New genetics study results reported from University of California.

"Repair of DNA double-strand breaks (DSBs) by homologous recombination is crucial for cell proliferation and tumour suppression. However, despite its importance, the molecular intermediates of mitotic DSB repair remain undefined," scientists in the United States report (see also Genetics).

"The double Holliday junction (DHJ), presupposed to be the central intermediate for more than 25 years(1), has only been identified during meiotic recombination(2). Moreover, evidence has accumulated for alternative, DHJ-independent mechanisms(3-6), raising the possibility that DHJs are not formed during DSB repair in mitotically cycling cells. Here we identify intermediates of DSB repair by …