Removal of the phage-shock protein PspB causes reduction of virulence in Salmonella enterica serovar Typhimurium independently of NRAMP1

The phage-shock protein (Psp) system is believed to manage membrane stress in all Enterobacteriaceae and has recently emerged as being important for virulence in several pathogenic species of this phylum. The core of the Psp system consists of the pspA-D operon and the distantly located pspG gene. In Salmonella enterica serovar Typhimurium (S. Typhimurium), it has recently been reported that PspA is essential for systemic infection of mice, but only in NRAMP1(+) mice, signifying that attenuation is related to coping with divalent cation starvation in the intracellular environment. In the present study, we investigated the contribution of individual psp genes to virulence of S. Typhimurium. Interestingly, deletion of the whole pspA-D set of genes caused attenuation in both NRAMP1(+) and NRAMP1(-) mice, indicating that one or more of the psp genes contribute to virulence independently of NRAMP1 expression in the host. Investigations of single gene mutants showed that knock out of pspB reduced virulence in both types of mice, while deletion of pspA only caused attenuation in NRAMP1(+) mice, and deletion of pspD had a minor effect in NRAMP1(-) mice, while deletions of either pspC or pspG did not affect virulence. Experiments addressed at elucidating the role of PspB in virulence revealed that PspB is dispensable for uptake to and intracellular replication in cultured macrophages and resistance to complement-induced killing. Furthermore, the Psp system of S. Typhimurium was dispensable during pIV-induced secretin stress. In conclusion, our results demonstrate that removal of PspB reduces virulence in S. Typhimurium independently of host NRAMP1 expression, demonstrating that PspB has roles in intra-host survival distinct from the reported contributions of PspA

Efficient mitochondrial targeting relies on co-operation of multiple protein signals in plants

To date, the most prevalent model for transport of pre-proteins to plant mitochondria is based on the activity of an N-terminal extension serving as a targeting peptide. Whether the efficient delivery of proteins to mitochondria is based exclusively on the action of the N-terminal extension or also on that of other protein determinants has yet to be defined. A novel mechanism is reported here for the targeting of a plant protein, named MITS1, to mitochondria. It was found that MITS1 contains an N-terminal extension that is responsible for mitochondrial targeting. Functional dissection of this extension shows the existence of a cryptic signal for protein targeting to the secretory pathway. The first 11 amino acids of the N-terminal extension are necessary to overcome the activity of this signal sequence and target the protein to the mitochondria. These data suggest that co-operation of multiple determinants within the N-terminal extension of mitochondrial proteins may be necessary for efficient mitochondrial targeting. It was also established that the presence of a tryptophan residue toward the C-terminus of the protein is crucial for mitochondrial targeting, as mutation of this residue results in a redistribution of MITS1 to the endoplasmic reticulum and Golgi apparatus. These data suggest a novel targeting model whereby protein traffic to plant mitochondria is influenced by domains in the full-length protein as well as the N-terminal extension

Green Edge ice camp campaigns : understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies

Enhanced interest in letters and numbers in autistic children

Abstract Background An intense and precocious interest in written material, together with a discrepancy between decoding and reading comprehension skills are defining criteria for hyperlexia, which is found in up to 20% of autistic individuals. It may represent the extreme end of a broader interest in written material in autism. This study examines the magnitude and nature of the interest in written material in a large population of autistic and non-autistic children. Methods All 701 children (391 autistic, 310 non-autistic) under the age of 7 referred to an autism assessment clinic over a span of 4 years were included. Ordinal logistic regressions assessed the association between diagnosis and the level of interest in letters and numbers. A nested sample of parents of 138 autistic, 99 non-autistic clinical, and 76 typically developing (TD) children completed a detailed questionnaire. Cox proportional hazards models analyzed the age of emergence of these interests. Linear regressions evaluated the association between diagnosis and interest level. The frequency of each behaviour showing interest and competence with letters and numbers were compared. Results In the two studies, 22 to 37% of autistic children had an intense or exclusive interest in letters. The odds of having a greater interest in letters was 2.78 times higher for autistic children than for non-autistic clinical children of the same age, and 3.49 times higher for the interest in numbers, even if 76% of autistic children were minimally or non-verbal. The age of emergence of these interests did not differ between autistic and TD children and did not depend on their level of oral language. Non-autistic children showed more interest in letters within a social context. Limitations The study holds limitations inherent to the use of a phone questionnaire with caregivers and missing sociodemographic information. Conclusions The emergence of the interest of autistic children toward written language is contemporaneous to the moment in their development where they display a strong deficit in oral language. Together with recent demonstrations of non-social development of oral language in some autistic children, precocious and intense interest in written material suggests that language acquisition in autism may follow an alternative developmental pathway

Spray coating of Ba0.6Sr0.4TiO3 nanoparticles: a low-cost and scalable process for the deposition of dielectric thin films

International audienc

Fabrication of High Capacitance Density Capacitor Using Spray Coated Ba0.6Sr0.4TiO3 Thin Films

International audienc

Efficiency of sympagic-benthic coupling revealed by analyses of n-3 fatty acids, IP25 and other highly branched isoprenoids in two filter-feeding Arctic benthic molluscs: Mya truncata and Serripes groenlandicus

