Clustering heterochromatin: Sir3 promotes telomere clustering independently of silencing in yeast

Arrays of Sir3 binding sites at telomeres are sufficient to promote long-range trans-telomere interactions

Particulate matter exposure during pregnancy is associated with birth weight, but not gestational age, 1962-1992: a cohort study

<p>Abstract</p> <p>Background</p> <p>Exposure to air pollutants is suggested to adversely affect fetal growth, but the evidence remains inconsistent in relation to specific outcomes and exposure windows.</p> <p>Methods</p> <p>Using birth records from the two major maternity hospitals in Newcastle upon Tyne in northern England between 1961 and 1992, we constructed a database of all births to mothers resident within the city. Weekly black smoke exposure levels from routine data recorded at 20 air pollution monitoring stations were obtained and individual exposures were estimated via a two-stage modeling strategy, incorporating temporally and spatially varying covariates. Regression analyses, including 88,679 births, assessed potential associations between exposure to black smoke and birth weight, gestational age and birth weight standardized for gestational age and sex.</p> <p>Results</p> <p>Significant associations were seen between black smoke and both standardized and unstandardized birth weight, but not for gestational age when adjusted for potential confounders. Not all associations were linear. For an increase in whole pregnancy black smoke exposure, from the 1^st(7.4 μg/m³) to the 25^th(17.2 μg/m³), 50^th(33.8 μg/m³), 75^th(108.3 μg/m³), and 90^th(180.8 μg/m³) percentiles, the adjusted estimated decreases in birth weight were 33 g (SE 1.05), 62 g (1.63), 98 g (2.26) and 109 g (2.44) respectively. A significant interaction was observed between socio-economic deprivation and black smoke on both standardized and unstandardized birth weight with increasing effects of black smoke in reducing birth weight seen with increasing socio-economic disadvantage.</p> <p>Conclusions</p> <p>The findings of this study progress the hypothesis that the association between black smoke and birth weight may be mediated through intrauterine growth restriction. The associations between black smoke and birth weight were of the same order of magnitude as those reported for passive smoking. These findings add to the growing evidence of the harmful effects of air pollution on birth outcomes.</p

Région juxtacentrométrique du chromosome 21 et plasticité génomique

MONTPELLIER-BU Médecine UPM (341722108) / SudocPARIS-BIUP (751062107) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Le proto-métabolisme : approche du fonctionnement bioéconomique d’un territoire agricole

The bioeconomy has become politically unavoidable for the transition to a carbon-free economy. It promotes the development of non-food uses of agricultural biomass. However, few methods and tools allow us—without prior fieldwork—to outline hypotheses on the bioeconomic functioning of a territory, from the stages of agricultural biomass production to its valorization. Thus, this article proposes an operational metabolic approach, based on open data, and a framework for analysis that deals with dimensions of embeddedness, autonomy, and energetic, environmental, and socioeconomic footprints. This proposal is put to the test within two territories, enabling a preliminary assessment to be made before any field application

Caractériser la biomasse d'origine agricole à l'échelle locale: Usages, gestion, valorisation et liens entre acteurs

National audienceThe strong development of non-food uses of biomass of agricultural origin (BAO) questionsthe competition of use of these biomasses and re-structuring of value chains at a local scale.To develop a territorial bioeconomy, one issue is to characterize the BAO, its ways ofvalorization and associated actors. This communication describes a metabolic approach ofthe functioning of the value chains using the BAO at local scale. This approach can be usedto build a tool used to exchange with local stakeholders to i) integrate their knowledge withdata from databases; ii) encourage their reflexivity and, even, implement territorialprospectives.Le fort développement des usages non alimentaires des biomasses d'origine agricole (BOA) questionne les concurrences d'usage de ces biomasses et la re-structuration des filières à l'échelle des territoires. Pour développer une bioéconomie territoriale, un des enjeux est de caractériser la BOA, ses modes de valorisation et les acteurs associés. Cette communication présente une approche métabolique du fonctionnement des filières utilisant la BOA d'un territoire. Cette approche permet de construire un outil d'échange avec les acteurs des territoires pour i) intégrer leurs connaissances à des données issues de bases de données ; ii) susciter leur réflexivité voire, de mettre en oeuvre des prospectives territoriales. Abstract The strong development of non-food uses of biomass of agricultural origin (BAO) questions the competition of use of these biomasses and restructuring of value chains at a local scale. To develop a territorial bioeconomy, one issue is to characterize the BAO, its ways of valorization and associated actors. This communication describes a metabolic approach of the functioning of the value chains using the BAO at local scale. This approach can be used to build a tool used to exchange with local stakeholders to i) integrate their knowledge with data from databases; ii) encourage their reflexivity and, even, implement territorial prospectives

Sir3 mediates long-range chromosome interactions in budding yeast

International audiencePhysical contacts between distant loci contribute to regulate genome function. However, the molecular mechanisms responsible for settling and maintaining such interactions remain poorly understood. Here, we investigate the well-conserved interactions between heterochromatin loci. In budding yeast, the 32 telomeres cluster in 3-5 foci in exponentially growing cells. This clustering is functionally linked to the formation of heterochromatin in subtelomeric regions through the recruitment of the silencing SIR complex composed of Sir2/3/4. Combining microscopy and Hi-C on strains expressing different alleles of SIR3, we show that the binding of Sir3 directly promotes long-range contacts between distant regions, including the rDNA, telomeres, and internal Sir3-bound sites. Furthermore, we unveil a new property of Sir3 in promoting rDNA compaction. Finally, using a synthetic approach, we demonstrate that Sir3 can bond loci belonging to different chromosomes together, when targeted to these loci, independently of its interaction with its known partners (Rap1, Sir4), Sir2 activity, or chromosome context. Altogether, these data suggest that Sir3 acts as a molecular bridge that stabilizes long-range interactions

Expression of Subtelomeric lncRNAs Links Telomeres Dynamics to RNA Decay in S. cerevisiae

International audienc

Recombination at subtelomeres is regulated by physical distance, double-strand break resection and chromatin status.

International audienceHomologous recombination (HR) is a conserved mechanism that repairs broken chromosomes via intact homologous sequences. How different genomic, chromatin and subnuclear contexts influence HR efficiency and outcome is poorly understood. We developed an assay to assess HR outcome by gene conversion (GC) and break-induced replication (BIR), and discovered that subtelomeric double-stranded breaks (DSBs) are preferentially repaired by BIR despite the presence of flanking homologous sequences. Overexpression of a silencing-deficient SIR3 mutant led to active grouping of telomeres and specifically increased the GC efficiency between subtelomeres. Thus, physical distance limits GC at subtelomeres. However, the repair efficiency between reciprocal intrachromosomal and subtelomeric sequences varies up to 15-fold, depending on the location of the DSB, indicating that spatial proximity is not the only limiting factor for HR EXO1 deletion limited the resection at subtelomeric DSBs and improved GC efficiency. The presence of repressive chromatin at subtelomeric DSBs also favoured recombination, by counteracting EXO1-mediated resection. Thus, repressive chromatin promotes HR at subtelomeric DSBs by limiting DSB resection and protecting against genetic information loss