Competitive interactions between species of fresh-water snails: I. Laboratory. IC. Comparative survival of Biomphalaria glabrata and B. Straminea kept out of water

Biomphalaria glabrata and B. straminea were submitted to an out-door laboratory experiment for testing their comparative ability to resist desiccation. Results have shown that B. straminea is significantly higher resistant than B. glabrata. After five months under such distressing condition the survival ratios were: B. glabrata 8.1 per cent and B. straminea 18.4 per cent.

Peroxisome proliferator-activated receptor structures: ligand specificity, molecular switch and interactions with regulators.

Peroxisome proliferator-activated receptors (PPARs) compose a family of nuclear receptors that mediate the effects of lipidic ligands at the transcriptional level. In this review, we highlight advances in the understanding of the PPAR ligand binding domain (LBD) structure at the atomic level. The overall structure of PPARs LBD is described, and important protein ligand interactions are presented. Structure-activity relationships between isotypes structures and ligand specificity are addressed. It is shown that the numerous experimental three-dimensional structures available, together with in silico simulations, help understanding the role played by the activating function-2 (AF-2) in PPARs activation and its underlying molecular mechanism. The relation between the PPARs constitutive activity and the intrinsic stability of the active conformation is discussed. Finally, the interactions of PPARs LBD with co-activators or co-repressors, as well as with the retinoid X receptor (RXR) are described and considered in relation to PPARs activation.

Cell-matrix interactions in Schistosomal portal fibrosis: a dynamic event

In recent years, one of the most significant progress in the understanding of liver diseases was the demonstration that liver fibrosis is a dynamic process resulting from a balance between synthesis and degradation of several matrix components, collagen in particular. Thus, fibrosis has been found to be a very early event during liver diseases, be it of toxic, viral or parasitic origin, and to be spontaneously reversible, either partially or totally. In liver fibrosis cell matrix interactions are dependent on the existence of the many factors (sometimes acting in combination) which produce the same events at the cellular and molecular levels. These events are: (i) the recruitment of fiber-producing cells, (ii) their proliferation, (iii) the secretion of matrix constituents of the extracellular matrix, and (iv) the remodeling and degradation of the newly formed matrix. All these events represent, at least in principle, a target for a therapeutic intervention aimed at influencing the experimentally induced hepatic fibrosis. In this context, hepatosplenic schistosomiasis is of particular interest, being an immune cell-mediated granulomatous disease and a model of liver fibrosis allowing extensive studies in human and animals as well as providing original in vitro models.

Immunoregulation in human Schistosomiasis by idiotypic interactions and lymphokine-mediated mechanisms

Anti-idiotypic (anti-Id) T cells from schistosomiasis patients or former patients proliferate upon exposure to polyclonal or monoclonal anti-soluble egg antigen (SEA) antibodies. Chloroquine does not inhibit, the response, which is induced by F(ab')2 (but not soluble Fab) fragments of these antibodies. Purified T cells from former patients require macrophages or exogenous IL-1 to respond to anti-SEA Ids and can respond to matrix-bound Fab fragments in the presence of IL-1. These anti-Id T cells recognize the Ids directly. Chronic schistosomiasis patients immunoregulate the production of a non-IL-2 lymphokine that stimulates IL-2 receptor expression on resting T cells. This regulation is reversed upon chemotherapeutic cure.

Prenatal Representations of Family in Parents and Coparental Interactions as Predictors of Triadic Interactions During Infancy

In this study, we explored the predictive role of family interactions and family representations in mothers and fathers during pregnancy for postnatal motherfatherinfant interactions during the first 2 years after birth. Families (N = 42) were seen at the fifth month of pregnancy and at 3 and 18 months after birth. During pregnancy, parents were asked to play with their baby at the first meeting by using a doll in accordance with the procedure of the prenatal Lausanne Trilogue Play (LTP; A. Corboz-Warnery & E. Fivaz-Depeursinge, 2001; E. Fivaz-Depeursinge, F. Frascarolo-Moutinot, & A. Corboz-Warnery, 2010). Family representations were assessed by administering the Family System Test (T. Gehring, 1998). Marital satisfaction and the history of the couple were assessed through self-reported questionnaires. At 3 and 18 months, family interactions were assessed in the postnatal LTP. Infant temperament was assessed through parent reports. Results show that (a) prenatal interactions and child temperament are the most important predictors of family interactions and (b) paternal representations are predictive of family interactions at 3 months. These results show that observational assessment of nascent family interactions is possible during pregnancy, which would allow early screening of family maladjustment. The findings also highlight the necessity of taking into account paternal representations as a significant variable in the development of family interactions.

Structural Interactions in Spatial Panels

Until recently, much effort has been devoted to the estimation of panel data regression models without adequate attention being paid to the drivers of diffusion and interaction across cross section and spatial units. We discuss some new methodologies in this emerging area and demonstrate their use in measurement and inferences on cross section and spatial interactions. Specifically, we highlight the important distinction between spatial dependence driven by unobserved common factors and those based on a spatial weights matrix. We argue that, purely factor driven models of spatial dependence may be somewhat inadequate because of their connection with the exchangeability assumption. Limitations and potential enhancements of the existing methods are discussed, and several directions for new research are highlighted.

Understanding Interactions in Social Networks and Committees

While much of the literature on cross section dependence has focused mainly on estimation of the regression coefficients in the underlying model, estimation and inferences on the magnitude and strength of spill-overs and interactions has been largely ignored. At the same time, such inferences are important in many applications, not least because they have structural interpretations and provide useful interpretation and structural explanation for the strength of any interactions. In this paper we propose GMM methods designed to uncover underlying (hidden) interactions in social networks and committees. Special attention is paid to the interval censored regression model. Our methods are applied to a study of committee decision making within the Bank of England’s monetary policy committee.

