SMC complexes differentially compact mitotic chromosomes according to genomic context

Structural maintenance of chromosomes (SMC) protein complexes are key determinants of chromosome conformation. Using Hi-C and polymer modelling, we study how cohesin and condensin, two deeply conserved SMC complexes, organize chromosomes in the budding yeast Saccharomyces cerevisiae. The canonical role of cohesin is to co-align sister chromatids, while condensin generally compacts mitotic chromosomes. We find strikingly different roles for the two complexes in budding yeast mitosis. First, cohesin is responsible for compacting mitotic chromosome arms, independently of sister chromatid cohesion. Polymer simulations demonstrate that this role can be fully accounted for through cis-looping of chromatin. Second, condensin is generally dispensable for compaction along chromosome arms. Instead, it plays a targeted role compacting the rDNA proximal regions and promoting resolution of peri-centromeric regions. Our results argue that the conserved mechanism of SMC complexes is to form chromatin loops and that distinct SMC-dependent looping activities are selectively deployed to appropriately compact chromosomes

Nanoparticles distribution and mechanical properties of aluminum-matrix nano-composites treated with external fields

Copyright © 2014 The Minerals, Metals & Materials Society. All rights reserved.Aluminum-matrix nano-composites have been produced after incorporating various hard ceramic nanoparticles (Al2O3, AIN and SiC) and Al2O3 microparticles into liquid metal by mechanical stirring. The mechanical stirring process is optimized to obtain distribution of nanoparticles in entire volume of the liquid. However, locally, nanoparticle clusters have been found. Application of the ultrasound to the slurry containing nanoparticles resulted in significantly improved particle dispersion and reduced nanoparticle clusters density. Nano-composites have been characterized by optical and scanning electron microscopy to see dispersion enhancement. Hardness was measured to study the local mechanical properties of these composites.ExoMet Project, which is co-funded by the European Commission in the 7th Framework Program (contract FP7-NMP3-LA-2012-280421), by the European Space Agency and by the individual partner organizations