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

Auswirkung von Weidedegradation auf die Zusammensetzung und Funktion mikrobieller Gemeinschaften in Böden des Tibetischen Plateaus

Das Tibetische Plateau, mit seinen Kobresia pygmea Weiden, stellt eine globale Senke für organischen Kohlenstoff (OC) dar. Überweidung führt zur Zerstörung der Kobresia Wurzelmatten und damit zur Graslanddegradation. Dies hat massive OC Verluste und die Destabilisierung des Ökosystems zur Folge. Diese Arbeit analysiert den Effekt der degradationsbedingten veränderten Zusammensetzung der organischen Bodensubstanz (SOM) auf die Zusammensetzung der mikrobiellen Gemeinschaft und deren Funktion entlang einer Sequenz von sechs Degradationsstufen. Dazu wurden die Aktivitäten von sechs extrazellulären Enzyme gemessen sowie die Zusammensetzung der bakteriellen und pilzlichen Gemeinschaft (mittels t-RFLP Analyse gefolgt von Illumina MiSeq Sequenzierung) analysiert. So konnte die Zusammensetzung der mikrobiellen Gemeinschaft mit den vertikalen Gradienten der δ13C und δ15N-Werte, sowie den Neutralzucker-, Cutin-, Suberin- und Ligningehalten in Beziehung gesetzt werden. Mit zunehmender Degradation deuten negativere δ13C-Werte auf eine relative Anreicherung an 13C-armen Makromolekülen wie bspw. Lignin hin. Zusammen mit ebenfalls verringerten δ15N-Werten und veränderten C/N-Verhältnissen belegt dies einen verstärkten SOM-Abbau. Gleichzeitig nimmt die Aktivität von hydrolytischen Enzymen, mit fortschreitender Degradation zu. Lediglich in der letzten Degradationsstufe ist ein drastischer Rückgang der Aktivität dieser Enzymgruppe zu beobachten. Im Gegensatz dazu zeigen Phenoloxidasen (Mineralisation komplexer SOM) zunehmende Aktivitäten mit steigender Degradation die mit einer Anreicherung dieser Substrate (z.B. Ligin) einhergeht. Die beobachteten Änderungen der Enzymaktivitäten sind mit einer veränderten Zusammensetzung der mikrobiellen Gemeinschaft, besonders des Unterbodens, begleitet. So nehmen Actinobacteria mit der Degradation ab während Nitrosomonas zunehmenden, was einen steigenden Verlust von mineralisiertem N aus dem Boden erklärt. Bis jetzt ist unklar ob die degradationsbedingten funktionellen und strukturellen Veränderungen der mikrobiellen Gemeinschaft der Kobresia Grasländer reversibel sind, oder ob mit steigendem Verlust an Nährstoffen und Boden ein Punkt erreicht wird, der eine Erholung der Kobresia-Matten nicht mehr erlaubt

Mesenchymal stem cells and myoblast differentiation under HGF and IGF-1 stimulation for 3D skeletal muscle tissue engineering

Background Volumetric muscle loss caused by trauma or after tumour surgery exceeds the natural regeneration capacity of skeletal muscle. Hence, the future goal of tissue engineering (TE) is the replacement and repair of lost muscle tissue by newly generating skeletal muscle combining different cell sources, such as myoblasts and mesenchymal stem cells (MSCs), within a three-dimensional matrix. Latest research showed that seeding skeletal muscle cells on aligned constructs enhance the formation of myotubes as well as cell alignment and may provide a further step towards the clinical application of engineered skeletal muscle. In this study the myogenic differentiation potential of MSCs upon co-cultivation with myoblasts and under stimulation with hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) was evaluated. We further analysed the behaviour of MSC-myoblast co-cultures in different 3D matrices. Results Primary rat myoblasts and rat MSCs were mono- and co-cultivated for 2, 7 or 14 days. The effect of different concentrations of HGF and IGF-1 alone, as well as in combination, on myogenic differentiation was analysed using microscopy, multicolour flow cytometry and real-time PCR. Furthermore, the influence of different three-dimensional culture models, such as fibrin, fibrin-collagen-I gels and parallel aligned electrospun poly-ε-caprolacton collagen-I nanofibers, on myogenic differentiation was analysed. MSCs could be successfully differentiated into the myogenic lineage both in mono- and in co-cultures independent of HGF and IGF-1 stimulation by expressing desmin, myocyte enhancer factor 2, myosin heavy chain 2 and alpha-sarcomeric actinin. An increased expression of different myogenic key markers could be observed under HGF and IGF-1 stimulation. Even though, stimulation with HGF/IGF-1 does not seem essential for sufficient myogenic differentiation. Three-dimensional cultivation in fibrin-collagen-I gels induced higher levels of myogenic differentiation compared with two-dimensional experiments. Cultivation on poly-ε-caprolacton-collagen-I nanofibers induced parallel alignment of cells and positive expression of desmin. Conclusions In this study, we were able to myogenically differentiate MSC upon mono- and co-cultivation with myoblasts. The addition of HGF/IGF-1 might not be essential for achieving successful myogenic differentiation. Furthermore, with the development of a biocompatible nanofiber scaffold we established the basis for further experiments aiming at the generation of functional muscle tissue

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

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

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

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

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