<figcaption> Credit: © ANDREW MEEHAN</figcaption>

Ending a two-decade search, investigators have experimental evidence that two replication forks diverging from a single origin are held together in space.

Tomoyuki Tanaka and his colleagues at the University of Dundee recently visualized DNA replication factories by inserting arrays of lac operators and tet operators into a Saccharomyces cerevisiae chromosome.1 These operators were placed equi-distant from a known origin of replication. By using GFP-tagged lacI and CFP-tagged TetR, Tanaka?s group was able to track the loci during replication. By analyzing the location and intensity of the fluorescence, the group concluded that the two chromosomal loci are close at the time of DNA replication and then separate afterwards.

"This finding will profoundly affect our understanding of chromosomes during replication," says Faculty of 1000 member Joel Huberman at the Roswell Park Cancer Institute in Buffalo, New York.

"I am relieved that the search for this is...

1. E. Kitamura et al., "Live-cell imaging reveals replication of individual replicons in eukaryotic replication factories," Cell, 125:1297-308, June 2006.

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