An in vitro model to assess the immunosuppressive effect of tick saliva on the mobilization of inflammatory monocyte-derived cells

Tick-borne pathogens cause potent infections. These pathogens benefit from molecules contained in tick saliva that have evolved to modulate host innate and adaptive immune responses. This is called "saliva-activated transmission" and enables tick-borne pathogens to evade host immune responses. Ticks feed on their host for relatively long periods; thus, mechanisms counteracting the inflammation-driven recruitment and activation of innate effector cells at the bite site, are an effective strategy to escape the immune response. Here, we developed an original in vitro model to evaluate and to characterize the immunomodulatory effects of tick saliva that prevent the establishment of a local inflammatory immune response. This model mimics the tick bite and enables the assessment of the effect of saliva on the inflammatory-associated dynamic recruitment of cells from the mononuclear phagocyte system. Using this model, we were able to recapitulate the dual effect of tick saliva on the mobilization of inflammatory monocyte-derived cells, i.e. (i) impaired recruitment of monocytes from the blood to the bite wound; and (ii) poor mobilization of monocyte-derived cells from the skin to the draining lymph node. This simple tool reconstitutes the effect of tick saliva in vivo, which we characterized in the mouse, and should enable the identification of important factors facilitating pathogen infection. Furthermore, this model may be applied to the characterization of any pathogen-derived immunosuppressive molecule affecting the establishment of the inflammatory immune response

A Novel Mouse c-fos Intronic Promoter That Responds to CREB and AP-1 Is Developmentally Regulated In Vivo

BACKGROUND: The c-fos proto-oncogene is an archetype for rapid and integrative transcriptional activation. Innumerable studies have focused on the canonical promoter, located upstream from the transcriptional start site. However, several regulatory sequences have been found in the first intron. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe an extremely conserved region in c-fos first intron that contains a putative TATA box, and functional TRE and CRE sites. This fragment drives reporter gene activation in fibroblasts, which is enhanced by increasing intracellular calcium and cAMP and by cotransfection of CREB or c-Fos/c-Jun expression vectors. We produced transgenic mice expressing a lacZ reporter controlled by the intronic promoter. Lac Z expression of this promoter is restricted to the developing central nervous system (CNS) and the mesenchyme of developing mammary buds in embryos 12.5 days post-conception, and to brain tissue in adults. RT-QPCR analysis of tissue mRNA, including the anlage of the mammary gland and the CNS, confirms the existence of a novel, nested mRNA initiated in the first intron. CONCLUSIONS/SIGNIFICANCE: Our results provide evidence for a novel, developmentally regulated promoter in the first intron of the c-fos gene

Early gametogenesis in the Pacific oyster: new insights using stem cell and mitotic markers

While our knowledge of bivalve gametogenesis has progressed in recent times, more molecular markers are needed in order to develop tissue imaging. Here, we identified stem cell and mitotic markers to further characterize oyster early gametogenesis, mainly through immunofluorescence microscopy. Intense alkaline phosphatase activity, a non-specific marker for stem cells, was detected on the outer edge of the gonad ducts at the post-spawning stage, suggesting an abundance of undifferentiated cells very early during the sexual cycle. This observation was confirmed using an antibody against Sox2, a transcription factor specific for stem or germline cells, which labeled cells in the gonad duct inner mass and ciliated epithelium early during the initial oyster sexual cycle. Moreover, Vasa, a cytoplasmic marker for germline cells, was also detected in the gonad acini and duct cells, thus confirming that germline cells were abundant early on. In addition, the binding of the minichromosome maintenance MCM6 protein to chromatin indicated the gonad acini and duct cells were engaged in the cell cycle. DNA replication was indeed confirmed by an abundant in vivo incorporation of BrdU into the duct cell chromatin. Finally, proliferation of acini and duct cells was demonstrated by the chromatin-bound Ser10-phosphorylated histone H3, a mitotic marker. The markers for the cell cycle and mitosis used here thus indicate that acini and duct cells were already actively dividing early during the oyster sexual cycle. In addition, together with the stem cell markers, these data reveal that the epithelium delimiting the duct outer edge contains a dynamic population of undifferentiated cells

Conservación y uso sostenible de la biodiversidad en los Andes colombianos. Resumen de resultados

Este documento presenta el resumen de los objetivos y resultados del proyecto "Conservación y uso sostenible de la biodiversidad en los Andes colombianos" (Proyecto Andes), sus indicadores de efecto, las lecciones aprendidas tras seis años de implementacióny la proyección que se deriva de los logros alcanzados. en él se recopilan en forma resumida los resultados que fueron alcanzados por el equipo técnico del Instituto, consultores y demás aliados en la ejecución del proyecto

Tetrameric and homodimeric camelid IgGs originate from the same IgH locus.

International audienceIn addition to producing conventional tetrameric IgGs, camelids have the particularity of producing a functional homodimeric IgG type lacking L (light) chains and only made up of two H (heavy) chains. This nonconventional IgG type is characterized by variable and constant regions referred to as V(H)H and C(H)H, respectively, and which differ from conventional V(H) and C(H) counterparts. Although the structural properties of homodimeric IgGs have been well investigated, the genetic bases involved in their generation are still largely unknown. In this study, we characterized the organization of genes coding for the H chains of tetrameric and homodimeric IgGs by constructing an alpaca (Lama pacos) genomic cosmid library. We showed that a single IgH locus in alpaca chromosome 4 contains all of the genetic elements required for the generation of the two types of Igs. The alpaca IgH locus is composed of a V region that contains both V(H)H and V(H) genes followed by a unique D(H)-J(H) cluster and C region genes, which include both C(H)H and C(H) genes. Although this general gene organization greatly resembles that of other typical mammalian V(n)-D(n)-J(n)-C(n) translocon IgH loci, the intermixed gene organization within the alpaca V and C regions reveals a new type of translocon IgH locus. Furthermore, analyses of cDNA coding for the membrane forms of IgG and IgM present in alpaca peripheral blood B cells are most consistent with the notion that the development of a B cell bearing homodimeric IgG passes through an IgM(+) stage, similar to the case for conventional IgG

Adult somatic progenitor cells and hematopoiesis in oysters

Long-lived animals show a non-observable age-related decline in immune defense, which is provided by blood cells that derive from self-renewing stem cells. The oldest living animals are bivalves. Yet, the origin of hemocytes, the cells involved in innate immunity, is unknown in bivalves and current knowledge about mollusk adult somatic stem cells is scarce. Here we identify a population of adult somatic precursor cells and show their differentiation into hemocytes. Oyster gill contains an as yet unreported irregularly folded structure (IFS) with stem-like cells bathing into the hemolymph. BrdU labeling revealed that the stem-like cells in the gill epithelium and in the nearby hemolymph replicate DNA. Proliferation of this cell population was further evidenced by phosphorylated-histone H3 mitotic staining. Finally, these small cells most abundant in the IFS epithelium were found positive for the stemness marker Sox2. We provide evidence for hematopoiesis by showing that co-expression of Sox2 and Cu/Zn SOD, a hemocyte-specific enzyme, does not occur in the gill epithelial cells but rather in the underlying tissues and vessels. We further confirm the hematopoietic features of these cells by the detection of Filamin, a protein specific for a sub-population of hemocytes, in large BrdU-labeled cells bathing into gill vessels. Altogether, our data show that progenitor cells differentiate into hemocytes in gill, which suggests that hematopoiesis occurs in oyster gills