Mutational spectrum of breast cancer by shallow whole-genome sequencing of cfDNA and tumor gene panel analysis.

Breast cancer (BC) has different molecular subgroups related to different risks and treatments. Tumor biopsies for BC detection are invasive and may not reflect tumor heterogeneity. Liquid biopsies have become relevant because they might overcome these limitations. We rationalize that liquid cfDNA biopsies through shallow whole genome sequencing (sWGS) could improve the detection of tumor alterations, complementing the genomic profiling. We evaluated the feasibility to detect somatic copy number alterations (SCNAs) in BC using shallow whole genome sequencing (sWGS) in cfDNA from archived samples from National Cancer Institute of Colombia patients. We sequenced tumor tissues from 38 BC patients with different molecular subtypes using a gene panel of 176 genes significantly mutated in cancer, and by liquid biopsies using sWGS on 20 paired samples to detect SCNAs and compare with the tumor samples. We identified an extensive intertumoral heterogeneity between the molecular subtypes of BC, with a mean tumor load of 602 mutations in the gene panel of tumor tissues. There was a 12.3% of concordance in deletions in the cfDNA-tumor pairs considering only the genes covered by the panel encompassing seven genes: BRCA1, CDK12, NF1, MAP2K4, NCOR1, TP53, and KEAP1 in three patients. This study shows the feasibility to complement the genomic analysis of tumor tissue biopsies to detect SCNA in BC using sWGS in cfDNA, providing a wider identification of potential therapeutic targets.

Mitigating flood risk and environmental change in show caves: Key challenges in the management of the Las Güixas cave (Pyrenees, Spain).

A successful management of a show cave requires knowledge of cave dynamics and the main risk factors. Show caves close to the water table are prone to sporadic flooding, which can threaten visitor safety and result in severe economic losses. Las Güixas cave, located in the Collarada Massif (Pyrenees - Spain), is representative of a show cave close to the water table that is exposed to energetic flash floods. We conducted a five-year comprehensive cave monitoring study including air temperature, relative humidity, CO2 concentration and water level. Additionally, we measured outside temperature and precipitation. Air temperature variations and ventilation dynamics occurring in most of the cave are controlled by the outside temperature due to entrances at different elevations, except in a non-ventilated area showing more stable hygrothermal characteristics and higher summer values of CO2 concentration. The study also identifies distinct CO2 sources related to the degassing of water and visitors' breathing. Monitoring data show that the rapid degassing of cave water during flooding may increase subsurface CO2 concentrations to levels well above the exposure limits. However, the strong ventilation observed inside the cave rapidly removes CO2 peaks produced by flooding and limits the anthropic CO2 rise to ∼100 ppm. Hydrograph analysis revealed a response time of 8-12 h in the cave water levels to external rainfall/snowmelt events. Based on these results, a flood alarm system supports sustainable show cave management and the number of visitors is optimized according to the environmental conditions of the cave. This monitoring study has greatly contributed to our knowledge of cave dynamics, which can serve to improve flood risk management and increase the profitability of the show cave. Nonetheless, extreme floods remain a significant concern for potential economic losses in the future, considering current climate change scenarios. Hydrological studies together with a long-term monitoring will allow evaluating the impact of future changes in climate and environmental parameters.

Hydrodynamics and water quality of a highly anthropized wetland: the case study of the Massaciuccoli basin (Tuscany, Italy).

