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Open Access Publications from the University of California

Complexity and content of the DNA and RNA in Trypanosoma cruzi

  • Author(s): Lanar, DE
  • Silven Levy, L
  • Manning, JE
  • et al.

The content and sequence complexity of the nuclear DNA and messenger RNA for epimastigotes of Trypanosoma cruzi were determined. From analysis of nuclear DNA reassociation studies and microspectrofluorometric measurements of laser induced fluorescence of cellular DNA, T. cruzi is found to be a diploid organism with a nuclear DNA content of 2.5 × 108nucleotide pairs (2.8 × 10-13g) and a kinetoplast DNA content of 4.9 × 107nucleotide pairs (5.4 × 10-14g). Reassociation kinetics of nuclear DNA of average length 0.4 kb reveals three kinetic components: a moderately repetitive component with a reiteration frequency of 5.1 × 103present in 9% of the fragments, a lowly repetitive component with a reiteration frequency of 32 present in 51% of the fragments, and a single-copy component present in 23% of the fragments. By saturation hybridization of total polysomal RNA to3H-labeled single-copy DNA, it was determined that 68% of the single-copy DNA was represented in the epimastigote polysomal RNA. This corresponds to ca. 12 000 different mRNA species. Of these, ca. 9000 are present as poly(A)+-RNA, while the remaining 3000 appear not to be polyadenylated. Kinetic analysis of the poly(A)+-RNA population indicates it is composed of at least three classes of RNAs of different abundancy levels: two sequences which occur ca. 3000 times per cell, ca. 750 sequences which occur about 20 times per cell, and ca. 15 500 sequences which occur 1-2 times per cell. © 1981.

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