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 variable number at many chromosomal ends. Both loss and increase in 2.3kb-repeat copy number are involved in chromosome-size polymorphisms. Subtelomeric losses leading to chromosome-size polymorphisms have been described by several authors in P.falciparum where the structure of subtelomeric regions is not known in detail. We therefore undertook their characterisation, by means of chromosome walking and jumping techniques, 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 ends in P.falciparum 3D7 chromosomes share a subtelomeric region, about 40kb long, covering (but not limited to) the Rep20 region. Non repetitive, AT-rich portions flanking the Rep20 region on both sides are also conserved at most chromosomal ends.

Distribucion de necator americanus y ancylostoma duodenate en Santa Cruz Bolivia / Distribution of necator americanus and ancylostoma duodenate in Santa Cruz Bolivia

Del estudio de 63 muestras de heces positivas al cultivo segun la tecnica de Harada-Mory, se concluye que la especie de Ancylostomia mas prevalente en Santa Cruz-Bolivia es A. duodenale con una proporcion A. duodenale-N.americanus de 1,22. Sin embargo la mayoria de las infecciones (49 %) son mixtas 27 y 24 %, corresponden a infecciones puras por A.duodenale y N. americanus respectivamente. Ademas, se presenta una revision de las caracteristicas morfologicas mas salientes en cada especie.