A major obstacle in genome sequencing, particularly in plants, is separating the protein-encoding genes from the repeats. Researchers at University of Georgia, Athens (UGA), using sorghum as a test case, have streamlined this process using a technique popular during the 1960s and 1970s--analysis of the renaturation kinetics of DNA, familiarly known as Cot curves.1 The revived approach is called CBCS, for Cot-based cloning and sequencing.2

The term "Cot" refers to the DNA concentration (Co) multiplied by incubation time (t). As DNA double helices are separated, the resulting single-stranded molecules reassociate into double helices; the more copies present, the faster the reassociation. Repeats rejoin faster and have a lower Cot value; more complex sequences have a harder time finding each other in the mix. A Cot curve plots the fraction of reassociated DNA against the logarithm of the Cot value.

CBCS has something for everyone, for it shatters and...

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