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Philosophical Transactions of the Royal Society B: Biological Sciences logoLink to Philosophical Transactions of the Royal Society B: Biological Sciences
. 2002 Jan 29;357(1417):89–99. doi: 10.1098/rstb.2001.1050

Genetic analysis of phenotype in Trypanosoma brucei: a classical approach to potentially complex traits.

Andy Tait 1, Dan Masiga 1, Johnstone Ouma 1, Annette MacLeod 1, Juergen Sasse 1, Sara Melville 1, Gabbi Lindegard 1, Anne McIntosh 1, Mike Turner 1
PMCID: PMC1692923  PMID: 11839186

Abstract

The genome of the African trypanosome, Trypanosoma brucei, is currently being sequenced, raising the question of how the data generated can be used to determine the function of the large number of genes that will be identified. There is a range of possible approaches, and in this paper we discuss the use of a classical genetic approach coupled with positional cloning based on the ability of trypanosomes to undergo genetic exchange. The genetics of these parasites is essentially similar to a conventional diploid Mendelian system with allelic segregation and an independent assortment of markers on different chromosomes. Data are presented showing that recombination occurs between markers on the same chromosome allowing the physical size of the unit of recombination to be determined. Analysis of the available progeny clones from a series of crosses shows that, in principal, large numbers of progeny can readily be isolated from existing cryopreserved products of mating and, taking these findings together, it is clear that genetic mapping of variable phenotypes is feasible. The available phenotypes for analysis are outlined and most are relevant to the transmission and pathogenesis of the parasite. Genetic maps from two crosses are presented based on the use of the technique of AFLP; these maps comprise 146 and 139 markers in 30 and 21 linkage groups respectively. Segregation distortion is exhibited by some of the linkage groups and the possible reasons for this are discussed. The general conclusion, from the results presented, is that a genetic-mapping approach is feasible and will, in the future, allow the genes determining a number of important traits to be identified.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ashton P. D., Curwen R. S., Wilson R. A. Linking proteome and genome: how to identify parasite proteins. Trends Parasitol. 2001 Apr;17(4):198–202. doi: 10.1016/s1471-4922(00)01947-4. [DOI] [PubMed] [Google Scholar]
  2. Barrett M. P., MacLeod A., Tovar J., Sweetman J. P., Tait A., Le Page R. W., Melville S. E. A single locus minisatellite sequence which distinguishes between Trypanosoma brucei isolates. Mol Biochem Parasitol. 1997 May;86(1):95–99. doi: 10.1016/s0166-6851(97)90009-8. [DOI] [PubMed] [Google Scholar]
  3. Carlton J., Mackinnon M., Walliker D. A chloroquine resistance locus in the rodent malaria parasite Plasmodium chabaudi. Mol Biochem Parasitol. 1998 May 15;93(1):57–72. doi: 10.1016/s0166-6851(98)00021-8. [DOI] [PubMed] [Google Scholar]
  4. Carruthers V. B., van der Ploeg L. H., Cross G. A. DNA-mediated transformation of bloodstream-form Trypanosoma brucei. Nucleic Acids Res. 1993 May 25;21(10):2537–2538. doi: 10.1093/nar/21.10.2537. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Carter N. S., Fairlamb A. H. Arsenical-resistant trypanosomes lack an unusual adenosine transporter. Nature. 1993 Jan 14;361(6408):173–176. doi: 10.1038/361173a0. [DOI] [PubMed] [Google Scholar]
  6. Gibson W. C. Analysis of a genetic cross between Trypanosoma brucei rhodesiense and T. b. brucei. Parasitology. 1989 Dec;99(Pt 3):391–402. doi: 10.1017/s0031182000059114. [DOI] [PubMed] [Google Scholar]
  7. Gibson W. C., Mizen V. H. Heritability of the trait for human infectivity in genetic crosses of Trypanosoma brucei ssp. Trans R Soc Trop Med Hyg. 1997 Mar-Apr;91(2):236–237. doi: 10.1016/s0035-9203(97)90236-4. [DOI] [PubMed] [Google Scholar]
  8. Gibson W. C. Will the real Trypanosoma b. gambiense please stand up. Parasitol Today. 1986 Sep;2(9):255–257. doi: 10.1016/0169-4758(86)90011-6. [DOI] [PubMed] [Google Scholar]
