ORGANIZATION AND CHROMOSOMAL LOCALIZATION OF BETA-TUBULIN GENES IN LEISHMANIA-DONOVANI

The genomic organization and chromosomal location of the beta-tublin isogenes in Leishmania donovani promastigotes has been studied by nucleic acid hybridization techniques using a cloned beta-tubulin gene. We have cloned a beta-tubulin gene fragment, 3.3 kbp long, from genomic DNA of Leishmania donovani using a heterologous beta-tubulin DNA as probe. Restriction maps of this clone have been prepared. It has been estimated that there are approximately 11-15 copies of the beta-tubulin genes per haploid genome. The majority of these isogenes are arranged in a tandem repeat with a length of 3.5 kbp on a single chromosome. In addition a few dispersed gene copies at different chromosomal loci were detected by pulse field gradient gel electrophoresis. Part of the internal coding region of the gene has been sequenced to confirm the identity of the beta-tubulin clone and is found to be nearly identical to that of Leishmania mexicana amazonesis.