How to succeed in parasitic life without sex? Asking Leishmania

Victoir, Kathleen; Dujardin, Jean‐Claude

doi:10.1016/s1471-4922(01)02199-7

Cited by 50 publications

(38 citation statements)

References 43 publications

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“…The rates of chromosome-level recombination that we observed ($10 À3 events/generation) are comparable to those reported for rates in other fungi at $10 À3 events/kb/generation (Awadalla 2003). Although high rates of chromosomal rearrangement have been observed at specific chromosomal loci of other pathogens (Henderson et al 1999;Victoir and Dujardin 2002;Kline et al 2003;Uhl et al 2003;Zhang et al 2003), few quantitative estimates of genomewide change are available to explain the variation apparent in clinical populations (Graeser et al 1996;Fries and Casadevall 1998;Iwaguchi et al 2000;Forche et al 2005). The rates determined in our study are certainly sufficient to generate heritable variation in C. albicans populations during a single passage through the host.…”

Section: Discussionsupporting

confidence: 84%

“…We conclude that conditions during growth in a mammalian host affect chromosome nondisjunction more strongly than they affect mitotic crossover or other recombination processes. While the type of rearrangements differs from the mutational spectrum observed in bacterial pathogens during growth in stressful conditions (Victoir and Dujardin 2002;Tenaillon et al 2004;Ponder et al 2005), common mechanisms involving recombination and repair may yet be identified. The rates of chromosome-level recombination that we observed ($10 À3 events/generation) are comparable to those reported for rates in other fungi at $10 À3 events/kb/generation (Awadalla 2003).…”

Section: Discussionmentioning

confidence: 98%

“…Obligate intracellular symbiotic microbes, such as Buchnera (Moran 1996) and Pneumocystis (Strobel and Arnold 2004), propagate asexually and often carry a minimal but stable genome, making them wholly dependent on life within their hosts (Wren 2000). Although both opportunistic and obligate pathogens commonly propagate by asexual means, these organisms often maintain large genomes and generate substantial genomic and phenotypic variation via genome rearrangements (Victoir and Dujardin 2002;Kline et al 2003) and heritable silencing at telomeres (Cross et al 1998;Borst 2002;Gupta 2005). Given that many commensal and apparently harmless symbionts may become invasive pathogens in immunocompromised hosts, the mechanisms underlying the maintenance of genetic variation and of the commensal state bear investigation (Levin et al 2000).…”

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confidence: 99%

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Evolution inCandida albicansPopulations During a Single Passage Through a Mouse Host

et al. 2009

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The mechanisms and rates by which genotypic and phenotypic variation is generated in opportunistic, eukaryotic pathogens during growth in hosts are not well understood. We evaluated genomewide genetic and phenotypic evolution in Candida albicans, an opportunistic fungal pathogen of humans, during passage through a mouse host (in vivo) and during propagation in liquid culture (in vitro). We found slower population growth and higher rates of chromosome-level genetic variation in populations passaged in vivo relative to those grown in vitro. Interestingly, the distribution of long-range loss of heterozygosity (LOH) and chromosome rearrangement events across the genome differed for the two growth environments, while rates of short-range LOH were comparable for in vivo and in vitro populations. Further, for the in vivo populations, there was a positive correlation of cells demonstrating genetic alterations and variation in colony growth and morphology. For in vitro populations, no variation in growth phenotypes was detected. Together, our results demonstrate that passage through a living host leads to slower growth and higher rates of genomic and phenotypic variation compared to in vitro populations. Results suggest that the dynamics of population growth and genomewide rearrangement contribute to the maintenance of a commensal and opportunistic life history of C. albicans.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 98%

mentioning

confidence: 99%

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Evolution inCandida albicansPopulations During a Single Passage Through a Mouse Host

et al. 2009

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“…Moreover, due to the benefits of sex in the long-term, that is the higher level of genetic diversity released by sexual reproduction, asexual lineages are generally considered as evolutionary dead ends (Maynard Smith, 1978;Kondrashov, 1993), although the debate is still running (Victoir and Dujardin, 2002;Lushai et al, 2003). From all these points of view, the mitotic parthenogenetic species of RKN appear as an outstanding exception.…”

Section: Introductionmentioning

confidence: 99%

Genetic variability and adaptive evolution in parthenogenetic root-knot nematodes