  9. Gibson W., Bailey M. Genetic exchange in Trypanosoma brucei: evidence for meiosis from analysis of a cross between drug-resistant transformants. Mol Biochem Parasitol. 1994 Apr;64(2):241–252. doi: 10.1016/0166-6851(94)00017-4. [DOI] [PubMed] [Google Scholar]
  10. Gibson W., Garside L. Genetic exchange in Trypanosoma brucei brucei: variable chromosomal location of housekeeping genes in different trypanosome stocks. Mol Biochem Parasitol. 1991 Mar;45(1):77–89. doi: 10.1016/0166-6851(91)90029-6. [DOI] [PubMed] [Google Scholar]
  11. Gibson W., Kanmogne G., Bailey M. A successful backcross in Trypanosoma brucei. Mol Biochem Parasitol. 1995 Jan;69(1):101–110. doi: 10.1016/0166-6851(94)00196-t. [DOI] [PubMed] [Google Scholar]
  12. Gibson W., Stevens J. Genetic exchange in the trypanosomatidae. Adv Parasitol. 1999;43:1–46. doi: 10.1016/s0065-308x(08)60240-7. [DOI] [PubMed] [Google Scholar]
  13. Hope M., MacLeod A., Leech V., Melville S., Sasse J., Tait A., Turner C. M. Analysis of ploidy (in megabase chromosomes) in Trypanosoma brucei after genetic exchange. Mol Biochem Parasitol. 1999 Oct 25;104(1):1–9. doi: 10.1016/s0166-6851(99)00103-6. [DOI] [PubMed] [Google Scholar]
  14. Jenni L., Marti S., Schweizer J., Betschart B., Le Page R. W., Wells J. M., Tait A., Paindavoine P., Pays E., Steinert M. Hybrid formation between African trypanosomes during cyclical transmission. Nature. 1986 Jul 10;322(6075):173–175. doi: 10.1038/322173a0. [DOI] [PubMed] [Google Scholar]
  15. Kirkman L. A., Su X. Z., Wellems T. E. Plasmodium falciparum: isolation of large numbers of parasite clones from infected blood samples. Exp Parasitol. 1996 Jun;83(1):147–149. doi: 10.1006/expr.1996.0058. [DOI] [PubMed] [Google Scholar]
  16. Lander E. S., Green P., Abrahamson J., Barlow A., Daly M. J., Lincoln S. E., Newberg L. A., Newburg L. MAPMAKER: an interactive computer package for constructing primary genetic linkage maps of experimental and natural populations. Genomics. 1987 Oct;1(2):174–181. doi: 10.1016/0888-7543(87)90010-3. [DOI] [PubMed] [Google Scholar]
  17. MacLeod A., Turner C. M., Tait A. A high level of mixed Trypanosoma brucei infections in tsetse flies detected by three hypervariable minisatellites. Mol Biochem Parasitol. 1999 Aug 20;102(2):237–248. doi: 10.1016/s0166-6851(99)00101-2. [DOI] [PubMed] [Google Scholar]
  18. Masiga D. K., Tait A., Turner C. M. Amplified restriction fragment length polymorphism in parasite genetics. Parasitol Today. 2000 Aug;16(8):350–353. doi: 10.1016/s0169-4758(00)01706-3. [DOI] [PubMed] [Google Scholar]
  19. Melville S. E., Gerrard C. S., Blackwell J. M. Multiple causes of size variation in the diploid megabase chromosomes of African tyrpanosomes. Chromosome Res. 1999;7(3):191–203. doi: 10.1023/a:1009247315947. [DOI] [PubMed] [Google Scholar]
  20. Melville S. E., Leech V., Gerrard C. S., Tait A., Blackwell J. M. The molecular karyotype of the megabase chromosomes of Trypanosoma brucei and the assignment of chromosome markers. Mol Biochem Parasitol. 1998 Aug 1;94(2):155–173. doi: 10.1016/s0166-6851(98)00054-1. [DOI] [PubMed] [Google Scholar]
  21. Pandey A., Mann M. Proteomics to study genes and genomes. Nature. 2000 Jun 15;405(6788):837–846. doi: 10.1038/35015709. [DOI] [PubMed] [Google Scholar]
  22. Savelkoul P. H., Aarts H. J., de Haas J., Dijkshoorn L., Duim B., Otsen M., Rademaker J. L., Schouls L., Lenstra J. A. Amplified-fragment length polymorphism analysis: the state of an art. J Clin Microbiol. 1999 Oct;37(10):3083–3091. doi: 10.1128/jcm.37.10.3083-3091.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Schweizer J., Tait A., Jenni L. The timing and frequency of hybrid formation in African trypanosomes during cyclical transmission. Parasitol Res. 1988;75(2):98–101. doi: 10.1007/BF00932707. [DOI] [PubMed] [Google Scholar]
  24. Scott A. G., Tait A., Turner C. M. Characterisation of cloned lines of Trypanosoma brucei expressing stable resistance to MelCy and suramin. Acta Trop. 1996 Feb;60(4):251–262. doi: 10.1016/0001-706x(96)00131-3. [DOI] [PubMed] [Google Scholar]