International audienceThe aim of this work was to determine the impact of sympagic (ice-associated) algal primary production on the quality of Arctic filter-feeding bivalves. For this purpose, we investigated the sea ice production of lipids (including omega-3 polyunsaturated fatty acids (n-3 PUFA) and highly branched isoprenoids (HBI)), as well as their subsequent incorporation into the truncate softshell clam (Mya truncata) and the Greenland cockle (Serripes groenlandicus), during the melting periods of two consecutive years in Baffin Bay. Lipid and primary production exhibited seasonal variability and overall contrasts between the two years, as a result of distinct physical forcings and the ensuing biological responses. Whilst less productive in terms of total lipids or chlorophyll a, spring 2016 was more productive than spring 2015 for n-3 PUFA, which are essential for benthic fauna. The sea ice diatom HBI biomarker IP25 was quantified in sea ice from both years. Interestingly, such production was preceded by a production of the hitherto ‘pelagic’ biomarker, HBI III, in sea ice. In bivalves, HBI contents and correlations confirmed the tightness of the Arctic sympagic-benthic coupling and highlighted that S. groenlandicus can be used as a sentinel species for assessing the degree of this coupling. The confirmation that bivalves incorporate sea-ice derived HBI III and not only IP25, may introduce uncertainties into the use of some HBI-based indices. Monitoring of the fatty acid contents of bivalves allowed identification of their spawning periods and suggests that M. truncata did not store enough n-3 PUFA to sustain its reproductive effort

Ba0.6Sr0.4TiO3 nanocrystals self assembly into thin films for the development of high capacitance Metal-Insulator-Metal (MIM)

International audienc

Longitudinal associations of household use of cleaning agents and asthma symptoms in women: The EGEA study

International audienceObjective To evaluate the associations between the evolution of household use of cleaning products with the asthma symptom score and its evolution over 8 years. Methods Our study is based on 509 women participating in the last two surveys of the Epidemiological study on the Genetics and Environment of Asthma (EGEA) study (EGEA2: 2003-2007 (44 years, 19% current smokers) and EGEA3: 2011-2013). We assessed an asthma symptom score and the use of household cleaning products through standardised questionnaires. We studied longitudinal associations of the evolution of weekly use of irritant or spayed cleaning products with (1) the asthma symptom score at EGEA3 and a stable symptom score between EGEA2-EGEA3 (negative binomial models) and (2) the incidence/evolution of asthma symptoms between EGEA2-EGEA3 (logistic/polytomous logistic regressions). Models accounted for familial dependence and were adjusted for age, smoking status, body mass index and occupational exposure to asthmagens. Results Persistent and increased (40% and 16%, respectively) weekly use of irritants or sprays were associated with a higher risk of asthma symptoms at EGEA3 (Mean Score Ratio (MSR)=1.51 (95% CI 1.06 to 2.14) and 1.33 (95% CI 0.85 to 2.08), respectively). A decreased use (19%) was associated with a lower risk of symptoms at EGEA3, compared with a persistent use (MSR=0.59 (95% CI 0.39 to 0.88)). We also observed an association between an increased use of sprays and the incidence of asthma symptoms (OR=2.30 (95% CI 1.08 to 4.91)), compared with no weekly use of irritants/sprays. Conclusions This longitudinal study, with repeated assessment of exposure and respiratory health, supports the hypothesis that a persistent or increased weekly use of sprayed cleaning products over time may have an adverse effect on the evolution of asthma symptoms

Removal of the phage-shock protein PspB causes reduction of virulence in <em>Salmonella enterica</em> serovar Typhimurium independently of NRAMP1.

The phage-shock protein (Psp) system is believed to manage membrane stress in all Enterobacteriaceae and has recently emerged as being important for virulence in several pathogenic species of this phylum. The core of the Psp system consists of the pspA-D operon and the distantly located pspG gene. In Salmonella enterica serovar Typhimurium (S. Typhimurium), it has recently been reported that PspA is essential for systemic infection of mice, but only in NRAMP1(+) mice, signifying that attenuation is related to coping with divalent cation starvation in the intracellular environment. In the present study, we investigated the contribution of individual psp genes to virulence of S. Typhimurium. Interestingly, deletion of the whole pspA-D set of genes caused attenuation in both NRAMP1(+) and NRAMP1(-) mice, indicating that one or more of the psp genes contribute to virulence independently of NRAMP1 expression in the host. Investigations of single gene mutants showed that knock out of pspB reduced virulence in both types of mice, while deletion of pspA only caused attenuation in NRAMP1(+) mice, and deletion of pspD had a minor effect in NRAMP1(-) mice, while deletions of either pspC or pspG did not affect virulence. Experiments addressed at elucidating the role of PspB in virulence revealed that PspB is dispensable for uptake to and intracellular replication in cultured macrophages and resistance to complement-induced killing. Furthermore, the Psp system of S. Typhimurium was dispensable during pIV-induced secretin stress. In conclusion, our results demonstrate that removal of PspB reduces virulence in S. Typhimurium independently of host NRAMP1 expression, demonstrating that PspB has roles in intra-host survival distinct from the reported contributions of PspA