We measured respiratory release rates of CO2 from various taxonomic groups of zooplankton during three cruises in winter, spring, and summer in the North Atlantic Ocean. Zooplankton species collected ...comprised different species of thaliacea (salps), mollusc thecosomes, amphipod hyperiids, copepods, decapods, and euphausiids. Hourly, individual rates ranged from a minimum of 0.02 μl h-1 for the smallest copepods (Oncaea sp. and Acartia) to a maximum of 90.6 μl CO2 for the largest euphausiids (Meganyctiphanes norvegica), corresponding to a range of weight-corrected rates of 0.1 μl CO2 for the thecosome Cymbulia peronii and 5.6 μl CO2 for the smallest copepods. Size was the major factor controlling the recorded rates. Allometric coefficients varied between 0.6 and 0.7 for weight and 1.5 and 2.2 for length, which is in agreement with the theoretical values and the values recorded for oxygen consumption. RQ values (CO2 released/O2 consumed) were computed for each group from simultaneous measurements of both respiratory processes. Model II regressions yielded mean RQs of 0.87 ± 0.40 for copepods, 0.94 ± 0.40 for thecosomes, and 1.35 ± 0.08 for large crustacean and salp species. We propose that the increase in RQ value from copepod to large crustacean species is related to the development of the muscular mass and activity rather than a simple shift in respiratory metabolic substrate. Realistic RQ values, taking species differences into account, should be used to derive population and community CO2 release rates from simpler oxygen consumption measurements.
Red cell diseases encompass a group of inherited or acquired erythrocyte disorders that affect the structure, function, or production of red blood cells (RBCs). These disorders can lead to various ...clinical manifestations, including anemia, hemolysis, inflammation, and impaired oxygen-carrying capacity. Oxidative stress, characterized by an imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense mechanisms, plays a significant role in the pathophysiology of red cell diseases. In this review, we discuss the most relevant oxidant species involved in RBC damage, the enzymatic and low molecular weight antioxidant systems that protect RBCs against oxidative injury, and finally, the role of oxidative stress in different red cell diseases, including sickle cell disease, glucose 6-phosphate dehydrogenase deficiency, and pyruvate kinase deficiency, highlighting the underlying mechanisms leading to pathological RBC phenotypes.
High-energy neutrinos could be produced in the interaction of charged cosmic rays with matter or radiation surrounding astrophysical sources. Even with the recent detection of extraterrestrial ...high-energy neutrinos by the IceCube experiment, no astrophysical neutrinosource has yet been discovered. Transient sources, such as gamma-ray bursts, core-collapse supernovae, or active galactic nuclei are promising candidates. Multi-messenger programs offer a unique opportunity to detect these transient sources. By combining the information provided by the ANTARES neutrino telescope with information coming from other observatories, the probability of detecting a source is enhanced, allowing the possibility of identifyinga neutrino progenitor from a single detected event. A method based on optical and X-ray follow-ups of high-energy neutrino alerts has been developed within the ANTARES collaboration. This method does not require any assumptions on the relation between neutrino and photon spectra other than time-correlation. This program, denoted as TAToO, triggers a network of robotic optical telescopes (TAROTand ROTSE) and the Swift-XRT with a delay of only a few seconds after a neutrino detection, and is therefore well-suited to search for fast transient sources. To identify an optical or Xraycounterpart to a neutrino signal, the images provided by the follow-up observations areanalysed with dedicated pipelines. A total of 42 alerts with optical and 7 alerts with X-ray images taken with a maximum delay of 24 hours after the neutrino trigger have been analyzed. No optical or X-ray counterparts associated to the neutrino triggers have been found, and upper limits on transient source magnitudes have been derived. The probability to reject the gamma-ray burst origin hypothesis has been computed for each alert.
A search for a neutrino signal from WIMP pair annihilations in the centre of the Earth has been performed with the data collected with the ANTARES neutrino telescope from 2007 to 2012. The event ...selection criteria have been developed and tuned to maximise the sensitivity of the experiment to such a neutrino signal. No significant excess of neutrinos over the expected background has been observed. Upper limits at 90% C.L. on the WIMP annihilation rate in the Earth and the spin independent scattering cross-section of WIMPs to nucleons σpSI were calculated for WIMP pair annihilations into either τ+τ−, W+W−, bb¯ or the non-SUSY νμν̄μ as a function of the WIMP mass (between 25GeV∕c2 and 1000GeV∕c2) and as a function of the thermally averaged annihilation cross section times velocity 〈σAv〉Earth of the WIMPs in the centre of the Earth. For masses of the WIMP close to the mass of iron nuclei (50GeV∕c2), the obtained limits on σpSI are more stringent than those obtained by other indirect searches.