  25. Shi H., Djikeng A., Mark T., Wirtz E., Tschudi C., Ullu E. Genetic interference in Trypanosoma brucei by heritable and inducible double-stranded RNA. RNA. 2000 Jul;6(7):1069–1076. doi: 10.1017/s1355838200000297. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Shirley M. W., Harvey D. A. A genetic linkage map of the apicomplexan protozoan parasite Eimeria tenella. Genome Res. 2000 Oct;10(10):1587–1593. doi: 10.1101/gr.149200. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Sibley L. D., LeBlanc A. J., Pfefferkorn E. R., Boothroyd J. C. Generation of a restriction fragment length polymorphism linkage map for Toxoplasma gondii. Genetics. 1992 Dec;132(4):1003–1015. doi: 10.1093/genetics/132.4.1003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Sternberg J., Tait A. Genetic exchange in African trypanosomes. Trends Genet. 1990 Oct;6(10):317–322. doi: 10.1016/0168-9525(90)90252-2. [DOI] [PubMed] [Google Scholar]
  29. Sternberg J., Turner C. M., Wells J. M., Ranford-Cartwright L. C., Le Page R. W., Tait A. Gene exchange in African trypanosomes: frequency and allelic segregation. Mol Biochem Parasitol. 1989 May 15;34(3):269–279. doi: 10.1016/0166-6851(89)90056-x. [DOI] [PubMed] [Google Scholar]
  30. Su X. z., Wellems T. E. Toward a high-resolution Plasmodium falciparum linkage map: polymorphic markers from hundreds of simple sequence repeats. Genomics. 1996 May 1;33(3):430–444. doi: 10.1006/geno.1996.0218. [DOI] [PubMed] [Google Scholar]
  31. Su X., Ferdig M. T., Huang Y., Huynh C. Q., Liu A., You J., Wootton J. C., Wellems T. E. A genetic map and recombination parameters of the human malaria parasite Plasmodium falciparum. Science. 1999 Nov 12;286(5443):1351–1353. doi: 10.1126/science.286.5443.1351. [DOI] [PubMed] [Google Scholar]
  32. Tait A., Buchanan N., Hide G., Turner C. M. Self-fertilisation in Trypanosoma brucei. Mol Biochem Parasitol. 1996 Feb-Mar;76(1-2):31–42. doi: 10.1016/0166-6851(95)02528-6. [DOI] [PubMed] [Google Scholar]
  33. Tait A., Turner C. M. Genetic exchange in Trypanosoma brucei. Parasitol Today. 1990 Mar;6(3):70–75. doi: 10.1016/0169-4758(90)90212-m. [DOI] [PubMed] [Google Scholar]
  34. Tasker M., Wilson J., Sarkar M., Hendriks E., Matthews K. A novel selection regime for differentiation defects demonstrates an essential role for the stumpy form in the life cycle of the African trypanosome. Mol Biol Cell. 2000 May;11(5):1905–1917. doi: 10.1091/mbc.11.5.1905. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Turner C. M., Aslam N., Dye C. Replication, differentiation, growth and the virulence of Trypanosoma brucei infections. Parasitology. 1995 Sep;111(Pt 3):289–300. doi: 10.1017/s0031182000081841. [DOI] [PubMed] [Google Scholar]
  36. Turner C. M., Sternberg J., Buchanan N., Smith E., Hide G., Tait A. Evidence that the mechanism of gene exchange in Trypanosoma brucei involves meiosis and syngamy. Parasitology. 1990 Dec;101(Pt 3):377–386. doi: 10.1017/s0031182000060571. [DOI] [PubMed] [Google Scholar]
  37. Vos P., Hogers R., Bleeker M., Reijans M., van de Lee T., Hornes M., Frijters A., Pot J., Peleman J., Kuiper M. AFLP: a new technique for DNA fingerprinting. Nucleic Acids Res. 1995 Nov 11;23(21):4407–4414. doi: 10.1093/nar/23.21.4407. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Walker-Jonah A., Dolan S. A., Gwadz R. W., Panton L. J., Wellems T. E. An RFLP map of the Plasmodium falciparum genome, recombination rates and favored linkage groups in a genetic cross. Mol Biochem Parasitol. 1992 Apr;51(2):313–320. doi: 10.1016/0166-6851(92)90081-t. [DOI] [PubMed] [Google Scholar]
  39. Welburn S. C., Maudlin I., Milligan P. J. Trypanozoon: infectivity to humans is linked to reduced transmissibility in tsetse. I. Comparison of human serum-resistant and human serum-sensitive field isolates. Exp Parasitol. 1995 Nov;81(3):404–408. doi: 10.1006/expr.1995.1131. [DOI] [PubMed] [Google Scholar]
  40. van Ooijen J. W. DrawMap: a computer program for drawing genetic linkage maps. J Hered. 1994 Jan-Feb;85(1):66–66. [PubMed] [Google Scholar]

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