Owing to increasing anthropogenic impacts, wetlands have suffered a serious environmental decline in recent decades. The sustainable management of these natural resources is fundamental to maintain both the ecosystems and the economic activities. The Lake Massaciuccoli and nearby areas represent one of the largest residual coastal marshy areas in Tuscany (Italy). This wetland is characterized by large-scale and intensive agricultural use and affected by reclamation activities, with consequent problems of erosion, subsidence and lake eutrophication and siltation. In this context, an integrated study combining hydrochemical data (water levels, electrical conductivity, pH, turbidity, major ions, trace metals) and stable isotopes (H, O, S) has been performed in the southernmost part of the basin, to better disentangle processes and interactions between groundwater and surface water and to understand the origin of solutes and their evolution. Our results indicated that both groundwater and surface water have a meteoric origin and that geochemical composition of groundwater is mainly affected by local geological and biological processes. Moreover, surface water is affected by sea water mixing and evapotranspiration/precipitation processes. The impact of agricultural activity and the use of fertilizers on the water quality appears to be limited as regards nitrates, indicating that less intense agricultural practices implemented in recent years have been successful. As regards sulfates, Fe, and Mn, we cannot fully elucidate the mechanisms underlying human influence, but the oscillation of water level and degradation of peat enhanced by reclamation and agriculture activities likely played an important role in controlling the fate of these elements. Overall, these results underline the importance of integrated approaches to disentangle geochemical processes and will be useful in supporting policy implementation and environmental protection in this valuable area of Tuscany. Findings from this work suggest the need for policy-making authorities to take actions as soon as possible to mitigate risks. Closer co-operation is essential between authorities and farmers to reduce inputs of fertilizers and chemicals into the lake and the surrounding area. Also, additional policy measures should be enforced to reduce the mechanical soil tillage and limit erosion and runoff, such as the NBSs implemented within the Phusicos Project.

The Mutographs biorepository: A unique genomic resource to study cancer around the world.

Large-scale biorepositories and databases are essential to generate equitable, effective, and sustainable advances in cancer prevention, early detection, cancer therapy, cancer care, and surveillance. The Mutographs project has created a large genomic dataset and biorepository of over 7,800 cancer cases from 30 countries across five continents with extensive demographic, lifestyle, environmental, and clinical information. Whole-genome sequencing is being finalized for over 4,000 cases, with the primary goal of understanding the causes of cancer at eight anatomic sites. Genomic, exposure, and clinical data will be publicly available through the International Cancer Genome Consortium Accelerating Research in Genomic Oncology platform. The Mutographs sample and metadata biorepository constitutes a legacy resource for new projects and collaborations aiming to increase our current research efforts in cancer genomic epidemiology globally.

Tiger sharks support the characterization of the world's largest seagrass ecosystem.

Seagrass conservation is critical for mitigating climate change due to the large stocks of carbon they sequester in the seafloor. However, effective conservation and its potential to provide nature-based solutions to climate change is hindered by major uncertainties regarding seagrass extent and distribution. Here, we describe the characterization of the world's largest seagrass ecosystem, located in The Bahamas. We integrate existing spatial estimates with an updated empirical remote sensing product and perform extensive ground-truthing of seafloor with 2,542 diver surveys across remote sensing tiles. We also leverage seafloor assessments and movement data obtained from instrument-equipped tiger sharks, which have strong fidelity to seagrass ecosystems, to augment and further validate predictions. We report a consensus area of at least 66,000 km2 and up to 92,000 km2 of seagrass habitat across The Bahamas Banks. Sediment core analysis of stored organic carbon further confirmed the global relevance of the blue carbon stock in this ecosystem. Data from tiger sharks proved important in supporting mapping and ground-truthing remote sensing estimates. This work provides evidence of major knowledge gaps in the ocean ecosystem, the benefits in partnering with marine animals to address these gaps, and underscores support for rapid protection of oceanic carbon sinks.

The Effect of Chlorhexidine, Amoxicillin, and Clindamycin on the Growth and Differentiation of Primary Human Osteoblasts.

PURPOSE: The objective of this study was to determine the effect of two antibiotics (amoxicillin and clindamycin) and one antiseptic (chlorhexidine digluconate [CHX]) on the growth and differentiation capacity of primary human osteoblasts. MATERIALS AND METHODS: Osteoblast proliferation was determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) technique after a 1-minute treatment with 400 µg/mL amoxicillin or 150 µg/mL clindamycin or CHX (0.12% or 0.2%). Flow cytometry was used for apoptosis/necrosis analysis. The study of cell differentiation was performed using a mineralization medium and staining of the nodules formed using red alizarin at 15 and 22 days of treatment with 400 µg/mL amoxicillin or 150 µg/mL clindamycin. Spectrophotometry was used to determine alkaline phosphatase (ALP) activity after 1 minute of treatment. RESULTS: Treatment of osteoblasts with 0.12% and 0.2% CHX for 1 minute induced a strong dose-dependent reduction in cell proliferation (P < .001) with a significant increase in the percentage of apoptotic cells (P = .004 and < .001, respectively). However, cell proliferation significantly increased (P < .05) after treatment with 150 µg/mL clindamycin. Treatment of the osteoblasts with 150 µg/mL clindamycin for 1 minute significantly increased the expression of ALP (P = .002). Calcium deposition was significantly higher (P < .001) in the 150 µg/mL clindamycin group. CONCLUSION: These data support the use of low doses of clindamycin and amoxicillin for intraoral bone graft decontamination and raise questions about the use of CHX. Osteoblast growth and differentiation may be favored by low doses of clindamycin, and it may be the decontaminant of choice for intraoral bone grafts, while CHX is shown as a less bone-friendly agent.

