2,023 research outputs found

    Optimization of ultrasound-assisted extraction of biomass from olive trees using response surface methodology

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    Olive tree pruning biomass (OTP) and olive mill leaves (OML) are the main residual lignocellulosic biomasses that are generated from olive trees. They have been proposed as a source of value-added compounds and biofuels within the biorefinery concept. In this work, the optimization of an ultrasound-assisted extraction (UAE) process was performed to extract antioxidant compounds present in OTP and OML. The effect of the three parameters, ethanol/water ratio (20, 50, 80% of ethanol concentration), amplitude percentage (30, 50, 70%) and ultrasonication time (5, 10, 15 min), on the responses of total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities (DPPH, ABTS and FRAP) were evaluated following a Box–Behnken experimental design. The optimal conditions obtained from the model, taking into account simultaneously the five responses, were quite similar for OTP and OML, with 70% amplitude and 15 min for both biomasses and a slight difference in the optimum concentration of ethanol. (54.5% versus 51.3% for OTP and OML, respectively). When comparing the antioxidant activities obtained with OTP and OML, higher values were obtained for OML (around 40% more than for OTP). The antioxidant activities reached experimentally under the optimized conditions were 31.6 mg of TE/g of OTP and 42.5 mg of TE/g of OML with the DPPH method, 66.5 mg of TE/g of OTP and 95.9 mg of TE/g of OML with the ABTS method, and 36.4 mg of TE/g of OTP and 49.7 mg of TE/g of OML with the FRAP method. Both OTP and OML could be a potential source of natural antioxidants

    Effects of cold winters and roost site stability on population development of non-native Asian ring-necked parakeets (Alexandrinus manillensis) in temperate Central Europe – Results of a 16-year census

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    Asian ring-necked parakeets (Alexandrinus manillensis, formerly Psittacula krameri, hereafter RNP) first bred in Germany in 1969. Since then, RNP numbers increased in all three major German subpopulations (Rhineland, Rhine-Main, Rhine-Neckar) over the period 2003–2018. In the Rhine-Neckar region, the population increased to more than fivefold within only 15 years. Interestingly, there was no significant breeding range expansion of  RNP in the period 2010–2018. In 2018, the total number of RNP in Germany amounted to >16,200 birds. Differences in RNP censuses between years were evident. Surprisingly, cold winters (extreme value, −13.7 °C) and cold weather conditions in the breeding season (coldest month average, −1.36 °C) were not able to explain between-year variation. This finding suggests that in general winter mortality is low – with exceptions for winters 2008/2009 and 2009/2010, and a population-relevant loss of broods is low in our study population. Surprisingly, the social behaviour in terms of spatio-temporal stability of roost sites could well explain positive and negative population trends. Years of spatially stable and regularly used roost sites seem to correlate with increasing population sizes. In contrast, known shifts of RNP among different roost sites or the formations of new roost sites by split are related to population stagnation or a decrease in numbers. Climate change may lead to further range expansion as cities not suitable yet for RNP may become so in the near future.

    Dominant predators mediate the impact of habitat size on trophic structure in bromeliad invertebrate communities

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    Local habitat size has been shown to influence colonization and extinction processes of species in patchy environments. However, species differ in body size, mobility, and trophic level, and may not respond in the same way to habitat size. Thus far, we have a limited understanding of how habitat size influences the structure of multitrophic communities and to what extent the effects may be generalizable over a broad geographic range. Here, we used water-filled bromeliads of different sizes as a natural model system to examine the effects of habitat size on the trophic structure of their inhabiting invertebrate communities. We collected composition and biomass data from 651 bromeliad communities from eight sites across Central and South America differing in environmental conditions, species pools, and the presence of large-bodied odonate predators. We found that trophic structure in the communities changed dramatically with changes in habitat (bromeliad) size. Detritivore : resource ratios showed a consistent negative relationship with habitat size across sites. In contrast, changes in predator : detritivore (prey) ratios depended on the presence of odonates as dominant predators in the regional pool. At sites without odonates, predator : detritivore biomass ratios decreased with increasing habitat size. At sites with odonates, we found odonates to be more frequently present in large than in small bromeliads, and predator : detritivore biomass ratios increased with increasing habitat size to the point where some trophic pyramids became inverted. Our results show that the distribution of biomass amongst food-web levels depends strongly on habitat size, largely irrespective of geographic differences in environmental conditions or detritivore species compositions. However, the presence of large-bodied predators in the regional species pool may fundamentally alter this relationship between habitat size and trophic structure. We conclude that taking into account the response and multitrophic effects of dominant, mobile species may be critical when predicting changes in community structure along a habitat-size gradient.Fil: Petermann, Jana S.. Freie Universitat Berlin. Institute of Biology; AlemaniaFil: Farjalla, Vinicius F.. Universidade Federal do Rio de Janeiro; BrasilFil: Jocque, Merlijn. State University Of New Jersey; Estados UnidosFil: Kratina, Pavel. Queen Mary University Of London. School of Biological and Chemical Sciences; Reino UnidoFil: Macdonald, Andrew. University Of British Columbia; CanadĂĄFil: Marino, Nicholas. Universidade Federal do Rio de Janeiro; BrasilFil: de Omena, Paula. Universidade Estadual de Campinas; BrasilFil: Piccoli, Gustavo. Universidade de Sao Paulo; BrasilFil: Richardson, Michael. Universidad de Puerto Rico; Puerto RicoFil: Richardson, Barbara. Universidad de Puerto Rico; Puerto RicoFil: Romero, Gustavo. Universidade Estadual de Campinas; BrasilFil: Videla, Martin. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico CĂłrdoba. Instituto Multidisciplinario de BiologĂ­a Vegetal (p); Argentina. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas, FĂ­sicas y Naturales. Centro de Investigaciones EntomolĂłgicas de CĂłrdoba; ArgentinaFil: Srivastava, Diane. University Of British Columbia; Canad

