title: Meiosis and haploid gametes in the pathogen Trypanosoma brucei.
abstract: In eukaryote pathogens, sex is an important driving force in spreading genes for drug resistance, pathogenicity, and virulence. For the parasitic trypanosomes that cause African sleeping sickness, mating occurs during transmission by the tsetse vector and involves meiosis, but haploid gametes have not yet been identified. Here, we show that meiosis is a normal part of development in the insect salivary glands for all subspecies of Trypanosoma brucei, including the human pathogens. By observing insect-derived trypanosomes during the window of peak expression of meiosis-specific genes, we identified promastigote-like (PL) cells that interacted with each other via their flagella and underwent fusion, as visualized by the mixing of cytoplasmic red and green fluorescent proteins. PL cells had a short, wide body, a very long anterior flagellum, and either one or two kinetoplasts, but only the anterior kinetoplast was associated with the flagellum. Measurement of nuclear DNA contents showed that PL cells were haploid relative to diploid metacyclics. Trypanosomes are among the earliest diverging eukaryotes, and our results support the hypothesis that meiosis and sexual reproduction are ubiquitous in eukaryotes and likely to have been early innovations.
authors.affiliation: School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK; Department of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DU, UK.
authors.forename: Lori
authors.initials: L
authors.lastname: Peacock
authors.affiliation: Department of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DU, UK.
authors.forename: Mick
authors.initials: M
authors.lastname: Bailey
authors.affiliation: Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Carrington
authors.affiliation: School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK. Electronic address: w.gibson@bris.ac.uk.
authors.forename: Wendy
authors.initials: W
authors.lastname: Gibson
mesh_terms: D000818:Animals; D002450:Cell Communication; D002467:Cell Nucleus / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D005854:Germ Cells / Q000166:cytology*; D006238:Haploidy; D008540:Meiosis; D014346:Trypanosoma brucei brucei / Q000166:cytology* / Q000235:genetics
chemical_list: D016054:DNA, Protozoan