Lymphocytes and the Dap12 Adaptor Are Key Regulators of Osteoclast Activation Associated with Gonadal Failure

Bone resorption by osteoclasts is necessary to maintain bone homeostasis. Osteoclast differentiation from hematopoietic progenitors and their activation depend on M-CSF and RANKL, but also requires co-stimulatory signals acting through receptors associated with DAP12 and FcRγ adaptors. Dap12 mutant mice (KΔ75) are osteopetrotic due to inactive osteoclasts but, surprisingly, these mice are more sensitive than WT mice to bone loss following an ovariectomy. Because estrogen withdrawal is known to disturb bone mass, at least in part, through lymphocyte interaction, we looked at the role of mature lymphocytes on osteoclastogenesis and bone mass in the absence of functional DAP12. Lymphocytes were found to stimulate an early osteoclast differentiation response from Dap12-deficient progenitors in vitro. In vivo, Rag1-/- mice lacking mature lymphocytes did not exhibit any bone phenotype, but lost their bone mass after ovariectomy like KΔ75 mice. KΔ75;Rag1-/- double mutant female mice exhibited a more severe osteopetrosis than Dap12-deficient animals but lost their bone mass after ovariectomy, like single mutants. These results suggest that both DAP12 and mature lymphocytes act synergistically to maintain bone mass under physiological conditions, while playing similar but not synergistic co-stimulatory roles in protecting bone loss after gonadal failure. Thus, our data support a role for lymphocytes during osteoclast differentiation and suggest that they may function as accessory cells when regular osteoclast function is compromised

Galectin-1 is required for the regulatory function of B cells

Galectin-1 (Gal-1) is required for the development of B cells in the bone marrow (BM), however very little is known about the contribution of Gal-1 to the development of B cell regulatory function. Here, we report an important role for Gal-1 in the induction of B cells regulatory function. Mice deficient of Gal-1 (Gal-1−/−) showed significant loss of Transitional-2 (T2) B cells, previously reported to include IL-10+ regulatory B cells. Gal-1−/− B cells stimulated in vitro via CD40 molecules have impaired IL-10 and Tim-1 expression, the latter reported to be required for IL-10 production in regulatory B cells, and increased TNF-α expression compared to wild type (WT) B cells. Unlike their WT counterparts, T2 and T1 Gal-1−/− B cells did not suppress TNF-α expression by CD4+ T cells activated in vitro with allogenic DCs (allo-DCs), nor were they suppressive in vivo, being unable to delay MHC-class I mismatched skin allograft rejection following adoptive transfer. Moreover, T cells stimulated with allo-DCs show an increase in their survival when co-cultured with Gal-1−/− T2 and MZ B cells compared to WT T2 and MZ B cells. Collectively, these data suggest that Gal-1 contributes to the induction of B cells regulatory function

Interconnections between hematopoiesis and bone : implications in bone homeostasis

LYON-ENS Sciences (693872304) / SudocSudocFranceF

Influence of periphyton substrates and rearing density on Liza aurata growth and production in marine nursery ponds

The main objectives of this investigation were to test the effects of (i) the presence of periphyton substrates, (ii) rearing density and (iii) supplemental feeding with dry feed on the growth and production of golden mullet (Liza aurata) juveniles. Twenty-six 1 m2-cages were installed in a French marine pond from April till June 2008. Mullets were stocked in cages with or without substrate at a density of 0, 20, 40 or 60 individuals per cage. Each treatment was carried out in triplicate. In addition, 20 fish were put in three tanks and fed ad libitum with dry feed. The results showed that (i) although mullets were seen to graze on periphyton substrates, their presence did not affect mullet growth and production. In future studies, meshed substrates could be attached on hard structures to improve the efficiency of mullet grazing; (ii) individual growth was higher at low density due to a lower competition for space and food. Production increased with rearing density reflecting that food availability was not limiting in control cages; (iii) growth and net yield of mullets were lower in fed tanks than in natural ponds where food seemed to be more appropriate for wild mullet juveniles and where stress factors were lower. Finally, in contrast to the individual growth rate, the net fish yield in this experiment was greater than that recorded in other extensive and semi-intensive systems. It was equivalent to yields observed in other periphyton-based systems. Periphyton developed on the meshed walls of cages probably increased the natural productivity of the pond. As part of sustainable aquaculture development, the effluents of intensive farms could be exploited to produce periphyton on inflexible substrates and to rear mullet adults, which are more herbivorous than juveniles. This type of integrated system could be developed with other mullet species, such as Chelon labrosus or Mugil cephalus, whose growth rates are higher than L. aurata. Mullet production could be exploited by the sale of fillets and dried ro

