Linking biofilm spatial structure to real-time microscopic oxygen decay imaging

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Biofouling on 2018, available online at: http://www.tandfonline.com/10.1080/08927014.2017.1423474Two non-destructive techniques, confocal laser scanning microscopy (CLSM) and planar optode (VisiSens imaging), were combined to relate the fine-scale spatial structure of biofilm components to real-time images of oxygen decay in aquatic biofilms. Both techniques were applied to biofilms grown for seven days at contrasting light and temperature (10/20°C) conditions. The geo-statistical analyses of CLSM images indicated that biofilm structures consisted of small (~100 µm) and middle sized (~101 µm) irregular aggregates. Cyanobacteria and EPS (extracellular polymeric substances) showed larger aggregate sizes in dark grown biofilms while, for algae, aggregates were larger in light-20°C conditions. Light-20°C biofilms were most dense while 10°C biofilms showed a sparser structure and lower respiration rates. There was a positive relationship between the number of pixels occupied and the oxygen decay rate. The combination of optodes and CLMS, taking advantage of geo-statistics, is a promising way to relate biofilm architecture and metabolism at the micrometric scale.Peer ReviewedPostprint (author's final draft

Hydrogel co-networks of gelatin methacryloyl and poly(ethylene glycol)diacrylate sustain 3D functional in vitro models of intestinal mucosa

[eng] Conventional in vitro cell culture models do not possess the complexity that the native tissues offer. Because of this, the functional properties of the tissues are not properly mimicked, which causes poorly predictive capabilities. Engineered tissues, which combine biofabrication and tissue engineering techniques, try to overcome this gap by providing the cells with an environment similar to the native tissue, recapitulating (I) the physicochemical and mechanical properties of the cellular matrix, (II) the multicellular complexity of the different tissue compartments, and (III) the 3D structures of the tissues. These new engineered models are key factors to improve the platforms for basic research studies, testing new drugs or modelling diseases. Among all the engineered tissues, the intestinal mucosa is not well represented. The intestinal mucosa is formed by the epithelium, which is a multicellular monolayer laying on top of the lamina propria, a connective tissue containing several cell types (mesenchymal cells, immune cells). The gold standard intestinal models are based on epithelial cell lines derived from colon cancer cells grown on the hard porous membranes of the Transwell® inserts. The lack of the intestinal stromal compartment and the growth on a hard surface give high transepithelial electrical resistance and low apparent permeability. Therefore, the development of better in vitro platforms, which integrates both compartments and provides epithelium-lamina propria cell interactions, is highly desirable. In this work, we describe an easy and cost-effective method to engineer a 3D intestinal mucosa model that combines both the epithelium and the lamina propria compartments. To build the 3D scaffolds we chose hydrogels as materials to mimic the physicochemical and mechanical properties of intestinal tissue. Thus, hydrogel co- networks of gelatin methacryolyl (GelMA), a natural polymer, and poly(ethylene glycol) diacrylate (PEGDA), a synthetic polymer, are photopolymerized. On one hand, GelMA provides biodegradation and cell adhesion sequences but it lacks long-term mechanical stability. On the other hand, PEGDA, is non-biodegradable and does not present cell adhesion motifs. Nevertheless, it has good mechanical properties. By this technique, the lamina propria compartment of the intestinal mucosa can be reproduced in vitro. To do that, GelMA and PEGDA polymers are laden with mesenchymal cells (fibroblasts or myofibroblasts) and/or immune cells (macrophages). We demonstrated that GelMA – PEGDA hydrogel co-networks support the growth of these cells and epithelial monolayers on top of the scaffolds. Embedding fibroblasts or myofibroblasts on the hydrogel co-networks enhance the formation and the maturity of the Caco-2 epithelial monolayers, providing barrier properties similar to in vivo. The presence of the stromal cells, also enhances the recovery of the epithelial integrity when the epithelium is temporally damaged. Finally, an immunocompetent model is obtained by the encapsulation of macrophages in the constructs. The presence of macrophages does not influence the formation of the epithelium. However, when the epithelial monolayer is disrupted, the presence of mesenchymal and immune cells in the stromal compartment increases cytokine secretion in a synergistic manner. Our model can successfully mimic the interactions between stromal and epithelial compartments found in vivo intestinal tissue, offering a potential platform to be used to study absorption and toxicity of drugs, as well as cell behaviour under physiological and pathological conditions.[cat] En l’intestí prim trobem la mucosa, la capa més externa de la paret intestinal, formada per dos compartiments, la lamina propia i l’epiteli, en els quals resideixen diferents tipus cel·lulars. La interacció entre els dos compartiments és essencial pel funcionament correcte del intestí. Actualment, els models intestinals in vitro es basen en el cultiu de línies cel·lulars epitelials sobre membranes dures i de plàstic, els quals no representen correctament ni la complexitat ni la organització cel·lular trobada en el intestí prim, ja que manquen de la lamina propria. Conseqüentment, els resultats obtinguts utilitzant aquests models són significativament poc fisiològics i no comparables amb els trobats en condicions in vivo (alts valors de resistència elèctrica transepitelial, subestimació dels valors d’absorció de molècules a través de la ruta paracel·lular i alteració en la expressió enzims digestius). Per reduir les distàncies entre els models intestinals in vitro i l’intestí, s’han de desenvolupar plataformes que modelitzin: (I) les propietats fisicoquímiques i mecàniques de la matriu extracel·lular, (II) els dos compartiments de la mucosa intestinal, i si pogués ser (III) l’arquitectura tridimensional. Per aconseguir aquests requeriments, en aquesta tesi s’utilitzen hidrogels formats per polímers naturals (gelatina metacrilada (GelMA)) co-polimeritzats amb polímers sintètics (poly(ethylene glycol) diacrylate (PEGDA)) com a substrat per imitar els dos compartiments intestinals. Per reproduir la lamina propria, els polímers de GelMA i PEGDA es dissolen juntament amb el fotoiniciador. Tot seguit, les cèl·lules residents de la lamina propria (fibroblasts, miofibroblasts o macròfags) es barregen amb la solució de pre-polimer, s’aboca a les piscines de PDMS, s’exposa a llum ultraviolada, i s’obté l’hidrogel amb les cèl·lules en el seu interior. Finalment, les cèl·lules epitelials es sembren a la superfície del hidrogel. En aquesta tesi, s’ha obtingut un hidrogel amb propietats fisicoquímiques i mecàniques similars a la matriu extracel·lular del intestí humà, i que permeten el cultiu cel·lular fins a 21 dies, imitant els dos compartiments. A més, la el co-cultiu de cèl·lules residents de la lamina propria juntament amb les cèl·lules epitelials, ens ha permès obtenir un model 3D de la mucosa intestinal in vitro amb propietats fisiològiques més semblants a la del intestí prim

