13 research outputs found
A primordial origin for the atmospheric methane of Saturn's moon Titan
The origin of Titan's atmospheric methane is a key issue for understanding
the origin of the Saturnian satellite system. It has been proposed that
serpentinization reactions in Titan's interior could lead to the formation of
the observed methane. Meanwhile, alternative scenarios suggest that methane was
incorporated in Titan's planetesimals before its formation. Here, we point out
that serpentinization reactions in Titan's interior are not able to reproduce
the deuterium over hydrogen (D/H) ratio observed at present in methane in its
atmosphere, and would require a maximum D/H ratio in Titan's water ice 30%
lower than the value likely acquired by the satellite during its formation,
based on Cassini observations at Enceladus. Alternatively, production of
methane in Titan's interior via radiolytic reactions with water can be
envisaged but the associated production rates remain uncertain. On the other
hand, a mechanism that easily explains the presence of large amounts of methane
trapped in Titan in a way consistent with its measured atmospheric D/H ratio is
its direct capture in the satellite's planetesimals at the time of their
formation in the solar nebula. In this case, the mass of methane trapped in
Titan's interior can be up to 1,300 times the current mass of atmospheric
methane.Comment: Accepted for publication in Icaru
A Specific Gut Microbiota Dysbiosis of Type 2 Diabetic Mice Induces GLP-1 Resistance through an Enteric NO-Dependent and Gut-Brain Axis Mechanism
Transcriptional response of yellow perch to changes in ambient metalconcentrations—A reciprocal field transplantation experiment
Recent local adaptation to pollution has been evidenced in several organisms inhabiting environments
heavily contaminated by metals. Nevertheless, the molecular mechanisms underlying adaptation to high
metal concentrations are poorly understood, especially in fishes. Yellow perch (Perca flavescens) populations
from lakes in the mining area of Rouyn-Noranda (QC, Canada) have been faced with metal
contamination for about 90 years. Here, we examine gene transcription patterns of fish reciprocally
transplanted between a reference and a metal-contaminated lake and also fish caged in their native lake.
After four weeks, 111 genes were differentially transcribed in metal-naïve fish transferred to the metalcontaminated
lake, revealing a plastic response to metal exposure. Genes involved in the citric cycle and
beta-oxidation pathways were under-transcribed, suggesting a potential strategy to mitigate the effects
of metal stress by reducing energy turnover. However, metal-contaminated fish transplanted to the reference
lake did not show any transcriptomic response, indicating a reduced plastic response capability
to sudden reduction in metal concentrations. Moreover, the transcription of other genes, especially ones
involved in energy metabolism, was affected by caging. Overall, our results highlight environmental stress
response mechanisms in yellow perch at the transcriptomic level and support a rapid adaptive response
to metal exposure through genetic assimilation.Keywords:
Transcriptome
Yellow perch
Metal exposure
Reciprocal transplantation
Cagin
Environmental concentrations of benz[a]anthracene induce developmental defects and DNA damage and impair photomotor response in Japanese medaka larvae
Benz[a]anthracene (BaA) is a ubiquitous polycyclic aromatic hydrocarbon found in numerous aquatic ecosystems. However, ecotoxicological data in aquatic organisms are scarce. To remedy this lack of data, Japanese medaka (Oryzias latipes) embryos were exposed to BaA and toxic effects were investigated at multiple toxicological endpoints. Japanese medaka embryos were incubated onto BaA-spiked artificial sediment for 9 days at low or moderate environmental concentrations ranging from 0.9 to 12 µg g−1 dw. BaA-exposed embryos exhibited significant tachycardia. BaA exposure was also shown to increase CYP1A activity in the hepato-biliary tissue as well as craniofacial deformities and DNA damage in pro-larvae. The photomotor response of BaA-exposed larvae was reduced in comparison to the control group. According to this set of tests, the lowest tested and observed effect concentration (LOEC) for Japanese medaka early life stages was equivalent to 0.92 µg g−1 dw of BaA. This concentration fall into the range of concentrations frequently encountered in sediments of polluted aquatic ecosystems. Taking into consideration these results, BaA represents a threat for fish early life stages in particular those developing onto or into contaminated sediments
Lixisenatide requires a functional gut-vagus nerve-brain axis to trigger insulin secretion in controls and type 2 diabetic mice
The secreted autotransporter toxin, Sat, functions as a virulence factor in Afa/Dr diffusely adhering Escherichia coli by promoting lesions in tight junction of polarized epithelial cells
Natural history, dynamics, and ecology of human papillomaviruses in genital infections of young women: protocol of the PAPCLEAR cohort study.
INTRODUCTION: Human papillomaviruses (HPVs) are responsible for one-third of all cancers caused by infections. Most HPV studies focus on chronic infections and cancers, and we know little about the early stages of the infection. Our main objective is to better understand the course and natural history of cervical HPV infections in healthy, unvaccinated and vaccinated, young women, by characterising the dynamics of various infection-related populations (virus, epithelial cells, vaginal microbiota and immune effectors). Another objective is to analyse HPV diversity within hosts, and in the study population, in relation to co-factors (lifestyle characteristics, vaccination status, vaginal microbiota, human genetics). METHODS AND ANALYSIS: The PAPCLEAR study is a single center longitudinal study following 150 women, aged 18-25 years, for up to 2 years. Visits occur every 2 or 4 months (depending on HPV status) during which several variables are measured, such as behaviours (via questionnaires), vaginal pH, HPV presence and viral load (via qPCR), local concentrations of cytokines (via MesoScale Discovery technology) and immune cells (via flow cytometry). Additional analyses are outsourced, such as titration of circulating anti-HPV antibodies, vaginal microbiota sequencing (16S and ITS1 loci) and human genotyping. To increase the statistical power of the epidemiological arm of the study, an additional 150 women are screened cross-sectionally. Finally, to maximise the resolution of the time series, participants are asked to perform weekly self-samples at home. Statistical analyses will involve classical tools in epidemiology, genomics and virus kinetics, and will be performed or coordinated by the Centre National de la Recherche Scientifique (CNRS) in Montpellier. ETHICS AND DISSEMINATION: This study has been approved by the Comite de Protection des Personnes Sud Mediterranee I (reference number 2016-A00712-49); by the Comite Consultatif sur le Traitement de l'Information en matiere de Recherche dans le domaine de la Sante (reference number 16.504); by the Commission Nationale Informatique et Libertes (reference number MMS/ABD/AR1612278, decision number DR-2016-488) and by the Agence Nationale de Securite du Medicament et des Produits de Sante (reference 20160072000007). Results will be published in preprint servers, peer-reviewed journals and disseminated through conferences. TRIAL REGISTRATION NUMBER: NCT02946346; Pre-results