Repression of flagellar genes in exponential phase by CsgD and CpxR, two crucial modulators of Escherichia coli biofilm formation.

Escherichia coli adapts its lifestyle to the variations of environmental growth conditions, swapping between swimming motility or biofilm formation. The stationary-phase sigma factor RpoS is an important regulator of this switch, since it stimulates adhesion and represses flagellar biosynthesis. By measuring the dynamics of gene expression, we show that RpoS inhibits the transcription of the flagellar sigma factor, FliA, in exponential growth phase. RpoS also partially controls the expression of CsgD and CpxR, two transcription factors important for bacterial adhesion. We demonstrate that these two regulators repress the transcription of fliA, flgM, and tar and that this regulation is dependent on the growth medium. CsgD binds to the flgM and fliA promoters around their -10 promoter element, strongly suggesting direct repression. We show that CsgD and CpxR also affect the expression of other known modulators of cell motility. We propose an updated structure of the regulatory network controlling the choice between adhesion and motility.

Bristle pattern formation in the thorax formation of Drosophila: a systems level approach

A fundamental question in developmental biology is how tissues are patterned to give rise to differentiated body structures with distinct morphologies. The Drosophila wing disc offers an accessible model to understand epithelial spatial patterning. It has been studied extensively using genetic and molecular approaches. Bristle patterns on the thorax, which arise from the medial part of the wing disc, are a classical model of pattern formation, dependent on a pre-pattern of trans-activators and –repressors. Despite of decades of molecular studies, we still only know a subset of the factors that determine the pre-pattern. We are applying a novel and interdisciplinary approach to predict regulatory interactions in this system. It is based on the description of expression patterns by simple logical relations (addition, subtraction, intersection and union) between simple shapes (graphical primitives). Similarities and relations between primitives have been shown to be predictive of regulatory relationships between the corresponding regulatory factors in other Systems, such as the Drosophila egg. Furthermore, they provide the basis for dynamical models of the bristle-patterning network, which enable us to make even more detailed predictions on gene regulation and expression dynamics. We have obtained a data-set of wing disc expression patterns which we are now processing to obtain average expression patterns for each gene. Through triangulation of the images we can transform the expression patterns into vectors which can easily be analysed by Standard clustering methods. These analyses will allow us to identify primitives and regulatory interactions. We expect to identify new regulatory interactions and to understand the basic Dynamics of the regulatory network responsible for thorax patterning. These results will provide us with a better understanding of the rules governing gene regulatory networks in general, and provide the basis for future studies of the evolution of the thorax-patterning network in particular.

Fibronectin distribution in the chick embryo during formation of the blastula.

The distribution of the fibronectin-rich extracellular matrix (ECM) in the chick embryo during formation of the blastula has been evaluated semiquantitatively using an electron microscopical immunogold staining technique. During the first 10 h of postlaying development, fibronectin was found in both embryonic area pellucida and extra-embryonic area opaca of the blastoderm. In the area pellucida, the fibronectin was (1) associated with the basal lamina of the epiblast, (2) present between epiblastic and hypoblastic cells and (3) occasionally internalized in hypoblastic cells. Along the embryonic axis, a transient and high density of ECM was associated with the front of the anteriorly and rapidly expanding hypoblast. Very high density of fibronectin was observed in the marginal zone of the area pellucida, where the epiblastic and deeper cell layers show contacts and intense re-arrangements. In the area opaca, fibronectin was at first found only sporadically between contacting cells, but its density increased steadily and markedly during the first day of development. These rapid and significant changes in the regional distribution of fibronectin-rich ECM are discussed with respect to the early morphogenesis of the chick embryo.

Influence of physico-chemical material characteristics on staphylococcal biofilm formation--a qualitative and quantitative in vitro analysis of five different calcium phosphate bone grafts.

Various compositions of synthetic calcium phosphates (CaP) have been proposed and their use has considerably increased over the past decades. Besides differences in physico-chemical properties, resorption and osseointegration, artificial CaP bone graft might differ in their resistance against biofilm formation. We investigated standardised cylinders of 5 different CaP bone grafts (cyclOS, chronOS (both β-TCP (tricalcium phosphate)), dicalcium phosphate (DCP), calcium-deficient hydroxyapatite (CDHA) and α-TCP). Various physico-chemical characterisations e.g., geometrical density, porosity, and specific surface area were investigated. Biofilm formation was carried out in tryptic soy broth (TSB) and human serum (SE) using Staphylococcus aureus (ATCC 29213) and S. epidermidis RP62A (ATCC 35984). The amount of biofilm was analysed by an established protocol using sonication and microcalorimetry. Physico-chemical characterisation showed marked differences concerning macro- and micropore size, specific surface area and porosity accessible to bacteria between the 5 scaffolds. Biofilm formation was found on all scaffolds and was comparable for α-TCP, chronOS, CDHA and DCP at corresponding time points when the scaffolds were incubated with the same germ and/or growth media, but much lower for cyclOS. This is peculiar because cyclOS had an intermediate porosity, mean pore size, specific surface area, and porosity accessible to bacteria. Our results suggest that biofilm formation is not influenced by a single physico-chemical parameter alone but is a multi-step process influenced by several factors in parallel. Transfer from in vitro data to clinical situations is difficult; thus, advocating the use of cyclOS scaffolds over the four other CaP bone grafts in clinical situations with a high risk of infection cannot be clearly supported based on our data.

