Quantification of H/D Isotope Effects on Protein Hydrogen-bonds by h3JNC′ and 1JNC′ Couplings and Peptide Group 15N and 13C′ Chemical Shifts

The effect of hydrogen/deuterium exchange on proteinhydrogen bond coupling constants h3JNC′ has been investigated in the small globular protein ubiquitin. The couplings across deuterated or protonated hydrogen bonds were measured by a long-range quantitative HA(CACO)NCO experiment. The analysis is combined with a determination of the HN/DN isotope effect on the amide group 1JNC′ couplings and the 15N and 13C′ chemical shifts. On average, H-bond deuteration exchange weakens h3JNC′ and strengthens 1JNC′ couplings. A correlation is found between the size of the 15N isotope shift, the 15N chemical shift, and the h3JNC′ coupling constants. The data are consistent with a reduction of donor-acceptor overlap as expected from the classical Ubbelohde effect and the common understanding that HN/DN exchange leads to a shortening of the N-hydron bond length. Abbreviations: H-bond - hydrogen bon

Chlordecone exposure and adverse effects in French West Indies populations

International audienceChlordecone (Kepone) is an organochlorine insecticide that has been used as insecticide and fungicide. In the French West Indies, Guadeloupe and Martinique, it was intensively applied to banana fields from 1973 to 1993 to control root borers. This pesticide undergoes no significant biotic or abiotic degradation in the environment and is still present in soils where it was applied. It was only in 1999 that health and environmental authorities became aware of the extent of the chlordecone pollution of environmental media, including soils, waterways, and the food chain. Earlier observations and toxicological studies have demonstrated that chlordecone is a reproductive and developmental toxicant, neurotoxic and carcinogenic in rodents, and is an endocrine-disrupting chemical because of its estrogenic properties both in vitro and in vivo. Several surveys have confirmed that the French West Indian population continues to be exposed to this chemical though consumption of contaminated foodstuffs. Here, we report the findings of various epidemiological studies conducted in the French West Indies to assess the impact of environmental exposure to chlordecone on the health of the population

Major T Cell Progenitor Activity in Bone Marrow–derived Spleen Colonies

Common lymphoid progenitors (CLP) are generated in adult bone marrow (BM), but the intermediate steps leading to T cell commitment are unknown, and so is the site at which this commitment occurs. Here, we show that colonies arising in the spleen 12 days after BM injection harbor T cell precursors that are undetectable in BM. These precursors did not generate myeloid cells in vivo but repopulated the thymus and the peripheral T cell compartment much faster than did CLP. Two lineage negative (Lin−) subpopulations were distinguished, namely CD44+ Thy1− cells still capable of natural killer generation and transient low-level B cell generation, and T cell–restricted CD44− Thy1+ cells. At a molecular level, frequency of CD3ɛ and preTα mRNA was very different in each subset. Furthermore, only the CD44− Thy1+ subset have initiated rearrangements in the T cell receptor β locus. Thus, this study identifies extramedullary T cell progenitors and will allow easy approach to T cell commitment studies

Pyrethroid insecticide exposure and cognitive developmental disabilities in children: The PELAGIE mother–child cohort

International audiencePyrethroid insecticides are widely used in agriculture and in homes. Despite the neurotoxicity of these insecticides at high doses, few studies have examined whether lower-level exposures could adversely affect children's neurodevelopment. The PELAGIE cohort included 3421 pregnant women from Brittany, France between 2002 and 2006. When their children reached their sixth birthday, 428 mothers from the cohort were randomly selected, successfully contacted and found eligible. A total of 287 (67%) mothers agreed to participate with their children in the neuropsychological follow-up. Two cognitive domains were assessed by the Wechsler Intelligence Scale for Children: verbal comprehension and working memory. Five pyrethroid and two organophosphate insecticide metabolites were measured in maternal and child first-void urine samples collected between 6 and 19 gestational weeks and at 6 years of age, respectively. Linear regression models were used to estimate associations between cognitive scores and urinary pyrethroid metabolite concentrations, adjusting for organophosphate metabolite concentrations and potential confounders. Maternal prenatal pyrethroid metabolite concentrations were not consistently associated with any children's cognitive scores. By contrast, childhood 3-PBA and cis-DBCA concentrations were both negatively associated with verbal comprehension scores (P-trend = 0.04 and P-trend < 0.01, respectively) and with working memory scores (P-trend = 0.05 and P-trend < 0.01, respectively). No associations were observed for the three other childhood pyrethroid metabolite concentrations (4-F-3-PBA, cis-DCCA, and trans-DCCA). Low-level childhood exposures to deltamethrin (as cis-DBCA is its principal and selective metabolite), in particular, and to pyrethroid insecticides, in general (as reflected in levels of the 3-PBA metabolite) may negatively affect neurocognitive development by 6 years of age. Whatever their etiology, these cognitive deficits may be of importance educationally, because cognitive impairments in children interfere with learning and social development. Potential causes that can be prevented are of paramount public health importanc

Formulaic sequence (FS) cannot be an umbrella term in SLA : Focusing on psycholinguistic FSs and their identification

The term formulaic sequence (FS) is used with a multiplicity of meanings in the SLA literature, some overlapping but others not, and researchers are not always clear in defining precisely what they are investigating, or in limiting the implicational domain of their findings to the type of formulaicity they focus on. The first part of the article provides a conceptual framework focusing on the contrast between linguistic or learner-external definitions, that is, what is formulaic in the language the learner is exposed to, such as idiomatic expressions or collocations, and psycholinguistic or learner-internal definitions, that is, what is formulaic within an individual learner because it presents a processing advantage. The second part focuses on the methodological consequences of adopting a learner-internal approach to the investigation of FSs, and examines the challenges presented by the identification of psycholinguistic formulaicity in advanced L2 learners, proposing a tool kit based on a hierarchical identification method

Urinary Biomarkers of Prenatal Atrazine Exposure and Adverse Birth Outcomes in the PELAGIE Birth Cohort

Background: Despite evidence of atrazine toxicity in developing organisms from experimental studies, few studies—and fewer epidemiologic investigations—have examined the potential effects of prenatal exposure

Centre Louis-Gernet de recherches comparées sur les sociétés anciennes

Emmanuelle Cagnac et Valérie Huet, maîtres de conférences à l’Université de Paris-VIIPierre Cordier, maître de conférences à l’Université de PoitiersFlorence Dupont, professeur à l’Université de Paris-VII Façons romaines de faire le Grec Les chercheurs du Centre Louis-Gernet (historiens de Rome et de la Grèce anciennes) avaient décidé d’engager pour deux ans une étude sur les relations interculturelles dans l’espace gréco-romain. Les Romains appellent « grecques » ou désignent d’un terme exhi..