平特五不中

Event

Mechanics, topology and geometry of mammalian chromosomes and nuclei and their epigenetic modulation

Tuesday, January 14, 2020 12:00to13:00
Montreal Neurological Institute deGrandpre Communications Centre, 3801 rue University, Montreal, QC, H3A 2B4, CA, 3801 rue University, Montreal, QC, H3A 2B4, CA
Price: 
Free Admission

平特五不中's Seminar Series in Quantitative Life Sciences and Medicine
Sponsored by CAMBAM, QLS, MiCM and the Ludmer Centre

Title:听Mechanics, topology and geometry of mammalian chromosomes and nuclei and their epigenetic modulation
Speaker:听John Marko,听Northwestern University
When:听Tuesday, January 14, 12-1pm听
Where:听Montreal Neurological Institute,听deGrandpre Communications Centre

Abstract:听I will discuss studies of the mechanics and structure of metaphase chromosomes and nuclei extracted from mammalian cells using glass micropipettes. Using a combination of mechanical, biochemical and genetic approaches we have shown that the metaphase chromosome is a "chromatin gel", without a contiguous protein scaffold, and via SMC2 siRNA experiments, that condensin plays a major role as a "crosslinker". I will also discuss the "loop-extrusion" model for establishment of chromatid structure, with special attention to how it generates compaction of chromosomes along their length, or "lengthwise compaction", and how this provides a mechanism for chromatid and chromosome individualization. I will then describe use of the same general approach to analyze the mechanics of mammalian G1 nuclei. The nucleus shows two distinct mechanical responses: an initial chromatin-dominated elastic behavior, followed by a stiffer, lamin-dominated regime at larger extension. The low-force chromatin-based elasticity can be modulated by changing histone acetylation and methylation, and the morphology of the nucleus is impacted by these changes, with heterochromatinization driving the nucleus to be stiffer and rounder, and with euchromatinization destabilizing nuclear shape.

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