How to stay together? Habitat use by three sympatric sharks in the western coast of Baja California Sur, Mexico.

Sharks are top predators and play an important role in the regulation of marine ecosystems at lower trophic position. Mustelus californicus, Sphyrna zygaena, and Isurus oxyrinchus prove to be important fishery resources along the western coast of Baja California Sur and cohabit the same coastal areas, probably sharing resources. However, our knowledge about ecological dynamics of multiple species coexisting and sharing similar habitat resources is still limited, particularly for predators such as sharks. Therefore, this study focuses on the analysis of trophic ecology of the sharks species, using carbon (13C) and nitrogen (15N) stable isotope values in muscle tissues coupled with trace element concentration (Hg, Se, and Cd) in muscle and hepatic tissues of sharks. The values of δ13C (M. californicus -17.3 ± 1.1‰, S. zygaena -17.9 ± 0.5‰, and I. oxyrinchus -18.3 ± 0.3‰) and δ15N (M. californicus 18.2 ± 1.1‰, S. zygaena 18.4 ± 0.9‰, and I. oxyrinchus 17.8 ± 1.1‰) indicated that these species feed in the Gulf of Ulloa all throughout the year, and for extended periods with similar habitat use and trophic niche. The above-mentioned statement is also a conclusion supported by the significant correlation between isotopic and trace element concentrations in the muscular tissues in all studied species. Thus, the results of the present study emphasize the habitat and niche characteristics of three sympatric sharks off the coast of Baja California Sur, Mexico.

SDHB exon 1 deletion: A recurrent germline mutation in Colombian patients with pheochromocytomas and paragangliomas.

Pheochromocytomas (PCCs) and paragangliomas (PGLs) (known as PPGL in combination) are rare neuroendocrine tumors of the adrenal medulla and extra-adrenal ganglia. About 40% of the patients with PPGL have a hereditary predisposition. Here we present a case-series of 19 unrelated Colombian patients with a clinical diagnosis of PPGL tumors that underwent germline genetic testing as part of the Hereditary Cancer Program developed at the Instituto Nacional de Cancerología, Colombia (INC-C), the largest reference cancer center in the country. Ten of 19 patients (52.63%) were identified as carriers of a pathogenic/likely pathogenic (P/LP) germline variant in a known susceptibility gene. The majority of the P/LP variants were in the SDHB gene (9/10): one corresponded to a nonsense variant c.268C>T (p.Arg90*) and eight cases were found to be carriers of a recurrent CNV consisting of a large deletion of one copy of exon 1, explaining 42% (8/19) of all the affected cases. Only one additional case was found to be a carrier of a missense mutation in the VHL gene: c.355T>C (p.Phe119Leu). Our study highlights the major role of SDHB in Colombian patients with a clinical diagnosis of PGL/PCC tumors and supports the recommendation of including the analysis of large deletions/duplications of the SDHB gene as part of the genetic counselling to improve the detection rate of hereditary cases and their clinical care.

Sex differences in diet and life conditions in a rural Medieval Islamic population from Spain (La Torrecilla, Granada): An isotopic and osteological approach to gender differentiation in al-Andalus.

