The non-canonical NF-κB pathway is induced by cytokines in pancreatic beta cells and contributes to cell death and proinflammatory responses in vitro

Aims/hypothesis: Activation of the transcription factor nuclear factor (NF)-κB by proinflammatory cytokines plays an important role in beta cell demise in type 1 diabetes. Two main signalling pathways are known to activate NF-κB, namely the canonical and the non-canonical pathways. Up to now, studies on the role of NF-κB activation in beta cells have focused on the canonical pathway. The aim of this study was to investigate whether cytokines activate the non-canonical pathway in beta cells, how this pathway is regulated and the consequences of its activation on beta cell fate. Methods: NF-κB signalling was analysed by immunoblotting, promoter reporter assays and real-time RT-PCR, after knockdown or overexpression of key genes/proteins. INS-1E cells, FACS-purified rat beta cells and the human beta cell line EndoC-βH1 exposed to cytokines were used as models. Results: IL-1β plus IFN-γ induced stabilisation of NF-κB-inducing kinase and increased the expression and cleavage of p100 protein, culminating in the nuclear translocation of p52, the hallmark of the non-canonical signalling. This activation relied on different crosstalks between the canonical and non-canonical pathways, some of which were beta cell specific. Importantly, cytokine-mediated activation of the non-canonical pathway controlled the expression of ‘late’ NF-κB-dependent genes, regulating both pro-apoptotic and inflammatory responses, which are implicated in beta cell loss in early type 1 diabetes. Conclusions/interpretation: The atypical activation of the non-canonical NF-κB pathway by proinflammatory cytokines constitutes a novel ‘feed-forward’ mechanism that contributes to the particularly pro-apoptotic effect of NF-κB in beta cells.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Cryptic diversity and ecosystem functioning : a complex tale of differential effects on decomposition

Marine ecosystems are experiencing accelerating population and species loss. Some ecosystem functions are decreasing and there is growing interest in the link between biodiversity and ecosystem functioning. The role of cryptic (morphologically identical but genetically distinct) species in this biodiversity–ecosystem functioning link is unclear and has not yet been formally tested. We tested if there is a differential effect of four cryptic species of the bacterivorous nematode Litoditis marina on the decomposition process of macroalgae. Bacterivorous nematodes can stimulate or slow down bacterial activity and modify the bacterial assemblage composition. Moreover, we tested if interspecific interactions among the four cryptic species influence the decomposition process. A laboratory experiment with both mono- and multispecific nematode cultures was conducted, and loss of organic matter and the activity of two key extracellular enzymes for the degradation of phytodetritus were assessed. L. marina mainly influenced qualitative aspects of the decomposition process rather than its overall rate: an effect of the nematodes on the enzymatic activities became manifest, although no clear nematode effect on bulk organic matter weight loss was found. We also demonstrated that species-specific effects on the decomposition process existed. Combining the four cryptic species resulted in high competition, with one dominant species, but without complete exclusion of other species. These interspecific interactions translated into different effects on the decomposition process. The species-specific differences indicated that each cryptic species may play an important and distinct role in ecosystem functioning. Functional differences may result in coexistence among very similar species

Geological, Physical and Chemical Foundations

Modern tidal flats are coastal geomorphological features with a recentgeologic history (Holocene period, 10,000 YBP) that are found globally, underdifferent climatic, hydrodynamic and sedimentological regimes. They are primarilycharacterized by fine-grained sedimentary deposits (silt and clay) that present uniquephysical and chemical properties, in comparison to other sediment types. The input ofsediments to mudflats can be either riverine, from offshore, and/or from the erosion ofcoastal sedimentary deposits. Tides and tidal currents are the dominant hydrodynamicforces shaping mudflats, with wave action playing a secondary role. Theoccurrence of intermittent or temporary flooding and the presence of variable redox(oxidation-reduction) conditions are typical features of mudflat sediments. Thetemporally and spatially variable changes from aerobic, oxidized states of mudflatsediment and porewater to anaerobic, reduced states drive particular redox reactionsthat govern the characteristic chemical processes and biogeochemical functioningthat distinguish mudflats from other coastal settings. Mudflat sediments are not inert;the high surface area:volume ratio of fine-grained sediment particles offers a vast andstructurally-complex landscape for colonization by microbes that rely on surfaceadhesionprocesses. Photosynthetic microalgae belonging to several taxonomicgroups (collectively known as microphytobenthos MPB) are the dominant microorganismsgrowing in association with sedimentary particles, and forming a biofilmlayer on top. In addition to physical forces, living benthic communities modifysediment properties as part of their normal physiology (micro- and macro-biota)and feeding, movement, and burrowing activity (meio- and macrofauna), especiallyin relation to stabilization and destabilization processes. These may ultimately havemarked effects on sediment stability and geomorphology. The interplay between suchbiological processes and sediments in mudflats is currently an active field of research.Fil: Pan, Jeronimo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pratolongo, Paula Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; ArgentinaFil: Cuadrado, Diana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentin