Development of EGene platform for functional annotation and database integration: application and validation on transcript sequences of Eimeria spp. of domestic fowl.

Parasitas protozoários do gênero Eimeria causam doenças entéricas na galinha doméstica. Nosso grupo gerou 15.000 sequências ORESTES para cada uma das três mais importantes espécies: E. tenella, E. maxima e E. acervulina. Nesse trabalho relatamos o desenvolvimento de alguns componentes da plataforma EGene (Durham et al. Bioinformatics 21: 2812-2813, 2005) e sua aplicação na anotação funcional de transcritos reconstruídos de Eimeria spp. Análises de ortologia identificaram genes conservados em diferentes parasitas apicomplexas, bem como genes restritos ao gênero Eimeria. Perfis de expressão digital obtidos de contagens de leituras de transcritos montados foram submetidos a análises de agrupamento. Os perfis foram inequivocamente associados com os distintos estágios de desenvolvimento e mostraram uma forte correlação com a ordem desses estágios no clico de vida dos parasitas. Todos os dados de sequenciamento, anotação e análise comparativa foram disponibilizados no portal público The Eimeria Transcript Database (http://www.coccidia.icb.usp.br/eimeriatdb).Protozoan parasites of the genus Eimeria cause enteric diseases in the domestic fowl. Our group has generated 15,000 ORESTES sequences for each one of the three most important species: E. tenella, E. maxima and E. acervulina. In the present work, we report the development of some components for EGene platform (Durham et al. Bioinformatics 21: 2812-2813, 2005) and their application in the functional annotation of reconstructed transcripts of Eimeria spp. Orthology analyses have identified genes conserved across different apicomplexan parasites, as well as genes restricted to the genus Eimeria. Digital expression profiles obtained from read countings of the assembled transcripts were submitted to clustering analyses. The profiles were unambiguously associated with the distinct developmental stages and strongly correlated with the order of the stages in the parasite life cycle. All sequencing data, annotation and comparative analysis were made available at The Eimeria Transcript Database (http://www.coccidia.icb.usp.br/eimeriatdb), a public web resource

The role of horizontal gene transfer in the evolutionary history of two bacterial gene classes

A Transferência Horizontal de Genes (THG) é um dos principais mecanismos de evolução bacterianos, impactando a evolução de praticamente todas famílias gênicas. Neste trabalho identificamos e avaliamos padrões de possíveis transferências horizontais de genes pertencentes a duas classes funcionais de dois níveis taxonômicos distintos. Caracterizamos a ocorrência e evolução de 45 genes importantes para a fixação de N2 em 479 genomas de Proteobacteria. Identificamos cinco potenciais aquisições de genes ligados a fixação de N2 por linhagens de Proteobacteria, as quais foram identificadas consistentemente em 36 dos genes analisados. Realizamos predições de transferências horizontais dos 45 entre todos os 479 genomas de Proteobacteria e identificamos possíveis enriquecimentos de THG, provavelmente ligados à sinais filogenéticos e ecológicos. Desenvolvemos um pipeline para identificação semi-automática de efetores do Sistema Secretor do Tipo III em Aeromonas, o qual reportou 21 famílias de potenciais efetores presentes em 105 genomas. Entre os 21 efetores identificados 17 foram descritos pela 1º vez em Aeromonas, corroborando a sensibilidade de nosso pipeline. Com o auxílio de nossos colaboradores foram realizados testes de citotoxidade para efetores identificados in silico, e apenas quatro não inibiram o crescimento de Saccharomyces cerevisiae. Por fim, desenvolvemos um método para agrupamento de famílias gênicas com histórias evolutivas similares que não requer a reconstrução de árvores filogenéticas, aumentando a eficiência computacional. Aplicamos o método desenvolvido para reconstrução da filogenia de Aeromonas, o qual mostrou-se compatível com dados presentes na literatura.Horizontal Gene Transfer (HGT) is one of main mechanisms of bacterial evolution, affecting virtually all gene families. In this document we identified and assessed putative horizontal transfers of genes from two functional classes from two distinct taxonomic levels. We characterized the distribution and evolution of 45 genes important to N2 fixation among 479 Proteobacteria genomes. We identified five potential distinct acquisitions of such genes by Proteobacteria lineages. The distinct origins are consistently identified in 36 out of the 45 assessed genes. We computed possible horizontal transfers of the 45 genes among the 479 Proteobacteria genomes, and we identified enrichments of HGT, likely related to phylogenetic and ecological signals. We developed a semi-automated pipeline to identify effectors of the Type III Secretion System within Aeromonas, which reported 21 putative effector families distributed among 105 genomes. Among the 21 likely effectors 17 have been described in Aeromonas for the first time, highlighting the sensibility of our pipeline. Our colaborators performed cytotoxicity tests for the 21 likely effector families identified by in silico analysis, and only four did not inhibited Saccharomyces cerevisiae growth. Lastly, we developed a method to cluster gene families according to shared evolutionary history, without the requirement of phylogenetic tree reconstruction, increasing computational efficiency. We applied this proposed method during Aeromonas phylogenetic reconstruction, and it showed up compatible with data available on the literature

A comparative transcriptome analysis reveals expression profiles conserved across three Eimeria spp. of domestic fowl and associated with multiple developmental stages

Coccidiosis of the domestic fowl is a worldwide disease caused by seven species of protozoan parasites of the genus Eimeria. The genome of the model species, Eimeria tenella, presents a complexity of 55-60 MB distributed in 14 chromosomes. Relatively few studies have been undertaken to unravel the complexity of the transcriptome of Eimeria parasites. We report here the generation of more than 45,000 open reading frame expressed sequence tag (ORESTES) cDNA reads of E. tenella, Eimeria maxima and Eimeria acervulina, covering several developmental stages: unsporulated oocysts, sporoblastic oocysts, sporulated oocysts, sporozoites and second generation merozoites. All reads were assembled to constitute gene indices and submitted to a comprehensive functional annotation pipeline. In the case of E. tenella, we also incorporated publicly available ESTs to generate an integrated body of information. Orthology analyses have identified genes conserved across different apicomplexan parasites, as well as genes restricted to the genus Eimeria. Digital expression profiles obtained from ORESTES/EST countings, submitted to clustering analyses, revealed a high conservation pattern across the three Eimeria spp. Distance trees showed that unsporulated and sporoblastic oocysts constitute a distinct clade in all species, with sporulated oocysts forming a more external branch. This latter stage also shows a close relationship with sporozoites, whereas first and second generation merozoites are more closely related to each other than to sporozoites. The profiles were unambiguously associated with the distinct developmental stages and strongly correlated with the order of the stages in the parasite life cycle. Finally, we present The Eimeria Transcript Database (http://www.coccidia.icb.usp.br/eimeriatdb), a website that provides open access to all sequencing data, annotation and comparative analysis. We expect this repository to represent a useful resource to the Eimeria scientific community, helping to define potential candidates for the development of new strategies to control coccidiosis of the domestic fowl. (C) 2011 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.FAPESP (Sao Paulo, Brazil) [03/14031-3]FAPESP (Sao Paulo, Brazil)National Council for Scientific and Technological Development (CNPq, Brazil)National Council for Scientific and Technological Development (CNPq), BrazilFAPESP [2009/12643-8]FAPESPCNPqCNP