ARTIFICIAL LINEAR MINICHROMOSOMES FOR TRYPANOSOMA-BRUCEI

We have constructed artificial linear mini-chromosomes for the parasit ic protozoan Trypanosoma brucei. These chromosomes exist at similar to 2 copies per cell, are indefinitely stable under selection but are lo st from 50% of the transformed population in similar to 7 generations when grown in the absence of selective pressure, Consistent with resul ts obtained earlier with natural chromosomes in T.brucei, the telomere s on these artificial chromosomes grow, adding similar to 1-1.5 telome ric repeats per generation, The activity of a procyclic acidic repetit ive protein (parp) gene promoter on these elements is unaffected by it s proximity to a telomere, implying the lack of a telomere-proximal po sition effect (TPE) in procyclic trypanosomes, Among other things, the se autonomously replicating dispensable genetic elements will provide a defined system for the study of nuclear DNA replication, karyotypic plasticity and other aspects of chromosomal behavior in this ancient e ukaryotic lineage.