pinecone/core-2020-05-10-deduplication huggingface dataset:
Electron microprobe monazite geochronology of granitic intrusions from the\ud
Montes de Toledo batholith (central Spain)

U–Th–Pb monazite dating by electron microprobe has been applied to three peraluminous granitic intrusions of the western Montes de Toledo\ud
batholith (MTB). Back scattered electron images of monazite crystals reveal a variety of internal textures: patchy zoning, overgrowths around\ud
older cores and unzoned crystals. On the basis of their zoning pattern and chemical composition, two monazite domains can be distinguished:\ud
(1) corroded cores and crystals with patchy zoning, exhibiting relatively constant Th/U ratios and broadly older ages, and (2) unzoned grains\ud
and monazite rims, with variable Th/U ratios and younger ages. The first monazite group represents inherited domains from metamorphic\ud
sources, which accounts for pre-magmatic monazite growth events. Two average ages from Torrico and Belvís de Monroy granites\ud
(33318 and 3335 Ma, respectively) relate these cores to a Viséan extensional deformation phase. The second group represents igneous\ud
monazites which have provided the following crystallization ages for the host granite: 29811 Ma (Villar del Pedroso), 3036Ma (Torrico)\ud
and 3143Ma (Belvís de Monroy). Two main magmatic pulses, the first about 314Ma and the second at the end of the Carboniferous\ud
(303–298Ma), might be envisaged in the western MTB. While Belvís de Monroy leucogranite is likely a syn- to late-tectonic intrusion,\ud
the Villar del Pedroso and Torrico plutons represent post-tectonic magmas with emplacement ages similar to those of equivalent\ud
intrusions from nearby Variscan magmatic sectors
Origin and maturation of lagoonal glauconites : a case study from the Oligocene Maniyara Fort Formation, western Kutch, India

An integrated study of the sedimentology, micropalaeontology, mineralogy and geochemistry of glauconites in the Oligocene Maniyara Fort
Formation (western Kutch, India), has been undertaken. Authigenic glauconites, mostly of evolved type, formed within a back-barrier lagoonal
environment. Foraminifera help constrain the biostratigraphy and along with sedimentological evidence, provide information on the
depositional conditions. Glauconite in the Maniyara Fort Formation occurs either as infillings within intra-particle pores of larger foraminifers,
or as an altered form of faecal pellets. X-ray diffraction studies reveal the less mature nature of glauconite infillings compared to the glauconite
pellets. Electron microprobe investigation confirms a relative enrichment of K2O and total Fe2O3 in the latter. Both varieties of glauconite
formed by initial authigenic precipitation of K-poor glauconite and subsequently matured by addition of potassium in the interlayer sites
and fixation of total iron in the octahedral sites; calcium, magnesium and aluminum were released from the glauconite structure concomitantly.
Alkaline conditions during the entire process of glauconite formation did not allow dissolution of foraminiferal tests. Mineralogical
and chemical characteristics of the Maniyara Fort Formation glauconites are more similar to deep marine glauconites than those reported from
other shallow or marginal marine settings. A low negative cerium anomaly, as well as abundant pyrite, suggests formation of glauconite in
sub-oxic micro-environments, created by decay of organic matter associated with foraminiferal chambers and faecal pellets. Sub-oxic condition
apparently prevailed relatively longer within the Maniyara Fort Formation lagoons.The Department of Science and
Technology, Government of Indiahttp://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-1034
Origin of Carboniferous sandstones fringing the northern margin of the Wales-Brabant Massif: insights from detrital zircon ages

