The toxicity of chlorpyrifos towards differentiating mouse N2a neuroblastoma cells

The aim of this work was to study the effects of chlorpyrifos (CPF) on the outgrowth of axons by differentiating mouse N2a neuroblastoma cells. This was achieved by morphological, Western blotting and enzymatic analyses of cells induced to differentiate in the presence and absence of CPF added either at the same time (co-differentiation) or 16 h after (post-differentiation) the induction of cell differentiation. The outgrowth of axon-like processes was impaired following 4 or 8 h exposure to CPF in both co- and post-differentiation experiments. Western blotting analysis revealed reduced levels of neurofilament heavy chain (NF-H) following 8 h of exposure but no significant effect at 4 h under both co- and post-differentiation conditions. By contrast, levels of the heat shock protein HSP-70 were raised at both time points, but only in co-differentiation experiments. Neuropathy target esterase (NTE) activity was lower than controls following 4 or 8 h of exposure under co-differentiation conditions, but not under any post-differentiation conditions. The results suggest that the inhibition of axon production and maintenance by CPF in differentiating N2a cells may involve multiple targets, which are different under co- and post-differentiation conditions

Technical note: No impact of alkenone extraction on foraminiferal stable isotope, trace element and boron isotope geochemistry

Recent advances in geochemical techniques mean that several robust proxies now exist to determine the past carbonate chemistry of the oceans. Foraminiferal δ11B and alkenone carbon isotopes allow us to reconstruct sea-surface pH and pCO2, respectively, and the ability to apply both proxies to the same sediment sample would give strongly paired datasets and reduce sample waste. However, no studies to date have examined whether the solvents and extraction techniques used to prepare alkenones for analysis also impact the geochemistry of foraminifera within those sediments. Here we examine six species pairs of planktic foraminifera, with half being taken from non-treated sediments and half being taken from sediments where alkenones have been extracted. We look for visual signs of contrasting preservation and compare analyses of δ18O, δ13C, δ11B and trace elements (Li, B, Na, Mn, Mg, Sr and U/Ca). We find no consistent geochemical offset between the treatments and excellent agreement in δ11B measurements between them. Our results show that boron isotope reconstructions of pH in foraminifera from alkenone-extracted sediments can be applied with confidence.</p

Anti-PrP antibodies block PrPSc replication in prion-infected cell cultures by accelerating PrPC degradation.

manuscript received October 15, 2003; revised manuscript received December 15, 2003; accepted December 16, 2003. We thanks P. Rondard, O Bischof, J.-L. Laplanche and J.-P. Pin for their fruitful discussions. we are grateful to S. barrère for her assistance in the statistical analysis of the data and H. McMahon for her assistance in reading the manuscript

Mammalian adaptation of influenza A(H7N9) virus is limited by a narrow genetic bottleneck

Human infection with avian influenza A(H7N9) virus is associated mainly with the exposure to infected poultry. The factors that allow interspecies transmission but limit human-to-human transmission are unknown. Here we show that A/Anhui/1/2013(H7N9) influenza virus infection of chickens (natural hosts) is asymptomatic and that it generates a high genetic diversity. In contrast, diversity is tightly restricted in infected ferrets, limiting further adaptation to a fully transmissible form. Airborne transmission in ferrets is accompanied by the mutations in PB1, NP and NA genes that reduce viral polymerase and neuraminidase activity. Therefore, while A(H7N9) virus can infect mammals, further adaptation appears to incur a fitness cost. Our results reveal that a tight genetic bottleneck during avian-to-mammalian transmission is a limiting factor in A(H7N9) influenza virus adaptation to mammals. This previously unrecognized biological mechanism limiting species jumps provides a measure of adaptive potential and may serve as a risk assessment tool for pandemic preparedness.published_or_final_versio