Niveau de contamination par le mercure des sédiments de surface et des crevettes du fjord du Saguenay

De 1947 à 1976, plusieurs dizaines de tonnes de mercure d'origine industrielle ont été déversées dans les eaux de la rivière Saguenay et une grande partie de ce métal toxique se retrouve aujourd'hui dans les sédiments du Fjord. Les sédiments de surface (0-2 cm) de 17 stations réparties sur tout le bassin intérieur du fjord ont été prélevés et analysés pour le mercure total. De plus, environ 150 crevettes (Pandalus borealis) ont été capturées à Sainte-Rose-du-Nord pour fins d'analyse du mercure et pour une expérience de bioaccumulation à partir d'une diète contaminée. L'analyse des données disponibles pour les sédiments de surface montre que les teneurs moyennes (0,93 ± 0,11 µg.g-1 poids sec) en mercure n'ont pas varié de façon significative au cours des dix dernières années dans la région de Sainte-Rose-du-Nord, située dans la moitié amont du bassin intérieur. Les concentrations de mercure dans le muscle comestible des crevettes varient de 0,13 à 0,58 µg.g-1 (poids humide) selon la taille avec une valeur moyenne de 0,36 ± 0,11 µg.g-1. On trouve une concentration moyenne de 0,26 ± 0,09 µg.g-1 dans le céphalothorax et la cuticule. Un accroissement rapide et important du mercure dans, l'appareil digestif a été observé chez tes crevettes adultes soumises à une diète de chair de moules préalablement contaminée (6,0 ± 1,0 µg.g-1). Un taux de bioaccumulation de 0,09 µg.g-1 par jour dans le muscle comestible a été estimé pour les 14 premiers jours de diète contaminée.From 1947 to 1976, many tons of industrial mercury were tipped into the Saguenay River and a large amount of this toxic heavy metal is now in the sediments of the Saguenay Fjord. Surface sediments (0-2 cm) were collected at seventeen stations along the inner basin of the Saguenay Fjord and analysed for total mercury content. About 150 shrimps (Pandalus borealis) fished in the Sainte-Rose-du-Nord area were also used for mercury analyses and the determination of mercury uptake rate from contaminated food. The mercury concentrations in surface sediments ranged from 0.18 to 0.20 µg.g-1 (dry weight) with a mean value of 0.63 µg.g-1. This mean level is about one order of magnitude higher than the background level found in deep sediments. The examination of available data for surface sediments in the Sainte-Rose-du-Nord vicinity, located in the first half of the inner basin, shows the "steady state" of the mercury contamination over the last 10 years. Indeed, the mercury concentrations observed in surface sediments ranged from 0.75 to 1.20 µg.g-1, with a mean value of 0.93 µg.g-1 since 1976. The steady state of mercury contamination can be explained by two hypothesis : (1) an unexpected highly active bioturbation mechanism contributes to the mercury remobilisation from lower sediment layers (10-20 cm) and its vertical transportation up to the surface, or (2) the anthropogenic upstream discharge of mercury was not really stopped in 1976 and one or many unidentified sources are still active along the Saguenay River. The mercury concentrations in the edible part of shrimps (fished in November 1985) ranged from 0.13 to 0.58 µg.g-l (wet weight) with an average value of 0.36 ± 0.11 µg.g-1. A positive and significative linear relationship (r = 0.786) is observed between the Hg concentration in the edible part and the total wet weight of the shrimp. The mean Hg in the edible part found in 1985 is not significantly different from the mean value reported in 1932. The mean concentration found in the cephalothorax and the cuticle (taken together) of shrimps was 0.26 ± 0.09 µg.g-1. In order to estimate the mercury uptake rate by shrimps from contaminated food, a number of adult shrimps were fed with pre-contaminated mussel tissues (0.6 ± 1.0 µg.g-1) for three weeks. A high and rapid increase of mercury concentration was observed in the digestive organs after only 24 hours. The uptake rate in the edible part was estimated at 0.09 µg.g-1 per day during the first fourteen days of the bioassay. These findings clearly indicate the fragility of the balance between the biota and the physical environment and how fast major changes can occur when the level of contamination of the diet is modified

Detection of antihydrogen annihilations with a Si-micro-strip and pure CsI detector

