Project description:BackgroundTrypanosomatids are parasitic flagellates well known because of some representatives infecting humans, domestic animals, and cultural plants. Many trypanosomatid species bear RNA viruses, which, in the case of human pathogens Leishmania spp., influence the course of the disease. One of the close relatives of leishmaniae, Leptomonas pyrrhocoris, has been previously shown to harbor viruses of the groups not documented in other trypanosomatids. At the same time, this species has a worldwide distribution and high prevalence in the natural populations of its cosmopolitan firebug host. It therefore represents an attractive model to study the diversity of RNA viruses.ResultsWe surveyed 106 axenic cultures of L. pyrrhocoris and found that 64 (60%) of these displayed 2-12 double-stranded RNA fragments. The analysis of next-generation sequencing data revealed four viral groups with seven species, of which up to five were simultaneously detected in a single trypanosomatid isolate. Only two of these species, a tombus-like virus and an Ostravirus, were earlier documented in L. pyrrhocoris. In addition, there were four new species of Leishbuviridae, the family encompassing trypanosomatid-specific viruses, and a new species of Qinviridae, the family previously known only from metatranscriptomes of invertebrates. Currently, this is the only qinvirus with an unambiguously determined host. Our phylogenetic inferences suggest reassortment in the tombus-like virus owing to the interaction of different trypanosomatid strains. Two of the new Leishbuviridae members branch early on the phylogenetic tree of this family and display intermediate stages of genomic segment reduction between insect Phenuiviridae and crown Leishbuviridae.ConclusionsThe unprecedented wide range of viruses in one protist species and the simultaneous presence of up to five viral species in a single Leptomonas pyrrhocoris isolate indicate the uniqueness of this flagellate. This is likely determined by the peculiarity of its firebug host, a highly abundant cosmopolitan species with several habits ensuring wide distribution and profuseness of L. pyrrhocoris, as well as its exposure to a wider spectrum of viruses compared to other trypanosomatids combined with a limited ability to transmit these viruses to its relatives. Thus, L. pyrrhocoris represents a suitable model to study the adoption of new viruses and their relationships with a protist host.
Project description:Uridine insertion/deletion (U-indel) editing of mitochondrial mRNA, unique to the protistan class Kinetoplastea, generates canonical as well as potentially non-productive editing events. While the molecular machinery and the role of the guide (g) RNAs that provide required information for U-indel editing are well understood, little is known about the forces underlying its apparently error-prone nature. Analysis of a gRNA:mRNA pair allows the dissection of editing events in a given position of a given mitochondrial transcript. A complete gRNA dataset, paired with a fully characterized mRNA population that includes non-canonically edited transcripts, would allow such an analysis to be performed globally across the mitochondrial transcriptome. To achieve this, we have assembled 67 minicircles of the insect parasite Leptomonas pyrrhocoris, with each minicircle typically encoding one gRNA located in one of two similar-sized units of different origin. From this relatively narrow set of annotated gRNAs, we have dissected all identified mitochondrial editing events in L. pyrrhocoris, the strains of which dramatically differ in the abundance of individual minicircle classes. Our results support a model in which a multitude of editing events are driven by a limited set of gRNAs, with individual gRNAs possessing an inherent ability to guide canonical and non-canonical editing.
Project description:Many high-quality genomes are available for dixenous (two hosts) trypanosomatid species of the genera Trypanosoma, Leishmania, and Phytomonas, but only fragmentary information is available for monoxenous (single-host) trypanosomatids. In trypanosomatids, monoxeny is ancestral to dixeny, thus it is anticipated that the genome sequences of the key monoxenous parasites will be instrumental for both understanding the origin of parasitism and the evolution of dixeny. Here, we present a high-quality genome for Leptomonas pyrrhocoris, which is closely related to the dixenous genus Leishmania. The L. pyrrhocoris genome (30.4 Mbp in 60 scaffolds) encodes 10,148 genes. Using the L. pyrrhocoris genome, we pinpointed genes gained in Leishmania. Among those genes, 20 genes with unknown function had expression patterns in the Leishmania mexicana life cycle suggesting their involvement in virulence. By combining differential expression data for L. mexicana, L. major and Leptomonas seymouri, we have identified several additional proteins potentially involved in virulence, including SpoU methylase and U3 small nucleolar ribonucleoprotein IMP3. The population genetics of L. pyrrhocoris was also addressed by sequencing thirteen strains of different geographic origin, allowing the identification of 1,318 genes under positive selection. This set of genes was significantly enriched in components of the cytoskeleton and the flagellum.
Project description:Abstract: The Kinetoplastida (Euglenozoa) are unicellular flagellates that include the trypanosomatid parasites, most notably Trypanosoma brucei, T.cruzi and Leishmania spp. These organisms cause substantial mortality and morbidity in humans and their livestock worldwide as the causative agents of African sleeping sickness, Chagas disease and leishmaniasis respectively. Draft genome sequences are available for several species of both Trypanosoma and Leishmania. Bodo saltans is a free-living heterotroph found worldwide in freshwater and marine habitats, and it is among the closest bodonid relatives of the trypanosomatids. The purpose of a B. saltans genome sequence is to provide an 'out-group' for comparative genomic analysis of the trypanosomatid parasites. It will provide a model of the ancestral trypanosomatid to distinguish those derived parts of the parasite genomes (i.e., unique trypanosomatid adaptations) from those which are a legacy of the free-living ancestor. To aid annotation of the B.saltans genome sequence, total genomic RNA was extracted on four occasions from the total cellular mass of 160ml of B.saltans cell culture, for the purposes of transcription profiling by high throughput sequencing. Cells were unmodified. B.saltans cells were grown in water at 4oC. Total genomic RNA was extracted from a cell pellet using TRIZOL reagent and ethanol precipitated. Poly A+ mRNA was purified from total RNA using oligo dT dyna bead selection and libraries were created using the Illumina RNA-seq protocol. The samples were sequenced on an Illumina HiSeq 2000. This data is part of a pre-publication release. For information on the proper use of pre-publication data shared by the Wellcome Trust Sanger Institute (including details of any publication moratoria), please see http://www.sanger.ac.uk/datasharing/
Project description:We developed a novel method for RNA-seq in Trypanosomatids called ‘Spliced-Leader Sequencing’ (SL-seq). The method is based on the fact that the 5’ end of Trypanosomatid mRNA is starts with a SL-sequence, and specifically enriches SL-containing RNA prior to sequencing. In this study we compared the performance and functional results obtained with SL-seq to those generated with conventional Illumina Stranded mRNA prep. Therefore we sequenced mRNA of Leishmania donovani logarithmic phase promastigotes, stationary phase promastigotes and intracellular amastigotes with both methods. We also sequenced controlled dilutions of Leishmania RNA with human RNA.
2017-05-30 | GSE95353 | GEO
Project description:insect species of medical legal importance
Project description:Streptococcus agalactiae (Lancefield’s group B Streptococcus, GBS) is a major bacterial species of genus Streptococcus and has medical and veterinary importance by affecting mainly humans (Maione et al., 2005; Johri et al., 2006), cattle (Keefe, 1997) and fish (Mian et al., 2009). The GBS is the most important pathogen for the Nile tilapia, a global commodity of the aquaculture sector, causing outbreaks of septicemia and meningoencephalitis (Hernández et al., 2009; Mian et al., 2009).