306 research outputs found

    The era of sustainable development and the challenge of climate change

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    Sustainability makes it possible to understand that the human being is facing a world with exhaustible resources and limited needs, with a population in constant growth and with economic progress based on obsolete technologies that generate a huge energy consumption, apart from billions of tons of wastes added to the ecosystem. These factors unleash catastrophic climatic consequences that have put the “world” on alert when is understood that there is a limit of planetary support capacity and that we are approaching the collapse of the ecosystem and endangering future generations, in addition to undermining the quality of life of all living beings because they exceed the capacity for natural balance of the ecosystems that support it. The increase in poverty, the overproduction of waste, the enormous North-South differences, the desertification and climate change are some of the main factors that human beings must face with great urgency. Regarding this last factor, it should be noted that today it has become a problem of multidimensional proportions that involves governments, organizations and entire societies with the aim of reducing its catastrophic global consequences and has been categorized as one of the greatest challenges of the world in the 21st century. Damage to the environment is becoming an issue that has received greater interest and attention over the years. Therefore, it is necessary a construct that includes ecological and development perspectives, that is, Sustainable Development. Under this context, this article aims to analyse in detail this concept, its origins and evolution, as well as its dimensions, to also establish its link with climate change, both inseparable factors.Sustainability makes it possible to understand that human beings are facing a world with exhaustible resources, with a constantly growing population and with economic progress based on obsolete technologies that generate overflowing energy consumption, generating billions of tonnes of waste that are added to the ecosystem. These factors trigger catastrophic climatic consequences that have put the “world” on alert as it realizes that there is a planetary carrying capacity limit and that we are approaching the collapse of the ecosystem and endangering future generations. In addition to undermining the quality of life of all living beings present, by exceeding the natural equilibrium capacity of the ecosystems that sustain it. In order to answer this question, this article has reviewed the literature on the subject that is the subject of so much debate. The aim of this article is therefore to analyse the concept in detail, in order to establish its link with climate change, both of which are inseparable factors. It has concluded that climate change today has become a problem of multidimensional proportions, that involves entire institutions and societies, in order to mitigate its catastrophic global consequences, and has been categorized as one of the greatest challenges of this century. Not only that, but social justice is becoming increasingly important for social actors interacting with the environment

    Equilibrium hydrostatic equation and Newtonian limit of the singular f(R) gravity

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    We derive the equilibrium hydrostatic equation of a spherical star for any gravitational Lagrangian density of the form L=gf(R)L=\sqrt{-g}f(R). The Palatini variational principle for the Helmholtz Lagrangian in the Einstein gauge is used to obtain the field equations in this gauge. The equilibrium hydrostatic equation is obtained and is used to study the Newtonian limit for f(R)=Ra23Rf(R)=R-\frac{a^{2}}{3R}. The same procedure is carried out for the more generally case f(R)=R1n+2an+1Rnf(R)=R-\frac{1}{n+2}\frac{a^{n+1}}{R^{n}} giving a good Newtonian limit.Comment: Revised version, to appear in Classical and Quantum Gravity

    The Gammaherpesvirus m2 Protein Manipulates the Fyn/Vav Pathway through a Multidocking Mechanism of Assembly

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    To establish latent infections in B-cells, gammaherpesviruses express proteins in the infected B-cells of the host that spuriously activate signalling pathways located downstream of the B-cell receptor. One such protein is M2, a murine gammaherpesvirus 68-encoded molecule that activates the Vav1/Rac1 pathway via the formation of trimolecular complexes with Scr family members. Previous reports have shown that the formation of this heteromolecular complex involves interactions between a proline rich region of M2 and the Vav1 and Fyn SH3 domains. Here, we show that the optimal association of these proteins requires a second structural motif encompassing two tyrosine residues (Tyr120 and 129). These residues are inducibly phosphorylated by Fyn in non-hematopoietic cells and constitutively phosphorylated in B-cells. We also demonstrate that the phosphorylation of Tyr120 creates specific docking sites for the SH2 domains of both Vav1 and Fyn, a condition sine qua non for the optimal association of these two signalling proteins in vivo. Interestingly, signaling experiments indicate that the expression of M2 in B-cells promotes the tyrosine phosphorylation of Vav1 and additional signaling proteins, a biological process that requires the integrity of both the M2 phosphotyrosine and proline rich region motifs. By infecting mice with viruses mutated in the m2 locus, we show that the integrity of each of these two M2 docking motifs is essential for the early steps of murine gammaherpesvirus-68 latency. Taken together, these results indicate that the M2 phosphotyrosine motif and the previously described M2 proline rich region work in a concerted manner to manipulate the signaling machinery of the host B-cell

    Compactifying the state space for alternative theories of gravity

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    In this paper we address important issues surrounding the choice of variables when performing a dynamical systems analysis of alternative theories of gravity. We discuss the advantages and disadvantages of compactifying the state space, and illustrate this using two examples. We first show how to define a compact state space for the class of LRS Bianchi type I models in RnR^n-gravity and compare to a non--compact expansion--normalised approach. In the second example we consider the flat Friedmann matter subspace of the previous example, and compare the compact analysis to studies where non-compact non--expansion--normalised variables were used. In both examples we comment on the existence of bouncing or recollapsing orbits as well as the existence of static models.Comment: 18 pages, revised to match published versio

