A multidimensional perspective on microbial interactions

Beyond being simply positive or negative, beneficial or inhibitory, microbial interactions can involve a diverse set of mechanisms, dependencies and dynamical properties. These more nuanced features have been described in great detail for some specific types of interactions, (e.g. pairwise metabolic cross-feeding, quorum sensing or antibiotic killing), often with the use of quantitative measurements and insight derived from modeling. With a growing understanding of the composition and dynamics of complex microbial communities for human health and other applications, we face the challenge of integrating information about these different interactions into comprehensive quantitative frameworks. Here, we review the literature on a wide set of microbial interactions, and explore the potential value of a formal categorization based on multidimensional vectors of attributes. We propose that such an encoding can facilitate systematic, direct comparisons of interaction mechanisms and dependencies, and we discuss the relevance of an atlas of interactions for future modeling and rational design efforts.R01 GM121950 - NIGMS NIH HHSPublished versio

Costless metabolic secretions as drivers of interspecies interactions in microbial ecosystems

Metabolic exchange mediates interactions among microbes, helping explain diversity in microbial communities. As these interactions often involve a fitness cost, it is unclear how stable cooperation can emerge. Here we use genome-scale metabolic models to investigate whether the release of “costless” metabolites (i.e. those that cause no fitness cost to the producer), can be a prominent driver of intermicrobial interactions. By performing over 2 million pairwise growth simulations of 24 species in a combinatorial assortment of environments, we identify a large space of metabolites that can be secreted without cost, thus generating ample cross-feeding opportunities. In addition to providing an atlas of putative interactions, we show that anoxic conditions can promote mutualisms by providing more opportunities for exchange of costless metabolites, resulting in an overrepresentation of stable ecological network motifs. These results may help identify interaction patterns in natural communities and inform the design of synthetic microbial consortia.We thank Dr. Niels Klitgord for pioneering ideas that inspired launch of this work. We are also grateful to David Bernstein, Joshua E. Goldford, Meghan Thommes, Demetrius DiMucci, and all members of the Segre Lab for helpful discussions. A.R.P. is supported by a National Academies of Sciences, Engineering, and Medicine Ford Foundation Predoctoral Fellowship and a Howard Hughes Medical Institute Gilliam Fellowship. This work was supported by funding from the Defense Advanced Research Projects Agency (purchase request no. HR0011515303, contract no. HR0011-15-C-0091), the U.S. Department of Energy (grants DE-SC0004962 and DE-SC0012627), the NIH (grants 5R01DE024468, R01GM121950, and Sub_P30DK036836_P&F), the National Science Foundation (grants 1457695 and NSFOCE-BSF 1635070), MURI Grant W911NF-12-1-0390, the Human Frontiers Science Program (grant RGP0020/2016), and the Boston University Inter-disciplinary Biomedical Research Office. (National Academies of Sciences, Engineering, and Medicine Ford Foundation Predoctoral Fellowship; Howard Hughes Medical Institute Gilliam Fellowship; HR0011515303 - Defense Advanced Research Projects Agency; HR0011-15-C-0091 - Defense Advanced Research Projects Agency; DE-SC0004962 - U.S. Department of Energy; DE-SC0012627 - U.S. Department of Energy; 5R01DE024468 - NIH; R01GM121950 - NIH; Sub_P30DK036836_PF - NIH; 1457695 - National Science Foundation; NSFOCE-BSF 1635070 - National Science Foundation; W911NF-12-1-0390 - MURI Grant; RGP0020/2016 - Human Frontiers Science Program; Boston University Inter-disciplinary Biomedical Research Office)Published versio

The Effect of the Number of Lending Banks on the Liquidity Constraints of Firms: Evidence From a Quasi-Experiment

We empirically explore whether firms have a target for the number of banks from which they borrow, and whether having multiple bank relationships has an impact on firms’ liquidity situation. A bank merger in Chile provides a quasi-experiment as it constitutes an exogenous reduction in the number of lenders for firms that were previously borrowing from both merging banks. We find that a significant percentage of firms whose number of bank relationships was reduced by the merger regain their original number of lenders. In particular, firms whose number of bank lending relationships was reduced from two to one as a result of the merger have a 23% higher probability of adding a new bank lending relationship in the five years following the merger than similar firms unaffected by the merger. Overall, we find that a reduction in firms’ number of bank lenders resulting from the merger reduced firms’ access to credit. In particular, a reduction from two to one bank lending relationships generated, on average, a 14.4% decrease in loan size for the affected companies compared to firms unaffected by the merger.

Feasibility of Using Bandwidth Efficient Modulation to Upgrade the CMS Tracker Readout Optical Links

Plans to upgrade the LHC after approximately 10 years of operation are currently being considered at CERN. A tenfold increase in luminosity delivered to the experiments is envisaged in the so-called Super LHC (SLHC). This will undoubtedly give rise to significantly larger data volumes from the detectors, requiring faster data readout. The possibility of upgrading the CMS Tracker analog readout optical links using a bandwidth efficient digital modulation scheme for deployment in the SLHC has been extensively explored at CERN. Previous theoretical and experimental studies determined the achievable data rate using a system based on Quadrature Amplitude Modulation (QAM) to be ~3-4Gbit/s (assuming no error correction is used and for an error rate of ~10-9). In this note we attempt to quantify the feasibility of such an upgrade in terms of hardware implementation complexity, applicability to the high energy physics (HEP) environment, technological feasibility and R&D effort required.Comment: CERN CMS Note. 16 pages, 10 figure

