63 research outputs found

    High‐resolution InSAR reveals localised pre‐eruptive deformation inside the crater of Agung volcano, Indonesia.

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    During a volcanic crisis, high-rate, localized deformation can indicate magma close to the surface, with important implications for eruption forecasting. However, only a few such examples have been reported, because frequent, dense monitoring is needed. High-resolution Synthetic Aperture Radar (SAR) is capable of achieving 15 cm of line-of-sight shortening occurred over a 400-by-400 m area on the crater floor in September-October 2017, accompanying a deep seismic swarm and flank dyke intrusion. We attribute the deformation to the pressurization of a shallow (<200 m deep) hydrothermal system by the injection of magmatic gases and fluids. We also observe a second pulse of intra-crater deformation of 3–5 cm within 4 days to 11 hr prior to the first phreatomagmatic eruption, which is consistent with interaction between the hydrothermal system and the ascending magma. This phreatomagmatic eruption created the central pathway used during the final stages of magma ascent. Our observations have important implications for understanding unrest and eruption forecasting, and demonstrate the potential of monitoring with high-resolution SAR

    Modified cantilever arrays improve sensitivity and reproducibility of nanomechanical sensing in living cells

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    Mechanical signaling involved in molecular interactions lies at the heart of materials science and biological systems, but the mechanisms involved are poorly understood. Here we use nanomechanical sensors and intact human cells to provide unique insights into the signaling pathways of connectivity networks, which deliver the ability to probe cells to produce biologically relevant, quantifiable and reproducible signals. We quantify the mechanical signals from malignant cancer cells, with 10 cells per ml in 1000-fold excess of non-neoplastic human epithelial cells. Moreover, we demonstrate that a direct link between cells and molecules creates a continuous connectivity which acts like a percolating network to propagate mechanical forces over both short and long length-scales. The findings provide mechanistic insights into how cancer cells interact with one another and with their microenvironments, enabling them to invade the surrounding tissues. Further, with this system it is possible to understand how cancer clusters are able to co-ordinate their migration through narrow blood capillaries

    Human-Specific Evolution and Adaptation Led to Major Qualitative Differences in the Variable Receptors of Human and Chimpanzee Natural Killer Cells

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    Natural killer (NK) cells serve essential functions in immunity and reproduction. Diversifying these functions within individuals and populations are rapidly-evolving interactions between highly polymorphic major histocompatibility complex (MHC) class I ligands and variable NK cell receptors. Specific to simian primates is the family of Killer cell Immunoglobulin-like Receptors (KIR), which recognize MHC class I and associate with a range of human diseases. Because KIR have considerable species-specificity and are lacking from common animal models, we performed extensive comparison of the systems of KIR and MHC class I interaction in humans and chimpanzees. Although of similar complexity, they differ in genomic organization, gene content, and diversification mechanisms, mainly because of human-specific specialization in the KIR that recognizes the C1 and C2 epitopes of MHC-B and -C. Humans uniquely focused KIR recognition on MHC-C, while losing C1-bearing MHC-B. Reversing this trend, C1-bearing HLA-B46 was recently driven to unprecedented high frequency in Southeast Asia. Chimpanzees have a variety of ancient, avid, and predominantly inhibitory receptors, whereas human receptors are fewer, recently evolved, and combine avid inhibitory receptors with attenuated activating receptors. These differences accompany human-specific evolution of the A and B haplotypes that are under balancing selection and differentially function in defense and reproduction. Our study shows how the qualitative differences that distinguish the human and chimpanzee systems of KIR and MHC class I predominantly derive from adaptations on the human line in response to selective pressures placed on human NK cells by the competing needs of defense and reproduction

    Cryo Electron Tomography of Herpes Simplex Virus during Axonal Transport and Secondary Envelopment in Primary Neurons

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    During herpes simplex virus 1 (HSV1) egress in neurons, viral particles travel from the neuronal cell body along the axon towards the synapse. Whether HSV1 particles are transported as enveloped virions as proposed by the ‘married’ model or as non-enveloped capsids suggested by the ‘separate’ model is controversial. Specific viral proteins may form a recruitment platform for microtubule motors that catalyze such transport. However, their subviral location has remained elusive. Here we established a system to analyze herpesvirus egress by cryo electron tomography. At 16 h post infection, we observed intra-axonal transport of progeny HSV1 viral particles in dissociated hippocampal neurons by live-cell fluorescence microscopy. Cryo electron tomography of frozen-hydrated neurons revealed that most egressing capsids were transported independently of the viral envelope. Unexpectedly, we found not only DNA-containing capsids (cytosolic C-capsids), but also capsids lacking DNA (cytosolic A-/B-capsids) in mid-axon regions. Subvolume averaging revealed lower amounts of tegument on cytosolic A-/B-capsids than on C-capsids. Nevertheless, all capsid types underwent active axonal transport. Therefore, even few tegument proteins on the capsid vertices seemed to suffice for transport. Secondary envelopment of capsids was observed at axon terminals. On their luminal face, the enveloping vesicles were studded with typical glycoprotein-like spikes. Furthermore, we noted an accretion of tegument density at the concave cytosolic face of the vesicle membrane in close proximity to the capsids. Three-dimensional analysis revealed that these assembly sites lacked cytoskeletal elements, but that filamentous actin surrounded them and formed an assembly compartment. Our data support the ‘separate model’ for HSV1 egress, i.e. progeny herpes viruses being transported along axons as subassemblies and not as complete virions within transport vesicles

    Ovarian cancer molecular pathology.

