Viva M•a•c

Benoit, Andrea

doi:10.3138/9781487510930

Cited by 9 publications

(13 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…However, the occurrence of basaltic glasses and high-Mg cumulates with radiogenic 87 Sr/ 86 Sr ratios along present-day mid-ocean ridges (e.g. Ross andElthon, 1993, Nonnotte et al, 2005;van der Zwan et al, 2017) and in ophiolites, (Amri et al, 1996;Benoit et al, 1999;Clenet et al, 2010;Lange et al, 2013) suggest more complex mechanisms for the generation of oceanic magmas involving the assimilation of altered lithospheric material. Experimental and melt inclusion studies highlight the important role of basaltic melt-lithospheric rocks reactions on the chemical composition of both mantle rocks and silicate melts (e.g., Morgan & Liang, 2003;Kvassnes and Grove, 2008;France et al, 2010;Van den Bleeken et al, 2010;2011;Borisova et al, 2012a;.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Sr isotope diversity of basalts and mafic cumulates possibly related to assimilation of seawater-altered rocks is common in spreading environment (Michael and Cornell, 1998;Lange et al, 2013;van der Zwan et al, 2017). Magmas resulting from the mixing between "asthenospheric" tholeiites and hydrated "lithospheric" melts of depleted andesitic affinity were proposed as parental for some puzzling occurrences of orthopyroxene-rich primitive cumulates along mid-ocean ridges and in ophiolites (Benoit et al, 1999;Nonnotte et al, 2005). The formation of such hybrid or/and depleted magmas due to assimilation of serpentinized mantle peridotite leads to the formation of the Moho transition zone composed by dunites and chromitites (Borisova et al, 2012a;Zagrtdenov et al, 2018;Rospabé et al, 2019a,b).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrated Peridotite–Basaltic Melt Interaction Part II: Fast Assimilation of Serpentinized Mantle by Basaltic Magma

et al. 2020

View full text Add to dashboard Cite

The most abundant terrestrial lavas, mid-ocean ridge and ocean island basalt (MORB and OIB), are commonly considered to be derived from a depleted MORB-mantle component (DMM) and more specific, variably enriched mantle plume sources. However, findings of oceanic lavas and mafic cumulates issued from melts, enriched in chlorine and having a radiogenic 87 Sr/ 86 Sr ratio, can be attributed to an interaction between the asthenosphere-derived melts and lithospheric peridotite variably hydrated due to penetration of hydrothermal water down to and below Moho level. To constrain mechanisms and rates responsible for the interaction, we report results of 15 experiments of reaction between serpentinite and tholeiitic basaltic melt at 0.2 -1.0 GPa and 1250 -1300°C. Results show that the reaction proceeds via a multi-stage mechanism: (i) transformation of serpentinite into Cr-rich spinel-bearing harzburgite (Fo92-95 mol.%) containing pore fluid, (ii) partial melting and dissolution of the harzburgite assemblage with formation of interstitial hydrous melts (up to 57 -60 wt% of SiO2 contents at 0.5 GPa pressure), and (iii) final assimilation of the Cr-rich spinel-bearing harzburgite/dunite and formation of hybrid basaltic melts with 12 -13 wt.% of MgO and elevated Cr (up to ~500 ppm) and Ni (up to ~200 ppm) contents. Assimilation of serpentinite by basaltic melt may occur under elevated melt/rock ratios (>2) and may lead to chromitite formation. We show that hybrid magmas produced by the progressive assimilation of serpentinized lithospheric mantle may be recognized by high Mg-numbers and high Cr and Ni contents of olivine and pyroxenes, an excess of SiO2, H2O and halogens in the melts, and some unusual isotopic composition (e.g., radiogenic 87 Sr/ 86 Sr, non-mantle δ 18 O and low 3 He/ 4 He). Our experiments provide evidence that MORB and high-Mg-Cr orthopyroxene-rich cumulates depleted in incompatible elements can be produced from common mid-ocean ridge basaltic melts modified by reaction with hydrated lithospheric peridotite. We established that the rate of assimilation of serpentinized peridotite is controlled by silica diffusion in the reacting hydrous basaltic melt. Our study challenges 3 traditional interpretation of the variations in MORB and OIB chemical and isotopic composition in terms of deep mantle plume source heterogeneities or/and degrees of partial melting.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrated Peridotite–Basaltic Melt Interaction Part II: Fast Assimilation of Serpentinized Mantle by Basaltic Magma

