MEDIUM-RANGE RESTRICTION MAPS OF 5 CHROMOSOMES OF LEISHMANIA-INFANTUMAND LOCALIZATION OF SIZE-VARIABLE REGIONS

The chromosomes of the human protozoan parasite Leishmania exhibit str iking size polymorphisms among different strains. To define the struct ural basis for these variations, we have constructed full-length restr iction maps of five chromosomes of 370 to 490 kb in Leishmania infantu m clone LEM1317. Rare-cutting sites for the enzymes Asci, DraI, XbaI, SspI, SpeI, and SfiI were mapped by partial and complete digestion of either gel-purified chromosomes or total DNA. Sixty-eight anonymous DN A probes were localized on these maps, as well as the mini-exon and di hydrofolate reductase-thymidilate synthase gene probes. These maps wer e compared with those from other strains of L. infantum and Leishmania donovani. This showed that the distribution of the restriction sites was conserved in these two close species. Four regions involved in the size variations of three chromosomes were localized; subtelomeric se quences were responsible for size variability in three of four cases. The whole of this study takes a particular significance in the frame o f the project of complete physical mapping and sequencing of the Leish mania genome. (C) 1996 Academic Press, Inc.