OBJECTIVES: Gender differentiation can influence the diet, physical activity, and health of human populations. Multifaceted approaches are therefore necessary when exploring the biological consequences of gender-related social norms in the past. Here, we explore the links between diet, physiological stress, physical activity, and gender differentiation in the Medieval Islamic population of La Torrecilla (Granada, Spain, 13th-15th century AD), by analyzing stable isotope patterns, stature, and long bone diaphyseal measurements. MATERIALS AND METHODS: The sample includes 96 individuals (48 females, 48 males) classified as young and middle adults (20-34 and 35-50 years of age respectively). Diet was reconstructed through the analysis of δ13 C and δ15 N. Stature, humeral and femoral diaphyseal shape and product of diaphyseal diameters served as proxies of physiological stress and physical activity. RESULTS: Isotopic ratios suggest a substantial dietary contribution of C4 plants (e.g., sorghum, millet), a variable access to animal proteins, and no differences between the sexes. Sexual dimorphism in stature derives from a markedly low female stature. Long bone diaphyseal properties suggest that men performed various physically stressful activities, whereas women were involved in less physically demanding activities (possibly related to household work). DISCUSSION: Gender differentiation in La Torrecilla was expressed by a possibly differential parental investment in male versus female offspring and by culturally sanctioned gender differences in the performance of physical tasks. Diet was qualitatively homogenous between the sexes, although we cannot rule out quantitative differences. Our results shed new light on the effects of gender-related social norms on human development and lifestyle.

Fine-scale metabolic discontinuity in a stratified prokaryote microbiome of a Red Sea deep halocline.

Deep-sea hypersaline anoxic basins are polyextreme environments in the ocean's interior characterized by the high density of brines that prevents mixing with the overlaying seawater, generating sharp chemoclines and redoxclines up to tens of meters thick that host a high concentration of microbial communities. Yet, a fundamental understanding of how such pycnoclines shape microbial life and the associated biogeochemical processes at a fine scale, remains elusive. Here, we applied high-precision sampling of the brine-seawater transition interface in the Suakin Deep, located at 2770 m in the central Red Sea, to reveal previously undocumented fine-scale community structuring and succession of metabolic groups along a salinity gradient only 1 m thick. Metagenomic profiling at a 10-cm-scale resolution highlighted spatial organization of key metabolic pathways and corresponding microbial functional units, emphasizing the prominent role and significance of salinity and oxygen in shaping their ecology. Nitrogen cycling processes are especially affected by the redoxcline with ammonia oxidation processes being taxa and layers specific, highlighting also the presence of novel microorganisms, such as novel Thaumarchaeota and anammox, adapted to the changing conditions of the chemocline. The findings render the transition zone as a critical niche for nitrogen cycling, with complementary metabolic networks, in turn underscoring the biogeochemical complexity of deep-sea brines.

Isotopic enrichment in Rhizoprionodon porosus (Poey, 1861) and Carcharhinus porosus (Ranzani, 1840) embryos.

Isotopic values of two Caribbean sharpnose shark Rhizoprionodon porosus litters (Poey, 1861) with two and three embryos and one litter of 11 smalltail shark Carcharhinus porosus embryos showed enriched 15 N and 13 C compared to their mothers. In R. porosus, embryonic isotope values were 3.06 ± 0.07‰ and 0.69 ± 0.15‰ greater than their mothers' for δ15 N and δ13 C, respectively, whereas in C. porosus, δ15 N and δ13 C were 1.79 ± 0.09‰ and 1.31 ± 0.17‰ greater in embryos than their mothers.

Stable-isotope analysis reveals sources of organic matter and ontogenic feeding shifts of a mangrove-dependent predator species, New Granada sea catfish, Ariopsis canteri.

To gain a better understanding on the trophic ecology of New Granada sea catfish, Ariopsis canteri, and their linkage to mangroves, nitrogen and stable carbon isotopes (δ15 N and δ13 C), as well as Bayesian mixing models, were used to explore trophic dynamics and potential ontogenic feeding shifts across different size classes: class I (8-20 cm), class II (21-32 cm) and class III (>32 cm). The study area was the estuary of the Atrato River Delta, where information about fish ecology is scarce. The δ13 C of size class I was lower (mean ± s.d. = -24.96 ± 0.69‰) than that of size classes II (-22.20 ± 0.90‰) and III (-22.00 ± 1.96‰). The δ15 N of size class I was lower (mean ± s.d. = 8.50 ± 0.67‰) than that of size classes II (9.77 ± 0.60‰) and III (10.00 ± 0.66‰). Body size was positively and significantly correlated to δ15 N and δ13 C. Individuals with LT > 32 cm presented the highest estimated trophic position (3.8). Five-source mixing models indicated that for class I, the mean estimated contribution of macroalgae was the highest (6%-57% c.i.), and for classes II and III, the mean estimated contribution of macrophytes was the highest (3%-53% c.i. and 4%-53% c.i., respectively). Ontogenetic feeding shifts of A. canteri were confirmed evidencing decreasing intraspecific competition between small and large individuals. Results suggest that mangroves are a nursery and feeding ground habitat for this species and that mangroves support A. canteri mainly due to the substrate/habitat that supports sources in the food webs. These results can be used in ecosystem-based fishery management focused on the protection of extensive mangrove areas in the southern Caribbean Sea.