A study of detrital zircon age populations in Namurian–Westphalian (Carboniferous) sandstones in the southern Central Pennine Basin of the UK has revealed considerable complexity in their provenance history. The Pendleian–Marsdenian Morridge Formation, which is known to have been derived from the Wales-Brabant Massif to the south on the basis of palaeocurrent and petrographic information, is dominated by zircons ultimately derived from the Caledonian belt to the north. These zircons were recycled from sandstones of northern origin that had been previously deposited over the massif during Middle to Late Devonian times. The Morridge Formation also includes Late Neoproterozoic zircons of local Wales-Brabant Massif origin. The south lobe of the Yeadonian Rough Rock has been previously interpreted as having a complex provenance including sediment of northern origin interbedded with sediment ascribed to a Wales-Brabant Massif source. However, the zircon spectrum lacks a Late Neoproterozoic component that would have been diagnostic of input from the Wales-Brabant Massif, and the provenance history of the Rough Rock south lobe therefore remains enigmatic. The Langsettian Ludgbridge Conglomerate is dominated by Late Neoproterozoic zircons of Wales-Brabant Massif origin, but even in this evidently proximal deposit, the provenance is complex since the main zircon group (ca. 640 Ma) cannot be matched with known local Neoproterozoic basement sources. The data either indicate the presence of hitherto-unknown magmatic rocks of this age adjacent to the South Staffordshire coalfield or indicate that the zircons were recycled from sediment with a more distal origin. Finally, the Duckmantian Top Hard Rock contains zircons that can be reconciled with a source in the Irish Caledonides, consistent with the palaeocurrent evidence, supplemented by zircons derived from the Wales-Brabant Massif, possibly including the Monian Composite Terrane of Anglesey. The study reinforces the important message that failure to recognize the presence of recycled zircon could lead to erroneous reconstructions of sediment provenance and transport history
Late Miocene magnetostratigraphy of Jianzha Basin in the northeastern margin of the Tibetan Plateau and changes in the East Asian summer monsoon

Jianzha Basin is located in the northeastern Tibetan Plateau (NETP) and contains a thick sequence of Cenozoic sediments that are an archive of information about the growth of the Tibetan Plateau and the evolution of the arid environment of the interior of Asia. Here, we present magnetostratigraphic and palaeoenvironmental records from a 361-m-thick sequence of Late Cenozoic eolian Red Clay and intercalated fluviolacustrine deposits in the Jianzha Basin. The magnetostratigraphic results show that the sediments have recorded a continuous geomagnetic polarity sequence from C5r.3r to C3r, spanning the interval from 11.8 to 5.8Ma in the Late Miocene. There are two intervals of rapidly fluctuating sedimentation rates between similar to 10 and similar to 6Ma, which we interpret as a response to a series of uplifts and expansions to the north and to the east in the NETP. The fluctuations in Rb/Sr ratio and magnetic susceptibility before similar to 8.57Ma reflect intensified East Asian summer monsoon (EASM) precipitation which resulted from the growth of the NETP. From similar to 8.57 to similar to 7.21Ma, the EASM was impacted by global cooling and ice build-up in the Northern Hemisphere in addition to the uplift of the Tibetan Plateau (TP) in the Late Miocene. From similar to 8.57 to similar to 7.21Ma, there is a lack of coherency between the fluctuations in MS and Rb/Sr ratio; however, subsequently, there is significant coherency between the Rb/Sr ratio and the deep-sea oxygen isotope record present. This suggests that from similar to 8.57Ma, the eolian Red Clay sediments in the Jianzha Basin were significantly affected by the addition of dust derived from the deforming and uplifting areas of the TP
Radiometric dating of late Quaternary loess in the northern piedmont of South Tianshan Mountains: Implications for reliable dating

Reliable chronologies are prerequisites when interpreting proxy records in terrestrial archives of Quaternary climate and environmental change. Optically stimulated luminescence (OSL) dating and accelerator mass spectrometry radiocarbon dating (AMS C-14) are commonly used to date late Quaternary loess deposits in the Chinese Loess Plateau, but the range and reliability of the two methods in Central Asia are still debated. In this study, we investigate both fine-grained quartz OSL and AMS C-14 dating of a late Quaternary loess section located at the northern piedmont of the South Tianshan Mountains in Central Asia and discuss the reliability of the two radiometric dating methods. The results show that the OSL and AMS C-14 ages are generally consistent with the stratigraphic sequence when the ages are younger than 25cal ka BP, which means that both can be used to establish a reliable chronology in the Ili Basin. But beyond this age, the OSL dating method seems to be a more reliable approach. The results also supported previous dates based on medium-grained quartz OSL dating of the Ili loess in the southern piedmont of the North Tianshan Mountains. Radiocarbon ages older than 25cal ka BP should be treated with caution, and attention must be paid to the influence of pedoturbation on OSL signals in the Central Asian loess. Multiple dating approaches for mutual authentication and exploring new dating materials are suggested in further loess chronological research. These findings will be helpful in establishing a reliable timescale and in reconstructing high-resolution environmental change in Central Asia
Constraining the denudation process in the eastern Sichuan Basin, China using low-temperature thermochronology and vitrinite reflectance data

