Physical Mapping of Repeated Sequences on Fish Chromosomes by Fluorescence In Situ Hybridization (FISH)

The opportunity to map genes and noncoding DNA sequences on the chromosomes by fluorescence in situ hybridization (FISH) has greatly enhanced the potential for fish karyotyping and comparative cytogenetics. The use of FISH allowed for significant advances in our understanding of the fish genome architecture, especially when applied to the study of the repetitive component of the genome, that is generally underestimated in the bioinformatic assembly. Here we provide a step-by-step protocol for FISH of repeated sequences onto chromosomes of fish species.