Elucidating the Possible Involvement of Maize Aquaporins and Arbuscular Mycorrhizal Symbiosis in the Plant Ammonium and Urea Transport under Drought Stress Conditions.

This study investigates the possible involvement of maize aquaporins which are regulated by arbuscular mycorrhizae (AM) in the transport in planta of ammonium and/or urea under well-watered and drought stress conditions. The study also aims to better understand the implication of the AM symbiosis in the uptake of urea and ammonium and its effect on plant physiology and performance under drought stress conditions. AM and non-AM maize plants were cultivated under three levels of urea or ammonium fertilization (0, 3 µM or 10 mM) and subjected or not to drought stress. Plant aquaporins and physiological responses to these treatments were analyzed. AM increased plant biomass in absence of N fertilization or under low urea/ ammonium fertilization, but no effect of the AM symbiosis was observed under high N supply. This effect was associated with reduced oxidative damage to lipids and increased N accumulation in plant tissues. High N fertilization with either ammonium or urea enhanced net photosynthesis (AN) and stomatal conductance (gs) in plants maintained under well-watered conditions, but 14 days after drought stress imposition these parameters declined in AM plants fertilized with high N doses. The aquaporin ZmTIP1;1 was up-regulated by both urea and ammonium and could be transporting these two N forms in planta. The differential regulation of ZmTIP4;1 and ZmPIP2;4 with urea fertilization and of ZmPIP2;4 with NH4+ supply suggests that these two aquaporins may also play a role in N mobilization in planta. At the same time, these aquaporins were also differentially regulated by the AM symbiosis, suggesting a possible role in the AM-mediated plant N homeostasis that deserves future studies.

Discovery of Afifi, the shallowest and southernmost brine pool reported in the Red Sea.

The previously uncharted Afifi brine pool was discovered in the eastern shelf of the southern Red Sea. It is the shallowest brine basin yet reported in the Red Sea (depth range: 353.0 to 400.5 m). It presents a highly saline (228 g/L), thalassohaline, cold (23.3 °C), anoxic brine, inhabited by the bacterial classes KB1, Bacteroidia and Clostridia and the archaeal classes Methanobacteria and Deep Sea Euryarcheota Group. Functional assignments deduced from the taxonomy indicate methanogenesis and sulfur respiration to be important metabolic processes in this environment. The Afifi brine was remarkably enriched in dissolved inorganic carbon due to microbial respiration and in dissolved nitrogen, derived from anammox processes and denitrification, according to high δ15N values (+6.88‰, AIR). The Afifi brine show a linear increase in δ18O and δD relative to seawater that differs from the others Red Sea brine pools, indicating a non-hydrothermal origin, compatible with enrichment in evaporitic environments. Afifi brine was probably formed by venting of fossil connate waters from the evaporitic sediments beneath the seafloor, with a possible contribution from the dehydration of gypsum to anhydrite. Such origin is unique among the known Red Sea brine pools.

Persistent High-Risk HPV Infection and Molecular Changes Related to the Development of Cervical Cancer.

This article is a preliminary investigational study that is aimed at giving hints about the interesting biomarkers involved in the transition process from low-grade cervix lesion to invasive cervical cancer. Our study focuses on the risk factors and tumour molecular changes in one patient. First in 1986, she was diagnosed a preinvasive cervix lesion. Then, 16 years later, she was diagnosed an invasive cervical cancer. The 2002 diagnosis was a squamous cell carcinoma of the cervix, stage IIIB (FIGO), whereas in 1986, she had been diagnosed a high-grade squamous intraepithelial cervical lesion. Retrospectively, the analysis of samples of preneoplastic lesions and invasive cervical cancer confirmed the histopathological diagnoses and detected the presence of HPV type and HPV-16 variants, as well as the overexpression of proteins such as hTERT, IGF1Rα, IGF1Rß, CAIX, and GLUT1. Finally, the Arg72Pro polymorphism was detected in TP53. The role of high-risk HPV and HPV-16 variants and of hTERT, IGF1Rα, IGF1Rß, CAIX, and GLUT1 variations seemed confirmed in the development and progression of cervical cancer. As a result, analyzing the molecular changes in one and same tumour that progresses from a low-grade cervix lesion to invasive cervical cancer could provide valuable information in order to improve detection, diagnosis, and treatment in the future.