2006

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Root-knot nematodes (RKN) of the genus Meloidogyne are biotrophic plant parasites of major agricultural importance, which exhibit very variable modes of reproduction, from classical amphimixis to mitotic parthenogenesis. This review focuses on those RKN species that reproduce exclusively by mitotic parthenogenesis (apomixis), in contrast to those that have meiotic/amphimitic events in their life cycle. Although populations of clonal organisms are often represented as being ecologically isolated and evolutionary inert, a considerable volume of literature provides evidence that asexual RKN are neither: they are widely distributed, extremely polyphagous, and amenable to selection and adaptive variation. The ancestors of the genus are unknown, but it is assumed that the parthenogenetic RKN have evolved from amphimictic species through hybridization and subsequent aneuploidization and polyploidization events. Molecular studies have indeed confirmed that the phylogenetic divergence between meiotic and mitotic RKN lineages occurred early, and have revealed an unexpected level of clonal diversity among populations within apomictic species. Laboratory experiments have shown that asexual RKN can rapidly adapt to new environmental constraints (eg host resistance), although with some fitness costs. Lastly, the molecular and chromosomal mechanisms that could contribute to genome plasticity leading to persistent genetic variation and adaptive evolution in apomictic RKN are discussed. It is concluded that RKN provide an excellent model system in which to study the dynamic nature and adaptive potential of clonal genomes.

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“…The largest number of genotypes identified in the Caatinga biome (Figure 2) can indicate the center of origin of L. infantum, which then disseminated to other areas of Bahia, although the colonization process (which took place more than 500 years ago) began in the Bahia foreshore and in other areas of Brazil's northeast. A bottleneck effect, rare mechanisms of exchange of genetic material, small mutations (TIBAYRENC & AYALA, 1999;LYTHGOE, 2000;VICTOIR & DUJARDIN, 2002), and evidence of sexual reproduction (KREUTZER et al, 1994;AKOPYANTS et al, 2009) can also justify the value of Fst and the variability found in the studied strains.…”

Section: Resultsmentioning

confidence: 82%

Genetic variability of Leishmania infantum in naturally infected dogs in the state of Bahia, Brazil

Carvalho

Albuquerque

Carneiro

et al. 2017

Rev. Bras. Parasitol. Vet.

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In Brazil, Leishmania infantum mainly affects humans and dogs. The state of Bahia presents many dogs that are positive for this parasite. Despite the importance of epidemiology in this region, there are still very few studies that have assessed the genetic characteristics of L. infantum. The aim of this study is to investigate the genetic variability of L. infantum isolated identified in naturally infected dogs, in order to verify occurrence of subpopulation of this parasite in the different biomes existing in the state of Bahia. Thirty-two samples of L. infantum were analyzed, which were obtained isolated in dogs from the Mata Atlântica (rainforest), Caatinga (semi-arid scrub forest), and Cerrado (a vast tropical savannah eco-region) Bahia municipalities' biomes. All animals presented with clinical changes suggestive of Leishmania spp. and they exhibited positive reactions to serological tests. kDNA analysis with RFLP markers revealed the presence of genetic variability and gene flow in subpopulations of L. infantum; samples from the Mata Atlântica areas were genetically more similar to those from the areas of Caatinga and they were less likely to resemble those of the Cerrado. This data may be used to investigate the dissemination of parasite in the canine population of state of Bahia.Keywords: Canine Leishmaniasis, PCR-RFLP, populations, enzyme, zoonosis. ResumoNo Brasil a Leishmania infantum afeta principalmente o homem e os cães. O estado da Bahia apresenta elevado número de cães positivos por este parasito. Apesar da importância epidemiologia para a região, ainda há poucos estudos que avaliam as características genéticas de L. infantum. Objetivou-se com este estudo investigar a variabilidade genética de cepas de L. infantum identificadas em cães naturalmente infectados, a fim de verificar a ocorrência de sobpopulações do parasito nos diferentes biomas existentes no estado da Bahia. Foram analisadas 32 amostras de L. infantum isoladas em cães de municípios baianos distribuídos nos biomas Mata Atlântica, Caatinga e Cerrado. Todos os animais apresentavam alterações clínicas sugestivas de Leishmania spp. e reação positiva em exames sorológicos. A análise do kDNA com marcadores RFLP revelaram a presença de variabilidade genética e fluxo gênico nas subpopulações de L. infantum sendo que as amostras das áreas de Mata Atlântica foram geneticamente mais semelhantes as das áreas de Caatinga e foram mais distantes daquelas oriundas do Cerrado. Estas informações podem auxiliar em investigações de dispersão do parasito na população canino do Estado da Bahia.

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How to succeed in parasitic life without sex? Asking Leishmania

Cited by 50 publications

References 43 publications

Evolution inCandida albicansPopulations During a Single Passage Through a Mouse Host

Evolution inCandida albicansPopulations During a Single Passage Through a Mouse Host

Genetic variability and adaptive evolution in parthenogenetic root-knot nematodes

Genetic variability of Leishmania infantum in naturally infected dogs in the state of Bahia, Brazil

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