Extrachromosomal DNA in the Apicomplexa

  • Iain Wilson
  • Malcolm Gardner
  • Kaveri Rangachari
  • Don Williamson
Part of the NATO ASI Series book series (volume 78)


Extrachromosomal DNA adds a new dimension to genetic studies in the Apicomplexa. At a fundamental level, it has the potential to give a new perspective on evolutionary relationships between various taxa. Unlike the polymorphic diversity of many malarial chromosomal genes, a high level of sequence conservation is apparent in the malarial extrachromosomal DNAs that have been examined [Feagin, 1992] suggesting that they will be useful in tracing the evolution of taxa and genetically defined populations. In addition, and in more practical terms, analysis of extrachromosomal DNA may help with the application of specific chemotherapeutic intervention to organellar metabolic pathways. Although it might be argued that these aspects are rather limited, the finding that in malaria there are two unrelated forms of extrachromosomal DNA with organellar characteristics [Wilson et al., 1991; Feagin et al., 1992] is both unexpected and of general scientific interest. Consequently, a full description of the extrachromosomal DNAs in Apicomplexans should be made to complement other studies, such as the construction of chromosomal maps, that aim to improve our understanding of the genetics of important pathogenic organisms like Toxoplasma and Plasmodium.


Inverted Repeat Toxoplasma Gondii Plasmodium Knowlesi Cruciform Structure Gene Cytochrome Oxidase 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Aikawa, M., Carter, R., Ito, Y., Nijhout, M.N. [ 1984 ] New observations on gametogenesis, fertilization, and zygote formation in Plasmodium falciparum. J. Protozool 31: 403–413.PubMedGoogle Scholar
  2. Barta, J.R., Jenkins, M.C., Danforth, H.D., [ 1991 ] Evolutionary relationships avaian Eimeria species among other Apicomplexan protozoa: Monophyly of the Apicomplexa is supported. Mol Biol Evol 8: 345–355.PubMedGoogle Scholar
  3. Borst, P., Overdulve, J.P., Weijers, P.J., Fase-Fowler, F., Van Den Berg, M. [ 1984 ] DNA circles with cruciforms from Isospora (Toxoplasma) gondii. Biochem Biophys Acta 781: 100–111.PubMedGoogle Scholar
  4. Creasey, A., Ranford-Cartwright, L.C., Balfe, P., Walliker, D., Moore, D., Williamson, D.H., Wilson, R.J.M., Carter, R. [1992] Uniparental inheritance of the cytochrome b gene in Plasmodium falciparum. In preparation.Google Scholar
  5. Divo, A.A., Geary, T.G., Jensen, J.B., Ginsburg, H. [ 1985 ] The mitochondrion of Plasmodium falciparum visualized by rhodamine 123 fluorescence. J. Protozool 32: 442–446.PubMedGoogle Scholar
  6. Feagin, J.E., [ 1992 ] The 6kb element of Plasmodium falciparum encodes mitochondrial cytochrome genes. Mol Biochem parasitol 52: 145–148.PubMedCrossRefGoogle Scholar
  7. Feagin, J.E., Werner, E., Garner, M.J., Williamson, D.H., Wilson R.J.M. [ 1992 ] Homologies between the contiguous and fragmented rRNAS of the two Plasmodium falciparum extrachromosomal DNAs are limited to core sequences. Nuc Acids Res 20: 879–887.CrossRefGoogle Scholar
  8. Gajadhar, A.A., Marquardt, W.C., Hall, R., Gunderson, J., Aritzia Carmona, E.V., Sogin, M.L. [ 1991 ] Ribosomal RNA sequences of Sarcocystis muris, Theileria annulata and Crypthecodinium cohnii reveal evolutionary relationships among apicomplexans, dinoflagellates, and ciliates. Mol Biochem Parasitol 45: 147–154.PubMedCrossRefGoogle Scholar
