We have used a chromosome-specific approach to generate a 300 kb long
‘contig’ across Leishmania major 500 kb
chromosome. Clones from a 13-hit genomic library served as templates to generate
end-specific probes that were used in
hybridization to a high density array of the library. The ‘contig’
generated contained 12 markers uniformly spaced. Three
restriction endonucleases were mapped within the map extending its resolution.
Map extension indicated a peculiar feature
of sequence organization in subtelomeric regions where chromosome-specificity of
mapping is lost. End-probes generated
from clones mapping to the extremes of a 300 kb ‘contig’ rescued
a high percentage of 2 types of clones from the genomic
library, 1 of which showed positive hybridization to the hexameric telomere
repeat. Fine mapping at these regions revealed
that these 2 clones contained elements common to all chromosomes of the
parasite. The physical map generated constitutes
ready-to-use data for the study of many aspects of genome organization.
Being cloned in a shuttle vector, the genomic
sequences reordered in the map can be used to generate genetic information
by transfection into the parasite.