Throughout mammal erythroid differentiation, erythroblasts undergo enucleation and organelle clearance becoming mature red blood cell. Organelles are cleared by autophagic pathways non-specifically ...targeting organelles and cytosolic content or by specific mitophagy targeting mitochondria. Mitochondrial functions are essential to coordinate metabolism reprogramming, cell death, and differentiation balance, and also synthesis of heme, the prosthetic group needed in hemoglobin assembly. In mammals, mitochondria subcellular localization and mitochondria interaction with other structures as endoplasmic reticulum and nucleus might be of importance for the removal of the nucleus, that is, the enucleation. Here, we aim to characterize by electron microscopy the changes in ultrastructure of cells over successive stages of human erythroblast differentiation. We focus on mitochondria to gain insights into intracellular localization, ultrastructure, and contact with other organelles. We found that mitochondria are progressively cleared with a significant switch between PolyE and OrthoE stages, acquiring a rounded shape and losing contact sites with both ER (MAM) and nucleus (NAM). We studied intracellular vesicle trafficking and found that endosomes and MVBs, known to be involved in iron traffic and heme synthesis, are increased during BasoE to PolyE transition; autophagic structures such as autophagosomes increase from ProE to OrthoE stages. Finally, consistent with metabolic switch, glycogen accumulation was observed in OrthoE stage.
We examined the effects of nutrient additions on rates of 14C-based particulate and dissolved primary production as well as O2-based metabolic rates in surface waters (8 m) of three anticyclonic ...eddies, located in the Western, Central and Eastern Mediterranean. Ship-board microcosm experiments employing additions of inorganic nitrogen (+N) and phosphorus (+P), alone and in combination (+NP), were conducted in June/July 2008 during the BOUM (Biogeochemistry from the Oligotrophic to the Ultra-oligotrophic Mediterranean) cruise. In all three experiments, particulate primary production was significantly stimulated by the additions of nitrogen (+N, +NP) while no effect was observed with the addition of phosphorus alone (+P). Percent extracellular release of photosynthate (PER) displayed the lowest values (4–8 %) in the +NP treatment. Among the three treatments (+N, +P, +NP), the +NP had the strongest effect on oxygen metabolic rates, leading to positive values of net community production (NCP > 0). These changes of NCP were mainly due to enhanced gross primary production (GPP) rather than reduced dark community respiration rates (DCR). In all three sites, in +NP treatment autotrophic production (whether expressed as GPP or PPtotal) was sufficient to fulfil the estimated carbon requirements of heterotrophic prokaryotes, while addition of nitrogen alone (+N) had a weaker effect on GPP, resulting in metabolically balanced systems. At the three sites, in treatments with N (+N, +NP), phytoplankton and heterotrophic prokaryote production were positively correlated. Heterotrophic conditions were observed in the Control and +P treatment at the central and eastern sites, and autotrophic production was not sufficient to supply estimated bacterial carbon demand, evidence of a decoupling of phytoplankton production and consumption by heterotrophic prokaryotes.
Deep convection plays a key role in the circulation, thermodynamics, and biogeochemical cycles in the Mediterranean Sea, which is considered to be a hotspot of biodiversity and climate change. In the ...framework of the DEWEX (Dense Water Experiment) project, the seasonal and annual budgets of dissolved inorganic carbon in the deep-convection area of the northwestern Mediterranean Sea are investigated over the period September 2012–September 2013 using a 3D coupled physical–biogeochemical–chemical modeling approach. At the annual scale, we estimate that the northwestern Mediterranean Sea's deep-convection region was a moderate sink of 0.5 mol C m−2 yr−1 of CO2 for the atmosphere. The model results show the reduction of oceanic CO2 uptake during deep convection and its increase during the abrupt spring phytoplankton bloom following the deep-convection events. We highlight the major roles in the annual dissolved inorganic carbon budget of both the biogeochemical and physical fluxes, which amount to −3.7 and 3.3 mol C m−2 yr−1, respectively, and are 1 order of magnitude higher than the air–sea CO2 flux. The upper layer (from the surface to 150 m depth) of the northwestern deep-convection region gained dissolved inorganic carbon through vertical physical transport and, to a lesser extent, oceanic CO2 uptake, and it lost dissolved inorganic carbon through lateral transport and biogeochemical fluxes. The region, covering 2.5 % of the Mediterranean, acted as a source of dissolved inorganic carbon for the surface and intermediate water masses of the Balearic Sea and southwestern Mediterranean Sea and could represent up to 22 % and 11 %, respectively, of the CO2 exchanges with the Atlantic Ocean at the Strait of Gibraltar.
