Fluorescence In Situ Hybridization (FISH) for the detection of chromosome aberrations and aneuploidy induced by environmental toxicants

Numerous chemicals as well as ionizing radiations of different qualities can induce damage to chromosome integrity and/or chromosome distribution at mitosis and meiosis. Fluorescence in situ hybridization with many kinds of probes complementary to different DNA sequences has been developed to detect and quantify specific types of structural and numerical aberrations in metaphase and interphase cells. Probes for the whole sequence of specific chromosomes are applied to metaphase cells to detect stable rearrangements, which can be relevant for cell transformation and tumor development. Probes that recognize the pericentromeric sequence of all chromosomes of a species are used to distinguish micronuclei that contain centromeres from those that do not, and, on this basis, infer whether they were induced by chromosome loss or chromosome break. Conversely, probes that recognize the pericentromeric sequence of specific chromosomes, if available, can be used to count the number of chromosomes in interphase nuclei to detect hyperploid cells possibly produced by chromosome nondisjunction. Finally, probes that hybridize to the telomeric sequence common to all chromosomes can be used to label telomeres and quantify their individual and mean length, a cell parameter that has been recently related to genomic instability. All these different techniques share the basic principles of fluorescence hybridization, with some specific adjustments. This chapter provides a general protocol useful for any of the above applications and comments to specific requirements or modifications.