SUBTELOMERIC STRUCTURE OF PLASMODIUM-FALCIPARUM CHROMOSOMES

Previous studies of subtelomeric regions in Plasmodium berghei led to the identification of subtelomeric repeats (2.3kb long) present in a v ariable number at many chromosomal ends. Both loss and increase in 2.3 kb-repeat copy number are involved in chromosome-size polymorphisms. S ubtelomeric losses leading to chromosome-size polymorphisms have been described by several authors in P.falciparum where the structure of su btelomeric regions is not known in detail. We therefore undertook thei r characterisation, by means of chromosome walking and jumping techniq ues, starting from the telomere-flanking sequence present in pPftel.1, the P.falciparum telomeric clone described by Vernick and McCutchan ( 1988). The results indicate that at least 20 (out of 28) chromosomal e nds in P.falciparum 3D7 chromosomes share a subtelomeric region, about 40kb long, covering (but not limited to) the Rep20 region. Non repeti tive, AT-rich portions flanking the Rep20 region on both sides are als o conserved at most chromosomal ends.