Extracellular matrix formation after transplantation of human embryonic stem cell-derived cardiomyocytes.

Transplantation of human embryonic stem cell-derived cardiomyocytes (hESC-CM) for cardiac regeneration is hampered by the formation of fibrotic tissue around the grafts, preventing electrophysiological coupling. Investigating this process, we found that: (1) beating hESC-CM in vitro are embedded in collagens, laminin and fibronectin, which they bind via appropriate integrins; (2) after transplantation into the mouse heart, hESC-CM continue to secrete collagen IV, XVIII and fibronectin; (3) integrin expression on hESC-CM largely matches the matrix type they encounter or secrete in vivo; (4) co-transplantation of hESC-derived endothelial cells and/or cardiac progenitors with hESC-CM results in the formation of functional capillaries; and (5) transplanted hESC-CM survive and mature in vivo for at least 24 weeks. These results form the basis of future developments aiming to reduce the adverse fibrotic reaction that currently complicates cell-based therapies for cardiac disease, and to provide an additional clue towards successful engraftment of cardiomyocytes by co-transplanting endothelial cells.

Itinéraires de formation et lignes biographiques

This paper proposes an analysis of training courses and their connection to other biographical lines, by highlighting their evolution according to social origin and gender. The variable of having received a diploma does not fully explain the longitudinal characteristics of the courses: the social inequalities prove to be also inequalities from the point of view of the followed itinerary. The range of available trajectories as well as the possibility of deviating in order to fulfil a custom trajectory depends on the social characteristics. The training course is connected to other biographical lines, in particular the family and the profession.

Religiosität in der moderne Welt. Bedingungen, Konstruktionen und sozialer Wandel