    Dynamics of f(R)-cosmologies containing Einstein static models

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    We study the dynamics of homogeneous isotropic FRW cosmologies with positive spatial curvature in f(R)f(R)-gravity, paying special attention to the existence of Einstein static models and only study forms of f(R)=Rnf(R)=R^n for which these static models have been shown to exist. We construct a compact state space and identify past and future attractors of the system and recover a previously discovered future attractor corresponding to an expanding accelerating model. We also discuss the existence of universes which have both a past and future bounce, a phenomenon which is absent in General Relativity.Comment: 14 pages, 6 figure

    RAS at the Golgi antagonizes malignant transformation through PTPRκ-mediated inhibition of ERK activation

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    © The Author(s) 2018.RAS GTPases are frequently mutated in human cancer. H- and NRAS isoforms are distributed over both plasma-membrane and endomembranes, including the Golgi complex, but how this organizational context contributes to cellular transformation is unknown. Here we show that RAS at the Golgi is selectively activated by apoptogenic stimuli and antagonizes cell survival by suppressing ERK activity through the induction of PTPRκ, which targets CRAF for dephosphorylation. Consistently, in contrast to what occurs at the plasma-membrane, RAS at the Golgi cannot induce melanoma in zebrafish. Inactivation of PTPRκ, which occurs frequently in human melanoma, often coincident with TP53 inactivation, accelerates RAS-ERK pathway-driven melanomagenesis in zebrafish. Likewise, tp53 disruption in zebrafish facilitates oncogenesis driven by RAS from the Golgi complex. Thus, RAS oncogenic potential is strictly dependent on its sublocalization, with Golgi complex-located RAS antagonizing tumor development.We are grateful to Drs: Ignacio Rubio, Yardena Samuels, Mariano Barbacid and Javier León for providing reagents; and Alicia Noriega, Sandra Zunzunegui y Victor Campa for technical support. Crespo laboratory is supported by grant SAF-2015 63638R (MINECO/ FEDER, UE); by Red Temática de Investigación Cooperativa sobre el Cáncer (RTICC). RD/12/0036/0033 and by Asociación Española Contra el Cáncer (AECC), grant GCB141423113. Work in the Hurlstone laboratory was unded by a grant from the European Research Council (ERC-2011-StG-282059 PROMINENT). B.C. is supported by a Retos Jóvenes Investigadores grant SAF2015-73364-JIN (AEI/FEDER, UE) and a grant from Fundación Francisco Cobos. X.R.B. is supported by grants from the CastillaLeón Government (BIO/SA01/15, CSI049U16), MINECO (SAF2015-64556-R, RD12/ 0036/0002), Worldwide Cancer Research (14-1248), Ramón Areces Foundation, andAECC (GC16173472GARC). Spanish funding to P.C., B.C., and X.R.B. is partially supported by the European Regional Development Fund

    Human Vav1 Expression in Hematopoietic and Cancer Cell Lines Is Regulated by c-Myb and by CpG Methylation

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    Vav1 is a signal transducer protein that functions as a guanine nucleotide exchange factor for the Rho/Rac GTPases in the hematopoietic system where it is exclusively expressed. Recently, Vav1 was shown to be involved in several human malignancies including neuroblastoma, lung cancer, and pancreatic ductal adenocarcinoma (PDA). Although some factors that affect vav1 expression are known, neither the physiological nor pathological regulation of vav1 expression is completely understood. We demonstrate herein that mutations in putative transcription factor binding sites at the vav1 promoter affect its transcription in cells of different histological origin. Among these sites is a consensus site for c-Myb, a hematopoietic-specific transcription factor that is also found in Vav1-expressing lung cancer cell lines. Depletion of c-Myb using siRNA led to a dramatic reduction in vav1 expression in these cells. Consistent with this, co-transfection of c-Myb activated transcription of a vav1 promoter-luciferase reporter gene construct in lung cancer cells devoid of Vav1 expression. Together, these results indicate that c-Myb is involved in vav1 expression in lung cancer cells. We also explored the methylation status of the vav1 promoter. Bisulfite sequencing revealed that the vav1 promoter was completely unmethylated in human lymphocytes, but methylated to various degrees in tissues that do not normally express vav1. The vav1 promoter does not contain CpG islands in proximity to the transcription start site; however, we demonstrated that methylation of a CpG dinucleotide at a consensus Sp1 binding site in the vav1 promoter interferes with protein binding in vitro. Our data identify two regulatory mechanisms for vav1 expression: binding of c-Myb and CpG methylation of 5′ regulatory sequences. Mutation of other putative transcription factor binding sites suggests that additional factors regulate vav1 expression as well

    Tracking pollutants in a municipal sewage network impairing the operation of a wastewater treatment plant

