The cohesin ring concatenates sister DNA molecules

Sister chromatid cohesion, which is essential for mitosis, is mediated by a multi-subunit protein complex called cohesin whose Scc1, Smc1, and Smc3 subunits form a tripartite ring structure. It has been proposed that cohesin holds sister DNAs together by trapping them inside its ring. To test this, we used site-specific cross-linking to create chemical connections at the three interfaces between the ring’s three constituent polypeptides, thereby creating covalently closed cohesin rings. As predicted by the ring entrapment model, this procedure produces dimeric DNA/cohesin structures that are resistant to protein denaturation. We conclude that cohesin rings concatenate individual sister minichromosome DNAs

Molecular basis for glycan recognition and reaction priming of eukaryotic oligosaccharyltransferase.

Oligosaccharyltransferase (OST) is the central enzyme of N-linked protein glycosylation. It catalyzes the transfer of a pre-assembled glycan, GlcNAc2Man9Glc3, from a dolichyl-pyrophosphate donor to acceptor sites in secretory proteins in the lumen of the endoplasmic reticulum. Precise recognition of the fully assembled glycan by OST is essential for the subsequent quality control steps of glycoprotein biosynthesis. However, the molecular basis of the OST-donor glycan interaction is unknown. Here we present cryo-EM structures of S. cerevisiae OST in distinct functional states. Our findings reveal that the terminal glucoses (Glc3) of a chemo-enzymatically generated donor glycan analog bind to a pocket formed by the non-catalytic subunits WBP1 and OST2. We further find that binding either donor or acceptor substrate leads to distinct primed states of OST, where subsequent binding of the other substrate triggers conformational changes required for catalysis. This alternate priming allows OST to efficiently process closely spaced N-glycosylation sites

High-resolution shotgun proteomics reveals that increased air [CO2] amplifies the acclimation response of coffea species to drought regarding antioxidative, energy, sugar, and lipid dynamics

Funding Information: This work received funding support from the European Union's Horizon 2020 research and innovation program (grant agreement No 727934 , project BreedCAFS), and from national funds from Fundação para a Ciência e a Tecnologia, I.P. (FCT) , Portugal, through the project PTDC/ASP-AGR/31257/2017 , and the research units UIDB/00239/2020 ( CEF ), and UIDP/04035/2020 (GeoBioTec) and under the Scientific Employment Stimulus - Individual Call (CEEC Individual) - 2021.01107.CEECIND/CP1689/CT0001 (IM) . Fellowships from the Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil (CNPq) , (to F.M. DaMatta and F.L. Partelli), and Fundação de Amparo à Pesquisa do Estado de Minas Gerais, Brazil (FAPEMIG, projects CRA-RED-00053-16 and APQ 01512-18 , to F.M. DaMatta) are also greatly acknowledged. Publisher Copyright: © 2022 Elsevier GmbHAs drought threatens crop productivity it is crucial to characterize the defense mechanisms against water deficit and unveil their interaction with the expected rise in the air [CO2]. For that, plants of Coffea canephora cv. Conilon Clone 153 (CL153) and C. arabica cv. Icatu grown under 380 (aCO2) or 700 μL L−1 (eCO2) were exposed to moderate (MWD) and severe (SWD) water deficits. Responses were characterized through the activity and/or abundance of a selected set of proteins associated with antioxidative (e.g., Violaxanthin de-epoxidase, Superoxide dismutase, Ascorbate peroxidases, Monodehydroascorbate reductase), energy/sugar (e.g., Ferredoxin-NADP reductase, NADP-dependent glyceraldehyde-3-phosphate dehydrogenase, sucrose synthase, mannose-6-phosphate isomerase, Enolase), and lipid (Lineolate 13S-lipoxygenase) processes, as well as with other antioxidative (ascorbate) and protective (HSP70) molecules. MWD caused small changes in both genotypes regardless of [CO2] level while under the single imposition to SWD, only Icatu showed a global reinforcement of most studied proteins supporting its tolerance to drought. eCO2 alone did not promote remarkable changes but strengthened a robust multi-response under SWD, even supporting the reversion of impacts already observed by CL153 at aCO2. In the context of climate changes where water constraints and [CO2] levels are expected to increase, these results highlight why eCO2 might have an important role in improving drought tolerance in Coffea species.publishersversionpublishe

Project finance para proyectos de APP en el Per? : evaluaci?n tributaria, contable y financiera