Les Suisses sont toujours plus nombreux à se distancer de la religion. Dans sa grande majorité, la population suisse entretient un rapport distant à la religion chrétienne et à la spiritualité. Elle estime cependant que les deux Eglises nationales jouent un rôle important auprès des personnes socialement défavorisée.Telle est la conclusion d'une étude menée dans le cadre du Programme national de recherche « Collectivités religieuses, Etat et société » (PNR 58).En quoi les habitants de Suisse croient-ils ? Jörg Stolz, Judith Könemann, Mallory Schneuwly-Purdie, Thomas Englberger et Michael Krueggeler, sociologues des religions, concluent que la grande majorité de la population helvétique affiche un rapport non pas indifférent ou négatif, mais distant à la religion et à la spiritualité. En d'autres termes, la plupart des habitants de notre pays ne croient pas en rien. Cette population de distants, identifiée ici pour la première fois par une recherche sociologique, va probablement continuer à augmenter à l'avenir, estiment les chercheurs.Toujours plus de personnes sans confession. Selon cette enquête représentative, au cours des dernières années, la part de chrétiens a continué à diminuer au sein de la population : 31% des habitants de Suisse sont catholiques, 32% protestants et 12% adeptes de religions non chrétiennes. C'est du côté des personnes sans confession que la mutation est la plus importante : ceux-ci constituent déjà près de 25% de la population. Mais le fait qu'un individu soit d'une confession donnée ou sans confession ne renseigne pas sur ses pratiques et ses représentations religieuses. Les sans confessions peuvent par exemple croire en Dieu ou pratiquer une spiritualité alternative.Les chercheurs distinguent quatre types de religiosité au sein de la population suisse : les distants (64%), les institutionnels (17%), les laïcs (10%) et les alternatifs (9%). Ces dernières décennies, le groupe formé par les institutionnels a fortement diminué. La proportion d'alternatifs n'a guère évolué, alors que les distants et les laïcs sont aujourd'hui plus nombreux.Les distants ne croient pas en rien. Les distants, qui constituent le groupe le plus important, ne croient pas en rien. Ils disposent de représentations religieuses et spirituelles, mais ces dernières ne jouent pas un rôle important dans leur vie et ils ne les activent que dans des situations exceptionnelles. La plupart d'entre eux sont membres de l'Eglise catholique ou protestante et s'acquittent d'impôts ecclésiastiques, mais leur appartenance confessionnelle ne leur apparaît pas importante. Ils se montrent également distants par rapport aux formes alternatives de religiosité, ainsi que vis-à-vis des personnes hostiles à la religion. Les institutionnels sont membres des deux Eglises nationales ou des Eglises évangéliques libres. Ils entretiennent une foi vivace en un Dieu unique, personnel et transcendant. Les alternatifs cultivent quant à eux des croyances holistiques et ésotériques, pratiquent l'astrologie, des techniques curatives de respiration et de mouvement, ainsi que d'autres rituels.Les laïcs, enfin, sont des personnes auxquelles toutes les formes de religiosité inspirent de l'indifférence, voire un refus. Les hommes plus hostiles à la religion que les femmes. Il est frappant de constater qu'au sein des personnes sans confession, ce ne sont pas les laïcs qui dominent (ils représentent seulement 20%), mais surtout les distants (68%). Les institutionnels affichent un niveau plutôt bas de formation, les distants et les laïcs un niveau moyen, et les alternatifs un haut niveau. Par ailleurs, on rencontre plus souvent des alternatifs chez les femmes (11%) que chez les hommes (4%). A l'inverse, les hommes présentent un taux plus élevé de laïcs (15%) que les femmes (5%).La Suisse est-elle un pays chrétien ?Indépendamment du type de religiosité, une nette majorité de la population considère que les Eglises jouent un rôle important pour les personnes socialement défavorisées. En revanche, ils leur attribuent une moindre importance pour ce qui les concerne personnellement. Les institutionnels sont fermement convaincus que la Suisse est marquée par la chrétienté. A l'inverse, les trois autres groupes - soit la majeure partie de la population - se montrent réservés sur cette question.Les chercheurs ont mené ce sondage représentatif en Suisse romande, alémanique et italienne auprès de 1'229 femmes et hommes. Le sondage a été complété par 73 entretiens semi standardisés et n'a pas pris en compte des adhérents d'autres religions.

Does locally delivered Zoledronate influence peri-implant bone formation? - Spatio-temporal monitoring of bone remodeling in vivo.

Bisphosphonates are known for their strong inhibitory effect on bone resorption. Their influence on bone formation however is less clear. In this study we investigated the spatio-temporal effect of locally delivered Zoledronate on peri-implant bone formation and resorption in an ovariectomized rat femoral model. A cross-linked hyaluronic acid hydrogel was loaded with the drug and applied bilaterally in predrilled holes before inserting polymer screws. Static and dynamic bone parameters were analyzed based on in vivo microCT scans performed first weekly and then biweekly. The results showed that the locally released Zoledronate boosted bone formation rate up to 100% during the first 17 days after implantation and reduced the bone resorption rate up to 1000% later on. This shift in bone remodeling resulted in an increase in bone volume fraction (BV/TV) by 300% close to the screw and 100% further away. The double effect on bone formation and resorption indicates a great potential of Zoledronate-loaded hydrogel for enhancement of peri-implant bone volume which is directly linked to improved implant fixation.

Unstable equilibrium: young adult women in family and career formation in Southern Europe

The paper examines the relationship between family formation (i.e., living with a partner and having children) and women’s occupational career in southern Europe (i.e., Greece, Italy, Portugal and Spain). The relationship is explored by analysing the impact that different family structures and male [nvolvement in caring activities have on women’s early occupational trajectories (i.e., remaining in the same occupational status, experiencing downward or upward mobility, or withdrawing from paid work). This research shows that male involvement in caring activities does not really push women ahead in their career, but the absolute lack of male support seems to negatively affect women’s permanence in paid work. These results apply to all southern European countries except Portugal, where the absolute absence of the partners’ support in caring activities does not seem to alter women’s determination to remain in paid work. The methodology applied consists of the estimation of multinomial logit regression models and the analysis is based on eight waves (1994-2001) of the European Community Household Panel (ECHP).

Identity formation in social networks websites: facebook and the interaction between young individuals in the cases of Slovenia and Catalonia

This paper lays down some theoretical framework for further research to be made on the subject of how identity of young Slovenian and Catalan users is forming within the social networking website Facebook. The author pursues his interest based on observation of how communicationand thus interaction between users is changing and how this is reflected in everyday practices. In so doing he tries to identify the connections between the individual, society and technology, asthese are more and more interwoven, and we cannot think one without the other in thecontemporary globalised world.