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    This work provides a screening of organic contaminants and characterization of the dissolved organic matter in the sewer network until the municipal wastewater treatment plant (WWTP), identifying the network areas with a higher degree of contamination and their impact on the WWTP performance, particularly in the activated sludge reactor. Three monitoring campaigns were carried out at six selected locations of the sewage system (PVZ-1, PVZ-2, PS-F, PS-VC, CP-VC, and PS-T), influent (WWTPINF) and effluent (WWTPEFF) of the WWTP. Advanced analytical techniques were employed, namely excitation/emission matrix fluorescence-parallel factor analysis (EEM-PARAFAC), size exclusion chromatography with organic carbon detector (SEC-OCD), and liquid chromatography with high-resolution-mass spectrometric detection (LC-HRMS). EEM-PARAFAC showed higher fluorescence intensity for the protein-like component (C2), particularly at CP-VC (near seafood industries) associated with the presence of surfactants (~50 mg/L). SEC-OCD highlighted the WWTP efficiency in removing low molecular weight acids and neutrals. LC-HRMS tentatively identified 108 compounds of emerging concern (CEC) and similar detection patterns were obtained for all wastewater samples, except for PVZ-2 (lower detection), many of which occurred in the effluent. Eight CECs included on relevant Watch-Lists were detected in all WWTPEFF samples. Furthermore, 111 surfactants were detected, the classes more frequently found being alcohol ethoxylates (AEOs), nonylphenol polyethoxylates (NPEOs) and linear alkylbenzene sulphonates (LAS). The continuous presence of LAS and NPEOs allied to surfactants concentrations in the WWTPINF of 15–20 mg/L, with CP-VC location (linked with food industries) as an important contributor, explain the morphological changes in the activated sludge and high LAS content in the dewatered sludge, which may have impacted WWTP performance.i) Base-UIDB/50020/2020 and Programmatic-UIDP/50020/2020 Funding of LSRE-LCM, funded by national funds through FCT/MCTES (PIDDAC); ii) European Regional Development Fund through the Interreg V-A Spain-Portugal Programme (POCTEP) 2014–2020 (ref. 0725_NOR_WATER_1_P); iii) Xunta de Galicia (Verónica Castro predoctoral contract: ED481A-2017/156, and ED431C2017/36), the Spanish Agencia Estatal de Investigación – MCIN/AEI/ 10.13039/501100011033 (ref. PID2020-117686RB-C32); iv) NORTE-01-0145-FEDER-000069 (Healthy Waters) co-funded by European Regional Development Fund (ERDF), through North Portugal Regional Operational Programme (NORTE2020), under the PORTUGAL 2020 Partnership Agreement. The authors also acknowledge Águas do Norte, S.A. for supporting the development of this work. Daniela F.S. Morais acknowledges her Ph.D. scholarship supported by FCT (SFRH/BD/146476/2019). Bianca M. Souza Chaves gratefully acknowledges her postdoctoral scholarship supported by CNPq through the Science Without Borders Program (Process No. 201989/2014-0). Vítor J.P. Vilar acknowledges the FCT Individual Call to Scientific Employment Stimulus 2017 (CEECIND/01317/2017)S

    Nuclear Vav3 is required for polycomb repression complex-1 activity in B-cell lymphoblastic leukemogenesis

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    Acute B-cell lymphoblastic leukemia (B-ALL) results from oligo-clonal evolution of B-cell progenitors endowed with initiating and propagating leukemia properties. The activation of both the Rac guanine nucleotide exchange factor (Rac GEF) Vav3 and Rac GTPases is required for leukemogenesis mediated by the oncogenic fusion protein BCR-ABL. Vav3 expression becomes predominantly nuclear upon expression of BCR-ABL signature. In the nucleus, Vav3 interacts with BCR-ABL, Rac, and the polycomb repression complex (PRC) proteins Bmi1, Ring1b and Ezh2. The GEF activity of Vav3 is required for the proliferation, Bmi1-dependent B-cell progenitor self-renewal, nuclear Rac activation, protein interaction with Bmi1, mono-ubiquitination of H2A(K119) (H2AK119Ub) and repression of PRC-1 (PRC1) downstream target loci, of leukemic B-cell progenitors. Vav3 deficiency results in de-repression of negative regulators of cell proliferation and repression of oncogenic transcriptional factors. Mechanistically, we show that Vav3 prevents the Phlpp2-sensitive and Akt (S473)-dependent phosphorylation of Bmi1 on the regulatory residue S314 that, in turn, promotes the transcriptional factor reprogramming of leukemic B-cell progenitors. These results highlight the importance of non-canonical nuclear Rho GTPase signaling in leukemogenesis.This project was funded by the National Institutes of Health Grants R01-CA273016 (N.N.N. and J.A.C.) and U54-DK126108 (J.A.C.), the Leukemia & Lymphoma Society of North America (J.A.C and N.N.N.; and N.N.N. and J.A.C.), and William Lawrence & Blanche Hughes Foundation (J.A.C. and N.N.)
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