Breakage in breakage–fusion–bridge cycle: an 80-year-old mystery

2021 marked the 80th anniversary of Barbara McClintock's pioneering article on the breakage–fusion–bridge (BFB) cycle. Of the three steps of the BFB cycle, breakage remains the least understood despite its major contribution to mutagenesis. We discuss recent findings shedding light on how chromatin bridges break in yeast and animal cells. 2021 marked the 80th anniversary of Barbara McClintock's pioneering article on the breakage–fusion–bridge (BFB) cycle. Of the three steps of the BFB cycle, breakage remains the least understood despite its major contribution to mutagenesis. We discuss recent findings shedding light on how chromatin bridges break in yeast and animal cells. double-stranded chromatin fibres connecting the segregated chromosome masses in anaphase or the daughter nuclei in telophase. They can also persist in the next interphase. A hallmark of dicentric chromosomes. a mutational process by which chromosome regions are shattered and reassembled by error-prone repair, resulting in highly rearranged chromosomes. transient DNA bridges connecting the segregated chromosome masses in anaphase. They originate from replication, recombination, or topological intermediates. In contrast to chromatin bridges, ultrafine bridges can often be resolved prior to cytokinesis without consequence and are not detectable by DNA staining due to their low DNA density.