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    Potential biological role of poly (ADP-ribose) polymerase (PARP) in male gametes

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    Maintaining the integrity of sperm DNA is vital to reproduction and male fertility. Sperm contain a number of molecules and pathways for the repair of base excision, base mismatches and DNA strand breaks. The presence of Poly (ADP-ribose) polymerase (PARP), a DNA repair enzyme, and its homologues has recently been shown in male germ cells, specifically during stage VII of spermatogenesis. High PARP expression has been reported in mature spermatozoa and in proven fertile men. Whenever there are strand breaks in sperm DNA due to oxidative stress, chromatin remodeling or cell death, PARP is activated. However, the cleavage of PARP by caspase-3 inactivates it and inhibits PARP's DNA-repairing abilities. Therefore, cleaved PARP (cPARP) may be considered a marker of apoptosis. The presence of higher levels of cPARP in sperm of infertile men adds a new proof for the correlation between apoptosis and male infertility. This review describes the possible biological significance of PARP in mammalian cells with the focus on male reproduction. The review elaborates on the role played by PARP during spermatogenesis, sperm maturation in ejaculated spermatozoa and the potential role of PARP as new marker of sperm damage. PARP could provide new strategies to preserve fertility in cancer patients subjected to genotoxic stresses and may be a key to better male reproductive health

    Controls on explosive-effusive volcanic eruption styles

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    One of the biggest challenges in volcanic hazard assessment is to understand how and why eruptive style changes within the same eruptive period or even from one eruption to the next at a given volcano. This review evaluates the competing processes that lead to explosive and effusive eruptions of silicic magmas. Eruptive style depends on a set of feedbacks involving interrelated magmatic properties and processes. Foremost of these are magma viscosity, gas loss, and external properties such as conduit geometry. Ultimately, these parameters control the speed at which magmas ascend, decompress and outgas en route to the surface, and thus determine eruptive style and evolution

    Validierung des SOPESS-Sprachscreenings im Rahmen des ikidS-Projektes

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    Hintergrund: Eine frĂŒhe Diagnostik und Behandlung von Entwicklungsstörungen vor der Einschulung ist fĂŒr den weiteren Bildungserfolg maßgeblich. Deshalb wurde das SozialpĂ€diatrische Entwicklungsscreening fĂŒr Schuleingangsuntersuchungen (SOPESS) entwickelt und in mehreren BundeslĂ€ndern flĂ€chendeckend eingefĂŒhrt.Material und Methoden: Die ZusammenhĂ€nge zwischen den Ergebnissen des SOPESS-Sprachscreening vor der Einschulung und der schulischen Sprachkompetenzen am Ende der ersten Klasse wurden als Teil einer umfassenden Evaluation untersucht.Daten der rheinland-pfĂ€lzischen Schuleingangsuntersuchung sowie der prospektiven Kindergesundheitsstudie ikidS wurden zusammengefĂŒhrt und ausgewertet. ZusammenhĂ€nge zwischen dem GesamtfĂ€higkeitswert Sprache am Ende der ersten Klasse (subjektive LehrkrafteinschĂ€tzung, Intervall-skaliertes Merkmal, Range -4 bis +4) und dem SOPESS-Sprachscreening vor Einschulung (ordinal-skaliertes Merkmal, 6 Risikostufen) wurden mittels linearen Regressionsmodellen mit und ohne BerĂŒcksichtigung von weiteren soziodemografischen und medizinischen PrĂ€diktoren untersucht (z.B. Alter bei Einschulung, Geschlecht, Sozialstatus der Eltern, Migrationshintergrund, bereits bekannte SprachauffĂ€lligkeit, Entwicklungsverzögerung, Hörstörung).Ergebnisse: In die Auswertung konnten 1357 Kinder einbezogen werden (48% MĂ€dchen, Alter bei Schuleingangsuntersuchung 4,9-7,2 Jahre). Es zeigte sich ein klarer, stetiger Zusammenhang zwischen den Risikostufen des SOPESS-Sprachscreenings und den schulischen Sprachkompetenzen. Die mittleren Sprachkompetenzen nahmen mit Zunahme der SOPESS Risikostufe von 0,8 Punkten (SD=1,7) fĂŒr die Stufe 0 auf -3,2 Punkte (SD=0,9) fĂŒr die Stufe 6 ab.Diskussion: Es zeigte sich ein klarer und unabhĂ€ngiger Zusammenhang zwischen dem vorschulischen SOPESS-Sprachscreening und den schulischen Sprachkompetenzen am Ende der ersten Klasse. Dieses Sprachscreening könnte daher - insbesondere unter Einbezug von weiteren soziodemografischen und medizinischen PrĂ€diktoren - die Basis fĂŒr eine gezielte Auswahl von weiteren Versorgungs- und/oder Fördermaßnahmen sein
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