A DIRECT METHOD FOR THE CHROMOSOMAL ASSIGNMENT OF DNA MARKERS IN LEISHMANIA

A simple method for the chromosomal assignment of any DNA marker would be an important tool for the ongoing project to map the genome of the protozoan parasite Leishmania. The Leishmania chromosomes enter pulse d field gel electrophoresis (PFGE) gels under current electrophoretic conditions, but their direct identification in a given strain is hampe red by their stacking in a few chromosomal bands, and by the very freq uent size variations of the same chromosome among parasite strains. To overcome these problems, we determined the complete karyotypes of 12 Old World Leishmania cloned strains. This enabled us to select three o f these strains that display great chromosome size polymorphisms, such that every chromosome can be individualized by a specific pattern aft er hybridization onto these three karyotypes. The complete resolution of the genomes of these three strains can be carried out with only thr ee electrophoretic conditions. This makes a series of three blots suff icient for the assignment of any new marker on a particular Leishmania chromosome. (C) 1997 Elsevier Science B.V.