Total alkalinity (AT) and dissolved inorganic carbon (CT) in the oceans are important properties with respect to understanding the ocean carbon cycle and its link to global change (ocean carbon sinks ...and sources, ocean acidification) and ultimately finding carbon-based solutions or mitigation procedures (marine carbon removal). We present a database of more than 44 400 AT and CT observations along with basic ancillary data (spatiotemporal location, depth, temperature and salinity) from various ocean regions obtained, mainly in the framework of French projects, since 1993. This includes both surface and water column data acquired in the open ocean, coastal zones and in the Mediterranean Sea and either from time series or dedicated one-off cruises. Most AT and CT data in this synthesis were measured from discrete samples using the same closed-cell potentiometric titration calibrated with Certified Reference Material, with an overall accuracy of ±4 µmol kg−1 for both AT and CT. The data are provided in two separate datasets – for the Global Ocean and the Mediterranean Sea (https://doi.org/10.17882/95414, Metzl et al., 2023), respectively – that offer a direct use for regional or global purposes, e.g., AT–salinity relationships, long-term CT estimates, and constraint and validation of diagnostic CT and AT reconstructed fields or ocean carbon and coupled climate–carbon models simulations as well as data derived from Biogeochemical-Argo (BGC-Argo) floats. When associated with other properties, these data can also be used to calculate pH, the fugacity of CO2 (fCO2) and other carbon system properties to derive ocean acidification rates or air–sea CO2 fluxes.
Un outillage lithique acheuléen, une riche faune du Pléistocène moyen et quatre dents d'hominidés ont été extraites du remplissage de la cavité de la carrière Thomas I, célèbre depuis la découverte ...en 1969 d'une hémimandibule humaine. Depuis 1988, des fouilles sont conduites dans ce site dans le cadre du programme franco-marocain « Casablanca ». Une riche faune mammalienne et quelques restes de reptiles et d'oiseaux sont associés à l'industrie lithique dans l'unité stratigraphique 4. La faune, introduite par les carnivores, indique un paysage peu boisé et le stade évolutif des divers taxons suggère un âge plus récent que celui de Tighenif (Algérie). Les marques de découpe sont absentes, ce qui pose la question du rôle des hominidés dans l'accumulation des restes fauniques. Le travail de la pierre était orienté vers la production d'éclats et de rares bifaces ont été introduits dans cette partie du site. Quatre dents humaines ont été exhumées entre 1994 et 2005. La datation ICP-MS par ablation laser combinant l'ESR et les séries de l'Uranium pour modéliser l'enrichissement en Uranium a été appliquée à une prémolaire humaine: elle a fourni un âge de $501 \ ^{+ \ 94}_{- \ 76}$ ka. De nouvelles mesures d'âge par OSL sur les sédiments encadrant la dent datée ont respectivement donné 420 ± 34 ka au dessus et 391 ± 32 ka en dessous confirmant un âge minimum centré sur une période relativement ancienne du Pléistocène moyen. The Thomas Quarry I locality became famous in 1969 with the discovery of a human half-mandible in a cave. From 1988 onwards, modern controlled excavations took place within the framework of the Franco-Moroccan co-operative project "Casablanca." The stratigraphy of Thomas I Quarry is complex and represents several major episodes of coastal sedimentation that are dated to the final Lower and early Middle Pleistocene on the basis of a detailed regional lithostratigraphical and microfaciological study and form the Oulad Hamida Morpho-stratigraphic Unit. Within this MSU, some lithostratigraphic units fossilize a polyphase palaeo-shoreline in which caves have developed. A continental sediment series dated to the Middle and Upper Pleistocene on lithostratigraphical and biochronological evidence and by OSL is preserved in the Hominid Cave (GH). The top of the GH general stratigraphy shows a red complex with abundant microfauna (stratigraphic unit 1). Below this, a multilayer dripstone floor interbedded with loose red sands (stratigraphic units 2-3) caps the lower stratigraphic units (4 and 5). Stratigraphic unit 4 contains artefacts, fauna and hominid fossils and rests on collapsed eolianite blocks imbedded in coarse sands which form stratigraphic unit 5; this lowermost intertidal unit fossilizes a notch in the polyphase shoreline. The