  9. Gardner, M.J., Williamson, D.H., Wilson, R.J.M. [ 1991 ] A circular DNA in malaria parasites encodes an RNA polymerase like that of prokaryotes and chloroplasts. Mol Biochem Parasitol 44: 115–124.PubMedCrossRefGoogle Scholar
  10. Howe, C. [1992] Plastid origin of an extrachromosomal DNA molecule from Plasmodium, causative agent of malaria. J Theor Biol. In press.Google Scholar
  11. Johnson, A.M., Murray, P.J., Illana, S., Baverstock, P.J. [ 1987 ] Rapid nucleotide sequence analysis of the small subunit ribosomal RNA of Toxoplasma gondii: evolutinary implications for the Apicomplexa. Mol Biochem Parasitol 25: 239–246.PubMedCrossRefGoogle Scholar
  12. Joseph, J.T., Aldritt, S.M., Unnasch, T., Puijalon, U., Wirth, D. [ 1989 ] Characterization of a conserved extrachromosomal element isolated from the avian malarial parasite Plasmodium gallinaceum. Mol Cell Biol 9: 3621–3629.PubMedGoogle Scholar
  13. Megson, A., Inman, G.J., Hunt, P.D., Baylis, H.A., Hall, R. [ 1991 ] The gene for apocytochrome B of Theileria annulata resides on a small linear extrachromosomal element. Mol Biochem Parasitol 48: 113–116.PubMedCrossRefGoogle Scholar
  14. Morden, C.W., Wolfe, K.H., dePamphilis, C.W., Palmer, J.D. [ 1991 ] Plastid translation and transcription genes in a non-photosynthetic plant: intact, missing and pseudo genes. EMBO J 10: 3281–3288.PubMedGoogle Scholar
  15. Morin, G.B., Cech, T.R. [ 1986 ] The telomeres of the linear mitochondrial DNA of Tetrahymena thermophila consist of 53 bp tandem repeats. Cell: 10: 873–883.CrossRefGoogle Scholar
  16. Nene, V., Gobright, E., Kairo, A [ 1992 ] A subset of Theileria parva mitochondrial proteins is encoded by a linear 7.1 kbp DNA molecule. J Cell Bio Suppl 16a: 116.Google Scholar
  17. Ossorio, P.N., Sibley, L.D., Boothroyd, J.C. [ 1991 ] Mitochondrial-like DNA sequences flanked by direct and inverted repeats in the nuclear genome of Toxoplasma gondii. J. Mol Biol 222: 525–536.PubMedCrossRefGoogle Scholar
  18. Palmer, J.D., [ 1985 ] Comparative organization of chloroplast genomes. Ann Rev Genet 19: 325–354.PubMedCrossRefGoogle Scholar
  19. Palmer, J.D. [ 1992 ] Green ancestry of malarial parasites? Curr Biol 2: 318–320.PubMedCrossRefGoogle Scholar
  20. Scholtysech, E., Mehlhorn, H., Hammond, D.M., [ 1972 ] Electron microscopic studies of microgametogenesis in coccidia and related groups. Z Parasitenk 38: 95–131.CrossRefGoogle Scholar
  21. Tanabe, K., Murakami, K [ 1984 ] Reduction in the mitochondrial membrane potential of Toxoplasma gondii after invasion of host cells. J Cell Sci 70: 73–81.PubMedGoogle Scholar
  22. Vaidya, A.B., Akella, R., Suplick, K. [ 1989 ] Sequences similar to two mitochondrial proteins and portions of ribosomal RNA in tandemly arrayed 6-kilobase-pair DNA of a malarial parasite. Mol Biochem Parasitol 35: 97–108 and Corrigendum 39: 295–296.Google Scholar
  23. Williamson, D.H., Wilson, R.J.M., Bates, P.A., McCready, S., Perler, F., Qiang, B [ 1985 ]. Nuclear and mitochondrial DNA of the primate malarial parasite Plasmodium knowlesi. Mol Biochem Parasitol 14: 199–209.PubMedCrossRefGoogle Scholar
  24. Wilson, R.J.M., Gardner, M.J., Feagin, J.E., Williamson, D.H., [ 1991 ] Have malaria parasites three genomes? Parasitology Today 7: 134–136.PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1993

Authors and Affiliations

  • Iain Wilson
    • 1
  • Malcolm Gardner
    • 1
    • 2
  • Kaveri Rangachari
    • 1
  • Don Williamson
    • 1
  1. 1.National Institute for Medical ResearchMill Hill LondonUK
  2. 2.Division of Experimental TherapeuticsWalter Reed Army Institute of ResearchUSA

Personalised recommendations