The Evolution of Human Chromosome 7 Syntenies in Eutheria, with Special Attention to Primates

Genetic and cytogenetic comparison in between man and non-human primates has largely contributed to the knowledge of the evolution of the Order Primates, and in particular of man. Recently, the "Chromosome painting" approach indicated a strong conservation of syntenies in Eutheria. At present, a more precise identification of breakpoints and evolutionary related rearrangements can be obtained by BAC and locus specific in situ hybridi- sation. In spite to this situation the evolutionary history of different human autosomes remains a dilemma; at the same time, high resolution banded chromosome analysis confirms to be a valuable tool for the preliminary detection of fine rearrangements. This review critically describes current information concerning the evolution of human chro- mosome 7 orthologous in several Eutherian groups. Included in this analysis are data on species belonging to 11 or- ders. Nevertheless, this study has been mainly focused on Primates were we considered data from 9 species of Prosimians, 25 species of Platirrhinae, and 51 species of Catarrhinae. Chromosome 7 synteny appeared in a mamma- lian ancestor in a dual form, generally described as 7a and 7b forms. These chromosomes underwent to several line- specific rearrangements in the different orders. A particular complexity in chromosome rearrangements has been highlighted in Primates. A chronologically fossil-tuned dynamic of the synteny is proposed, starting from classical and molecular cytogenetics specific landmarks which appeared throughout evolution.