| 1. |
- Jerlström-Hultqvist, Jon, et al.
(author)
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Hydrogenosomes in the diplomonad Spironucleus salmonicida
- 2013
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 4, s. 2493-
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Journal article (peer-reviewed)abstract
- Acquisition of the mitochondrion is a key event in the evolution of the eukaryotic cell, but diversification of the organelle has occurred during eukaryotic evolution. One example of such mitochondria-related organelles (MROs) are hydrogenosomes, which produce ATP by substrate- level phosphorylation with hydrogen as a byproduct. The diplomonad parasite Giardia intestinalis harbours mitosomes, another type of MRO. Here we identify MROs in the salmon parasite Spironucleus salmonicida with similar protein import and Fe-S cluster assembly machineries as in Giardia mitosomes. We find that hydrogen production is prevalent in the diplomonad genus Spironucleus, and that S. salmonicida MROs contain enzymes characteristic of hydrogenosomes. Evolutionary analyses of known hydrogenosomal components indicate their presence in the diplomonad ancestor, and subsequent loss in Giardia. Our results suggest that hydrogenosomes are metabolic adaptations predating the split between parabasalids and diplomonads, which is deeper than the split between animals and fungi in the eukaryotic tree.
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| 2. |
- Jerlström-Hultqvist, Jon, et al.
(author)
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Stable transfection of the diplomonad parasite Spironucleus salmonicida
- 2012
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In: Eukaryotic Cell. - 1535-9778 .- 1535-9786. ; 11:11, s. 1353-1361
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Journal article (peer-reviewed)abstract
- Eukaryotic microbes are highly diverse and many lineages remain poorly studied. One such lineage, the diplomonads, a group of binucleate heterotrophic flagellates, has mainly been studied due to the impact of Giardia intestinalis, an intestinal, diarrhea-causing parasite in humans and animals. Here we describe the development of a stable transfection system for use in Spironucleus salmonicida, a diplomonad casuing systemic spironucleosis in salmonid fish. We designed vectors in cassette format carrying epitope tags for localization (3xHA, 2xOLLAS, 3xMYC) and purification of proteins (2xStrepII-FLAG or SBP-GST) under the control of native or constitutive promoters. Three selectable markers, puromycin acetyltransferase (pac), blasticidin S-deaminase (bsr) or neomycin phosphotransferase (nptII) were successfully applied for generation of stable transfectants. Site-specific integration on the S. salmonicida chromosome was shown to be possible using the bsr resistance gene. We epitope-tagged six proteins and confirmed their expression by Western Blot. Next, we demonstrated the utility of these vectors by recording the sub-cellular localizations of the six proteins by laser scanning confocal microscopy. Finally, we describe the creation of a S. salmonicida double transfectant suitable for co-localization studies. The transfection system described herein and the imminent completion of the S. salmonicida genome will make it possible to use comparative genomics as an investigative tool to explore specific as well as general diplomonad traits, benefiting research on both Giardia and Spironucleus.
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| 3. |
- Xu, Feifei, et al.
(author)
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The genome of Spironucleus salmonicida highlights a fish pathogen adapted to fluctuating environments
- 2014
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In: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 10:2, s. e1004053-
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Journal article (peer-reviewed)abstract
- Spironucleus salmonicida causes systemic infections in salmonid fish. It belongs to the group diplomonads, binucleated heterotrophic flagellates adapted to micro-aerobic environments. Recently we identified energy-producing hydrogenosomes in S. salmonicida. Here we present a genome analysis of the fish parasite with a focus on the comparison to the more studied diplomonad Giardia intestinalis. We annotated 8067 protein coding genes in the ∼12.9 Mbp S. salmonicida genome. Unlike G. intestinalis, promoter-like motifs were found upstream of genes which are correlated with gene expression, suggesting a more elaborate transcriptional regulation. S. salmonicida can utilise more carbohydrates as energy sources, has an extended amino acid and sulfur metabolism, and more enzymes involved in scavenging of reactive oxygen species compared to G. intestinalis. Both genomes have large families of cysteine-rich membrane proteins. A cluster analysis indicated large divergence of these families in the two diplomonads. Nevertheless, one of S. salmonicida cysteine-rich proteins was localised to the plasma membrane similar to G. intestinalis variant-surface proteins. We identified S. salmonicida homologs to cyst wall proteins and showed that one of these is functional when expressed in Giardia. This suggests that the fish parasite is transmitted as a cyst between hosts. The extended metabolic repertoire and more extensive gene regulation compared to G. intestinalis suggest that the fish parasite is more adapted to cope with environmental fluctuations. Our genome analyses indicate that S. salmonicida is a well-adapted pathogen that can colonize different sites in the host.
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