Genetic diversity and phylogenetic relationships of coevolving symbiont-harboring insect trypanosomatids, and their neotropical dispersal by invader African blowflies (Calliphoridae)

This study is about the inter- and intra-specific genetic diversity of trypanosomatids of the genus Angomonas, and their association with Calliphoridae (blowflies) in Neotropical and Afrotropical regions. Microscopic examination of 3,900 flies of various families, mostly Calliphoridae, revealed that 31% of them harbored trypanosomatids. Small subunit rRNA (SSU rRNA) barcoding showed that Angomonas predominated (46%) over the other common trypanosomatids of blowflies of genera Herpetomonas and Wallacemonas. Among Angomonas spp., A. deanei was much more common than the two-other species, A. desouzai and A. ambiguus. Phylogenetic analyses based on SSU rRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) and internal transcribed spacer rDNA (ITS rDNA) sequences revealed a marked genetic diversity within A. deanei, which comprised four infraspecific genotypes (Dea1– Dea4), and four corresponding symbiont genotypes (Kcr1–Kcr4). Host and symbiont phylogenies were highly congruent corroborating their co-divergence, consistent with host-symbiont interdependent metabolism and symbiont reduced genomes shaped by a long coevolutionary history. We compared the diversity of Angomonas/symbionts from three genera of blowflies, Lucilia, Chrysomya and Cochliomyia. A. deanei, A. desouzai, and A. ambiguus were found in the three genera of blowflies in South America. In Africa, A. deanei and A. ambiguus were identified in Chrysomya. The absence of A. desouzai in Africa and its presence in Neotropical Cochliomyia and Lucilia suggests parasite spillback of A. desouzai into Chrysomya, which was most likely introduced four decades ago from Africa into the Neotropic. The absence of correlation between parasite diversity and geographic and genetic distances, with identical genotypes of A. deanei found in the Neotropic and Afrotropic, is consistent with disjunct distribution due to the recent human-mediated transoceanic dispersal of Angomonas by Chrysomya. This study provides the most comprehensive data gathered so far on the genetic repertoires of a genus of trypanosomatids found in flies from a wide geographical range.The PROAFRICA, INCT-EPIAMO, and PROSUL programs of CNPq, PNIPB of Capes, and FAPESP (Process 2016/07487-0). CAPEs (PNPD) granted a postdoctoral scholarship to TB.http://www.frontiersin.org/Microbiologyam2018Veterinary Tropical Disease

The phylogeography of trypanosomes from South American alligatorids and African crocodilids is consistent with the geological history of South American river basins and the transoceanic dispersal of Crocodylus at the Miocene

Background: Little is known about the diversity, phylogenetic relationships, and biogeography of trypanosomes infecting non-mammalian hosts. In this study, we investigated the influence of host species and biogeography on shaping the genetic diversity, phylogenetic relationship, and distribution of trypanosomes from South American alligatorids and African crocodilids. Methods: Small Subunit rRNA (SSU rRNA) and glycosomal Glyceraldehyde Phosphate Dehydrogenase (gGAPDH) genes were employed for phylogenetic inferences. Trypanosomes from crocodilians were obtained by haemoculturing. Growth behaviour, morphology, and ultrastructural features complement the molecular description of two new species strongly supported by phylogenetic analyses. Results: The inferred phylogenies disclosed a strongly supported crocodilian-restricted clade comprising three subclades. The subclade T. grayi comprised the African Trypanosoma grayi from Crocodylus niloticus and tsetse flies. The subclade T. ralphi comprised alligatorid trypanosomes represented by Trypanosoma ralphi n. sp. From Melanosuchus niger, Caiman crocodilus and Caiman yacare from Brazilian river basins. T. grayi and T. ralphi were sister subclades. The basal subclade T. terena comprised alligatorid trypanosomes represented by Trypanosoma terena n. sp. from Ca. yacare sharing hosts and basins with the distantly genetic related T. ralphi. This subclade also included the trypanosome from Ca. crocodilus from the Orinoco basin in Venezuela and, unexpectedly, a trypanosome from the African crocodilian Osteolaemus tetraspis. Conclusion: The close relationship between South American and African trypanosomes is consistent with paleontological evidence of recent transoceanic dispersal of Crocodylus at the Miocene/Pliocene boundaries (4–5 mya), and host-switching of trypanosomes throughout the geological configuration of South American hydrographical basins shaping the evolutionary histories of the crocodilians and their trypanosomes.We are grateful to many people who kindly helped us in crocodilian capture\ud and sample collection in Brazil, Venezuela, and Guinea Bissau. We would like\ud to thank Dr. Miguel U. Trefault Rodrigues for the animal identifications. We\ud acknowledge the Brazilian Ministry of Science, Technology and Innovation\ud (MCTI) for support through the Mamirauá Institute for Sustainable\ud Development (IDSM). We thank Cristina Schwartz for the coordination of the\ud work in Guinea Bissau. We also thank Marcio C. Valentin from the Laboratory\ud of Electron Microscopy, Institute of Biosciences, USP, and Carlos E. Jared and\ud Marta M. Antoniazzi from the Institute Butantan, São Paulo, SP, Brazil, for\ud their kindly permission to use their electron microscopic facilities. This work\ud was supported by CNPq (PROAFRICA and PROSUL) and CAPES (Programa\ud Nacional de Incentivo à Pesquisa em Parasitologia Básica). LBV was\ud postdoctoral fellow sponsored by CNPq-MCTI (PROTAX – National Program\ud of Taxonomy) and CAPES (PNPD). BRF is recipient of a scholarship from\ud CNPq (PROTAX)

