A family of repeated DNA sequences in Toxoplasma gondii: Cloning, sequence analysis, and use in strain characterization

A Toxoplasma gondii genomic library was constructed in λEMBL3. Repeated fragments were detected by hybridization with radiolabeled total DNA from the parasite and one recombinant was chosen due to its strong hybridization signal. By using electrophoretic and hybridization analysis, four cross-hybridizating restriction fragments were selected and sequenced. The determined nucleotide sequence of these fragments (TGR1 A, TGR1 E, TGR2, and TGR4) has shown a complex system of conserved and degenerated repeats in which TGR1 E corresponds to the most conserved element. This last sequence was used to investigate restriction fragment length polymorphisms among several T. gondii strains by Southern blotting.