Role of the Wnt receptor Frizzled-1 in presynaptic differentiation and function

<p>Abstract</p> <p>Background</p> <p>The <it>Wnt </it>signaling pathway regulates several fundamental developmental processes and recently has been shown to be involved in different aspects of synaptic differentiation and plasticity. Some <it>Wnt </it>signaling components are localized at central synapses, and it is thus possible that this pathway could be activated at the synapse.</p> <p>Results</p> <p>We examined the distribution of the <it>Wnt </it>receptor Frizzled-1 in cultured hippocampal neurons and determined that this receptor is located at synaptic contacts co-localizing with presynaptic proteins. Frizzled-1 was found in functional synapses detected with FM1-43 staining and in synaptic terminals from adult rat brain. Interestingly, overexpression of Frizzled-1 increased the number of clusters of Bassoon, a component of the active zone, while treatment with the extracellular cysteine-rich domain (CRD) of Frizzled-1 decreased Bassoon clustering, suggesting a role for this receptor in presynaptic differentiation. Consistent with this, treatment with the Frizzled-1 ligand <it>Wnt-3a </it>induced presynaptic protein clustering and increased functional presynaptic recycling sites, and these effects were prevented by co-treatment with the CRD of Frizzled-1. Moreover, in synaptically mature neurons <it>Wnt-3a </it>was able to modulate the kinetics of neurotransmitter release.</p> <p>Conclusion</p> <p>Our results indicate that the activation of the <it>Wnt </it>pathway through Frizzled-1 occurs at the presynaptic level, and suggest that the synaptic effects of the <it>Wnt </it>signaling pathway could be modulated by local activation through synaptic Frizzled receptors.</p

Terminal 18q deletions are stabilized by neotelomeres

Background: All human chromosomes are capped by tandem repeat (TTAGGG)n sequences that protect them against end-to-end fusion and are essential to chromosomal replication and integrity. Therefore, after a chromosomal breakage, the deleted chromosomes must be stabilized by retaining the telomere or acquiring a new cap, by telomere healing or telomere capture. There are few reports with molecular approaches on the mechanisms involved in stabilization of 18q terminal deletions.Results: in this study we analyzed nine patients with 18q terminal deletion identified by G-banding and genomic array. FISH using PNA probe revealed telomeric signals in all deleted chromosomes tested. We fine-mapped breakpoints with customized arrays and sequenced six terminal deletion junctions. in all six deleted chromosomes sequenced, telomeric sequences were found directly attached to the breakpoints. Little or no microhomology was found at the breakpoints and none of the breaks sequenced were located in low copy repeat (LCR) regions, though repetitive elements were found around the breakpoints in five patients. One patient presented a more complex rearrangement with two deleted segments and an addition of 17 base pairs (bp).Conclusions: We found that all six deleted chromosomes sequenced were probably stabilized by the healing mechanism leading to a neotelomere formation.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo, Dept Morphol & Genet, BR-04023900 São Paulo, BrazilEmory Univ, Sch Med, Dept Human Genet, Atlanta, GA 30322 USAUniversidade Federal de São Paulo, Dept Biophys, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, Lab Citogenom, BR-05403000 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Morphol & Genet, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04023900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pathol, Lab Citogenom, BR-05403000 São Paulo, BrazilFAPESP: 2012/51150-0FAPESP: 2012/15572-7Web of Scienc

Investigation of selected genomic deletions and duplications in a cohort of 338 patients presenting with syndromic obesity by multiplex ligation-dependent probe amplification using synthetic probes