New insights into the evolution of the Trypanosoma cruzi clade provided by a new trypanosome species tightly linked to Neotropical Pteronotus bats and related to an Australian lineage of trypanosomes

Abstract\ud \ud Background\ud Bat trypanosomes are implicated in the evolution of the T. cruzi clade, which harbours most African, European and American trypanosomes from bats and other trypanosomes from African, Australian and American terrestrial mammals, including T. cruzi and T. rangeli, the agents of the American human trypanosomiasis. The diversity of bat trypanosomes globally is still poorly understood, and the common ancestor, geographical origin, and evolution of species within the T. cruzi clade remain largely unresolved.\ud \ud \ud Methods\ud Trypanosome sequences were obtained from cultured parasites and from museum archived liver/blood samples of bats captured from Guatemala (Central America) to the Brazilian Atlantic Coast. Phylogenies were inferred using Small Subunit (SSU) rRNA, glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH), and Spliced Leader (SL) RNA genes.\ud \ud \ud Results\ud Here, we described Trypanosoma wauwau n. sp. from Pteronotus bats (Mormoopidae) placed in the T. cruzi clade, then supporting the bat-seeding hypothesis whereby the common ancestor of this clade likely was a bat trypanosome. T. wauwau was sister to the clade T. spp-Neobats from phyllostomid bats forming an assemblage of trypanosome species exclusively of Noctilionoidea Neotropical bats, which was sister to an Australian clade of trypanosomes from indigenous marsupials and rodents, which possibly evolved from a bat trypanosome. T. wauwau was found in 26.5 % of the Pteronotus bats examined, and phylogeographical analysis evidenced the wide geographical range of this species. To date, this species was not detected in other bats, including those that were sympatric or shared shelters with Pteronotus. T. wauwau did not develop within mammalian cells, and was not infective to Balb/c mice or to triatomine vectors of T. cruzi and T. rangeli.\ud \ud \ud Conclusions\ud \ud Trypanosoma wauwau n. sp. was linked to Pteronotus bats. The positioning of the clade T. wauwau/T.spp-Neobats as the most basal Neotropical bat trypanosomes and closely related to an Australian lineage of trypanosomes provides additional evidence that the T. cruzi clade trypanosomes likely evolved from bats, and were dispersed in bats within and between continents from ancient to unexpectedly recent times.This work was supported by grants from the Brazilian agencies CNPq (PROSUL,\ud PRAFRICA and PROTAX), CAPES (PNIPB and PNPD) and FAPESP. The analysis of\ud bats from Central America, Suriname and Guyana was supported by grant\ud ‘Investissements d’Avenir’ from the Agence Nationale de la Recherche, Canada\ud (ANR-10-LABX-25-01). Archived samples from Brazilian Pteronotus were donated\ud to ACP by VC Tavares, A Césari, PA Rocha, FM Martins, MOG Lopes, CS Bernabé,\ud TG Oliveira, E Gonçalves and M Marcos. We are grateful to many student from\ud USP and researches of other universities for the inestimable help in the\ud fieldworks. We also thanks JA Rosa for the generous contribution with\ud triatomines from the insectary of UNESP-Araraquara, and CE Jared and MM\ud Antoniazzi for the access to electron microscopic facilities of the Institute\ud Butantan, Brazil. Luciana Lima is postdoctoral fellow sponsored by FAPESP, and\ud Oneida Espinosa-Álvarez is recipient of a PhD fellowship from CNPq (PROTAX)

Scientific Practice in Modeling Diseases: Stances from Cancer Research and Neuropsychiatry

