Application of Neurochemical Markers for Assessing Health Effects after Developmental Methylmercury and PCB Coexposure

Cholinergic muscarinic receptors (MRs) and monoamine oxidase activity (MAO-B), expressed both in brain and blood cells, were investigated in animals and exposed subjects to assess (i) MeHg (0.5–1 mg/kg/day GD7-PD7) and/or PCB153 (20 mg/kg/day GD10–GD16) effects on cerebellar MAO-B and MRs, and lymphocyte MRs, in dams and offspring 21 days postpartum; (ii) MAO-B in platelets and MRs in lymphocytes of a Faroese 7-year-old children cohort, prenatally exposed to MeHg/PCBs. Animal Data. MAO-B was altered in male cerebellum by MeHg, PCB153, and their combination (35%, 45%, and 25% decrease, resp.). Cerebellar MRs were enhanced by MeHg alone in dams (87%) and male pups (27%). PCB153 alone and in mixture did not modify cerebellar MRs. Similarly to brain, lymphocyte MRs were enhanced in both dams and offspring by MeHg alone. All changes were caused by 1 MeHg mg/kg/day, the lower dose was ineffective. Human Data. Both biomarkers showed homogeneous distributions within the cohort (MRs, range 0.1–36.78 fmol/million cells; MAO-B, 0.95–14.95 nmol/mg protein/h). No correlation was found between the two biomarkers and neurotoxicant concentrations in blood (pre- and postnatally)

Effets de l’inoculation mycorhizienne sur le sesame (Sesamum indicum L.) en conditions naturelles

La présence des microorganismes symbiotiques dans le sol constitue un atout pour la majorité des cultures. L’inoculation avec des champignons mycorhiziens à arbuscules (CMA) est considérée comme un des moyens biologiques permettant à la culture de résister aux stress biotiques et abiotiques, et d’augmenter la productivité. Mais en conditions naturelles, la combinaison de plusieurs facteurs a une influence majeure dans l’établissement de la mycorhization. L’inoculation du sésame (Sesamum indicum L.) avec deux souches de Glomus est expérimentée en milieu naturel, dans un dispositif en split-plot avec quatre répétitions. Cetteinoculation mycorhizienne en milieu naturel a produit les effets suivants : le taux de mycorhization des plants inoculés reste bas ; l’inoculation n’a pas eu un effet significatif sur le rendement en graines, le nombre decapsules et la biomasse totale comparativement aux plants témoins naturellement infectés. Cela montre que, la mycorhization naturelle a eu une efficacité comparable à celle des souches inoculées sur le sesame. On peut déduire que les sols de cette zone de Bambey contiendraient des souches de champignons mycorhiziens à arbuscules (CMA) indigènes aussi efficaces que des souches sélectionnées.© 2013 International Formulae Group. All rights reserved.Mots clés : Mycorhization naturelle, Glomus mosseae, Glomus fasciculatum, sésame, productivité

The broad-band X-ray spectrum of the dipping Low Mass X-ray Binary EXO0748--676

We present results of a 0.1-100 keV BeppoSAX observation of the dipping LMXRB EXO 0748-676 performed in 2000 November. During the observation the source exhibited X-ray eclipses, type I X-ray bursts and dipping activity over a wide range of orbital phases. The 0.1-100keV "dip-free"(ie. dipping and eclipsing intervals excluded) spectrum is complex,especially at low-energies where a soft excess is present. Two very different spectral models give satisfactory fits. The first is the progressive covering model, consisting of separately absorbed black body and cut-off power-law components.The second model is an absorbed cut-off power-law together with a moderately ionized absorber with a sub-solar abundance of Fe and a 2.13 keV absorption feature (tentatively identified with Si xiii). This ionized absorber may be the same feature as seen by Chandra during dips from EXO 0748-676.Comment: 7 pages, 5 figures, paper accepted for publication in Astronomy and Astrophysic

Genetic Polymorphism in Evolving Population

We present a model for evolving population which maintains genetic polymorphism. By introducing random mutation in the model population at a constant rate, we observe that the population does not become extinct but survives, keeping diversity in the gene pool under abrupt environmental changes. The model provides reasonable estimates for the proportions of polymorphic and heterozygous loci and for the mutation rate, as observed in nature

