DNA Fluorescent Labeling With CRISPR/dCas9

CRISPR is an acquired immune system of prokaryotes such as bacteria and archaea against the invasion of exogenous DNA from virus or plasmid.CRISPR has become a great technology of concern to biochemists due to the convenience and rapidness over the last years.In contrast to the application in gene knocking-out,gene editing and gene regulation,rarely has it been applied to label chromosomal loci to detect the chromosome dynamics.Here we used a dual color CRISPR system to track the pair wise loci during the cell cycle.In this system,sgRNA and dCas9 were labeled by FPs or Tags such as Halo or SNAP which will conjugate to a variety of organic fluorescent dyes.Combination of RNA adapter(MS2 or PP7)and the corresponding MS2 or PP7 coat proteins fused with different fluorescent proteins were used as well.The relaxation,fold and compaction of chromosome were revealed at different stage by comparing the radii of movement,location and genomic distance.Furthermore,the relationship between cell cycle stage and structure of chromosome may be revealed at various levels.