Acheulean lithic assemblage recovered by recent excavations in GH stratigraphic unit 4 is similar to the series collected at the time of the discovery of the first Homo fossil in 1969. It is manufactured mainly on various quartzites available close to the site as pebbles of small to medium size and some blocks as well as a few flint nodules collected in a secondary position from beach deposits. The flint nodules derive from the phosphatic plateau of the Meseta hinterland and were carried to the ocean by wadis. The assemblage consists of chopper-cores (mainly unifacial unidirectional cores with a retouched cutting edge) and cores, semi-cortical flakes obtained by direct and bipolar knapping, along with rare handaxes made from large flakes or from flat pebbles, handaxe-like cores, hammerstones and anvils. Stone knapping was mainly oriented towards flake production and a few handaxes were probably imported to the site. A rich mammalian macrofauna supplemented by the addition of a few reptiles and birds is associated with the lithics in GH stratigraphic unit 4. The abundance and diversity of carnivores attest to their use of the cave. The most common species is a middle-size canid, with enlarged crushing part of the dentition. The fauna indicates an open woodland environment and suggests an age younger than Tighenif in Algeria, but the remoteness of this latter site, its distance from the seashore, and the fact that it is an open-air site may account for some of the differences. Preliminary taphonomic analysis of the megafauna indicates that the carcasses were processed by carnivores. Cut-marks are still absent from this assemblage despite the association with refitted lithic artefacts, which raises the question of any human role in the bone accumulations. Similar cases of accumulations created by humans, carnivores and porcupines have already been described in the Mediterranean area. However, the studied assemblage comes from inside the cave, whereas any human occupation may well have been concentrated closer to the entrance. Geological studies have demonstrated that unit 4 containing the assemblage results from several sedimentary processes having possibly mixed artefacts with bones previously accumulated by predators. Between 1994 and 2005, four teeth of Homo were recovered in stratigraphic unit 4, a right upper premolar (ThI 94 OA 23-24), another right upper premolar (ThI 95 SA 26 no 89), a first left upper incisor (ThI 95 SA 26 no 90) and a left upper premolar (ThI 2005 PA 24 no 107). The teeth are larger than those of modern humans and show moderate to heavy wear Laser ablation ICP-MS dating combining tESR and U-series data for modelling U-uptake has given an US/ESR age of $501 \ ^{+ \ 94}_{- \ 76}$ ka for a human premolar while new OSL measurements yielded an age of 420 ± 34 ka for sediments immediately above the dated tooth and 391 ± 32 ka below. Nevertheless, biostratigraphy and lithostratigraphy point to greater antiquity, towards the base of the Middle Pleistocene.
The abundance and activity of the major members of the heterotrophic microbial community – from viruses to ciliates – were studied along a longitudinal transect across the Mediterranean Sea in the ...summer of 2008. The Mediterranean Sea is characterized by a west to-east gradient of deepening of DCM (deep chlorophyll maximum) and increasing oligotrophy reflected in gradients of biomass and production. However, within this well documented longitudinal trend, hydrological mesoscale features exist and likely influence microbial dynamics. Here we present data from a W-E transect of 17 stations during the period of summer stratification. Along the transect the production and fate of organic matter was investigated at three selected sites each one located in the centre of an anticyclonic eddy: in the Algero-Provencal Basin (St. A), the Ionian Basin (St. B), and the Levantine Basin (St. C). The 3 geographically distant eddies showed low values of the different heterotrophic compartments of the microbial food web, and except for viruses in site C, all integrated (0–150 m) stocks were higher in reference stations located in the same basin outside the eddies. During our study the 3 eddies showed equilibrium between GPP (Gross Primary Production) and DCR (Dark Community Respiration). Integrated PPp (Particulate Primary Production) values at A, B and C varied from ~140 to ~190 mg C m−2.
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