Which are the properties of mammalian GA-sequences?
 In this article we identify for the first time explicitly the GA-sequences as a class of fractal genomic sequences that are easy to recognize and to extract, and are scattered densely throughout the chromosomes of a large number of genomes from different species and kingdoms including the human genome.  most GA-sequences [1] shared chains of tetra-GA-motifs and contained upstream poly(A)-segments. Although not integral parts of them, Alu-elements were found immediately upstream of all human and chimpanzee GA-sequences with an upstream poly(A)-segment The article hypothesizes that genome navigation uses these properties of GA-sequences in the following way The article describes DNA sequences of mammalian genomes that are longer than 50 bases, but consist exclusively of G's and A's ('pure GA-sequences'). With the exception of a small number of poly-A-, poly-G-, poly-GA-, and poly-GAAA-sequences (combined<0.5%), all pure GA-sequences of the mammals tested were unique individuals, contained several repeated short GA-containing motifs, and shared a common hexa-nucleotide spectrum.