools were tested for bacteries and noroviruses. Norovirus was detected using RT-PCR and sequence analysis. Attack rate, relative risks (RR) and its 95% confidence intervals (CI) were calculated to assess the association between food consumption and disease. Results: The global attack rate of the outbreak was 55%. The main symptoms were abdominal pain (90%), nausea (85%), vomiting (70%) and diarrhoea (42.5%). The disease remitted in 24-48 hours. Norovirus was detected in seven faecal samples, one of them was from an asymptomatic food handler who had not eaten the suspected food (round of beef), but cooked and served the lunch. Analysis of the two suspected foods isolated no pathogenic bacteria and detected no viruses. Molecular analysis showed that the viral strain was the same in ill patients and in the asymptomatic food handler (genotype GII.2 Melksham-like). Conclusions: In outbreaks of foodborne disease, the search for viruses in affected patients and all food handlers, even in those that are asymptomatic, is essential. Health education of food handlers with respect to hand washing should be promoted

Receptor Sorting within Endosomal Trafficking Pathway Is Facilitated by Dynamic Actin Filaments

Early endosomes (EEs) are known to be a sorting station for internalized molecules destined for degradation, recycling, or other intracellular organelles. Segregation is an essential step in such sorting, but the molecular mechanism of this process remains to be elucidated. Here, we show that actin is required for efficient recycling and endosomal maturation by producing a motile force. Perturbation of actin dynamics by drugs induced a few enlarged EEs containing several degradative vacuoles and also interfered with their transporting ability. Actin repolymerization induced by washout of the drug caused the vacuoles to dissociate and individually translocate toward the perinuclear region. We further elucidated that cortactin, an actin-nucleating factor, was required for transporting contents from within EEs. Actin filaments regulated by cortactin may provide a motile force for efficient sorting within early endosomes. These data suggest that actin filaments coordinate with microtubules to mediate segregation in EEs

Connected parents: combining online and off-line parenthood in vlogs and blogs

This article explores evaluative discourse in a corpus sample of parents' vlogs (video blogs) and blogs (henceforth v/ blogs) dealing with family tasks and responsibilities, as a reflection of underlying values concerning parenthood. It pays special attention to the important role played by the expression of attitude, understood as "ways of feeling" and including the meanings of affect, judgement and appreciation, together with positive politeness in the social practices of the discursive construction of online and off-line parenthood. Analysis and description of the data show two main patterns in parents' practices, either aiming at perfection through juggling and multi-tasking or building resistance to the demands of families and society. Results show that parents frequently exploit the system of affect for building positive face and rapport, while indirectly expressing judgement of social esteem and social sanction, which construct their identities as mothers and fathers and those of the members of their communities of practice. The corpus for the study consists of a random sample of 400 evaluative units in posts and comments on v/ blogs dealing with family tasks and responsibilities (200 in English and 200 in Spanish, with half the sample being drawn from fathers' and the other half from mothers' v/ blogs). I will approach the analysis of the data from appraisal (Martin and White 2005, Bednarek 2008) and politeness theory (Brown and Levinson 1987) in order to explore the features of evaluative discourse and the management of face. The methodology for processing the data borrows quantitative techniques from Corpus Linguistics, including the coding and statistical treatment of the sample with UAM Corpus Tools (O'Donnell 2011), together with Pragmatics and Discourse Analysis (DA), as done in some previous research (Santamaría-García 2011, 2014).Project "EMO-FUNDETT: EMOtion and language at work", I+D FFI2013-47792-C2-1-P, sponsored by the Spanish Ministry of Science and Innovatio

Curvature of Double-Membrane Organelles Generated by Changes in Membrane Size and Composition

Transient double-membrane organelles are key players in cellular processes such as autophagy, reproduction, and viral infection. These organelles are formed by the bending and closure of flat, double-membrane sheets. Proteins are believed to be important in these morphological transitions but the underlying mechanism of curvature generation is poorly understood. Here, we describe a novel mechanism for this curvature generation which depends primarily on three membrane properties: the lateral size of the double-membrane sheets, the molecular composition of their highly curved rims, and a possible asymmetry between the two flat faces of the sheets. This mechanism is evolutionary advantageous since it does not require active processes and is readily available even when resources within the cell are restricted as during starvation, which can induce autophagy and sporulation. We identify pathways for protein-assisted regulation of curvature generation, organelle size, direction of bending, and morphology. Our theory also provides a mechanism for the stabilization of large double-membrane sheet-like structures found in the endoplasmic reticulum and in the Golgi cisternae

Isolation and Characterization of Intestinal Epithelial Cells from Normal and SIV-Infected Rhesus Macaques

Impairment of intestinal epithelial barriers contributes to the progression of HIV/SIV infection and leads to generalized HIV-induced immune-cell activation during chronic infection. Rhesus macaques are the major animal model for studying HIV pathogenesis. However, detailed characterization of isolated rhesus epithelial cells (ECs) from intestinal tissues is not well defined. It is also not well documented whether isolated ECs had any other cell contaminants from intestinal tissues during the time of processing that might hamper interpretation of EC preparations or cultures. In this study, we identify and characterize ECs based on flow cytometry and immunohistochemistry methods using various enzymatic and mechanical isolation techniques to enrich ECs from intestinal tissues. This study shows that normal healthy ECs differentially express HLA-DR, CD23, CD27, CD90, CD95 and IL-10R markers. Early apoptosis and upregulation of ICAM-1 and HLA-DR in intestinal ECs are thought to be the key features in SIV mediated enteropathy. The data suggest that intestinal ECs might be playing an important role in mucosal immune responses by regulating the expression of different important regulatory and adhesion molecules and their function