255 research outputs found

    Effects of Global Warming on Ancient Mammalian Communities and Their Environments

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    Current global warming affects the composition and dynamics of mammalian communities and can increase extinction risk; however, long-term effects of warming on mammals are less understood. Dietary reconstructions inferred from stable isotopes of fossil herbivorous mammalian tooth enamel document environmental and climatic changes in ancient ecosystems, including C(3)/C(4) transitions and relative seasonality.Here, we use stable carbon and oxygen isotopes preserved in fossil teeth to document the magnitude of mammalian dietary shifts and ancient floral change during geologically documented glacial and interglacial periods during the Pliocene (approximately 1.9 million years ago) and Pleistocene (approximately 1.3 million years ago) in Florida. Stable isotope data demonstrate increased aridity, increased C(4) grass consumption, inter-faunal dietary partitioning, increased isotopic niche breadth of mixed feeders, niche partitioning of phylogenetically similar taxa, and differences in relative seasonality with warming.Our data show that global warming resulted in dramatic vegetation and dietary changes even at lower latitudes (approximately 28 degrees N). Our results also question the use of models that predict the long term decline and extinction of species based on the assumption that niches are conserved over time. These findings have immediate relevance to clarifying possible biotic responses to current global warming in modern ecosystems

    Genetic control of Eucalyptus urophylla and E. grandis resistance to canker caused by Chrysoporthe cubensis

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    Chrysophorte cubensis induced canker occurs in nearly all tropical and subtropical regions where eucalypts are planted, causing losses in both wood quality and volume productivity, especially so in the warmer and more humid regions of Brazil. The wide inter and intra-specific genetic variability of resistance to canker among Eucalyptus species facilitates the selection of resistant plants. In this study, we evaluated resistance to this pathogen in five Eucalyptus grandis (G) and 15 E. urophylla (U) trees, as well as in 495 individuals from 27 progenies derived from crosses between the trees. In the field, six-months-old test seedlings were inoculated with C. cubensis. Lesion length in the xylem and bark was measured eight months later. The results demonstrated that xylem lesions could preferentially be used for the selection of resistant clones. Eight trees (7 U and 1 G) were susceptible, and the remainder (8 U and 4 G) resistant. Individual narrow and broad sense heritability estimates were 17 and 81%, respectively, thereby suggesting that canker resistance is quantitative and highly dependent on dominance and epistasis

    Matched sizes of activating and inhibitory receptor/ligand pairs are required for optimal signal integration by human Natural Killer cells

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    It has been suggested that receptor-ligand complexes segregate or co-localise within immune synapses according to their size, and this is important for receptor signaling. Here, we set out to test the importance of receptor-ligand complex dimensions for immune surveillance of target cells by human Natural Killer (NK) cells. NK cell activation is regulated by integrating signals from activating receptors, such as NKG2D, and inhibitory receptors, such as KIR2DL1. Elongating the NKG2D ligand MICA reduced its ability to trigger NK cell activation. Conversely, elongation of KIR2DL1 ligand HLA-C reduced its ability to inhibit NK cells. Whereas normal-sized HLA-C was most effective at inhibiting activation by normal-length MICA, only elongated HLA-C could inhibit activation by elongated MICA. Moreover, HLA-C and MICA that were matched in size co-localised, whereas HLA-C and MICA that were different in size were segregated. These results demonstrate that receptor-ligand dimensions are important in NK cell recognition, and suggest that optimal integration of activating and inhibitory receptor signals requires the receptor-ligand complexes to have similar dimensions

    6-thioguanine treatment in inflammatory bowel disease: A critical appraisal by a European 6-TG working party

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    Recently, the suggestion to use 6-thioguanine (6-TG) as an alternative thiopurine in patients with inflammatory bowel disease (IBD) has been discarded due to reports about possible (hepato) toxicity. During meetings arranged in Vienna and Prague in 2004, European experts applying 6-TG further on in IBD patients presented data on safety and efficacy of 6-TG. After thorough evaluation of its risk-benefit ratio, the group consented that 6-TG may still be considered as a rescue drug in stringently defined indications in IBD, albeit restricted to a clinical research setting. As a potential indication for administering 6-TG, we delineated the requirement for maintenance therapy as well as intolerance and/or resistance to aminosalicylates, azathioprine, 6-mercaptopurine, methotrexate and infliximab. Furthermore, indications are preferred in which surgery is thought to be inappropriate. The standard 6-TG dosage should not exceed 25 mg daily. Routine laboratory controls are mandatory in short intervals. Liver biopsies should be performed after 6-12 months, three years and then three-yearly accompanied by gastroduodenoscopy, to monitor for potential hepatotoxicity, including nodular regenerative hyperplasia (NRH) and veno-occlusive disease (VOD). Treatment with 6-TG must be discontinued in case of overt or histologically proven hepatotoxicity. Copyright (c) 2006 S. Karger AG, Basel

    Inhibition of glutamine synthetase in monocytes from patients with acute-on-chronic liver failure resuscitates their antibacterial and inflammatory capacity