(Re)Construint relacions de parentiu : una aproximació a les famílies recompostes mixtes (Catalunya)

La crítica de Schneider (1984) al parentiu com a domini analític va suposar que sorgissin noves reflexions en torn a la manera d'analitzar les múltiples transformacions que han succeït en aquest àmbit. Canvis que qüestionen les concepcions culturals occidentals basades principalment en el "parentiu de sang", és a dir, en la biogenètica, a l'hora d'establir relacions de parentiu. En aquest article es proposa analitzar els processos de construcció de paternitat i maternitat en el context de les famílies recompostes mixtes, residents a Catalunya, des de la perspectiva de la Antropologia del Parentiu centrada en la criança, socialització i adscripció de la nova prole al grup. Es presenten les propostes teòriques i metodològiques utilitzades per a l'anàlisi d'aquestes realitats familiars i s'exposen els resultats més rellevants fruit del treball de recerca del Màster corresponent a la primera i segona fase de l'estudi longitudinal proposat. Cal destacar la innovació que la temàtica presenta, doncs a més d'aportar nova informació i coneixement etnogràfic a un tema força estudiat des de l'Antropologia, s'està treballant amb un focus de població de difícil accés ja que no apareix fàcilment en censos o registres oficials.Schneider (1984) criticism to kinship as an analytic domain made possible that new reflections around the way we analyze the multiple transformations that have been arosen in this field. These changes bring in to question the cultural conceptions based mainly on blood kinship, which is to say in biogenetics, when we establish kinship relationships. It is proposed in this article to analyze the parenthood construction processes in the context of mixed step-families living in Catalunya, seen through the Anthropology of Kinship focused on parenting, socialization and adscription of new offspring into the group. Theoretical and methodological proposals used for the analysis of these familiar realities are presented here. Afterwards the most relevant results out coming from the final master project dealing with the first and second phase of the longitudinal analysis are exposed. The innovation that this topic presents needs to be highlighted, because besides the contribution of new information and ethnographic knowledge about a common studied topic in anthropology, we are working with a spotlight population due to it's hardly to appreciate in census or official registers