The temperature history of samples and maximum palaeogeothermal profiles of boreholes were reconstructed based on low‐temperature thermochronology and vitrinite reflectance data, and the results provide limits for the timescale and amount of uplift–denudation of the eastern Sichuan Basin. The thermal history showed that the uplifting and cooling of eastern Sichuan Basin began around the Late Cretaceous (approximately 100–80 Ma). The region had experienced a continuous cooling process from the Late Cretaceous until the present, with the geothermal gradient decreasing from 32–36 °C/km to 20–23 °C/km. The amount of denudation at the Puguang region in north‐eastern Sichuan was approximately 2.3 km, whereas that at south‐eastern Sichuan was 1.9 km, and the erosion thickness in the eastern Sichuan fold belt that was revealed via the field samples is 2.3 ± 0.3–2.6 ± 0.3 km. The north‐eastern Sichuan experienced sustained cooling with inconspicuous fluctuations, whereas the thrust belt and the south‐eastern Sichuan Basin presented 2–4 stages with different cooling rates. It may indicate that the eastern Sichuan fold belt experienced a complex structural evolution, characterized by episodic upliftings and deformations since Late Cretaceous, while a different and gentle deformation took place in the northeastern Sichuan Basin
Selenium and tellurium concentrations of Carboniferous British coals

The authors wish to thank Kier Group, the British Coal Utilisation Research Association (BCURA) and Uniper (E.On) for kindly providing coal samples. The authors are grateful to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), and Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS) for supporting this study. The authors are grateful for the thorough and constructive comments from two anonymous reviewers, as well as the careful editorial handling of Prof. Ian Somerville. This work was supported by the NERC under Grant number NE/L001764/1.Peer reviewedPublisher PD
Causes of variation in crystal morphology in metamorphogenic\ud
pyrite deposits of the Cameros Basin (N Spain)

The low-grade metasediments of lthe Cameros Basin, northem Spain, host a number of deposits of spectacular quality pyrite mineralization. These formed during regional metamorphism and the pyrite crystals exhibit a wide range of  morphologies. On the basis of pyrite crystal habit, the deposits can be classified into two groups: Group 1 comprises deposits with cubic, elongated or platy crystals; Group 11 comprises deposits charactenzed by pyntohedra and cubo-pyritohedra with striated faces, along with blocky crystals and he-grained aggregates. Group 1 deposits are formed in sequences dorninated by meandriform fluviatile sediments, while Group 11 is hosted by deltaic plain and lacustrine metasediments. Temperature differences between deposits and As content are possible causes of the different  ynte morphologies in the deposits, but no significant variation exists between the two groups for either factor. Comparison with experimentally grown pyrite crystals suggests that Group 1 deposits have morphologies indicative of lower degrees of pyrite supersaturation than pyrite crystals in Group 11 deposits. The sedimentary facies hosting Group 11 deposits provides a greater availability of sedimentary sulphur (pyrite and sulphates). Moreover, reactions involving sulphate during metamorphism may have modified fluid chernistry, which would also act to produce higher degrees of pynte saturation in fluids derived from the sulphate-rich deltaic plain and lacustrine metasediments  osting the Group 11 deposits. This hypothesis is confirmed by sulphur isotope data on the pyrites, which show a larger component of 34S-Enriched sulphate-derived sulphur in these deposits
Apoptosis of Inflammatory Cells in Immune Control of the Nervous System: Role of Glia

