Barking up the Right Tree: Using Tree Bark to Track Airborne Particles in School Environment and Link Science to Society.

Children's exposure to air pollution affects both their health and learning skills. Fine and ultrafine particulate matter (PM2.5, PM1), notably issued from traffic sources in urban centers, belong to the most potential harmful health hazards. However their monitoring and the society's awareness on their dangers need to be consolidated. In this study, raising teacher and pupil involvement for air quality improvement in their schools environment is reached through developing a passive monitoring technique (bio-sensors made of tree bark). The experiment was implemented in two urban elementary schools situated close to a main traffic road of the city of Toulouse (South of France). Magnetic properties, carbonaceous fraction measurements, and scanning electronic microscopy (SEM-EDX) investigations were realized both on passive bio-sensors and filters issued from active sampling. We find that traffic is the main PM1 source for both outdoors and indoors at schools. Higher levels of outdoor PM in the school's environments compared to urban background are reached especially in the cold period. The schools proximity to a main traffic source and lack of ventilation are the main causes for observed PM1 accumulation in classrooms. The co-working experiment with educational teams and pupils shows that the use of bio-sensors is a driver for children empowerment to air pollution and therefore represents a potential key tool for the teachers though limiting eco-anxiety. As PM accumulation is observed in many scholar environments across Europe, the proposed methodology is a step toward a better assessment of PM impact on pupil's health and learning skills.

Up-regulation of insulin-like growth factor binding protein-5 is independent of muscle cell differentiation, sensitive to rapamycin, but insensitive to wortmannin and LY294002.

Skeletal myoblast differentiation is stimulated by insulin-like growth factors (IGFs). The autocrine action of IGFs is mediated through the type-1 IGF receptor (IGFR-1) and modulated by IGF binding proteins (IGFBPs) secreted by the cells. The mouse C2 myoblast cell line stably transfected with a vector producing IGF-II antisense RNA was used to show that specific IGFBP expression changes with the state of the cells: high levels of IGFBP-2 messenger RNA (mRNA) were found only in proliferating myoblasts, whereas IGFBP-3 mRNA was induced in quiescent cells. Secretion of IGFBP5 was strongly stimulated during differentiation. Insulin and IGF dose-response experiments showed that up-regulation of IGFBP-5 resulted from IGFR-1 activation. Drugs interfering with IGFR-1 signaling and inhibiting myoblast differentiation had different effects on IGFBP-5 up-regulation. Two phosphatidylinositol 3-kinase (PI 3-kinase) inhibitors, wortmaninn and LY294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one], failed to alter IGFBP-5 up-regulation, which persisted in the absence of differentiation. Rapamycin which indirectly prevents activation of the p70 ribosomal protein-S6 kinase (p70S6k), suppressed IGFBP-5 induction. Because the PI3-kinase inhibitors block p70S6k, neither kinase would be required for IGFR-1-dependent IGFBP-5 induction. In C2 anti-IGF-II myoblasts, IGFBP-5 induction is therefore rapamycin-sensitive and independent of differentiation.

Wortmannin inhibits IGF-dependent differentiation in the mouse myogenic cell line C2.

Evidence has accumulated that suggests that insulin-like growth factors (IGFs) exert a positive influence on myoblast differentiation. We have undertaken to study the signalling events required for differentiation resulting from type-1 IGF receptor stimulation in C2 myoblasts, where autocrine production of IGF-II was abolished by means of antisense RNA. Exposure of the cells to IGFs leads to a rapid and sustained activation of phosphatidyl-inositol 3-kinase followed by the expression of Myod, myogenin and differentiation. The fungal metabolite, wortmannin, inhibits both PI 3-kinase and muscle differentiation with an IC 50 in the nanomolar range. IGFs are also known to cause a rapid activation of MAP kinase. However, the synthetic inhibitor of MEK, PD098059, which prevents MAP kinase activation, does not affect myoblast differentiation. These results provide evidence that PI 3-kinase, but not MAP kinase, is required for insulin-like growth factor receptor-dependent differentiation of muscle cells.

Transforming growth factor-beta inhibition of insulin-like growth factor-binding protein-5 synthesis in skeletal muscle cells involves a c-Jun N-terminal kinase-dependent pathway.

Transforming growth factor-beta (TGF-beta) and insulin-like growth factors (IGFs) play critical roles in the control of myogenesis. Insulin-like growth factor-binding protein-5 (IGFBP-5), by regulating the bioavailability of IGFs, is involved in controlling IGF-dependent differentiation. We investigated the effects of TGF-beta on the IGFBP-5 production induced by IGFs in mouse myoblasts. TGF-beta leads to a decrease in IGFBP-5 synthesis at both transcript and protein levels, and blocked muscle differentiation. The Smad proteins and the c-Jun N-terminal kinase (JNK) have been shown to be involved in TGF-beta signaling pathways. We provide evidence that the JNK pathway, rather than Smad proteins, is involved in the response of muscle cells to TGF-beta. This factor failed to stimulate the GAL4-Smad 2/3 transcriptional activities of the constructs used to transfect myoblasts. Moreover, stable expression of the antagonistic Smad7 did not abolish the inhibitory effect of TGF-beta on IGFBP-5 production whereas expression of a dominant-negative version of MKK4, an upstream activator of JNK, did. We also showed, using a specific inhibitor, that the p38 mitogen-activated protein kinase (p38 MAPK) was not involved in the inhibition of IGFBP-5 production. Thus, TGF-beta-mediated IGFBP-5 inhibition is independent of Smads and requires activation of the JNK signaling pathway.