title: Correlations of three-dimensional motion of chromosomal loci in yeast revealed by the double-helix point spread function microscope.
abstract: Single-particle tracking has been applied to study chromatin motion in live cells, revealing a wealth of dynamical behavior of the genomic material once believed to be relatively static throughout most of the cell cycle. Here we used the dual-color three-dimensional (3D) double-helix point spread function microscope to study the correlations of movement between two fluorescently labeled gene loci on either the same or different budding yeast chromosomes. We performed fast (10 Hz) 3D tracking of the two copies of the GAL locus in diploid cells in both activating and repressive conditions. As controls, we tracked pairs of loci along the same chromosome at various separations, as well as transcriptionally orthogonal genes on different chromosomes. We found that under repressive conditions, the GAL loci exhibited significantly higher velocity cross-correlations than they did under activating conditions. This relative increase has potentially important biological implications, as it might suggest coupling via shared silencing factors or association with decoupled machinery upon activation. We also found that on the time scale studied (∼0.1-30 s), the loci moved with significantly higher subdiffusive mean square displacement exponents than previously reported, which has implications for the application of polymer theory to chromatin motion in eukaryotes.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, CA 94305.
authors.forename: Mikael P
authors.initials: MP
authors.lastname: Backlund
authors.affiliation: Department of Cell and Developmental Biology, University of California, Berkeley, Berkeley, CA 94720.
authors.forename: Ryan
authors.initials: R
authors.lastname: Joyner
authors.affiliation: Department of Cell and Developmental Biology, University of California, Berkeley, Berkeley, CA 94720 Institute of Biochemistry, Department of Biology, ETH Zürich, 8093 Zürich, Switzerland.
authors.forename: Karsten
authors.initials: K
authors.lastname: Weis
authors.affiliation: Department of Chemistry, Stanford University, Stanford, CA 94305 wmoerner@stanford.edu.
authors.forename: W E
authors.initials: WE
authors.lastname: Moerner
mesh_terms: D002843:Chromatin / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D015825:Chromosomes, Fungal / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D056426:Genetic Loci; D008853:Microscopy / Q000295:instrumentation / Q000379:methods; D009038:Motion; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D002843:Chromatin