Comunicação de Ciência - Porquê, como e para quem falar de ciência

Por que é que os seminários dos cientistas te parecem todos iguais? Quantas vezes assististe a apresentações sobre o que deveria ter sido um tema inspirador, para apenas seres embalado ao ritmo de um tom monocórdico letrado por jargão científico? E ser biólogo é ser criativo? Provavelmente não, será a resposta da maioria. Os biólogos são cientistas e, como tal, o importante é serem rigorosos, objectivos e analíticos. Afinal que importância pode ter a falta de entusiasmo, de clareza e de empatia a comunicar? Para a ciência, muita Para a sociedade também! É que embora os cientistas sejam considerados domínios de autoridade, a ciência e a tecnologia (C&T) são muitas vezes postas em causa, por exemplo em temas como a vacinação ou as alterações climáticas. Essa contestação reflecte o modo como a C&T são por vezes mal comunicadas na sociedade e por isso, não entendidas pelo público comum. Este workshop tem como objetivos: dar a conhecer várias abordagens para comunicar ciência a um público leigo e fornecer algumas ferramentas para a divulgação dos trabalhos de investigação, de forma a permitir uma melhor interação com os diferentes públicos-alvoinfo:eu-repo/semantics/publishedVersio

Algunos rizobios van armados para luchar contra otras bacterias y para interaccionar con leguminosas

Los rizobios son bacterias del suelo que pueden interaccionar con leguminosas específicas y multiplicarse en estructuras radiculares especializadas llamadas nódulos. En los nódulos las bacterias realizan la fijación biológica de nitrógeno proporcionando una ventaja a estas plantas para crecer en medios pobres en nitrógeno. La relación entre los rizobios y las leguminosas es específica y está mediada por diferentes señales químicas intercambiadas entre los actores. Una de esas señales son proteínas llamadas efectores, que secretan las bacterias al citoplasma vegetal. Se han descritos diferentes sistemas de secreción y uno de ellos se denomina sistema de secreción tipo VI (T6SS). Los T6SS actúan como nanopistolas y pueden disparar efectores que pueden matar a otras bacterias. Este trabajo presenta la importancia del T6SS de Rhizobiumetli Mim1, en la simbiosis con judías, leucenas y mimosas y frente a otras bacterias

HIV-Infected Subjects With Poor CD4 T-Cell Recovery Despite Effective Therapy Express High Levels of OX40 and α4β7 on CD4 T-Cells Prior Therapy Initiation

Background HIV-infected subjects with suboptimal CD4 restoration despite suppressive combined antiretroviral treatment (cART) (immunodiscordant subjects) have been classically characterized after a variable period of time under cART. Recently, we have reported that an increased frequency of proliferating CD4 T-cells in these subjects is already present before the cART onset. The potential contribution of peripheral compensatory homeostatic proliferation (HP) is yet unknown. We aimed to analyze the expression of HP-related cellular markers on CD4 T-cells of immunodiscordant subjects before cART. Go to: Methods We analyzed the expression of OX40 and α4β7 on peripheral CD4 T-cells from immunodiscordant and control subjects (n = 21 each group) before cART initiation, and also on available follow-up samples (after 24 month of suppressive cART). Additionally, we tested the expression of these markers in an in vitro system for the study of human HP processes. Go to: Results Immunodiscordant subjects showed increased levels of OX40 and α4β7 on CD4 T-cells before cART initiation. While the cART tended to reduce these levels, immunodiscordant subjects still maintained comparatively higher levels of OX40 and α4β7 after 24 months under suppressive cART. These HP-related markers were upregulated in vitro during the human HP, especially during the fast HP. Go to: Conclusion Our results are compatible with exacerbated HP processes in immunodiscordant subjects, already before the cART onset.Fondo de Investigación Sanitaria FIS PI14/01693 PI13/0796 PI16/0503Fondos Europeos para el Desarrollo Regional (FEDER) CTS2593Junta de Andalucía. Consejería de Economía, Innovación, Ciencia y Empleo CTS2593AGAUR 2017SGR948GILEAD GLD14/293The Spanish AIDS Research Network of Excellence RD12/0017/0029 RD16/0025/0019 RD16/0025/0006Junta de Andalucía. Consejería de Salud y Bienestar Social C-0013-201

Video games and literature: case studies of three Hispanic-American intertexts

Esta investigación establece relaciones entre distintas producciones videolúdicas y obras literarias representativas del ámbito hispanoamericano. El vínculo entre el mundo de los videojuegos y la literatura es un tema aún poco explorado, pero adquiere relevancia en el actual dominio de las narrativas transmedia de la cultura contemporánea. Se analiza desde una perspectiva ludoficcional, narratológica y sociocultural un conjunto de remediaciones videolúdicas sobre la novela El ingenioso hidalgo Don Quijote de la Mancha (1615) de Miguel de Cervantes Saavedra; el videojuego Intimate, infinite (Robert Yang, 2014) basado en el cuento “El jardín de senderos que se bifurcan” (1941) de Jorge Luis Borges; y el videojuego Space invaders (Taito, 1978) que inspiró la novela homónima de la escritora chilena Nona Fernández (2013). Se sostiene que la significación de estos artefactos culturales adquiere mayor sentido cuando se establecen los vínculos con otros intertextos y cuando se los examina desde la configuración de los mundos ludoficcionales