Spatial Interactions in Hedonic Pricing Models: The Urban Housing Market of Aveiro, Portugal

Spatial heterogeneity, spatial dependence and spatial scale constitute key features of spatial analysis of housing markets. However, the common practice of modelling spatial dependence as being generated by spatial interactions through a known spatial weights matrix is often not satisfactory. While existing estimators of spatial weights matrices are based on repeat sales or panel data, this paper takes this approach to a cross-section setting. Specifically, based on an a priori definition of housing submarkets and the assumption of a multifactor model, we develop maximum likelihood methodology to estimate hedonic models that facilitate understanding of both spatial heterogeneity and spatial interactions. The methodology, based on statistical orthogonal factor analysis, is applied to the urban housing market of Aveiro, Portugal at two different spatial scales.

Host-microorganism interactions in lung diseases.

Until recently, the airways were thought to be sterile unless infected; however, a shift towards molecular methods for the quantification and sequencing of bacterial DNA has revealed that the airways harbour a unique steady-state microbiota. This paradigm shift is changing the way that respiratory research is approached, with a clear need now to consider the effects of host-microorganism interactions in both healthy and diseased lungs. We propose that akin to recent discoveries in intestinal research, dysbiosis of the airway microbiota could underlie susceptibility to, and progression and chronicity of lung disease. In this Opinion article, we summarize current knowledge of the airway microbiota and outline how host-microorganism interactions in the lungs and other tissues might influence respiratory health and disease.

Les débuts de la communication à trois. Interactions visuelles triadiques entre père, mère et bébé

Plusieurs auteurs ont montré que les échanges visuels entre des mères dépressives ou psychotiques et leur bébé présentent de multiples perturbations : dans cet article, les auteurs proposent une étude exploratoire portant sur les échanges visuels père-mère- bébé (9-18 semaines) dans deux groupes de familles, un groupe suivi pour des difficultés du post-partum et un groupe témoin. Les observations sont réalisées dans le cadre d'un jeu à trois structuré selon diverses modalités d'interaction (un parent joue avec l'enfant en présence de l'autre parent / les deux parents jouent conjointement avec le bébé). Les variables retenues concernent d'une part le niveau d'attention visuelle conjointe des partenaires, d'autre part l'évolution de cette attention visuelle au cours du jeu. Les résultats révèlent que les échanges visuels sont plus intenses dans les familles fonctionnelles, ce qui semble indiquer que l'engagement visuel triadique établi par les partenaires peut être représentatif du fonctionnement de la triade à un moment donné de son développement. D'autre part, l'analyse de l'évolution de l'engagement visuel au travers des différents contextes de jeu amène les auteurs à proposer l'hypothèse d'une « alliance triadique » établie conjointement par les trois partenaires et formant la matrice de leurs échanges dyadiques et triadiques. De façon plus générale, les auteurs supposent que l'établissement de cette alliance joue un rôle déterminant pour le développement et l'autonomisa- tion du bébé au sein de sa famille. Disorders in the visual interaction between depressive or psychotic mothers and their baby have been widely described : in this paper, the authors propose an exploratory study of father-mother-infant visual interaction (infants are 9-18 weeks old) in two groups of families, voluntary families and families in therapy for post-par turn disorders. The observations are gathered during a three-partner play, involving different kinds of triadic interaction (one parent plays with the infant, the other parent being « only present » / both parents play together with the child). The analyses have focused on the amount of visual attention shared by the partners and on the evolution of visual interaction during the game. Results show that triadic interaction is more intense in functional triads, which means that shared visual attention may be representative of the more general functioning of the family at a definite stage of its development. Furthermore, considering the sequential organization of visual interaction throughout the game led the authors to the construct of a « triadic alliance », jointly established by the three partners and providing a matrix for their dyadic and triadic interaction. On a more general level, such an alliance could play an important role for the development and the autonomy of the baby within his j her family.

Dynamin-SNARE interactions control trans-SNARE formation in intracellular membrane fusion.

The fundamental processes of membrane fission and fusion determine size and copy numbers of intracellular organelles. Although SNARE proteins and tethering complexes mediate intracellular membrane fusion, fission requires the presence of dynamin or dynamin-related proteins. Here we study these reactions in native yeast vacuoles and find that the yeast dynamin homologue Vps1 is not only an essential part of the fission machinery, but also controls membrane fusion by generating an active Qa SNARE-tethering complex pool, which is essential for trans-SNARE formation. Our findings provide new insight into the role of dynamins in membrane fusion by directly acting on SNARE proteins.

Ecological-economic modelling of interactions between wild and commercial bees and pesticide use

The decline in extent of wild pollinators in recent years has been partly associated with changing farm practices and in particular with increase of pesticide use. In this paper we combine ecological modelling with economic analysis of a single farm output under the assumption that both pollination and pest control are essential inputs. We show that the drive to increase farm output can lead to a local decline in the wild bee population. Commercial bees are often considered an alternative to wild pollinators, but we show that their introduction can lead to further decline and finally local extinction of wild bees. The transitions between different outcomes are characterised by threshold behaviour and are potentially difficult to predict and detect in advance. Small changes in economic (input prices) and ecological (wild bees carrying capacity and effect of pesticides on bees) can move the economic-ecological system beyond the extinction threshold. We also show that increasing the pesticide price or decreasing the commercial bee price might lead to reestablishment of wild bees following their local extinction. Thus, we demonstrate the importance of combining ecological modelling with economics to study the provision of ecosystem services and to inform sustainable management of ecosystem service providers.