Mini-exon gene repeats of Trypanosoma (Nannomonas) congolense have internal repeats of 190 base pairs

Abstract

Genomic DNA hybridizations reveal that the mini-exon gene repeats of Trypanosoma (Nannomonas) congolense contain from one to greater than 20 internal tandem repeats of 190 base pairs (bp). The sequences of two mini-exon gene repeats were determined, one with three internal 190 bp repeats and one with a single 190 bp sequence. These internal repeats appear just after a very dC/dT-rich region, in the non-transcribed spacer regions between adjacent mini-exon transcription units. They do not occur in the genomes of the three other Trypanosoma species nor in the mini-exon gene repeats of four other kinetoplastids previously investigated. The mini-exon coding region of T. congolense differs in four positions from the T. brucei mini-exon sequence and in one position from a consensus sequence of the mini-exons found in other trypanosomatids. Pulse field gradient gels show that the mini-exon gene repeats of T. congolense are on large, greater than 2 megabase pair, chromosome(s).