Karyotype comparison betweenp.chabudiand P.falciparum:analysis of a P.ChabaudicDNA containing sequences highty repetitive in P.falciparum

Abstract

The molecular karyotypes of P. chabaudi and P. falciparum have been compared by pulse field gradient electrophoresis. P. chabaudi has 3 extra chromosomes in the 750-2000 Kb range although the overall number appears to be 14 as is the case for P. falciparum. The chromosomal location of the rRNA genes has been determined for P. chabaudi together with that of a 24 Kd antigen gene. The corresponding cDNA 443 may code for a protein unusually rich in tyrosine and contains sequences highly repetitive in P. falciparum.

Molecular karyotype of Plasmodium falciparum: conserved linkage groups and expendable histidine-rich protein genes.

“…The fastest-moving chromosome of each clone is genetically equivalent, though highly polymorphic in size (2-5). We have established its identity in D10, E12, and 3D7 with probes for RESA (16) and Ag169 (17), with four other randomly chosen fragments from libraries of chromosome 1 fragments (10) in isolates HB3, KI, NF7 (data not shown), and with ribosomal RNA (3,6). Furthermore, RESA mapped to the smallest chromosome in five independent isolates taken directly from patients (4, 5).…”

“…The genome of Plasmodium falciparum was resolved into at least 7 (2-5) chromosomes in the earliest studies. Subsequently, at least 11 chromosomes were resolved (6) and hence the most recent estimate approximates the total of 14 chromosomes obtained by electron microscopic observation of kinetochores (7).…”

“…The P. falciparum chromosomes are highly polymorphic in size, both in cultured isolates and in parasites obtained directly from patients (2)(3)(4)(5)(6). Although the karyotype of a cloned line is stable during the asexual cycle, some size variation occurs in vitro that may result from deletions of genes such as the knob-associated histidine-rich protein (KAHRP) gene (4,8).…”

“…Cloned P. falciparum sequences have provided markers to define chromosomes 1-4 in a number of isolates (2)(3)(4)(5)(6)(8)(9)(10), and a number of other markers, mainly genes for antigens, were used here. Most previous mapping assignments to larger chromosomes are obsolete due to the lack of resolution on earlier gels.…”

Organization of subtelomeric repeats in Plasmodium berghei.

“…This fact prompted us, some years ago, to start to look for telomeric sequences in Plasmodium species which would also allow the exploration of subtelomeric portions. The first telomeric fragment (pTel.1) cloned from Plasmodium berghei (22) contained a series of tandem 7-base-pair (bp) repeats (which later proved to be present in all the chromosomes of all the Plasmodium species tested [5,13,16]) and part of the basic element of a 2.3-kilobase (kb) repeat family.…”