98 research outputs found
Le conservatoire botanique de Porquerolles
En raison des menaces de voir disparaître plusieurs centaines d'espèces, sous-espèces ou variétés de plantes méditerranéennes françaises, il a été créé le conservatoire botanique de Porquerolles. Ce dernier remplit à la fois un rôle de conservation, d'expérimentation et de formation du public
Crystal structure of the two-RRM domain of hnRNP A1 (UP1) complexed with single-stranded telomeric DNA
Human hnRNP A1 is a versatile single-stranded nucleic acid-binding protein that functions in various aspects of mRNA maturation and in telomere length regulation. The crystal structure of UP1, the amino-terminal domain of human hnRNP A1 containing two RNA-recognition motifs (RRMs), bound to a 12-nucleotide single-stranded telomeric DNA has been determined at 2.1 Angstrom resolution. The structure of the complex reveals the basis for sequence-specific recognition of the single-stranded overhangs of human telomeres by hnRNP A1. It also provides insights into the basis for high-affinity binding of hnRNP A1 to certain RNA sequences, and for nucleic acid binding and functional synergy between the RRMs. In the crystal structure, a UP1 dimer binds to two strands of DNA, and each strand contacts RRM1 of one monomer and RRM2 of the other. The two DNA strands are antiparallel, and regions of the protein flanking each RRM make important contacts with DNA. The extensive protein-protein interface seen in the crystal structure of the protein-DNA complex and the evolutionary conservation of the interface residues suggest the importance of specific protein-protein interactions for the sequence-specific recognition of single-stranded nucleic acids. Models for regular packaging of telomere 3' overhangs and for juxtaposition of alternative 5' splice sites are proposed
INPOP08, a 4-D planetary ephemeris: From asteroid and time-scale computations to ESA Mars Express and Venus Express contributions
The latest version of the planetary ephemerides developed at the Paris
Observatory and at the Besancon Observatory is presented here. INPOP08 is a
4-dimension ephemeris since it provides to users positions and velocities of
planets and the relation between TT and TDB. Investigations leading to improve
the modeling of asteroids are described as well as the new sets of observations
used for the fit of INPOP08. New observations provided by the European Space
Agency (ESA) deduced from the tracking of the Mars Express (MEX) and Venus
Express (VEX) missions are presented as well as the normal point deduced from
the Cassini mission. We show the huge impact brought by these observations in
the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon
barycenter orbits.Comment: 14 pages. submitted to A&A. accepted in A&
Pandoraea fibrosis sp. Nov., a novel pandoraea species isolated from clinical respiratory samples
© 2019 IUMS. Pandoraea species have been isolated from diverse environmental samples and are emerging important respiratory pathogens, particularly in people with cystic fibrosis (CF). In the present study, two bacterial isolates initially recovered from consecutive sputum samples collected from a CF patient and identified as Pandoraea pnomenusa underwent a polyphasic taxonomic analysis. The isolates were found to be Gram-negative, facultative anaerobic motile bacilli and subsequently designated as strains 6399 T (=LMG29626 T =DSM103228 T ) and 7641 (=LMG29627=DSM103229), respectively. Phylogenetic analysis based on 16S rRNA and gyrB gene sequences revealed that 6399 T and 7641 formed a distinct phylogenetic lineage within the genus Pandoraea. Genome sequence comparison analysis indicated that strains 6399 T and 7641 are clonal and share 100 % similarity, however, similarity to other type strains (ANIb 73.2–88.8 %, ANIm 83.5–89.9 % and OrthoANI 83.2– 89.3 %) indicates that 6399 T and 7641 do not belong to any of the reported type species. The major cellular fatty acids of 6399 T were C 16: 0 (32.1 %) C 17: 0 cyclo (18.7 %) and C 18: 1 !7c (14.5 %), while Q-8 was the only respiratory quinone detected. The major polar lipids identified were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The genomic DNA G+C content of 6399 T was 62.9 (mol%). Strain 6399 T can be differentiated from other members of Pandoraea by the absence of C 19: 0 !8c cyclo and by the presence of C 17: 0 !8c cyclo. Together our data show that the bacterial strains 6399 T and 7641 represent a novel species of the genus Pandoraea, for which the name Pandoraea fibrosis sp. nov. is proposed (type strain 6399 T )
Analysis of adenovirus VA RNAI structure and stability using compensatory base pair modifications
Adenovirus VA RNAs are short non-coding transcripts that assist in maintaining viral protein expression in infected cells. Six sets of mismatch and compensatory base pair mutants of VA RNAI were examined by gel mobility and RNA UV melting to assess the contribution of each structural domain to its overall structure and stability. Each domain of VA RNAI was first assigned to one of two apparent unfolding transitions in the wild-type melting profile. The Terminal Stem and Central Domain unfold in a single cooperative apparent transition with an apparent Tm of ∼60°C. In contrast, the Apical Stem unfolds independently and with much higher apparent Tm of ∼83°C. Remarkably, this domain appears to behave as an almost entirely autonomous unit within the RNA, mirroring the functional division within the RNA between PKR binding and inhibition. The effects of mismatch and compensatory mutations at five of the six sites on the RNA melting profile are consistent with proposed base pairing and provide further validation of the current secondary structure model. Mutations in the Central Domain were tested in PKR inhibition assays and a component of the VA RNAI Central Domain structure essential for PKR inhibitory activity was identified
Orbital effects of a monochromatic plane gravitational wave with ultra-low frequency incident on a gravitationally bound two-body system
We analytically compute the long-term orbital variations of a test particle
orbiting a central body acted upon by an incident monochromatic plane
gravitational wave. We assume that the characteristic size of the perturbed
two-body system is much smaller than the wavelength of the wave. Moreover, we