et al. 2020

View full text Add to dashboard Cite

show abstract

“…This technique combines the sensitivity of polarimetry to molecular orientation and order with the specificity of SHG for fibrillar collagen. P-SHG measurements therefore provide additional information about the orientation and hierarchical structure of collagen fibers in the tissue [14][15][16][17][18][19]. However, P-SHG microscopy requires the acquisition of an image sequence recorded with a series of linear incident polarizations and is therefore a slow technique.…”

mentioning

confidence: 99%

Monitoring dynamic collagen reorganization during skin stretching with fast polarization‐resolved second harmonic generation imaging

Ducourthial

Affagard

Schmeltz

et al. 2019

Journal of Biophotonics

View full text Add to dashboard Cite

The mechanical properties of biological tissues are strongly correlated to the specific distribution of their collagen fibers. Monitoring the dynamic reorganization of the collagen network during mechanical stretching is however a technical challenge, because it requires mapping orientation of collagen fibers in a thick and deforming sample. In this work, a fast polarization‐resolved second harmonic generation microscope is implemented to map collagen orientation during mechanical assays. This system is based on line‐to‐line switching of polarization using an electro‐optical modulator and works in epi‐detection geometry. After proper calibration, it successfully highlights the collagen dynamic alignment along the traction direction in ex vivo murine skin dermis. This microstructure reorganization is quantified by the entropy of the collagen orientation distribution as a function of the stretch ratio. It exhibits a linear behavior, whose slope is measured with a good accuracy. This approach can be generalized to probe a variety of dynamic processes in thick tissues.

show abstract

“…The structure of PENT is broadly similar to that of MfpA [13], the founding member of the PRP family, except that MfpA lacks the N-terminal α-helix present in PENT. PENT is also structurally similar to the fourth luminal domain of the human synaptic vesicle protein 2C (SV2C), which is a receptor for botulinum neurotoxin serotypes A, D and F from Clostridium botulinum [36]. The fact that PENT is present in this bacterium while being similar to the receptor for the neurotoxin it produces is interesting.…”

Section: Discussionmentioning

confidence: 99%

Cotranslational folding of a pentarepeat β-helix protein

Notari

Martínez‐Carranza

Farias-Rico

et al. 2018

Preprint

View full text Add to dashboard Cite

It is becoming increasingly clear that many proteins start to fold cotranslationally, before the entire polypeptide chain has been synthesized on the ribosome. One class of proteins that a priori would seem particularly prone to cotranslational folding is repeat proteins, i.e., proteins that are built from an array of nearly identical sequence repeats. However, while the folding of repeat proteins has been studied extensively in vitro with purified proteins, only a handful of studies have addressed the issue of cotranslational folding of repeat proteins. Here, we have determined the structure and studied the cotranslational folding of a β-helix pentarepeat protein from the human pathogen Clostridium botulinum -a homolog of the Fluoroquinolone Resistance Protein MfpA -using an assay in which the SecM translational arrest peptide serves as a force sensor to detect folding events. We find that cotranslational folding of a segment corresponding to the first four of the eight β-helix coils in the protein produces enough force to release ribosome stalling, and that folding starts when this unit is ~35 residues away from the P-site, near the distal end of the ribosome exit tunnel. An additional folding transition is seen when the whole PENT moiety emerges from the exit tunnel. The early cotranslational formation of a folded unit may be important to avoid misfolding events in vivo, and may reflect the minimal size of a stable β-helix since it is structurally homologous to the smallest known β-helix protein, a four-coil protein that is stable in solution.

show abstract

Viva M•a•c

Cited by 9 publications

References 0 publications

Hydrated Peridotite–Basaltic Melt Interaction Part II: Fast Assimilation of Serpentinized Mantle by Basaltic Magma

Hydrated Peridotite–Basaltic Melt Interaction Part II: Fast Assimilation of Serpentinized Mantle by Basaltic Magma

Monitoring dynamic collagen reorganization during skin stretching with fast polarization‐resolved second harmonic generation imaging

Cotranslational folding of a pentarepeat β-helix protein

Contact Info

Product

Resources

About