Todas las organizaciones en el mundo requieren recursos econ?micos para desarrollar sus actividades cotidianas, refinanciar deudas o iniciar nuevos proyectos para incursionar en distintos negocios. Para obtener el financiamiento, dichos agentes econ?micos eval?an cu?l es el tipo de apalancamiento ?ptimo. En la actualidad, el financiamiento bancario denominado tradicional constituye una fuente de recursos econ?micos, principalmente de corto plazo, respaldado con los activos o el patrimonio de la empresa, que debe sustentar el r?cord crediticio a lo largo de su actividad comercial. Sin embargo, como las entidades bancarias otorgan cr?ditos sobre procedimientos regulados, con plazos y tasas predeterminadas seg?n los protocolos internos de cada entidad financiera, los proyectos de inversi?n promovidos por empresas sin historial financiero, que solo se sustentan en sus flujos futuros, tienen muchas dificultades para desarrollarse. Entre las causas de dichas dificultades se encuentran la falta de aprobaci?n crediticia, y los esquemas de financiamiento, sobre todo de largo plazo y de gran inversi?n, que no se ajustan a los est?ndares bancarios tradicionales. Ante esta ineficiencia del financiamiento tradicional, el presente trabajo de investigaci?n trata sobre una nueva herramienta o instrumento que ha surgido como una alternativa m?s flexible de apalancamiento financiero para los agentes econ?micos interesados en desarrollar un proyecto muy arriesgado o de gran inversi?n y de largo plazo, denominado project finance. Este se ha consolidado como una herramienta de financiamiento de proyectos de alto grado de inversi?n, cuyo sustento son los flujos de caja futuros, predecibles y cuantificables. Por ello, el objetivo principal de este trabajo de investigaci?n es sistematizar los principales aspectos tributarios, contables y financieros del project finance con el fin de contribuir a la toma de decisiones para la ejecuci?n de proyectos de inversi?n bajo la modalidad de APP utilizando un esquema eficiente de financiamiento no tradicional. Si bien en el Per? existe suficiente experiencia y conocimiento de campo para desarrollar este tipo de proyectos de inversi?n, estos no se encuentran sistematizados

Reconciling differences in natural tags to infer demographic and genetic connectivity in marine fish populations

Processes regulating population connectivity are complex, ranging from extrinsic environmental factors to intrinsic individual based features, and are a major force shaping the persistence of fish species and population responses to harvesting and environmental change. Here we developed an integrated assessment of demographic and genetic connectivity of European flounder Platichthys flesus in the northeast Atlantic (from the Norwegian to the Portuguese coast) and Baltic Sea. Specifically, we used a Bayesian infinite mixture model to infer the most likely number of natal sources of individuals based on otolith near core chemical composition. Simultaneously, we characterised genetic connectivity via microsatellite DNA markers, and evaluated how the combined use of natural tags informed individual movement and long-term population exchange rates. Individual markers provided different insights on movement, with otolith chemistry delineating Norwegian and Baltic Sea sources, whilst genetic markers showed a latitudinal pattern which distinguished southern peripheral populations along the Iberian coast. Overall, the integrated use of natural tags resulted in outcomes that were not readily anticipated by individual movement or gene flow markers alone. Our ecological and evolutionary approach provided a synergistic view on connectivity, which will be paramount to align biological and management units and safeguard species’ biocomplexityFundação para a Ciência e a Tecnologia | Ref. UID/MAR/04292/2013Fundação para a Ciência e a Tecnologia | Ref. PTDC/AAG-GLO/5849/2014Fundação para a Ciência e a Tecnologia | Ref. PTDC/MAR-EST/2098/201

The Islet Estrogen Receptor-α Is Induced by Hyperglycemia and Protects Against Oxidative Stress-Induced Insulin-Deficient Diabetes

The female steroid, 17β-estradiol (E2), is important for pancreatic β-cell function and acts via at least three estrogen receptors (ER), ERα, ERβ, and the G-protein coupled ER (GPER). Using a pancreas-specific ERα knockout mouse generated using the Cre-lox-P system and a Pdx1-Cre transgenic line (PERαKO−/−), we previously reported that islet ERα suppresses islet glucolipotoxicity and prevents β-cell dysfunction induced by high fat feeding. We also showed that E2 acts via ERα to prevent β-cell apoptosis in vivo. However, the contribution of the islet ERα to β-cell survival in vivo, without the contribution of ERα in other tissues is still unclear. Using the PERαKO−/− mouse, we show that ERα mRNA expression is only decreased by 20% in the arcuate nucleus of the hypothalamus, without a parallel decrease in the VMH, making it a reliable model of pancreas-specific ERα elimination. Following exposure to alloxan-induced oxidative stress in vivo, female and male PERαKO−/− mice exhibited a predisposition to β-cell destruction and insulin deficient diabetes. In male PERαKO−/− mice, exposure to E2 partially prevented alloxan-induced β-cell destruction and diabetes. ERα mRNA expression was induced by hyperglycemia in vivo in islets from young mice as well as in cultured rat islets. The induction of ERα mRNA by hyperglycemia was retained in insulin receptor-deficient β-cells, demonstrating independence from direct insulin regulation. These findings suggest that induction of ERα expression acts to naturally protect β-cells against oxidative injury