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    OBJECTIVE: Acute-on-chronic liver failure (ACLF) is associated with dysfunctional circulating monocytes whereby patients become highly susceptible to bacterial infections. Here, we identify the pathways underlying monocyte dysfunction in ACLF and we investigate whether metabolic rewiring reinstates their phagocytic and inflammatory capacity. // DESIGN: Following phenotypic characterisation, we performed RNA sequencing on CD14+CD16- monocytes from patients with ACLF and decompensated alcoholic cirrhosis. Additionally, an in vitro model mimicking ACLF patient-derived features was implemented to investigate the efficacy of metabolic regulators on monocyte function. // RESULTS: Monocytes from patients with ACLF featured elevated frequencies of interleukin (IL)-10-producing cells, reduced human leucocyte antigen DR isotype (HLA-DR) expression and impaired phagocytic and oxidative burst capacity. Transcriptional profiling of isolated CD14+CD16- monocytes in ACLF revealed upregulation of an array of immunosuppressive parameters and compromised antibacterial and antigen presentation machinery. In contrast, monocytes in decompensated cirrhosis showed intact capacity to respond to inflammatory triggers. Culturing healthy monocytes in ACLF plasma mimicked the immunosuppressive characteristics observed in patients, inducing a blunted phagocytic response and metabolic program associated with a tolerant state. Metabolic rewiring of the cells using a pharmacological inhibitor of glutamine synthetase, partially restored the phagocytic and inflammatory capacity of in vitro generated- as well as ACLF patient-derived monocytes. Highlighting its biological relevance, the glutamine synthetase/glutaminase ratio of ACLF patient-derived monocytes positively correlated with disease severity scores. // CONCLUSION: In ACLF, monocytes feature a distinct transcriptional profile, polarised towards an immunotolerant state and altered metabolism. We demonstrated that metabolic rewiring of ACLF monocytes partially revives their function, opening up new options for therapeutic targeting in these patients

    Diet and food strategies in a southern al-Andalusian urban environment during Caliphal period, ecija, Sevilla

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    The Iberian medieval period is unique in European history due to the widespread socio-cultural changes that took place after the arrival of Arabs, Berbers and Islam in 711 AD. Recently, isotopic research has been insightful on dietary shifts, status, resource availability and the impact of environment. However, there is no published isotopic research exploring these factors in southern Iberian populations, and as the history of this area differs to the northern regions, this leaves a significant lacuna in our knowledge. This research fills this gap via isotopic analysis of human (n = 66) and faunal (n = 13) samples from the 9th to the 13th century Écija, a town renowned for high temperatures and salinity. Stable carbon (δ13C) and nitrogen (δ15N) isotopes were assessed from rib collagen, while carbon (δ13C) values were derived from enamel apatite. Human diet is consistent with C3 plant consumption with a very minor contribution of C4 plants, an interesting feature considering the suitability of Écija to C4 cereal production. δ15N values vary among adults, which may suggest variable animal protein consumption or isotopic variation within animal species due to differences in foddering. Consideration of δ13C collagen and apatite values together may indicate sugarcane consumption, while moderate δ15N values do not suggest a strong aridity or salinity effect. Comparison with other Iberian groups shows similarities relating to time and location rather than by religion, although more multi-isotopic studies combined with zooarchaeology and botany may reveal subtle differences unobservable in carbon and nitrogen collagen studies alone.OLC is funded by Plan Galego I2C mod.B (ED481D 2017/014). The research was partially funded by the projects “Galician Paleodiet” and by Consiliencia network (ED 431D2017/08) Xunta de GaliciaS

    Anthropic resource exploitation and use of the territory at the onset of social complexity in the Neolithic-Chalcolithic Western Pyrenees: a multi-isotope approach

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    Carbon (δ13C) and nitrogen (δ15N) stable isotope analyses from bone collagen provide information about the dietary protein input, while strontium isotopes (87Sr/86Sr) from tooth enamel give us data about provenance and potential territorial mobility of past populations. To date, isotopic results on the prehistory of the Western Pyrenees are scarce. In this article, we report human and faunal values of the mentioned isotopes from the Early-Middle Neolithic site of Fuente Hoz (Anuntzeta) and the Late Neolithic/Early Chalcolithic site of Kurtzebide (Letona, Zigoitia). The main objectives of this work are to analyze the dietary and territorial mobility patterns of these populations. Furthermore, as an additional aim, we will try to discuss social ranking based on the isotope data and existing literature on this topic in the region of study. Our results show that, based on the bioavailable Sr values, both purported local and non-local humans were buried together at the sites. Additionally, they suggest similar resource consumption based on C3 terrestrial resources (i.e. ovicaprids, bovids, and suids) as the main part of the protein input. Overall, this study sheds light on how individuals from different backgrounds were still buried together and shared the same dietary lifestyle at a time in the Prehistory of Iberia when social complexities started to appear

    The Steady State Great Ape? Long Term Isotopic Records Reveal the Effects of Season, Social Rank and Reproductive Status on Bonobo Feeding Behavior

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    Dietary ecology of extant great apes is known to respond to environmental conditions such as climate and food availability, but also to vary depending on social status and life history characteristics. Bonobos (Pan paniscus) live under comparatively steady ecological conditions in the evergreen rainforests of the Congo Basin. Bonobos are an ideal species for investigating influences of sociodemographic and physiological factors, such as female reproductive status, on diet. We investigate the long term dietary pattern in wild but fully habituated bonobos by stable isotope analysis in hair and integrating a variety of long-term sociodemographic information obtained through observations. We analyzed carbon and nitrogen stable isotopes in 432 hair sections obtained from 101 non-invasively collected hair samples. These samples represented the dietary behavior of 23 adult bonobos from 2008 through 2010. By including isotope and crude protein data from plants we could establish an isotope baseline and interpret the results of several general linear mixed models using the predictors climate, sex, social rank, reproductive state of females, adult age and age of infants. We found that low canopy foliage is a useful isotopic tracer for tropical rainforest settings, and consumption of terrestrial herbs best explains the temporal isotope patterns we found in carbon isotope values of bonobo hair. Only the diet of male bonobos was affected by social rank, with lower nitrogen isotope values in low-ranking young males. Female isotope values mainly differed between different stages of reproduction (cycling, pregnancy, lactation). These isotopic differences appear to be related to changes in dietary preference during pregnancy (high protein diet) and lactation (high energy diet), which allow to compensate for different nutritional needs during maternal investment
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