Interlaboratory test for stable carbon isotope analysis of dissolved inorganic carbon in geothermal fluids.

RATIONALE: Stable carbon isotope ratios have many applications in natural sciences. In the first worldwide interlaboratory proficiency test, the discrepancies in measured δ13 CDIC values of natural waters were up to σ = ±3‰. Therefore, we continued the investigation on the analytical data quality assurance of individual laboratories and internal consistency among laboratories worldwide. METHODS: We designed and performed an interlaboratory comparison exercise for δ13 C analyses of ten water and two solid samples (Na2 CO3 , CaCO3 ), including two synthetic samples prepared by dissolving the carbonates individually. Three laboratories analyzed an additional sample set to assess solution stability, at least one month after the first set analysis period. The δ13 C values were measured using dual inlet isotope ratio mass spectrometry (DI-IRMS) or continuous flow (CF)-IRMS. RESULTS: The δ13 C values of solid Na2 CO3 and its aqueous solution were -5.06 ± 0.21‰ and 5.32 ± 0.24‰, respectively, while the δ13 C value of solid CaCO3 was -4.49 ± 0.93‰. Similarly, the lake water has a consistent value (2.45 ± 0.19‰). The δ13 C values of geothermal water have a wide dispersion among individual laboratory measurements and among those of different laboratories; however, a trend exists in the δ13 C values measured at the three sampling points of each well. CONCLUSIONS: The δ13 C values of solid Na2 CO3 and its solution, and lake water (i.e. DIC concentration samples >100 mg/L carbon) are consistent among all the participating laboratories. The dispersion in the δ13 C values of solid CaCO3 is associated with its lower chemical affinity than that of Na2 CO3 . The poor reproducibility in the δ13 C values of geothermal fluids, collected at three points of a geothermal well, despite overall consistent trends regarding their collection points suggests inadequate sample handling (atmospheric CO2 exchange) and/or inappropriate analytical approaches (incomplete H3 PO4 acid reaction).

A Polyextreme Hydrothermal System Controlled by Iron: The Case of Dallol at the Afar Triangle.

One of the latest volcanic features of the Erta Ale range at the Afar Triangle (NE Ethiopia) has created a polyextreme hydrothermal system located at the Danakil depression on top of a protovolcano known as the dome of Dallol. The interaction of the underlying basaltic magma with the evaporitic salts of the Danakil depression has generated a unique, high-temperature (108 °C), hypersaline (NaCl supersaturated), hyperacidic (pH values from 0.1 to -1.7), oxygen-free hydrothermal site containing up to 150 g/L of iron. We find that the colorful brine pools and mineral patterns of Dallol derive from the slow oxygen diffusion and progressive oxidation of the dissolved ferrous iron, the iron-chlorine/-sulfate complexation, and the evaporation. These inorganic processes induce the precipitation of nanoscale jarosite-group minerals and iron(III)-oxyhydroxides over a vast deposition of halite displaying complex architectures. Our results suggest that life, if present under such conditions, does not play a dominant role in the geochemical cycling and mineral precipitation at Dallol as opposed to other hydrothermal sites. Dallol, a hydrothermal system controlled by iron, is a present-day laboratory for studying the precipitation and progressive oxidation of iron minerals, relevant for geochemical processes occurring at early Earth and Martian environments.

The 13C method as a robust alternative to 14C-based measurements of primary productivity in the Mediterranean Sea.

