KARYOTYPE ANALYSIS OF THE MONOGENETIC TRYPANOSOMATID LEPTOMONAS-COLLOSOMA

In order to develop a genetic system for the monogenetic trypanosomati ds, we have analyzed the molecular karyotype of Leptomonas collosoma b ased on chromosome separation by clamped homogeneous electric field (C HEF) gel electrophoresis. The chromosome location of 5 RNA coding gene s (SL, U6, 5S, 7SL and rRNA) and 2 protein coding genes (for HSP83 and alpha-tubulin) was determined. All of the L. collosoma genes examined were found on at least 2 chromosomes, which differ in size in the ran ge of 100-500 kb, suggesting that the organism is diploid. The weighte d sum of L. collosoma chromosomes separated by CHEF analysis was appro ximately 62 +/- 3 Mb, whereas the genome size determined by FACS was e stimated at approx. 80 Mb. This suggests that some of the homologous c hromosomes differ in their size. The analysis presented here may facil itate studies on the function of individual genes, and on the genetic stability of this organism.