La parentalidad desde el parentesco. Un concepto antropológico e interdisciplinar

La parentalidad, entendida como un corpus de comportamientos, relaciones sociales,sentimientos culturalmente pautados y representaciones culturales vinculado a la procreación y crianza constituye un tema más que emergente, re-emergente, en el campo de estudio del parentesco, no tanto por su contenido (formas diversas de cuidados parentales se han descrito en la Antropología Social clásica y en otras Ciencias Sociales), como por el uso del término ‘parentalidad’ para referirse a esas prácticas de crianza. Se presenta en este artículo el ámbito de la parentalidad desde la Antropología del Parentesco a partir de la definición propuesta por el Getp-GRAFO y utilizando algunos rudimentos metodológicos de la historia conceptual, se intentará asimismo establecer la genealogía del concepto de parentalidad en el seno de la disciplina antropológica. Este concepto no ha sido, ni mucho menos, patrimonio exclusivo de nuestra disciplina. Una parte significativa de las publicaciones sobre parentalidad consiste en trabajos corales, en los que se aborda el fenómeno desde diferentes perspectivas disciplinarias y muchos de ellos tienen una vertiente práctica que los relaciona con el ámbito de la intervención social. Se trata, pues, de un tópico idóneo para explorar la colaboración entre disciplinas.Palabras clave: parentalidad, procreación y crianza, antropología del parentesco, historia conceptual, interdisciplinariedad.AbstractParenthood, understood as a set of behaviors, social relationships, culturally patterned feelings and cultural representations linked to procreation and child rearing is a re-emerging (rather than emerging) topic in the study of kinship. This is not so much due to its content (diverse types of parental care have been described in classical social anthropology and other social sciences), but rather because of the use of the term “parenthood” to refer to these child rearing practices. This article presents the field of parenthood from the anthropology of kinship on the basis of the definition proposed by the Getp-GRAFO. And, by using some methodological rudiments of conceptual history, we will also establish the genealogy of this concept of parenthood at the core of the anthropology. This concept has by no means been exclusive to our discipline. A significant number of publications on parenthood are joint efforts, in which the phenomenon is approached from different disciplinary perspectives. Moreover, many of them have a practical aspect related to the field of social intervention. It is therefore an appropriate topic for exploring interdisciplinary collaborations.Keywords: parenthood, procreation and child rearing, anthropology of kinship, conceptual history,interdisciplinarity

A mechanistic model (BCC-PSSICO) to predict changes in the hydraulic properties for bio-amended variably saturated soils

This is the peer reviewed version of the following article: [Carles Brangarí, A., X. Sanchez-Vila, A. Freixa, A. M. Romaní, S. Rubol, and D. Fernàndez-Garcia (2017), A mechanistic model (BCC-PSSICO) to predict changes in the hydraulic properties for bio-amended variably saturated soils, Water Resour. Res., 53, 93–109, doi:10.1002/2015WR018517], which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/2015WR018517/abstract. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The accumulation of biofilms in porous media is likely to influence the overall hydraulic properties and, consequently, a sound understanding of the process is required for the proper design and management of many technological applications. In order to bring some light into this phenomenon we present a mechanistic model to study the variably saturated hydraulic properties of bio-amended soils. Special emphasis is laid on the distribution of phases at pore-scale and the mechanisms to retain and let water flow through, providing valuable insights into phenomena behind bioclogging. Our approach consists in modeling the porous media as an ensemble of capillary tubes, obtained from the biofilm-free water retention curve. This methodology is extended by the incorporation of a biofilm composed of bacterial cells and extracellular polymeric substances (EPS). Moreover, such a microbial consortium displays a channeled geometry that shrinks/swells with suction. Analytical equations for the volumetric water content and the relative permeability can then be derived by assuming that biomass reshapes the pore space following specific geometrical patterns. The model is discussed by using data from laboratory studies and other approaches already existing in the literature. It can reproduce (i) displacements of the retention curve toward higher saturations and (ii) permeability reductions of distinct orders of magnitude. Our findings also illustrate how even very small amounts of biofilm may lead to significant changes in the hydraulic properties. We, therefore, state the importance of accounting for the hydraulic characteristics of biofilms and for a complex/more realistic geometry of colonies at the pore-scale.Peer ReviewedPostprint (author's final draft