    Transfer hydrogenation and antiproliferative activity of tethered half-sandwich organoruthenium catalysts

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    We report the synthesis and characterization of four neutral organometallic tethered complexes, [Ru(η6-Ph(CH2)3-ethylenediamine-N-R)Cl], where R = methanesulfonyl (Ms, 1), toluenesulfonyl (Ts, 2), 4-trifluoromethylbenzenesulfonyl (Tf, 3), and 4-nitrobenzenesulfonyl (Nb, 4), including their X-ray crystal structures. These complexes exhibit moderate antiproliferative activity toward human ovarian, lung, hepatocellular, and breast cancer cell lines. Complex 2 in particular exhibits a low cross-resistance with cisplatin. The complexes show potent catalytic activity in the transfer hydrogenation of NAD+ to NADH with formate as hydride donor in aqueous solution (310 K, pH 7). Substituents on the chelated ligand decreased the turnover frequency in the order Nb > Tf > Ts > Ms. An enhancement of antiproliferative activity (up to 22%) was observed on coadministration with nontoxic concentrations of sodium formate (0.5–2 mM). Complex 2 binds to nucleobase guanine (9-EtG), but DNA appears not to be the target, as little binding to calf thymus DNA or bacterial plasmid DNA was observed. In addition, complex 2 reacts rapidly with glutathione (GSH), which might hamper transfer hydrogenation reactions in cells. Complex 2 induced a dose-dependent G1 cell cycle arrest after 24 h exposure in A2780 human ovarian cancer cells while promoting an increase in reactive oxygen species (ROS), which is likely to contribute to its antiproliferative activity

    Personal care product use and lifestyle affect phthalate and DINCH metabolite levels in teenagers and young adults

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    Humans are widely exposed to phthalates and their novel substitutes, and considering the negative health effects associated with some phthalates, it is crucial to understand population levels and exposure determinants. This study is focused on 300 urine samples from teenagers (aged 12-17) and 300 from young adults (aged 18-37) living in Czechia collected in 2019 and 2020 to assess 17 plasticizer metabolites as biomarkers of exposure. We identified widespread phthalate exposure in the study population. The diethyl phthalate metabolite monoethyl phthalate (MEP) and three di (2-ethylhexyl) phthalate metabolites were detected in the urine of >99% of study participants. The highest median concentrations were found for metabolites of low-molecular-weight (LMW) phthalates: mono-n-butyl phthalate (MnBP), monoisobutyl phthalate (MiBP) and MEP (60.7; 52.6 and 17.6 Όg/L in young adults). 1,2-cyclohexanedicarboxylic acid diisononyl ester (DINCH) metabolites were present in 68.2% of the samples with a median of 1.24 Όg/L for both cohorts. Concentrations of MnBP and MiBP were similar to other European populations, but 5-6 times higher than in populations in North America. We also observed large variability in phthalate exposures within the study population, with 2-3 orders of magnitude differences in urinary metabolites between high and low exposed individuals. The concentrations varied with season, gender, age, and lifestyle factors. A relationship was found between high levels of MEP and high overall use of personal care products (PCPs). Cluster analysis suggested that phthalate exposures depend on season and multiple lifestyle factors, like time spent indoors and use of PCPs, which combine to lead to the observed widespread presence of phthalate metabolites in both study populations. Participants who spent more time indoors, particularly noticeably during colder months, had higher levels of high-molecular weight phthalate metabolites, whereas participants with higher PCP use, particularly women, tended to have higher concentration of LMW phthalate metabolites.Authors thank the Research Infrastructure RECETOX RI (No. LM2018121) and CETOCOEN EXCELLENCE (CZ.02.1.01/0.0/0.0/17_043/0009632) for a supportive background. The work was supported by the Operational Programme Research, Development and Innovation – project Cetocoen Plus (CZ.02.1.01/0.0/0.0/15_003/0000469) and the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 857560. This study has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 733032. We thank all collaborating field workers, laboratory and administrative personnel, and especially the cohort participants who invested their time and provided samples and information for this study. This study reflects only the authors’ view and the European Commission is not responsible for any use that may be made of the information it contains.S