Due to the increasing constraints on using the radioactive isotope 14C to measure primary productivity (14C-PP), we determined the surface carbon fixation rates in the Mediterranean Sea, using the alternative stable isotope 13C method (13C-PP). Rates obtained (13C-POCp) were compared with simultaneous 14C-POCp measurements in samples of different volumes (72 mL and 1.2 L). We also tested the variation of the percentage of dissolved primary production (PER), to the total productivity using organic and inorganic filters (14C method). 13C-POCp rates ranged from 0.4, in the Ionian basin, to 1.5 mgC m-3 h-1 in the Ligurian region. These results agreed with those found with the 14C-PP in 1.2-L samples (two sample t-test, t = 1.035, df = 22, P = 0.31). However, we found that 14C-POCp rates derived from 72-mL incubations were 46% lower than those measured with 13C-PP. The discrepancy between large and small volume incubations was likely due to differences in the number of large phytoplankton cells within the community. PER values measured with silver membrane filters yielded similar results than those obtained using polycarbonate filters. Our findings showed that when the sample size is carefully chosen, the 13C-PP provide comparable results to 14C-PP even in waters of low productivity in the Mediterranean Sea.

Assembling the Dead, Gathering the Living: Radiocarbon Dating and Bayesian Modelling for Copper Age Valencina de la Concepción (Seville, Spain).

The great site of Valencina de la Concepción, near Seville in the lower Guadalquivir valley of southwest Spain, is presented in the context of debate about the nature of Copper Age society in southern Iberia as a whole. Many aspects of the layout, use, character and development of Valencina remain unclear, just as there are major unresolved questions about the kind of society represented there and in southern Iberia, from the late fourth to the late third millennium cal BC. This paper discusses 178 radiocarbon dates, from 17 excavated sectors within the c. 450 ha site, making it the best dated in later Iberian prehistory as a whole. Dates are modelled in a Bayesian statistical framework. The resulting formal date estimates provide the basis for both a new epistemological approach to the site and a much more detailed narrative of its development than previously available. Beginning in the 32nd century cal BC, a long-lasting tradition of simple, mainly collective and often successive burial was established at the site. Mud-vaulted tholoi appear to belong to the 29th or 28th centuries cal BC; large stone-vaulted tholoi such as La Pastora appear to date later in the sequence. There is plenty of evidence for a wide range of other activity, but no clear sign of permanent, large-scale residence or public buildings or spaces. Results in general support a model of increasingly competitive but ultimately unstable social relations, through various phases of emergence, social competition, display and hierarchisation, and eventual decline, over a period of c. 900 years.

Inter-laboratory test for oxygen and hydrogen stable isotope analyses of geothermal fluids: Assessment of reservoir fluid compositions.

RATIONALE: Knowledge of the accuracy and precision for oxygen (δ18 O values) and hydrogen (δ2 H values) stable isotope analyses of geothermal fluid samples is important to understand geothermal reservoir processes, such as partial boiling-condensation and encroachment of cold and reinjected waters. The challenging aspects of the analytical techniques for this specific matrix include memory effects and higher scatter of delta values with increasing total dissolved solids (TDS) concentrations, deterioration of Pt-catalysts by dissolved/gaseous H2 S for hydrogen isotope equilibration measurements and isotope salt effects that offset isotope ratios determined by gas equilibration techniques. METHODS: An inter-laboratory comparison exercise for the determination of the δ18 O and δ2 H values of nine geothermal fluid samples was conducted among eleven laboratories from eight countries (CeMIEGeo2017). The delta values were measured by dual inlet isotope ratio mass spectrometry (DI-IRMS), continuous flow IRMS (CF-IRMS) and/or laser absorption spectroscopy (LAS). Moreover, five of these laboratories analyzed an additional sample set at least one month after the analysis period of the first set. Statistical evaluation of all the results was performed to obtain the expected isotope ratios of each sample, which were then subsequently used in deep reservoir fluid composition calculations. RESULTS: The overall analytical precisions of the measurements were ± 0.2‰ for δ18 O values and ± 2.0‰ for δ2 H values within the 95% confidence interval. CONCLUSIONS: The measured and calculated δ18 O and δ2 H values of water sampled at the weir box, separator and wellhead of geothermal wells suggest the existence of hydrogen and oxygen isotope-exchange equilibrium between the liquid and vapor phases at all sampling points in the well. Thus, both procedures for calculating the isotopic compositions of the deep geothermal reservoir fluid - using either the analytical data of the liquid phase at the weir box together with those of vapor at the separator or the analytical data of liquid and vapor phases at the separator -are equally valid.