title: How not to search for isochores: a reply to Cohen et Al.
abstract: In a recent paper in these pages, Cohen et al. search for isochores in the human genome, based on a system of attributes that they assign to isochores. The putative isochores that they find and choose for presentation are almost all below 45% GC and cover only about 41% of the genome. Closer inspection reveals that the authors' methodology systematically loses GC-rich isochores because it does not anticipate the considerable fluctuations and corresponding long-range correlations that characterize mammalian DNA and that are highest in GC-rich DNA. Thus, they over-fragment GC-rich isochores (and also many GC-poor isochores) beyond recognition.
authors.forename: Oliver
authors.initials: O
authors.lastname: Clay
authors.forename: Giorgio
authors.initials: G
authors.lastname: Bernardi
mesh_terms: D001482:Base Composition; D020862:GC Rich Sequence; D015894:Genome, Human; D006801:Humans; D032085:Isochores; D008957:Models, Genetic
chemical_list: D032085:Isochores