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Article: Diversity, host switching and evolution of Plasmodium vivax infecting African great apes.
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ABSTRACT: Plasmodium vivax is considered to be absent from Central and West Africa because of the protective effect of Duffy negativity. However, there are reports of persons returning from these areas infected with this parasite and observations suggesting the existence of transmission. Among the possible explanations for this apparent paradox, the existence of a zoonotic reservoir has been proposed. May great apes be this reservoir? We analyze the mitochondrial and nuclear genetic diversity of P. vivax parasites isolated from great apes in Africa and compare it to parasites isolated from travelers returning from these regions of Africa, as well as to human isolates distributed all over the world. We show that the P. vivax sequences from parasites of great apes form a clade genetically distinct from the parasites circulating in humans. We show that this clade's parasites can be infectious to humans by describing the case of a traveler returning from the Central African Republic infected with one of them. The relationship between this P. vivax clade in great apes and the human isolates is discussed.Proceedings of the National Academy of Sciences 05/2013; · 9.68 Impact Factor -
Article: How clonal are Trypanosoma and Leishmania?
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ABSTRACT: The clonal theory of parasitic protozoa has been recently challenged by researchers stating that recombination in Kinetoplastida is much more frequent than previously believed, or that selfing and homogamy should be distinguished from 'strict' clonality. These researchers and many others show that the concept of clonality proposed by us is not correctly understood. A recapitulation of the clonal theory will thus be addressed herein. Comparisons with various other pathogens evidence general features among them and enhance our understanding of Trypanosoma and Leishmania population genetics. The relevance is considerable not only for our knowledge of the basic biology of these organisms but also for applied research: molecular epidemiology (strain-typing), clinical research, vaccine and drug design, and experimental evolution.Trends in Parasitology 04/2013; · 5.14 Impact Factor -
Article: Reproductive clonality of pathogens: A perspective on pathogenic viruses, bacteria, fungi, and parasitic protozoa.
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ABSTRACT: We propose that clonal evolution in micropathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure, a definition already widely used for all kinds of pathogens, although not clearly formulated by many scientists and rejected by others. The two main manifestations of clonal evolution are strong linkage disequilibrium (LD) and widespread genetic clustering ("near-clading"). We hypothesize that this pattern is not mainly due to natural selection, but originates chiefly from in-built genetic properties of pathogens, which could be ancestral and could function as alternative allelic systems to recombination genes ("clonality/sexuality machinery") to escape recombinational load. The clonal framework of species of pathogens should be ascertained before any analysis of biomedical phenotypes (phylogenetic character mapping). In our opinion, this model provides a conceptual framework for the population genetics of any micropathogen.Proceedings of the National Academy of Sciences 09/2012; · 9.68 Impact Factor -
Article: DNA variation in the phenotypically-diverse brown alga Saccharina japonica.
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ABSTRACT: BACKGROUND: Saccharina japonica (Areschoug) Lane, Mayes, Druehl et Saunders is an economically important and highly morphologically variable brown alga inhabiting the northwest Pacific marine waters. On the basis of nuclear (ITS), plastid (rbcLS) and mitochondrial (COI) DNA sequence data, we have analyzed the genetic composition of typical Saccharina japonica (TYP) and its two common morphological varieties, known as the "longipes" (LON) and "shallow-water" (SHA) forms seeking to clarify their taxonomical status and to evaluate the possibility of cryptic species within S. japonica. RESULTS: The data show that the TYP and LON forms are very similar genetically in spite of drastic differences in morphology, life history traits, and ecological preferences. Both, however, are genetically quite different from the SHA form. The two Saccharina lineages are distinguished by 109 fixed single nucleotide differences as well as by seven fixed length polymorphisms (based on a 4,286 bp concatenated dataset that includes three gene regions). The GenBank database reveals a close affinity of the TYP and LON forms to S. japonica and the SHA form to S. cichorioides. The three gene markers used in the present work have different sensitivity for the algal species identification. COI gene was the most discriminant gene marker. However, we have detected instances of interspecific COI recombination reflecting putative historical hybridization events between distantly related algal lineages. The recombinant sequences show highly contrasted level of divergence in the 5'- and 3'- regions of the gene, leading to significantly different tree topologies depending on the gene segment (5'- or 3'-) used for tree reconstruction. Consequently, the 5'-COI "barcoding" region (~ 650 bp) can be misleading for identification purposes, at least in the case of algal species that might have experienced historical hybridization events. CONCLUSION: Taking into account the potential roles of phenotypic plasticity in evolution, we conclude that the TYP and LON forms represent examples of algae phenotypic diversification that enables successful adaptation to contrasting shallow- and deep-water marine environments, while the SHA form is very similar to S. cichorioides and should be considered a different species. Practical applications for algal management and conservation are briefly considered.BMC Plant Biology 07/2012; 12(1):108. · 3.45 Impact Factor -
Article: In the light of evolution VI: brain and behavior.
Proceedings of the National Academy of Sciences 06/2012; 109 Suppl 1:10607-11. · 9.68 Impact Factor
