Characterising Inter-Individual Growth Variability of Patella vulgata Shell Through Calcein Marking Experiments: Consequences for Palaeo-Environmental Studies

International audienceSclerochronological data from archaeological shell middens provides crucial information about past environments and subsistence practices of coastal human populations. These studies rely on a strong knowledge of species-specific growth patterns, as it is the main driver of the quantity and quality of information recorded in biogenic carbonates. The limpet Patella vulgata is highly represented in eastern Atlantic shell middens. In this study, the micro-increment formation of its shell was investigated through in situ marking experiments, using calcein fluorochrome (150 mg.L−1) coupled with cohort study and local SST recording. Calcein-stained growth structures confirmed the efficacy of the fluorochrome, and our results shows a disturbed tidal increment formation, with on average more than one increment per day, but less than one increment per tide. Growth is not mainly influenced by environmental factors, but could be forced by competition among limpets and endogenous factor (age and sex), resulting in a highly heterogenous population in terms of growth rates. Growth interruption could not be detected solely by micro-increment observation, causing a major issue for cross-calibration with recorded temperatures, sclerochronological estimation of growth and isotopic profiles. For palaeo-environmental application, we recommend to consider that there is no general population pattern, even at a micro-habitat scale

Variations of the stable isotope ratios of carbon and oxygen of the Patella vulgata (Linnæus, 1758) shells according to the vertical zonation of collect

Isotopic investigations performed on carbonated shells from anthropogenic middens provide information about past environments and cultural practices of the human populations who left these vestiges. Patella vulgata, an intertidal gastropod that inhabits northwest Atlantic rocky shores, is commonly occurring as shells in European shell middens, constituting therefore a good candidate for isotopic studies. However, high tidal ranges characterize most of European Atlantic coastlines, and species largely distributed upper to lower foreshore, as Patella sp., may encounter pronounced variations in immersion time depending on their elevation in the intertidal zone, which could affect their shell stable isotopic ratios. In this study, we compared carbon and oxygen stable isotopes of Patella vulgata shells collected in the same station at three different cotidal levels. Isotopic measurements are analyzed in terms of individual growth and aim to characterize the cotidal origin of the specimens. Our results demonstrate the absence of a significant link between the cotidal level on the shore and the growth and δ18O profiles of the shell, as high shore and low shore shells show the highest similitude while medium shore shells had a reduced growth with a higher heterogeneity. Consequently, the SST reconstructions were not significantly different. Thus, the use of the δ18O of archaeological shells as an SST proxy appears unaffected by the cotidal origin of the specimens. In contrast, the δ13C scales from the high shore (lower δ13C values) to the low shore (higher δ13C), constituting a promising new proxy for determining the precise elevation in the intertidal zone where the shells were collected

Isotopic signature of ancient limpet shells as indicator of seasonal harvesting patterns in archaeological context

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Determining a season of collect from oxygen isotopes of Patella vulgata shells: the case of Molene archipelago (Finistère, France)

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Les coquilles de patelles anciennes comme sources de connaissances paléoenvironnementales et ethnoarchéologiques : le cas de l’amas coquillier de l’île de Béniguet en mer d’Iroise

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Les coquilles de patelles anciennes, sources de connaissances paléo-environnementales et archéoanthropologiques

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Ancient limpet shells as paleo-environmental and ethno-archaeological archives: the case of Beniguet Island's shell middens (Iroise Sea)

International audienceDuring the winter 2013-2014, severe storm events caused a coastal erosion in the southern part of the Beniguet Island (Brittany, France). The associated shoreline retreat had uncovered three layers of shell middens interbedded into an aeolian sand dune deposit. From several radiocarbon dating crossed with the study of ceramic and lithic contents, the shell middens were dated to the Final Neolithic (2400 BC), the Early Bronze Age (2000 BC) and the Early Middle Age (800 AD) respectively. This site offers a unique opportunity to collect two types of information: palaeo-environmental (palaeo-temperature of sea water) and archaeological (determination of harvest season). In this study, we focus on gastropod of the genus Patella which represent 90% of the remains found in this midden. This organism is potentially a highly valuable archive for these environments because they are intertidal and relatively sedentary. We studied the growth rings in the outer calcitic layer of individual limpet shells from the Neolithic, Early Bronze Age and Present Day populations. We report here the results of δ18O analyses. We found a similarity between the reconstructed palaeo-temperature in the Neolithic and the Present periods (between 13 and 14 • C in summer and about 8 – 9 • C in winter). However, palaeo-temperatures of the Early Bronze Age shells are significantly lower in winter (5 – 6 • C). Moreover, the initial results of the δ18O analyses at the margin of these shells showed that they were harvested during a specific season (end of spring or early summer). Additional work will be done to address questions about shell growth dynamics of these species. These results confirm the interest of using ancient limpet shells as palaeo-environmental and archaeological archives