Background: Certain rare syndromes with developmental delay or intellectual disability caused by genomic copy number variants (CNVs), either deletions or duplications, are associated with higher rates of obesity. Current strategies to diagnose these syndromes typically rely on phenotype-driven investigation. However, the strong phenotypic overlap between syndromic forms of obesity poses challenges to accurate diagnosis, and many different individual cytogenetic and molecular approaches may be required. Multiplex ligation-dependent probe amplification (MLPA) enables the simultaneous analysis of multiple targeted loci in a single test, and serves as an important screening tool for large cohorts of patients in whom deletions and duplications involving specific loci are suspected. Our aim was to design a synthetic probe set for MLPA analysis to investigate in a cohort of 338 patients with syndromic obesity deletions and duplications in genomic regions that can cause this phenotype.Results: We identified 18 patients harboring copy number imbalances; 18 deletions and 5 duplications. the alterations in ten patients were delineated by chromosomal microarrays, and in the remaining cases by additional MLPA probes incorporated into commercial kits. Nine patients showed deletions in regions of known microdeletion syndromes with obesity as a clinical feature: in 2q37 (4 cases), 9q34 (1 case) and 17p11.2 (4 cases). Four patients harbored CNVs in the DiGeorge syndrome locus at 22q11.2. Two other patients had deletions within the 22q11.2 'distal' locus associated with a variable clinical phenotype and obesity in some individuals. the other three patients had a recurrent CNV of one of three susceptibility loci: at 1q21.1 'distal', 16p11.2 'distal', and 16p11.2 'proximal'.Conclusions: Our study demonstrates the utility of an MLPA-based first line screening test to the evaluation of obese patients presenting with syndromic features. the overall detection rate with the synthetic MLPA probe set was about 5.3% (18 out of 338). Our experience leads us to suggest that MLPA could serve as an effective alternative first line screening test to chromosomal microarrays for diagnosis of syndromic obesity, allowing for a number of loci (e.g., 1p36, 2p25, 2q37, 6q16, 9q34, 11p14, 16p11.2, 17p11.2), known to be clinically relevant for this patient population, to be interrogated simultaneously.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ São Paulo, Inst Biosci, Dept Genet & Evolutionary Biol, Human Genome & Stem Cell Ctr, São Paulo, BrazilUniv São Paulo, Sch Med, Children Inst, Genet Unit,Dept Pediat, São Paulo, BrazilUniv São Paulo, Sch Med, Dept Med Genet, Neurogenet Unit, BR-14049 Ribeirao Preto, BrazilUniversidade Federal de São Paulo, Ctr Med Genet, Dept Morphol, São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Med Genet, Dept Morphol, São Paulo, BrazilFAPESP: 09/52523-1FAPESP: 1998/14254-2CNPq: 304381/2007-1Web of Scienc

J-PLUS: analysis of the intracluster light in the Coma cluster

The intracluster light (ICL) is a luminous component of galaxy clusters composed of stars that are gravitationally bound to the cluster potential but do not belong to the individual galaxies. Previous studies of the ICL have shown that its formation and evolution are intimately linked to the evolutionary stage of the cluster. Thus, the analysis of the ICL in the Coma cluster will give insights into the main processes driving the dynamics in this highly complex system. Using a recently developed technique, we measure the ICL fraction in Coma at several wavelengths, using the J-PLUS unique filter system. The combination of narrow- and broadband filters provides valuable information on the dynamical state of the cluster, the ICL stellar types, and the morphology of the diffuse light. We use the Chebyshev-Fourier Intracluster Light Estimator (CICLE) to disentangle the ICL from the light of the galaxies, and to robustly measure the ICL fraction in seven J-PLUS filters. We obtain the ICL fraction distribution of the Coma cluster at different optical wavelengths, which varies from $\sim 7\%-21\%$, showing the highest values in the narrowband filters J0395, J0410, and J0430. This ICL fraction excess is distinctive pattern recently observed in dynamically active clusters (mergers), indicating a higher amount of bluer stars in the ICL compared to the cluster galaxies. Both the high ICL fractions and the excess in the bluer filters are indicative of a merging state. The presence of younger/lower-metallicity stars the ICL suggests that the main mechanism of ICL formation for the Coma cluster is the stripping of the stars in the outskirts of infalling galaxies and, possibly, the disruption of dwarf galaxies during past/ongoing mergers.Comment: 10 pages, 3 figures, 1 table. Accepted for publication in A&

The Large Aperture GRB Observatory

The Large Aperture GRB Observatory (LAGO) is aiming at the detection of the high energy (around 100 GeV) component of Gamma Ray Bursts, using the single particle technique in arrays of Water Cherenkov Detectors (WCD) in high mountain sites (Chacaltaya, Bolivia, 5300 m a.s.l., Pico Espejo, Venezuela, 4750 m a.s.l., Sierra Negra, Mexico, 4650 m a.s.l). WCD at high altitude offer a unique possibility of detecting low gamma fluxes in the 10 GeV - 1 TeV range. The status of the Observatory and data collected from 2007 to date will be presented.Comment: 4 pages, proceeding of 31st ICRC 200