Construire une approche participative en géoprospective pour établir un développement agricole durable dans la région de Leziria do Tejo (Portugal)

International audienceAddressing the gaps between theory, research and practice, this paper explores a hybrid mindset of participatory action research (PAR), geoprospective and participatory geographical information system (PGIS). This approach brings together stakeholders, policy-makers and researchers – in an agricultural peri-urban region of Portugal: the Lezíria do Tejo region – to anticipate the possible changes in agricultural territories, while taking spatial dynamics into account. It uses a four-step methodology which integrates qualitative and quantitative approaches to select stakeholders’ interview areas, implement prospective workshops to engage and explore the stakeholders’ interests and encourage actions towards finding solutions for long-term agricultural sustainability in this region. The results from our study highlight that more participative approaches such as the ones developed here must be implemented towards decision-making, since they help to dispel the distrust between stakeholders, strengthen community cohesion and also contribute to build common solutions drawing upon various perspectives. From a PAR perspective, this work contributes to bridge the gap between academia and practitioners, as is shown by a willingness of the practitioners to actively participate in the research under progress.Abordant la question des écarts entre théorie, recherche et pratique, cet article examine une démarche hybridant recherche-action participative, géoprospective et système d’information géographique (SIG) participatif. Cette démarche regroupe des acteurs de terrain, des acteurs politiques et des chercheurs, dans une région agricole périurbaine du Portugal, la Lezíria do Tejo, afin d’anticiper les changements possibles des territoires agricoles, en tenant compte des dynamiques spatiales. Nous utilisons une méthode en quatre étapes qui intègre à la fois des approches quantitatives et qualitatives, pour sélectionner les zones d’enquête et identifier les intérêts des parties prenantes. L’objectif de notre démarche associée à l’établissement de scénarios à long terme est d’encourager les actions en faveur de solutions pour une agriculture durable dans cette région. Les résultats mettent en lumière toute la pertinence des approches participatives – à l’instar de celle développée dans cet article – pour éclairer les prises de décisions des différentes catégories d’acteurs. En effet, ces démarches aident à dissiper les méfiances entre acteurs, renforcent la cohésion communautaire et amènent à bâtir des solutions communes à partir de visions différentes. Fondé sur une approche de recherche-action participative, ce travail contribue à réduire le fossé entre le monde académique et le monde opérationnel, révélé par la volonté des professionnels eux-mêmes de participer aux avancées de la recherche

DAP12 overexpression induces osteopenia and impaired early hematopoiesis.

ITAM-bearing transmembrane signaling adaptors such as DAP12 and FcRγ are important players in bone homeostasis, but their precise role and functions are still unknown. It has been shown that osteoclast differentiation results from the integration of the RANK and of the DAP12 and FcRγ signaling pathways. DAP12-deficient mice suffer from a mild osteopetrosis and culture of their bone marrow cells in the presence of M-CSF and RANKL, fails to give rise to multinucleated osteoclasts. Here, we report that mice overexpressing human DAP12 have an osteopenic bone phenotype due to an increased number of osteoclasts on the surface of trabecular and cortical bone. This enhanced number of osteoclasts is associated with an increased number of proliferating myeloid progenitors in Tg-hDAP12 mice. It is concomitant with an arrest of B cell development at the Pre-Pro B/Pre B stage in the bone marrow of Tg-hDAP12 mice and important decrease of follicular and marginal B cells in the spleen of these animals. Our data show that the overexpression of DAP12 results in both increased osteoclastogenesis and impaired hematopoiesis underlining the relationship between bone homeostasis and hematopoiesis

