High conservation of the fine-scale organisation of chromosome 5 between two pathogenic Leishmania species

In a previous work we showed a remarkable conservation of the general struc ture of the genome (chromosome number and synteny) among different pathogen ic species of Old World Leishmania, indicating the absence of major interch romosomal rearrangements during evolution. In the present study, we have co mpared the fine structure of chromosome 5 among two of these divergent spec ies (Leishmania major and Leishmania infantum) by means of physical mapping . Remarkably, the 42 markers jointly mapped on these two chromosomes were f ound in an identical order along the chromosome. This perfect colinearity o f the markers is in striking contrast to the large genetic distance that se parates these species and suggests that conservation of the fine-scale orga nisation of chromosomes may be critical in Leishmania. If this colinearity is confirmed on the whole of the chromosome set, the current systematic seq uencing programme of the genome of L.major should greatly help in the devel opment of comparative genetics between different species of Leishmania.