Telomeres in warm-blooded vertebrates are composed of GC-rich isochores.
We have hybridized the vertebrate telomeric sequence (TTAGGG)n on DNA compositional fractions from 13 mammalian species and 3 avian species, representing 9 and 3 orders, respectively. Our results indicate that the 50- to 100-kb fragments derived from telomeric regions are composed of GC-rich and GC-richest isochores. Previous works from our laboratory demonstrated that single-copy sequences from the human H3 isochore family (the GC-richest and gene-richest isochore in the human genome) share homology with compositionally correlated compartments of warm-blooded vertebrates. This correlation suggested that the GC-richest isochores are, as in the human genome, the gene-richest regions of warm-blooded vertebrates' genome. Moreover, this evidence suggests that telomeric regions are the most gene-dense region of all warm-blooded vertebrates. The implications of these findings are discussed.
Perani
P
P
Laboratoire de Génétique Moléculaire, Université de Paris VII, 2 Place Jussieu, 75005 Paris, France.
Cacciò
S
S
Saccone
S
S
Andreozzi
L
L
Bernardi
G
G
D000818:Animals; D001717:Birds; D015139:Blotting, Southern; D004247:DNA; D015246:Deoxyribonuclease EcoRI; D020862:GC Rich Sequence; D006801:Humans; D008322:Mammals; D012091:Repetitive Sequences, Nucleic Acid; D016615:Telomere
D004247:DNA; D015246:Deoxyribonuclease EcoRI