Arrays of repetitive DNA elements in the largest chromosomes of Toxoplasma gondii

A novel tandemly repeated DNA structure of Toxoplasma gondii that meets the requirements assigned for satellital DNA was characterized. A DNA fragment of 1002 bp contains two different elements of repetitive DNA families named ABGTg7 and ABGTg8.2. Both repeats are members of a more complex tandem structure where ABGTg7-like monomers can be arranged either as direct tandems or flanked by other related or non-related repeats. Pulse-field gel electrophoresis analysis showed that these repeats hybridize with the largest T. gondii chromosomes. Bal31 sensitivity assays indicated that these elements are located near the telomeres and along other regions too. Five genomic lambda phages were isolated and two different completed clusters of the repeated structure were analyzed.Key words: Toxoplasma gondii, tandem repeat, satellite DNA, molecular karyotype, telomere.