Vies insulaires et contraintes environnementales durant la Préhistoire : exemple de l’archipel de Molène

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Food-Derived Hemorphins Cross Intestinal and Blood–Brain Barriers In Vitro

A qualitative study is presented, where the main question was whether food-derived hemorphins, i.e., originating from digested alimentary hemoglobin, could pass the intestinal barrier and/or the blood–brain barrier (BBB). Once absorbed, hemorphins are opioid receptor (OR) ligands that may interact with peripheral and central OR and have effects on food intake and energy balance regulation. LLVV-YPWT (LLVV-H4), LVV-H4, VV-H4, VV-YPWTQRF (VV-H7), and VV-H7 hemorphins that were previously identified in the 120 min digest resulting from the simulated gastrointestinal digestion of hemoglobin have been synthesized to be tested in in vitro models of passage of IB and BBB. LC-MS/MS analyses yielded that all hemorphins, except the LLVV-H4 sequence, were able to cross intact the human intestinal epithelium model with Caco-2 cells within 5–60 min when applied at 5 mM. Moreover, all hemorphins crossed intact the human BBB model with brain-like endothelial cells (BLEC) within 30 min when applied at 100 µM. Fragments of these hemorphins were also detected, especially the YPWT common tetrapeptide that retains OR-binding capacity. A cAMP assay performed in Caco-2 cells indicates that tested hemorphins behave as OR agonists in these cells by reducing cAMP production. We further provide preliminary results regarding the effects of hemorphins on tight junction proteins, specifically here the claudin-4 that is involved in paracellular permeability. All hemorphins at 100 µM, except the LLVV-H4 peptide, significantly decreased claudin-4 mRNA levels in the Caco-2 intestinal model. This in vitro study is a first step toward demonstrating food-derived hemorphins bioavailability which is in line with the growing body of evidence supporting physiological functions for food-derived peptides

Treatment guidelines of metastatic colorectal cancer in older patients from the French Society of Geriatric Oncology (SoFOG)

International audienceBackground: Several guidelines dedicated to metastatic colorectal cancer (mCRC) are available. Since 2013 no recent guidelines are specifically dedicated to older patients and based on a systematic review. Materials and methods: A multidisciplinary Task Force with digestive oncologists, geriatricians and methodologists from the SoFOG was formed in 2016 to update recommendations on medical treatment of mCRC based on a systematic review of publications from 2000 to 2018. Search strategy has followed a standardized protocol from the formulation of clinical questions and definition of a search algorithm to the selection of complete articles for recommendations. Results: The four selected key questions were: For which older patients with mCRC can we considered: (1) Any chemotherapy, (2) Mono or poly-chemotherapy, (3) Anti-angiogenic therapy, (4) Other targeted therapy. Main recommendations for older patients are: (1) Omission of chemotherapy should be discussed with a geriatrician for patients with severe comorbidities, advanced dementia, uncontrolled psychiatric disorder or severe loss of autonomy. (2) If tumor response is not the main aim, a mono-chemotherapy with 5-fluorouracil combined with bevacizumab is recommended as first-line. (3) For patients with symptoms related to metastases or with a planned metastasis ablation, a doublet chemotherapy combined with bevacizumab or anti-EGFR antibody in the context of a RAS wild type tumor is recommended as first-line. Preliminary data suggest that regorafenib may be used, in its registered indication, in patients under 80 with a performance status of 0 and no autonomy alterations and that trifluridine-tipiracil may be used with a tight supervising of hematological function