BeppoSAX observation of the eclipsing dipping X-ray binary X1658-298

Results of a 2000 August 12-13 BeppoSAX observation of the 7.1 hr eclipsing, dipping, bursting, transient, low-mass X-ray binary (LMXRB) X1658-298 are presented. The spectrum outside of eclipses, dips and bursts can be modeled by the combination of a soft disk-blackbody and a harder Comptonized component with a small amount (1.3 10E21 atom/cm2) of low-energy absorption. In contrast, an RXTE observation 18 months earlier during the same outburst, measured an absorption of 5.0 10E22 atom/cm2. Such a change is consistent with a thinning of the accretion disk as the outburst progresses. Structured residuals from the best-fit spectral model are present which are tentatively identified with Ne-K/Fe-L and Fe-K shell emission. The spectral changes during dips are complex and may be modeled by a strong (~3 10E23 atom/cm2) increase in absorption of the Comptonized component only, together with reductions in normalizations of both spectral components. This behavior is in contrast to the ``complex continuum'' model for X-ray dip sources, where the softer blackbody component rapidly suffers strong absorption. It is however, similar to that found during recent XMM-Newton observations of the eclipsing, dipping, LMXRB EXO0748-676.Comment: 11 pages. Accepted for publication in A&A

The broad band spectral properties of galactic X-ray binary pulsars

BeppoSAX observed several galactic binary X-ray pulsars during the Science Verification Phase and in the first year of the regular program. The complex emission spectra of these sources are an ideal target for the BeppoSAX instrumentation, that can measure the emission spectra in an unprecedented broad energy band. Using this capability of BeppoSAX a detailed observational work can be done on the galactic X-ray pulsars. In particular the 0.1-200 keV energy band allows the shape of the continuum emission to be tightly constrained. A better determination of the underlying continuum allows an easier detection of features superimposed onto it, both at low energy (Fe K and L, Ne lines) and at high energies (cyclotron features). We report on the spectral properties of a sample of X-ray pulsars observed with BeppoSAX comparing the obtained results. Some ideas of common properties are also discussed and compared with our present understanding of the emission mechanisms and processes.Comment: 6 pages, 2 figures. Uses espcrc2.sty (included).To appear in Proceedings of "The Active X-ray Sky: Results from BeppoSAX and Rossi-XTE

Timing and spectral changes of the Be X-ray transient EXO 0531-6609.2 through high and low state

We report on spectral and timing analysis of BeppoSAX data of the 13.6 s period transient X-ray pulsar EXO 0531-6609.2. Observations were carried out in March 1997 and October 1998, catching the source during a high and a low emission state, respectively. Correspondingly, the X-ray luminosity is found at a level of 4.2x10^37 erg/s and 1.5x10^36 erg/s in the two states. In the high state the X-ray emission in the energy range 1-100 keV is well fitted by an absorbed power-law with photon index Gamma ~1.7 plus a blackbody component with a characteristic temperature of ~3.5 keV. Moreover, we find an evidence of an iron emission at ~6.8 keV, typical feature in this class of sources but never revealed before in the EXO 0531-6609.2 spectrum. In the low state an absorbed power-law with Gamma ~0.4 is sufficient to fit the 1-10 keV data. During BeppoSAX observations EXO 0531-6609.2 display variations of the pulse profile with the X-ray flux: it showed single peaked and double peaked profiles in the low and high state, respectively. Based on these two observations we infer a spin-up period derivative of -(1.14+/-0.08)x10^-10 s/s. By comparing these with other period measurements reported in literature we find an alternating spin-up and spin-down behaviour that correlates well with the X-ray luminosity.Comment: 6 pages, 8 figures, A&

BeppoSAX observations of the X-ray binary pulsar 4U1626-67

We report on observations of the low-mass X-ray binary 4U1626-67 performed during the BeppoSAX Science Verification Phase. We present the broad-band 0.1-100 keV pulse averaged spectrum, that is well fit by a two-component function: a 0.27 +/- 0.02 keV blackbody and an absorbed power law with a photon index of 0.89 +/- 0.02. A very deep and narrow absorption feature at 38 keV, attributable to electron cyclotron resonance, is clearly visible in the broad-band spectrum. It corresponds to a neutron star magnetic field strength of 3.3 x 10^{12} G. The 4U1626-67 pulse profiles show a dramatic dependance on energy: the transition between the low energy (E<10 keV) "bi-horned" shape to the high-energy (E>10 keV) sinusoidal profile is clearly visible in our data. The modulation index shows a monotonic increase with energy.Comment: 4 pages, 2 figures. Uses espcrc2.sty (included). To appear in Proceedings of "The Active X-ray Sky: Results from BeppoSAX and Rossi-XTE