also suppose that the wave's frequency is much smaller than the particle's
orbital one. We make neither a priori assumptions about the direction of the
wavevector nor on the orbital geometry of the planet. We find that, while the
semi-major axis is left unaffected, the eccentricity, the inclination, the
longitude of the ascending node, the longitude of pericenter and the mean
anomaly undergo non-vanishing long-term changes. They are not secular trends
because of the slow modulation introduced by the tidal matrix coefficients and
by the orbital elements themselves. They could be useful to indepenedently
constrain the ultra-low frequency waves which may have been indirectly detected
in the BICEP2 experiment. Our calculation holds, in general, for any
gravitationally bound two-body system whose characteristic frequency is much
larger than the frequency of the external wave. It is also valid for a generic
perturbation of tidal type with constant coefficients over timescales of the
order of the orbital period of the perturbed particle.Comment: LaTex2e, 24 pages, no figures, no tables. Changes suggested by the
referees include
More anxious than depressed: prevalence and correlates in a 15-nation study of anxiety disorders in people with type 2 diabetes mellitus
Background Anxiety disorder, one of the highly disabling, prevalent and common mental disorders, is known to be more prevalent in persons with type 2 diabetes mellitus (T2DM) than the general population, and the comorbid presence of anxiety disorders is known to have an impact on the diabetes outcome and the quality of life. However, the information on the type of anxiety disorder and its prevalence in persons with T2DM is limited. Aims To assess the prevalence and correlates of anxiety disorder in people with type 2 diabetes in different countries.
Methods People aged 18–65 years with diabetes and treated in outpatient settings were recruited in 15 countries and underwent a psychiatric interview with the Mini-International Neuropsychiatric Interview. Demographic and medical record data were collected. Results A total of 3170 people with type 2 diabetes (56.2% women; with mean (SD) duration of diabetes 10.01 (7.0) years) participated. The overall prevalence of anxiety disorders in type 2 diabetic persons was 18%; however, 2.8% of the study population had more than one type of anxiety disorder. The most prevalent anxiety disorders were generalised anxiety disorder (8.1%) and panic disorder (5.1%). Female gender, presence of diabetic complications, longer duration of diabetes and poorer glycaemic control (HbA1c levels) were significantly associated with comorbid anxiety disorder. A higher prevalence of anxiety disorders was observed in Ukraine, Saudi Arabia and Argentina with a lower prevalence in Bangladesh and India.
Conclusions Our international study shows that people with type 2 diabetes have a high prevalence of anxiety disorders, especially women, those with diabetic complications, those with a longer duration of diabetes and poorer glycaemic control. Early identification and appropriate timely care of psychiatric problems of people with type 2 diabetes is warranted
The PKR-binding domain of adenovirus VA RNAI exists as a mixture of two functionally non-equivalent structures
VA RNAI is a non-coding adenoviral transcript that counteracts the host cell anti-viral defenses such as immune responses mediated via PKR. We investigated potential alternate secondary structure conformations within the PKR-binding domain of VA RNAI using site-directed mutagenesis, RNA UV-melting analysis and enzymatic RNA secondary structure probing. The latter data clearly indicated that the wild-type VA RNAI apical stem can adopt two different conformations and that it exists as a mixed population of these two structures. In contrast, in two sequence variants we designed to eliminate one of the possible structures, while leaving the other intact, each formed a unique secondary structure. This clarification of the apical stem pairing also suggests a small alteration to the apical stem–loop secondary structure. The relative ability of the two apical stem conformations to bind PKR and inhibit kinase activity was measured by isothermal titration calorimetry and PKR autophosphorylation inhibition assay. We found that the two sequence variants displayed markedly different activities, with one being a significantly poorer binder and inhibitor of PKR. Whether the presence of the VA RNAI conformation with reduced PKR inhibitory activity is directly beneficial to the virus in the cell for some other function requires further investigation
Observational constraints on spatial anisotropy of G from orbital motions
A phenomenological anisotropic variation \Delta G/G of the Newtonian
gravitational coupling parameter G, if real, would affect the orbital dynamics
of a two-body gravitationally bound system in a specific way. We analytically
work out the long-term effects that such a putative modification of the usual
Newtonian inverse-square law would induce on the trajectory of a test particle
orbiting a central mass. Without making any a-priori simplifying assumptions
concerning the orbital configuration of the test particle, it turns out that
its osculating semi-major axis a, eccentricity e, pericenter \varpi and mean
anomaly M undergo long-term temporal variations, while the inclination I and
the node \Omega are left unaffected. Moreover, the radial and the transverse
components of the position and the velocity vectors r and v of the test
particle experience non-vanishing changes per orbit, contrary to the
out-of-plane ones. Then, we compute our theoretical predictions for some of the
major bodies of the solar system by orienting the gradient of G(r) towards the
Galactic Center and keeping it fixed over the characteristic timescales
involved. By comparing our calculation to the latest observational
determinations for the same bodies, we infer \Delta G/G <= 10^-17 over about 1
au. Finally, we consider also the Supermassive Black Hole hosted by the
Galactic Center in Sgr A^* and the main sequence star S2 orbiting it in about
16 yr, obtaining just \Delta G/G <= 10^-2 over 1 kau.Comment: LaTex2e, 18 pages, no figures, 4 tables. Accepted by Classical and
Quantum Gravity (CQG). Typo fixed. Reference update
- …