Hybrid formation between African trypanosomes during cyclical transmission

Jenni, L.; Marti, Sabrina; Schweizer, J.; Betschart, Bruno; Page, R.; Wells, Jerry M.; Tait, Andrew; Paindavoine, Pascale; Pays, Étienne; Steinert, Maurice

doi:10.1038/322173a0

Cited by 313 publications

(175 citation statements)

References 14 publications

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“…It has been inferred from the degree of enzyme polymorphism found amongst isolates (Tait, 1980) and demonstrated in laboratory experiments (Jenni, Marti, Schweizer, Betschart, Page, Wells, Tait, Paindavoine, Pays & Steinert, 1986) that genetic recombination occurs in T. brucei. Exchange of genetic material has yet to be demonstrated between stocks of T. congolense.…”

Section: Discussionmentioning

confidence: 99%

Genetically discrete populations of Trypanosoma congolense from livestock on the Kenyan coast

et al. 1988

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SUMMARYTwenty-seven stocks of Nannomonas trypanosomes isolated from livestock in 1982 on a ranch at Kilifi on the Kenyan coast were characterized by isoenzyme electrophoresis and by the abilities of the parasite's DNA to hybridize to two repetitive sequence DNA probes. All the Kilifi stocks which were examined had isoenzyme patterns which were markedly different from the 75 patterns previously described from 78 stocks of Trypanosoma congolense. On average only 15% of the enzyme bands present in the Kilifi stocks were present in those stocks of T. congolense which had previously been surveyed for isoenzymes. The DNA from all the Kilifi stocks which had been examined for isoenzymes hybridized with only the repetitive sequence probe isolated from a clone of a Kilifi stock. In contrast, the DNA from all 27 Kilifi stocks failed to hybridize with a repetitive sequence probe isolated from a clone from a different stock of T. congolense. Thus, the trypanosomes in all the Kilifi stocks examined were both phenotypically and genotypically discrete. These genetically discrete trypanosomes have also been detected in 2 stocks isolated from livestock from another location on the Kenyan coast. The results show that there is a wide range of genetic heterogeneity within the trypanosomes currently classified as T. congolense. We suggest that the limits of this genetic heterogeneity could represent incipient speciation.

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Section: Discussionmentioning

confidence: 99%

Genetically discrete populations of Trypanosoma congolense from livestock on the Kenyan coast

et al. 1988

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“…Variability as a result of sexual recombination events was unlikely because recombination as a consequence of mating [21] is thought to occur only in the natural vector, the tsetse fly and has never been described in mitotically replicating, cultivated procyclic trypanosomes [15]. Moreover, mating events would be reflected by a Mendelian inheritance pattern within the megabase pair chromosomes of clonal populations, which was not seen.…”

Section: Discussionmentioning

confidence: 99%

Diversity and dynamics of the minichromosomal karyotype in Trypanosoma brucei

Alsford

Wickstead

Ersfeld

et al. 2001

Molecular and Biochemical Parasitology

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The genome of African trypanosomes contains a large number of minichromosomes. Their only proposed role is in the expansion of the parasites' repertoire of telomeric variant surface glycoprotein (VSG) genes as minichromosomes carry silent VSG gene copies in telomeric locations. Despite their importance as VSG gene donors, little is known about the actual composition of the minichromosomal karyotype and the stability of its inheritance. In this study we show, by using high-resolution pulsed-field electrophoresis, that a non-clonal trypanosome population contains an extremely diverse pattern of minichromosomes, which can be resolved into less complex clone-specific karyotypes by non-selective cloning. We show that the minichromosome patterns of such clones are stable over at least 360 generations. Furthermore, using DNA markers for specific minichromosomes, we demonstrate the mitotic stability of these minichromosomes within the population over a period of more than 5 years. Length variation is observed for an individual minichromosome and is most likely caused by a continuous telomeric growth of approximately 6 bp per telomere per cell division. This steady telomeric growth, counteracted by stochastic large losses of telomeric sequences is the most likely cause of minichromosome karyotype heterogeneity within a population.

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“…In T. brucei, meiosis is predicted to occur in the tsetse fly vector because this, rather than the mammalian host, is the site of genetic exchange (2). When a tsetse fly feeds on an infected host, ingested trypanosomes first differentiate and multiply in the midgut for a week or so before migrating to the salivary glands (SGs), where they differentiate into epimastigotes that attach to the SG epithelium via an elaborated flagellar membrane (25).…”

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Identification of the meiotic life cycle stage of Trypanosoma brucei in the tsetse fly

Peacock

Ferris

Sharma

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

128

156

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Elucidating the mechanism of genetic exchange is fundamental for understanding how genes for such traits as virulence, disease phenotype, and drug resistance are transferred between pathogen strains. Genetic exchange occurs in the parasitic protists Trypanosoma brucei , T. cruzi , and Leishmania major , but the precise cellular mechanisms are unknown, because the process has not been observed directly. Here we exploit the identification of homologs of meiotic genes in the T. brucei genome and demonstrate that three functionally distinct, meiosis-specific proteins are expressed in the nucleus of a single specific cell type, defining a previously undescribed developmental stage occurring within the tsetse fly salivary gland. Expression occurs in clonal and mixed infections, indicating that the meiotic program is an intrinsic but hitherto cryptic part of the developmental cycle of trypanosomes. In experimental crosses, expression of meiosis-specific proteins usually occurred before cell fusion. This is evidence of conventional meiotic division in an excavate protist, and the functional conservation of the meiotic machinery in these divergent organisms underlines the ubiquity and basal evolution of meiosis in eukaryotes.

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Hybrid formation between African trypanosomes during cyclical transmission

Cited by 313 publications

References 14 publications

Genetically discrete populations of Trypanosoma congolense from livestock on the Kenyan coast

Genetically discrete populations of Trypanosoma congolense from livestock on the Kenyan coast

Diversity and dynamics of the minichromosomal karyotype in Trypanosoma brucei

Identification of the meiotic life cycle stage of Trypanosoma brucei in the tsetse fly

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