THE BEREZNEY LAB IN SPOTLIGHT

The genetic material of eukaryotes is packaged into a seemingly simple, yet complex structure, termed the nucleus. Though significant progress has been made in the understanding of basic functional proc-esses at the molecular level, including DNA replica-tion, transcription, and RNA processing, the func-tional co-ordination of these events in space and time is still obscure. The higher-order organization of functional domains and individual genes inside the nucleus is currently being deciphered using a combi-nation of in vivo and in situ labeling methods, sophis-ticated high resolution multi-dimensional microscopy, and computerized image analysis (Berezney et al., 2005). Utilizing these approaches, we have the ability to visualize, track, and quantify the three-dimensional (3D) arrangement and movement of chromatin do-mains and replication sites in living cells. A recently published study from our lab unraveled the 3D zoning of the fundamental processes of replication and transcription (Wei et al., 1998). The genome within the mammalian nucleus during interphase is ar-ranged into discrete chromosome territories. Pres-ently, we are using multi-color fluorescence in situ hybridization (FISH) to visualize and analyze the 3D organization of chromosome territories, centromeres, telomeres, and individual genes in the interphase nucleus of various normal and cancer cell lines (see LABS @ UB Figure 1. Gene and functional organization, as unraveled by multi-labeling methods. (A) Three-dimensional image ren-dering of an interphase WI38 lung fibroblast nucleus, labeled for both transcriptionally active and inactive X chromo-some territories (green), DNA replication sites (yellow), and a dystrophin gene probe (red). (B) Magnified portion of fig-ure (A). (C) Metaphase spreads of WI38 lung fibroblasts, labeled for chromosome 4 (green), and chromosome 4 cen-tromeres (red). DNA is counterstained with DAPI (blue) to visualize other chromosomes. B i