    Just Another Day on Twitter: A Complete 24 Hours of Twitter Data

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    At the end of October 2022, Elon Musk concluded his acquisition of Twitter. In the weeks and months before that, several questions were publicly discussed that were not only of interest to the platform's future buyers, but also of high relevance to the Computational Social Science research community. For example, how many active users does the platform have? What percentage of accounts on the site are bots? And, what are the dominating topics and sub-topical spheres on the platform? In a globally coordinated effort of 80 scholars to shed light on these questions, and to offer a dataset that will equip other researchers to do the same, we have collected all 375 million tweets published within a 24-hour time period starting on September 21, 2022. To the best of our knowledge, this is the first complete 24-hour Twitter dataset that is available for the research community. With it, the present work aims to accomplish two goals. First, we seek to answer the aforementioned questions and provide descriptive metrics about Twitter that can serve as references for other researchers. Second, we create a baseline dataset for future research that can be used to study the potential impact of the platform's ownership change

    The role of grazers in early-life stages of Cystoseira sensu lato can be crucial in the restoration of marine forests

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    Grazing is one of the most important biological factors controlling the abundance of early-life stages of fucoids and one of the major issues when restoring marine forests. Benthic macroinvertebrates (e.g., sea urchins) and fish shape and regulate benthic macroalgal communities from polar to tropical regions and can be responsible for regime shifts leading to the predominance of turfs and/or barren grounds. However, other herbivores (i.e., mesograzers) could also significantly participate in the grazing, especially on early-life stages, hampering the persistence and capacity of Cystoseira sensu lato populations to recover after major disturbances and being a cause of failure of restoration actions. We performed experiments in the field and in mesocosm in order to investigate the herbivory pressure and the effects of different grazers on recruits of Cystoseira compressa. The results highlight that non-strict herbivorous invertebrates, such as Clibanarius erythropus, Cerithium vulgatum, and Idotea balthica, graze on recruits of Cystoseira s.l. spp., with I. balthica showing the highest consumption rate. We concluded that biotic factors such as herbivory, which affect key life stages, can be crucial for the conservation of Cystoseira s.l. forests and need to be better understood and considered on a case-by-case basis when planning restoration actions

    FAMIN is a multifunctional purine enzyme enabling the purine nucleotide cycle

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    Mutations in FAMIN cause arthritis and inflammatory bowel disease in early childhood, and a common genetic variant increases risk for Crohn’s disease and leprosy. We developed an unbiased liquid chromatography mass spectrometry screen for enzymatic activity of this orphan protein. We report that FAMIN phosphorolytically cleaves adenosine into adenine and ribose-1-phosphate. Such activity was considered absent from eukaryotic metabolism. FAMIN and its prokaryotic paralogues additionally have adenosine deaminase, purine nucleoside phosphorylase, and S-methyl-5'-thioadenosine phosphorylase activity, hence combine activities of the namesake enzymes of central purine metabolism. FAMIN enables in macrophages a purine nucleotide cycle (PNC) between adenosine and inosine monophosphate and adenylosuccinate, which consumes aspartate and releases fumarate in a manner involving fatty acid oxidation and ATP-citrate lyase activity. This macrophage PNC synchronises mitochondrial activity with glycolysis by balancing electron transfer to mitochondria, thereby supporting glycolytic activity and promoting oxidative phosphorylation and mitochondrial H+ and phosphate recycling.Includes ERC. Wellcome Trust and MRC

    Cross-Species Single-Cell Analysis Reveals Divergence of the Primate Microglia Program

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    Summary Microglia, the brain-resident immune cells, are critically involved in many physiological and pathological brain processes, including neurodegeneration. Here we characterize microglia morphology and transcriptional programs across ten species spanning more than 450 million years of evolution. We find that microglia express a conserved core gene program of orthologous genes from rodents to humans, including ligands and receptors associated with interactions between glia and neurons. In most species, microglia show a single dominant transcriptional state, whereas human microglia display significant heterogeneity. In addition, we observed notable differences in several gene modules of rodents compared with primate microglia, including complement, phagocytic, and susceptibility genes to neurodegeneration, such as Alzheimer’s and Parkinson’s disease. Our study provides an essential resource of conserved and divergent microglia pathways across evolution, with important implications for future development of microglia-based therapies in humans
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