The genetic information stored in genome sequences is spatially organized in several different ways and as a result of several different processes. The Helix group has been studying this aspect of genome sequences for several years.

 Isochores: the base composition of vertebrate genome sequences is not homogeneous, long regions with distinct G+C content exists, which are called isochores. Many different aspects of isochores are studied in the project team: their variation among mammals and among other vertebrates; their evolutionary origin; the mechanisms that create and maintain them; their interactions with the process of sequence evolution; their interactions with other aspects of genome organization such as the density of genes and of transposable elements.

 Chirochores : the base composition of the two strands of the DNA double helix differ in most bacterial genomes; homogeneous regions in terms of single strand base composition are called chirochores. The study of chirochores is oriented towards understanding their origin, their evolution, their impact on other topics such as DNA replication, codon usage, gene identification, gene expression, and their detection using dedicated software.

 Transposable elements: most eukaryotic genomes contain substantial quantities of sequences called transposable elements that are repeated from a few to several hundred thousand times. The spatial organization of these elements is studied in itself and in relation to other genomic components such as genes, introns, chromosomes, centromeres, telomeres.