The petrology of a hazardous volcano: Calbuco (Central Southern VolcanicZone, Chile)

peer reviewedThe recurrent explosive eruptions of Calbuco (Andean Southern Volcanic Zone (SVZ)) threat a rapidly expanding tour- istic and economic region of Chile. Providing tighter constraints on its magmatic system is therefore important for better monitoring its activity. Calbuco is also distinguished by hornblende-bearing assemblages that contrast with the anhydrous parageneses of most Central SVZ volcanoes. Here we build on previous work to propose a detailed petrological model of the magmatic system beneath Calbuco. Geochemical data acquired on a hundred samples collected in the four units of the volcano show no secular compositional change indicating a steady magmatic system since ~ 300 ka. A tholeiitic Al2O3-rich (20 wt. %) basalt (Mg# = 0.59) is the parent magma of a differentiation trend straddling the tholeiitic/calc-alkaline fields and displaying a narrow compositional Daly gap. Amphibole crystallization was enabled by the higher H2O content of the basalt (3–3.5 wt. % H2O at 50 wt. % SiO2) compared to neighboring volcanoes. This characteristic is inherited from the primary mantle melt and possibly results from a lower degree of partial melting induced by the mantle wedge thermal structure. Although macrocrysts are not all in chemical equilibrium with their host rocks and were thus presumably unlocked from the zoned crystal mush and transported in the carrier melt, the bulk-rock trend follows both experimental liquid lines of descent and the chemical trend of calculated melts in equilibrium with amphibole (AEMs). These contradictory observations can be reconciled if minerals are transported in near cotectic proportions. The AEMs overlap the Daly gap revealing that the missing liquid compositions were present in the storage region. Geothermobarometers all indicate that the chemical diversity from basalt to dacite was acquired at a shallow depth (210–460 MPa). We suggest that differentiation from the primary magma to the parental basalt took place either in the same storage region or at the MOHO.CDR J.00066.14, PDR T.0079.18, Odysseus grant (ON

Calbuco (Central Southern Volcanic Zone, Chile): a hazardous volcano

CDR J.00066.14, PDR T.0079.18, Odysseus grant (ON

Genome-wide analysis of Brucella melitensis genes required throughout intranasal infection in mice

Brucellae are facultative intracellular Gram-negative coccobacilli that chronically infect various mammals and cause brucellosis. Human brucellosis is among the most common bacterial zoonoses and the vast majority of cases are attributed to B .melitensis .Using transposon sequencing (Tn-seq) analysis, we showed that among 3369 predicted genes of the B .melitensis genome, 861 are required for optimal growth in rich medium and 186 additional genes appeared necessary for survival of B .melitensis in RAW 264.7 macrophages in vitro .As the mucosal immune system represents the first defense against Brucella infection, we investigated the early phase of pulmonary infection in mice. In situ analysis at the single cell level indicates a succession of killing and growth phases, followed by heterogenous proliferation of B .melitensis in alveolar macrophages during the first 48 hours of infection. Tn-seq analysis identified 94 additional genes that are required for survival in the lung at 48 hours post infection. Among them, 42 genes are common to RAW 264.7 macrophages and the lung conditions, including the T4SS and purine synthesis genes. But 52 genes are not identified in RAW 264.7 macrophages, including genes implicated in lipopolysaccharide (LPS) biosynthesis, methionine transport, tryptophan synthesis as well as fatty acid and carbohydrate metabolism. Interestingly, genes implicated in LPS synthesis and β oxidation of fatty acids are no longer required in Interleukin (IL)-17RA -/- mice and asthmatic mice, respectively. This demonstrates that the immune status determines which genes are required for optimal survival and growth of B .melitensis in vivo .info:eu-repo/semantics/publishe

“Interactive Technology Assessment” and Beyond: the Field Trial of Genetically Modified Grapevines at INRA-Colmar

International audienc

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