In 2002, the ATHENA collaboration reported the creation and detection of cold (~15 K) antihydrogen atoms [1]. The observation was based on the complete reconstruction of antihydrogen annihilations, simultaneous and spatially correlated annihilations of an antiproton and a positron. Annihilation byproducts are measured with a cylindrically symmetric detector system consisting of two layers of double sided Si-micro-strip modules that are surrounded by 16 rows of 12 pure CsI crystals (13 x 17.5 x 17 mm^3). This paper gives a brief overview of the experiment, the detector system, and event reconstruction. Reference 1. M. Amoretti et al., Nature 419, 456 (2002).Comment: 7 pages, 5 figures; Proceedings for the 8th ICATPP Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications (Como, Italy October 2003) to be published by World Scientific (style file included

Improvement in the molecular diagnosis of Machado-Joseph disease

Abstract BACKGROUND: Direct detection of the gene mutation allows for the confirmation of the clinical diagnosis of Machado-Joseph disease (MJD), the most frequent cause of autosomal dominant spinocerebellar ataxia worldwide. OBJECTIVE: To address the main difficulties in our national MJD predictive testing program. The first was the emergence of intermediate alleles, for which it is not yet possible to determine whether they will cause disease. The second was the issue of homoallelism, ie, homozygosity for 2 normal alleles with exactly the same (CAG)(n) length, which occurs in about 10% of all test results. METHODS: A large pedigree with 1 affected patient carrying a 71 and a 51 CAG repeat and 2 asymptomatic relatives carrying the 51 CAG repeat and normal-size alleles underwent clinical and molecular studies. Intragenic haplotypes for these alleles were determined. A representative sample of the healthy population in the region was obtained to assess the distribution of the normal (CAG)(n) length. We established the genotype for 4 intragenic polymorphisms in the gene for MJD (MJD1) in 21 homoallelic individuals, to distinguish their 2 normal chromosomes. In addition, we developed a new Southern blot method to completely exclude cases of nonamplification of expanded alleles in the homoallelic individuals. RESULTS: The study of the family in which the 51 CAG repeat was found suggests that the allele is apparently not associated with disease. These intermediate alleles were not present in a large sample of the healthy population from the same region. Intragenic polymorphisms allowed distinction of the 2 different normal alleles in all cases of homoallelism. The absence of an expanded allele was also confirmed by Southern blot. CONCLUSIONS: We propose an improved protocol for molecular testing for MJD. These strategies, developed to overcome the practical difficulties mostly in the presymptomatic and prenatal diagnosis of MJD, should prove useful for other polyglutamine-related disorders

Familiäre Kavernome des Zentralnervensystems: Eine klinische und genetische Studie an 15 deutsche Familien

Zusammenfassung: 1928 beschrieb Hugo Friedrich Kufs erstmalig eine Familie mit zerebralen, retinalen und kutanen Kavernomen. Mittlerweile wurden über 300 weitere Familien beschrieben. Ebenfalls wurden drei Genloci 7q21-q22 (mit dem Gen CCM1), 7p15-p13 (Gen CCM2) und 3q25.2-q27 (Gen CCM3) beschrieben, in denen Mutationen zu Kavernomen führen. Das Genprodukt von CCM1 ist das Protein Krit1 (Krev Interaction Trapped 1), das über verschiedene Mechanismen mit der Angiogenese interagiert. Das neu entdeckte CCM2-Gen enkodiert ein Protein, das möglicherweise eine dem Krit1 ähnliche Funktion in der Regulation der Angiogenese hat. Das CCM3-Gen wurde noch nicht beschrieben. In dieser Arbeit werden sowohl die klinischen und genetischen Befunde bei 15 deutschen Familien beschriebe

Inherited cavernous malformations of the central nervous system: clinical and genetic features in 19 Swiss families

Cavernous malformations (CCMs) are benign, well-circumscribed, and mulberry-like vascular malformations that may be found in the central nervous system in up to 0.5% of the population. Cavernous malformations can be sporadic or inherited. The common symptoms are epilepsy, hemorrhages, focal neurological deficits, and headaches. However, CCMs are often asymptomatic. The familiar form is associated with three gene loci, namely 7q21-q22 (CCM1), 7p13-p15 (CCM2), and 3q25.2-q27 (CCM3) and is inherited as an autosomal dominant trait with incomplete penetrance. The CCM genes are identified as Krit 1 (CCM1), MGC4607 (CCM2), and PDCD10 (CCM3). Here, we present the clinical and genetic features of CCMs in 19 Swiss families. Furthermore, surgical aspects in such families are also discusse