In the last few decades, philosophy of science has increasingly focused on multilevel models and causal mechanistic explanations to account for complex biological phenomena. On the one hand, biological and biomedical works make extensive use of mechanistic concepts; on the other hand, philosophers have analyzed an increasing range of examples taken from different domains in the life sciences to test\u2014support or criticize\u2014the adequacy of mechanistic accounts. The article highlights some challenges in the elaboration of mechanistic explanations with a focus on cancer research and neuropsychiatry. It jointly considers fields, which are usually dealt with separately, and keeps a close eye on scientific practice. The article has a twofold aim. First, it shows that identification of the explananda is a key issue when looking at dynamic processes and their implications in medical research and clinical practice. Second, it discusses the relevance of organizational accounts of mechanisms, and questions whether thorough self-sustaining mechanistic explanations can actually be provided when addressing cancer and psychiatric diseases. While acknowledging the merits of the wide ongoing debate on mechanistic models, the article challenges the mechanistic approach to explanation by discussing, in particular, explanatory and conceptual terms in the light of stances from medical cases

First report of Rhodnius montenegrensis (Hemiptera: Reduviidae: Triatominae) infection by Trypanosoma rangeli

Introduction: This study reports for the first time the infection of Rhodnius montenegrensis by Trypanosoma rangeli. Methods: The triatomines were manually collected in Attalea speciosa in the municipality of Buritis, Rondônia. The identification of the trypanosomatid species was confirmed by multiplex PCR. Results: All of the collected triatomines were R. montenegrensis. The analysis confirmed that all of the adults were infected with the epimastigote form of T. rangeli. Conclusions: This report of a new vector of T. rangeli raises a warning for the State of Rondônia because the simultaneous presence of T. rangeli with T. cruzi in the same geographic region enables the occurrence of mixed infections in hosts and vectors, which complicates the differential diagnosis

Phylogenetic Analyses Based on Small Subunit rRNA and Glycosomal Glyceraldehyde-3-Phosphate Dehydrogenase Genes and Ultrastructural Characterization of Two Snake Trypanosomes: Trypanosoma serpentis n. sp from Pseudoboa nigra and Trypanosoma cascavelli from Crotalus durissus terrificus

We sequenced the small subunit (SSU) rRNA and glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) genes of two trypanosomes isolated from the Brazilian snakes Pseudoboa nigra and Crotalus durissus terrificus. Trypanosomes were cultured and their morphometrical and ultrastructural features were characterized by light microscopy and scanning and transmission electron microscopy. Phylogenetic trees inferred using independent or combined SSU rRNA and gGAPDH data sets always clustered the snake trypanosomes together in a clade closest to lizard trypanosomes, forming a strongly supported monophyletic assemblage (i.e. lizard-snake clade). The positioning in the phylogenetic trees and the barcoding based on the variable V7-V8 region of the SSU rRNA, which showed high sequence divergences, allowed us to classify the isolates from distinct snake species as separate species. The isolate from P. nigra is described as a new species, Trypanosoma serpentis n. sp., whereas the isolate from C. d. terrificus is redescribed here as Trypanosoma cascavelli.Brazilian agency CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES/CNPq (PNPD

Análise morfológica, biológica e molecular confirmam a infecção de macacos mantidos em cativeiro por Trypanosoma (Herpetosoma) lewisi no Brasil

In this study we characterize trypanosomes isolated from domestic rats and captive monkeys, with morphology similar to T. (H.) lewisi. Phylogenetic inference using SSU rDNA sequences clustered new Brazilian isolates with T. (H.) lewisi, forming a homogeneous clade separate from other species of the subgenus Trypanosoma (Herpetosoma). Behaviour of the monkey isolates in culture and in experimentally infected rats was also compatible with T. (H.) lewisi. To clarify the relationship between the species within the clade T. (H.) lewisi, polymorphic ITS1 rDNA sequences were analyzed. The results confirm that the strains of rats and monkeys of Brazil are closely related and confirm that the new isolates are T. (H.) lewisi, a species that until recently was considered to be restricted to rodents. Cases of human infections in Asia suggest that T. (H.) lewisi may be an opportunistic parasite of primatesNeste estudo, caracterizamos tripanossomas isolados de ratos domésticos e de macacos mantidos em cativeiro, com morfologia similar a T. (H.) lewisi. Inferências filogenéticas utilizando sequências de SSU rDNA agruparam os novos isolados brasileiros com T. (H.) lewisi e as outras espécies relacionadas do subgênero Trypanosoma (Herpetosoma) em um clado homogêneo. O comportamento biológico dos isolados de macaco em cultura e em ratos infectados experimentalmente foi compatível com T. (H.) lewisi. Para esclarecer o relacionamento entre as espécies dentro do clado T. (H.) lewisi, sequências polimórficas de ITS1 rDNA foram analisadas. Os resultados confirmam que os novos isolados de ratos e macacos do Brasil são T. (H.) lewisi, espécie que até recentemente era considerada restrita a roedores, mas que já se mostrou um parasita oportunista de primatas em casos de infecções humanas na Ási