Water Cherenkov Detectors response to a Gamma Ray Burst in the Large Aperture GRB Observatory

In order to characterise the behaviour of Water Cherenkov Detectors (WCD) under a sudden increase of 1 GeV - 1 TeV background photons from a Gamma Ray Burst (GRB), simulations were conducted and compared to data acquired by the WCD of the Large Aperture GRB Observatory (LAGO). The LAGO operates arrays of WCD at high altitude to detect GRBs using the single particle technique. The LAGO sensitivity to GRBs is derived from the reported simulations of the gamma initiated particle showers in the atmosphere and the WCD response to secondaries.Comment: 5 pages, proceeding of the 31st ICRC 200

HI-NESS:a family of genetically encoded DNA labels based on a bacterial nucleoid-associated protein

The interplay between three-dimensional chromosome organisation and genomic processes such as replication and transcription necessitates in vivo studies of chromosome dynamics. Fluorescent organic dyes are often used for chromosome labelling in vivo. The mode of binding of these dyes to DNA cause its distortion, elongation, and partial unwinding. The structural changes induce DNA damage and interfere with the binding dynamics of chromatin-associated proteins, consequently perturbing gene expression, genome replication, and cell cycle progression. We have developed a minimally-perturbing, genetically encoded fluorescent DNA label consisting of a (photo-switchable) fluorescent protein fused to the DNA-binding domain of H-NS - a bacterial nucleoid-associated protein. We show that this DNA label, abbreviated as HI-NESS (H-NS-based indicator for nucleic acid stainings), is minimally-perturbing to genomic processes and labels chromosomes in eukaryotic cells in culture, and in zebrafish embryos with preferential binding to AT-rich chromatin.Genome Instability and Cance

Fisheries and Oceanography off Galicia, NW Spain: Mesoscale Spatial and Temporal Changes in Physical Processes and Resultant Patterns of Biological Productivity

The Galician shelf off NW Spain (43N degrees 9W degrees) exhibits mesoscale spatial and temporal changes in biological productivity associated with upwelling. Spatial heterogeneity results from local geomorphic and land-sea interactions superimposed on the large scale atmospheric processes that produce upwelling. Wind-induced upwelling events, commonly of short (i.e., week) duration, are more common in the summer than in the winter. A Series of cruises, including some time series sampling, and satellite imagery analysis showed that surface upwelling was more common and persistent on the northern coast compared with the western coast off the coastal embayments, the Rias Bajas. Nearshore off the rias, coastal runoff, which is greater in the rainy winter/spring versus the dry summer, affected upwelling. In early summer, upwelling less often reaches the surface because of increased water column stratification associated with lower surface salinities and thus upwelling is not detected by satellite imagery. Conversely, in late summer, upwelling more often reaches the surface because coastal runoff is reduced during the dry summer months and the water column tends to be less stratified. Plankton biomass and rate processes along the Galician shelf reflected both ambient hydrographic conditions as well as prior history of upwelling or downwelling. Phytoplankton and bacterioplankton were in greatest abundance during upwelling conditions (June through August); in contrast, both zooplankton and fish larvae exhibited highest abundances in March, when there were upwelling conditions prior to our cruise. Spatial differences in the duration and frequency of upwelling events, in combination with advection of water masses, are critical to the patterns of water column productivity and sardine fisheries production off the Galician coast. More persistent upwelling at this NW corner of the Iberian peninsula Supports large sardine fisheries because zooplankton and larval fish populations have time to respond to the higher primary production. Farther down the western Galician coast, the episodic upwelling and resultant intermittent primary production does not support a stable food supply needed to support fisheries. Times series sampling revealed mean response times of bacteria, phytoplankton, and zooplankton to be on the order of a day, days, and weeks, respectively. Sardines showed no spawning response in the relatively short time series sampling. The observed distributional patterns of fish eggs and larvae showed some offshore transport of fish larvae that were spawned inshore during upwelling periods and aggregation of larvae in a convergence zone northwest of Cabo Villano