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Logo of bmcgenoBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Genomics
BMC Genomics. 2009; 10: 538.
Published online Nov 18, 2009. doi:  10.1186/1471-2164-10-538
PMCID: PMC2783168
The isochore patterns of invertebrate genomes
Rosalia Cammarano,1 Maria Costantini,corresponding author1 and Giorgio Bernardicorresponding author1
1Stazione Zoologica Anton Dohrn, 80121 Naples, Italy
corresponding authorCorresponding author.
Rosalia Cammarano: cammaran/at/; Maria Costantini: mcosta/at/; Giorgio Bernardi: bernardi/at/
Received July 3, 2009; Accepted November 18, 2009.
Previous investigations from our laboratory were largely focused on the genome organization of vertebrates. We showed that these genomes are mosaics of isochores, megabase-size DNA sequences that are fairly homogeneous in base composition yet belong to a small number of families that cover a wide compositional spectrum. A question raised by these results concerned how far back in evolution an isochore organization of the eukaryotic genome arose.
The present investigation deals with the compositional patterns of the invertebrates for which full genome sequences, or at least scaffolds, are available. We found that (i) a mosaic of isochores is the long-range organization of all the genomes that we investigated; (ii) the isochore families from the invertebrate genomes matched the corresponding families of vertebrates in GC levels; (iii) the relative amounts of isochore families were remarkably different for different genomes, except for those from phylogenetically close species, such as the Drosophilids.
This work demonstrates not only that an isochore organization is present in all metazoan genomes analyzed that included Nematodes, Arthropods among Protostomia, Echinoderms and Chordates among Deuterostomia, but also that the isochore families of invertebrates share GC levels with the corresponding families of vertebrates.
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