Normal individuals have T lymphocytes capable of reacting to central nervous system (CNS) antigens such as myelin basic protein (MBP) (Martin et al., [1990]). In view of recent evidence indicating that T cells are much more cross-reactive than previously thought (Mason, [1998]), it is likely that these autoreactive T cells are often primed by exposure to cross-reacting environmental antigens. Indeed it has been shown that viral and bacterial peptides can activate myelin-reactive human T cells (Wucherpfennig and Strominger, [1995]; Hemmer et al., [1997]). Furthermore, normal healthy subjects experience surges of increased frequencies of circulating myelin-reactive T cells that might be driven by cross-reactive environmental antigens (Pender et al., [2000]). Such activated myelin-reactive T cells would be expected to enter the CNS in healthy individuals, because activated T cells of any specificity, including autoreactive T cells, enter the normal CNS parenchyma (Wekerle et al., [1986]; Hickey et al., [1991]). If CNS-reactive T cells survive in the CNS, they have the potential to attack the CNS, either directly or through the recruitment of other inflammatory cells, and thus lead to CNS damage such as demyelination. Therefore, the physiological control of autoreactive T cells in the CNS is likely to have an important role in preventing the development of autoimmune CNS disorders such as multiple sclerosis (MS) (Pender, [1998]). T-cell apoptosis in the CNS has been proposed to be an important mechanism for controlling autoimmune attacks on the CNS (Pender et al., [1992]; Schmied et al., [1993]). Although other mechanisms, such as immune deviation (Wenkel et al., [2000]), may possibly also contribute to the control of the immune response in the CNS, this review will focus on T-cell apoptosis in the CNS and the role of glia in this process
S100B expression defines a state in which GFAP-expressing cells lose their neural stem cell potential and acquire a more mature developmental stage.
 : 
S100B is absent in SVZ GFAP expressing cells

International audienceDuring the postnatal development, astrocytic cells in the neocortex progressively lose their neural stem cell (NSC) potential, whereas this peculiar attribute is preserved in the adult subventricular zone (SVZ). To understand this fundamental difference, many reports suggest that adult subventricular GFAP-expressing cells might be maintained in immature developmental stage. Here, we show that S100B, a marker of glial cells, is absent from GFAP-expressing cells of the SVZ and that its onset of expression characterizes a terminal maturation stage of cortical astrocytic cells. Nevertheless, when cultured in vitro, SVZ astrocytic cells developed as S100B expressing cells, as do cortical astrocytic cells, suggesting that SVZ microenvironment represses S100B expression. Using transgenic s100b-EGFP cells, we then demonstrated that S100B expression coincides with the loss of neurosphere forming abilities of GFAP expressing cells. By doing grafting experiments with cells derived from beta-actin-GFP mice, we next found that S100B expression in astrocytic cells is repressed in the SVZ, but not in the striatal parenchyma. Furthermore, we showed that treatment with epidermal growth factor represses S100B expression in GFAP-expressing cells in vitro as well as in vivo. Altogether, our results indicate that the S100B expression defines a late developmental stage after which GFAP-expressing cells lose their NSC potential and suggest that S100B expression is repressed by adult SVZ microenvironment
Spontaneous NA+ transients in individual mitochondria of intact astrocytes.

Mitochondria in intact cells maintain low Na(+) levels despite the large electrochemical gradient favoring cation influx into the matrix. In addition, they display individual spontaneous transient depolarizations. The authors report here that individual mitochondria in living astrocytes exhibit spontaneous increases in their Na(+) concentration (Na(mit)(+) spiking), as measured using the mitochondrial probe CoroNa Red. In a field of view with approximately 30 astrocytes, up to 1,400 transients per minute were typically detected under resting conditions. Na(mit)(+) spiking was also observed in neurons, but was scarce in two nonneural cell types tested. Astrocytic Na(mit)(+) spikes averaged 12.2 +/- 0.8 s in duration and 35.5 +/- 3.2 mM in amplitude and coincided with brief mitochondrial depolarizations; they were impaired by mitochondrial depolarization and ruthenium red pointing to the involvement of a cation uniporter. Na(mit)(+) spiking activity was significantly inhibited by mitochondrial Na(+)/H(+) exchanger inhibition and sensitive to cellular pH and Na(+) concentration. Ca(2+) played a permissive role on Na(mit)(+) spiking activity. Finally, the authors present evidence suggesting that Na(mit)(+) spiking frequency was correlated with cellular ATP levels. This study shows that, under physiological conditions, individual mitochondria in living astrocytes exhibit fast Na(+) exchange across their inner membrane, which reveals a new form of highly dynamic and localized functional regulation
Development of the Schwann cell lineage: from the neural crest to the myelinated nerve

