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Patrick J. Keeling - One of the best experts on this subject based on the ideXlab platform.
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revealing the metabolic capacity of streblomastix Strix and its bacterial symbionts using single cell metagenomics
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Sebastian C Treitli, Filip Husnik, Patrick J. Keeling, