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Ciclo de vida de Fasciola hepatica 1.
Epidemiologia e tratamento da Fasciolose 1. Objetivos do Capitulo Objetivo geral do trabalho apresentado no Capitulo. Although flukicidal drugs are available, re-infection and emerging resistance are demanding new efficient and inexpensive control strategies. Understanding the molecular mechanisms underlying the host-parasite interaction provide relevant clues in this search, while enlightening the physiological adaptations to parasitism.
Genomics and transcriptomics are still in their infancy in F. Here, we provide an initial glimpse to the transcriptomics of the NEJ, the first stage to interact with the mammalian host. We catalogued more than clusters generated from the analysis of F.
A set of putative F.
These novel sequences along with a set of parasite transcripts absent in the host genomes are putative new targets for future antiparasitic drugs or vaccine development. Comparisons of the F. Notably, GC content, codon usage and amino acid frequencies are remarkably different in Schistosomes to F.
Functional annotation of predicted proteins showed a general representation of diverse biological functions. Besides proteases and antioxidant enzymes expected to participate in the early interaction with the host, mucin-like proteins and others involved in gene expression, protein synthesis, cell signaling and mitochondrial enzymes were identified. The knowledge of the genes expressed by the invasive stage of F.
The integration of the emerging transcriptomics, and proteomics data and the advent of functional platelmontos tools in this organism are positioning F. A forma adulta de F.
– Estudamos juntos
A B Figura 1. A Ciclo vital do platelminto F. Duas linhagens de F. Da mesma forma que outros helmintos, F. Alguns estudos demonstram que Dado que a Um estudo realizado por Pietrafita e col. O primeiro componente deste sistema a ser Estes dados sugerem que F. Muitas das enzimas AOX presentes em F. No caso de F. Por outro lado, sabe-se que F. Justificativa Este trabalho teve como objeto de estudo o platelminto parasita F. BMC Genomics exerclcios, The common liver fluke Fasciola hepatica is the agent platemlintos a zoonosis with significant economic consequences in livestock production worldwide, and increasing relevance to human health in developing countries.
Here we provide an initial glimpse to the transcriptomics of the NEJ, the first stage to interact with the mammalian host. These novel sequences along with a set of parasite transcripts absent in the host genomes are putative platelminos targets for future anti-parasitic drugs or vaccine development.
Besides proteases and antioxidant enzymes expected to participate in the early interaction with the host, various proteins involved in gene expression, protein synthesis, cell signaling and mitochondrial enzymes were identified. Differential expression of secreted protease platekmintos family platelmitnos between juvenile and adult stages may respond to different needs during host colonization.
The knowledge of the genes expressed by the invasive stage of Fasciola hepatica is a starting point to unravel key aspects of this parasite’s biology.
Background Fasciola hepatica, the common exerficios fluke, is recognized as one of the most important parasitic helminths affecting livestock worldwide. Along with the related species F. During the last decade, its relevance as a zoonotic agent in parts of Latin America and Africa has also emerged, with millions at risk of infection [2,3].
Although effective drugs such as triclabendazole are available, they only provide interim control of the disease, since cattle and sheep are easily reinfected. This is an Open Access article distributed under the terms of the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction exercicjos any medium, provided the original work is properly cited.
The life cycle of F. Mammals get infected by ingestion of the quiescent larvae metacercariae encysted in the vegetation. An interplay of extrinsic signals from the playelmintos digestive enzymes, bile salts, redox potential, ph, temperature among others and intrinsic factors from the parasite enzymes and secretions determine the emergence of a motile larvae . The newly excysted juveniles NEJ actively penetrate and transverse the gut wall into the wxercicios cavity within two or three hours.
By four or five days post-infection the parasites reach and penetrate the liver, and continue burrowing through the parenchyma for platemintos weeks. Within the major bile ducts the parasites mature and start to release eggs, that can be found in the bile and feces from 8 weeks post-infection . Unlike mature flukes living in the immunologically safe environment of the bile ducts, NEJ are susceptible targets of the immune response.
Vaccination studies also show that effective protection is correlated with reduced exerccios damage, a signature of previous destruction of the early NEJs. Despite the crucial role of this stage in determining the further success of the infective process, information regarding NEJs, is very limited, mainly due to the scarce availability of material to explore diverse platslmintos of the parasite biology.
Principal roles for stage specific proteases and antioxidant enzymes in the early infection have been demonstrated by us and others . Recent proteomic studies were able to reveal important differences among F. However, the identification of the juvenile specific proteins was limited by the paucity of mrna sequences exercivios match to peptide mass fingerprinting data. While more than protein sequences and 10, EST are available from the adult stage, only 22 mrna sequences from NEJ sbore corresponding to cathepsin B and L-like cysteine proteinases were deposited at the Genbank by July Consequently we decided to conduct a transcriptomic analysis in order to identify the gene repertoire expressed by the invasive stage of F.
Transcriptomic approaches in Schistosoma mansoni and S. Furthermore, they have been invaluable tools for the assembly and annotation of the recently released genomes of these important human parasites [18,19], opening new avenues for discovery [20,21]. EST have also been applied successfully to a limited set of other trematodes, namely Echinostoma plahelmintos , Clonorchis sinensis , Paragonimus westermani  and Opisthorchis viverrini .
Here we report the analysis of a limited set of NEJ expressed sequence tags, identifying putative stage, species and flatworm specific sequences. This first glimpse of the physiology of the invasive larvae opens new prospects for the understanding of the host-parasite interaction eventually leading to the development of new mechanisms to control fasciolosis, and warrants further analysis using new generation sequencing technologies.
Results and Discussion Construction of a newly excysted juvenile F. Since the starting parasite material exfrcicios limiting, a modified size fractioning step of the products was introduced in order to improve the yield  Additional File 1. More than four thousand reads were produced and analyzed using the Partigene pipeline .
Quality and vector trimming drastically reduced the starting ESTs to high quality sequences, mainly due to the presence of multimers of the adapters used in the generation of the libraries see methods. This setback could be expected considering the minimal amount of starting material, and might be corrected using 5′ blocked adapters in lower concentrations.
The resulting high quality sequences were clustered into different contigs clusters and singletons The most highly abundant EST in juvenile F. Polyadenylated LSU rrna has already been described in other platyhelminths , platelmkntos in fact, F. Considering that only 22 sequences from NEJ were available in Genbank by July 15 of them encoding cathepsinsthe present report represents a pertinent contribution to the knowledge of the genes expressed by the invasive stage of the common liver fluke.
To compare the data obtained from the juvenile stage to the adult sequences, sobrd retrieved and analyzed using the Partigene pipeline more than 10, EST reads from F. These results are very similar to a recently reported analysis of the same dataset performed using a different pipeline .
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More than half of the juvenile contigs A set of 91 juvenile contigs On the other hand, there are several juvenile contigs that are absent from the adult database, although represented in other organisms suggesting that they might represent stage specific transcripts Figure 1. The absence of some of them from the adult dataset might suggest that the representation of the adult libraries is still partial. Interestingly, 64 contigs The NEJ contigs generated by the Partigene pipeline were compared by Blast with the set of databases corresponding to diverse taxons listed in Additional file 2and the results aggregated by their conservation in diverse taxonomic groups.
Groups correspond to sequences finding hits in all taxa tested commonall metazoans, all bilaterians or exclusively in flatworms or in F. Sequences producing positive hits with some taxa but not with others i. Sequences producing hits with the adult stage ESTs dataset within each category are indicated in orange in the inner circle. Also 56 contigs To further characterize conservation patterns between different metazoan lineages, we analyzed the distribution of tblastx hits by three-way comparisons using the Simitri program .
As expected, the F. Consistent with the reports from the schistosomes genomes, we detected slightly more shared genes being them also more similar with the complete genomes of vertebrates than with insects and nematodes [18,19]. These results further support the idea that ancient genomes were gene rich, and that lineage specific gene gain and loss events were frequent during metazoan evolution, particularly within the ecdysozoans .
While the relevance of genes shared between trematodes and their hosts has been highlighted, since they may be crucial for parasite adapta. The complete set of contigs generated by the Partigene pipeline was compared by tblastx with a set of ESTs or cdna databases indicated in Additional file 2. The resulting tblastx scores were transformed in coordinates and represented in a triangular graph with Simitri. Each sequence is represented by a dot colour coded by its aggregated blast score and placed in the middle area if found in the three databases, on the corresponding cathetus if found in two databases.
Sequences that match in only one of the databases or have no hits are not depicted, but their numbers are indicated. For clarity angle bisector lines were added. Comparisons are shown among A trematodes, cestodes, and turbellaria B cnidarians, mollusks, and annelids C flatworms excluding F.
Additionally, since we included in the study partial genomes from other lophotrochozoans annelids and mollusks we were able to compare the Fasciola dataset to these organisms and other phyla. This is relevant since flatworm position in modern phylogeny is still debated, being placed either within or as sister group of the lophotrochozoa .
The conserved set of liver fluke genes is almost equally distant from cnidarians, mollusks, and annelids, but slightly closer to the two lophotrochozoans than the model ecdysozoans or vertebrates Figure 2B, D, and Additional File 4.