Building a prospective participatory approach for long-term agricultural sustainability in the Lezíria do Tejo region (Portugal)

Addressing the gaps between theory, research and practice, this paper explores a hybrid mindset of participatory action research (PAR), geoprospective and participatory geographical information system (PGIS). This approach brings together stakeholders, policy-makers and researchers – in an agricultural peri-urban region of Portugal, the Lezíria do Tejo region – to anticipate the possible changes in agricultural territories, while taking spatial dynamics into account. It uses a four-step methodology which integrates qualitative and quantitative approaches to select stakeholders’ interview areas, implement prospective workshops to engage and explore the stakeholders’ interests and encourage actions towards finding solutions for long-term agricultural sustainability in this region. The results from our study highlight that more participative approaches such as the ones developed here must be implemented towards decision-making, since they help to dispel the distrust between stakeholders, strengthen community cohesion and also contribute to build common solutions drawing upon various perspectives. From a PAR perspective, this work contributes to bridge the gap between academia and practitioners, as is shown by a willingness of the practitioners to actively participate in the research under progress.Abordant la question des écarts entre théorie, recherche et pratique, cet article examine une démarche hybridant recherche-action participative, géoprospective et système d’information géographique (SIG) participatif. Cette démarche regroupe des acteurs de terrain, des acteurs politiques et des chercheurs, dans une région agricole périurbaine du Portugal, la Lezíria do Tejo, afin d’anticiper les changements possibles des territoires agricoles, en tenant compte des dynamiques spatiales. Nous utilisons une méthode en quatre étapes qui intègre à la fois des approches quantitatives et qualitatives, pour sélectionner les zones d’enquête et identifier les intérêts des parties prenantes. L’objectif de notre démarche associée à l’établissement de scénarios à long terme est d’encourager les actions en faveur de solutions pour une agriculture durable dans cette région. Les résultats mettent en lumière toute la pertinence des approches participatives – à l’instar de celle développée dans cet article – pour éclairer les prises de décisions des différentes catégories d’acteurs. En effet, ces démarches aident à dissiper les méfiances entre acteurs, renforcent la cohésion communautaire et amènent à bâtir des solutions communes à partir de visions différentes. Fondé sur une approche de recherche-action participative, ce travail contribue à réduire le fossé entre le monde académique et le monde opérationnel, révélé par la volonté des professionnels eux-mêmes de participer aux avancées de la recherche.En este artículo se analiza un proceso que combina la investigación-acción participativa, la geoprospectiva y sistemas de información geográfica (SIG), tratando así la diferencia entre teoría, investigación y práctica. Este dispositivo reúne agentes de terreno, políticos e investigadores en una región agrícola periférica de Lezíria do Tejo, Portugal, para anticipar los cambios posibles en los territorios agrícolas y considerando las fuerzas espaciales. Se utiliza un método en cuatro etapas con el fin de integrar enfoques cuantitativos y cualitativos, de seleccionar las zonas para la encuesta y de determinar los intereses de las personas concernientes. El objetivo, conjunto a la proposición de escenarios de largo plazo, consiste en apoyar acciones favorables a resoluciones para una agricultura sostenible en la región. Los resultados hacen resaltar la pertinencia de los dispositivos de participación para alumbrar la toma de decisión de los diferentes protagonistas. Tal proceso ayuda a disipar la desconfianza entre los participantes, refuerza la cohesión colectiva y permite soluciones comunes a puntos de vista divergentes. El trabajo de investigación-acción participativa contribuye a reducir el abismo entre el mundo académico y el operacional indicado por los profesionales deseosos de participar al progreso de la investigación.info:eu-repo/semantics/publishedVersio