During recent years, several Leishmania infantum genes have been cloned and
characterized. Here, we have summarized the available information on the
gene organization and expression in this protozoan parasite. From a
comparative analysis, the following outstanding features were found to be
common to most of the genes characterized: tandemly organized genes with
conserved coding regions and divergent untranslated regions, polycistronic
transcription and post-transcriptional regulation of gene expression. The
analysis of chromosomes of L. infantum by pulsed-field electrophoresis
showed the existence of both size and number polymorphisms such that each
strain has a distinctive molecular karyotype. Despite this variability,
highly conserved physical linkage groups exists among different strains of
L. infantum and even among Old World Leishmania species. Gene mapping on
the L. infantum molecular karyotype evidenced a bias in chromosomal
distribution of, at least, the evolutionary conserved genes.