The myelinating and nonmyelinating Schwann cells in peripheral nerves are derived from the neural crest, which is a transient and multipotent embryonic structure that also generates the other main glial subtypes of the peripheral nervous system (PNS). Schwann cell development occurs through a series of transitional embryonic and postnatal phases, which are tightly regulated by a number of signals. During the early embryonic phases, neural crest cells are specified to give rise to Schwann cell precursors, which represent the first transitional stage in the Schwann cell lineage, and these then generate the immature Schwann cells. At birth, the immature Schwann cells differentiate into either the myelinating or nonmyelinating Schwann cells that populate the mature nerve trunks. In this review, we will discuss the biology of the transitional stages in embryonic and early postnatal Schwann cell development, including the phenotypic differences between them and the recently identified signaling pathways, which control their differentiation and maintenance. In addition, the role and importance of the microenvironment in which glial differentiation takes place will be discussed
Upregulation of p21Cip1 in activated glial cells

El pdf es la versión pre-print.The cdk inhibitor p21Cip1, also named p21Cip1/Waf1, is intimately involved in coupling growth arrest to cellular differentiation in several cell types. p21Cip1 is a multifunctional protein that might regulate cell-cycle progression at different levels. In a recent study, we found no differences in the rate of proliferation between glial cells from wild-type and p21Cip1−/− mice. In the present study, we examined differences in glial activation between glial cells from wild-type and p21Cip1−/− mice, using mixed glial cultures, microglia-enriched cultures, and astrocyte-enriched cultures. We compared the effect of lipopolysaccharide and two forms (oligomeric and fibrillar) of the 1-42 β-amyloid peptide on glial activation. We observed an attenuation of nuclear translocation of the nuclear factor kappa-B in p21Cip1−/− glial cells, when compared with glial cells from wild-type mice. In contrast, tumor necrosis factor-α release was enhanced in p21Cip1−/−microglial cells. In addition glial activation induced by lipopolysaccharide and the fibrillar form of the 1-42 β-amyloid peptide upregulated p21Cip1. Our results support a role for p21Cip1 in the activation of glial cells, particularly in microglia.This work was supported by grants PI 050658 and PI040778 from the Instituto de Salud Carlos III of the Spanish Ministry of Health and Consumer Affairs and V-2006-TV063031-O from the Fundació La Marató de TV3
Conduction block and glial injury induced in developing central white matter by glycine, GABA, noradrenalin or nicotine, studied in isolated neonatal rat optic nerve

This is the author’s submitted draft of the paper published as Glia, 2009, 57 (11), pp. 1168-1177.  The definitive version is available at www3.interscience.wiley.com, Doi: 10.1002/glia.20839.The damaging effects of excessive glutamate receptor activation have been highlighted recently during injury in developing central white matter. We have examined the effects of acute exposure to four other neurotransmitters that have known actions on white matter. 80 min of Glycine or GABA-A receptor activation produced a significant fall in the compound action potential recorded from isolated post-natal day 10 rat optic nerve. This effect was largely reversed upon washout.  Nicotinic acetylcholine receptor (nAChR) or adrenoreceptor activation with noradrenalin resulted in an ~35% block of the action potential that did not reverse during a 30 min washout period. While the effect of nAChR activation was blocked by a nAChR antagonist, the effect of noradrenalin was not ablated by α- or β-adrenoreceptor blockers applied alone or in combination. In the absence of noradrenalin, co-perfusion with α- or β-adrenoreceptor blockers resulted in non-reversible nerve failure indicating that tonic adrenoreceptor activation is required for nerve viability, while over activation of these receptors is also damaging. Nerves exposed to nAChR + adrenoreceptor activation showed no axon pathology but had extensive glial injury revealed by ultrastructural analysis. Oligodendroglia exhibited regions of membrane vacuolization while profound changes were evident in astrocytes and included the presence of swollen and expanded mitochondria, vacuolization, cell processes disintegration and membrane breakdown. Blinded assessment revealed higher levels of astrocyte injury than oligodendroglial injury. The findings show that over-activation of neurotransmitter receptors other than those for glutamate can produce extensive injury to developing white matter, a phenomenon that may be clinically significant