The islet estrogen receptor-alpha is induced by hyperglycemia and protects against oxidative stress-induced insulin-deficient diabetes

The female steroid, 17beta-estradiol (E2), is important for pancreatic beta-cell function and acts via at least three estrogen receptors (ER), ERalpha, ERbeta, and the G-protein coupled ER (GPER). Using a pancreas-specific ERalpha knockout mouse generated using the Cre-lox-P system and a Pdx1-Cre transgenic line (PERalphaKO (-)/(-)), we previously reported that islet ERalpha suppresses islet glucolipotoxicity and prevents beta-cell dysfunction induced by high fat feeding. We also showed that E2 acts via ERalpha to prevent beta-cell apoptosis in vivo. However, the contribution of the islet ERalpha to beta-cell survival in vivo, without the contribution of ERalpha in other tissues is still unclear. Using the PERalphaKO (-)/(-) mouse, we show that ERalpha mRNA expression is only decreased by 20% in the arcuate nucleus of the hypothalamus, without a parallel decrease in the VMH, making it a reliable model of pancreas-specific ERalpha elimination. Following exposure to alloxan-induced oxidative stress in vivo, female and male PERalphaKO (-)/(-) mice exhibited a predisposition to beta-cell destruction and insulin deficient diabetes. In male PERalphaKO (-)/(-) mice, exposure to E2 partially prevented alloxan-induced beta-cell destruction and diabetes. ERalpha mRNA expression was induced by hyperglycemia in vivo in islets from young mice as well as in cultured rat islets. The induction of ERalpha mRNA by hyperglycemia was retained in insulin receptor-deficient beta-cells, demonstrating independence from direct insulin regulation. These findings suggest that induction of ERalpha expression acts to naturally protect beta-cells against oxidative injury

Structural analysis of massive galaxies using HST deep imaging at z < 0.5

Taking advantage of HST CANDELS data, we analyze the lowest redshift (z<0.5) massive galaxies in order to disentangle their structural constituents and study possible faint non-axis-symmetric features. Due to the excellent HST spatial resolution for intermediate-z objects, they are hard to model by purely automatic parametric fitting algorithms. We performed careful single and double S\'ersic fits to their galaxy surface brightness profiles. We also compare the model color profiles with the observed ones and also derive multi-component global effective radii attempting to obtain a better interpretation of the mass-size relation. Additionally, we test the robustness of our measured structural parameters via simulations. We find that the S\'ersic index does not offer a good proxy for the visual morphological type for our sample of massive galaxies. Our derived multi-component effective radii give a better description of the size of our sample galaxies than those inferred from single S\'ersic models with GALFIT. Our galaxy population lays on the scatter of the local mass-size relation, indicating that these massive galaxies do not experience a significant growth in size since z~0.5. Interestingly the few outliers are late-type galaxies, indicating that spheroids must reach the local mass-size relation earlier. For most of our sample galaxies, both single and multi-component S\'ersic models with GALFIT show substantial systematic deviations from the observed SBPs in the outskirts. These residuals may be partly due to several factors, namely a non-optimal data reduction for low surface brightness features, the existence of prominent stellar haloes for massive galaxies and could also arise from conceptual shortcomings of parametric 2D image decomposition tools. They consequently propagate into galaxy color profiles

BRCA2-HSF2BP oligomeric ring disassembly by BRME1 promotes homologous recombination

In meiotic homologous recombination (HR), BRCA2 facilitates loading of the recombinases RAD51 and DMC1 at the sites of double-strand breaks (DSBs). The HSF2BP-BRME1 complex interacts with BRCA2. Its absence causes a severe reduction in recombinase loading at meiotic DSB. We previously showed that, in somatic cancer cells ectopically producing HSF2BP, DNA damage can trigger HSF2BP-dependent degradation of BRCA2, which prevents HR. Here, we report that, upon binding to BRCA2, HSF2BP forms octameric rings that are able to interlock into a large ring-shaped 24-nucleotide oligomer. Addition of BRME1 leads to dissociation of both of these ring structures and cancels the disruptive effect of HSF2BP on cancer cell resistance to DNA damage. It also prevents BRCA2 degradation during interstrand DNA crosslink repair in Xenopus egg extracts. We propose that, during meiosis, the control of HSF2BP-BRCA2 oligomerization by BRME1 ensures timely assembly of the ring complex that concentrates BRCA2 and controls its turnover, thus promoting HR.</p