Loss of neuronal potassium/chloride cotransporter 3 (KCC3) is responsible for the degenerative phenotype in a conditional mouse model of hereditary motor and sensory neuropathy associated with agenesis of the corpus callosum

Disruption of the potassium/chloride cotransporter 3 (KCC3), encoded by the SLC12A6 gene, causes hereditary motor and sensory neuropathy associated with agenesis of the corpus callosum (HMSN/ACC), a neurodevelopmental and neurodegenerative disorder affecting both the peripheral nervous system and CNS. However, the precise role of KCC3 in the maintenance of ion homeostasis in the nervous system and the pathogenic mechanisms leading to HMSN/ACC remain unclear. We established two Slc12a6 Cre/LoxP transgenic mouse lines expressing C-terminal truncated KCC3 in either a neuron-specific or ubiquitous fashion. Our results suggest that neuronal KCC3 expression is crucial for axon volume control. We also demonstrate that the neuropathic features of HMSN/ACC are predominantly due to a neuronal KCC3 deficit, while the auditory impairment is due to loss of non-neuronal KCC3 expression. Furthermore, we demonstrate that KCC3 plays an essential role in inflammatory pain pathways. Finally, we observed hypoplasia of the corpus callosum in both mouse mutants and a marked decrease in axonal tracts serving the auditory cortex in only the general deletion mutant. Together, these results establish KCC3 as an important player in both central and peripheral nervous system maintenance

High angular resolution N-band observation of the silicate carbon star IRAS08002-3803 with the VLTI/MIDI instrument

We present the results of N-band spectro-interferometric observations of the silicate carbon star IRAS08002-3803 with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory (ESO). The observations were carried out using two unit telescopes (UT2 and UT3) with projected baseline lengths ranging from 39 to 47 m. Our observations of IRAS08002-3803 have spatially resolved the dusty environment of a silicate carbon star for the first time and revealed an unexpected wavelength dependence of the angular size in the N band: the uniform-disk diameter is found to be constant and ~36 mas (72 Rstar) between 8 and 10 micron, while it steeply increases longward of 10 micron to reach ~53 mas (106 Rstar) at 13 micron. Model calculations with our Monte Carlo radiative transfer code show that neither spherical shell models nor axisymmetric disk models consisting of silicate grains alone can simultaneously explain the observed wavelength dependence of the visibility and the spectral energy distribution (SED). We propose that the circumstellar environment of IRAS08002-3803 may consist of two grain species coexisting in the disk: silicate and a second grain species, for which we consider amorphous carbon, large silicate grains, and metallic iron grains. Comparison of the observed visibilities and SED with our models shows that such disk models can fairly -- though not entirely satisfactorily -- reproduce the observed SED and N-band visibilities. Our MIDI observations and the radiative transfer calculations lend support to the picture where oxygen-rich material around IRAS08002-3803 is stored in a circumbinary disk surrounding the carbon-rich primary star and its putative low-luminosity companion.Comment: 15 pages, 8 figures, accepted for publication in A&

Novel integrative genomic tool for interrogating lithium response in bipolar disorder

We developed a novel integrative genomic tool called GRANITE (Genetic Regulatory Analysis of Networks Investigational Tool Environment) that can effectively analyze large complex data sets to generate interactive networks. GRANITE is an open-source tool and invaluable resource for a variety of genomic fields. Although our analysis is confined to static expression data, GRANITE has the capability of evaluating time-course data and generating interactive networks that may shed light on acute versus chronic treatment, as well as evaluating dose response and providing insight into mechanisms that underlie therapeutic versus sub-therapeutic doses or toxic doses. As a proof-of-concept study, we investigated lithium (Li) response in bipolar disorder (BD). BD is a severe mood disorder marked by cycles of mania and depression. Li is one of the most commonly prescribed and decidedly effective treatments for many patients (responders), although its mode of action is not yet fully understood, nor is it effective in every patient (non-responders). In an in vitro study, we compared vehicle versus chronic Li treatment in patient-derived lymphoblastoid cells (LCLs) (derived from either responders or non-responders) using both microRNA (miRNA) and messenger RNA gene expression profiling. We present both Li responder and non-responder network visualizations created by our GRANITE analysis in BD. We identified by network visualization that the Let-7 family is consistently downregulated by Li in both groups where this miRNA family has been implicated in neurodegeneration, cell survival and synaptic development. We discuss the potential of this analysis for investigating treatment response and even providing clinicians with a tool for predicting treatment response in their patients, as well as for providing the industry with a tool for identifying network nodes as targets for novel drug discovery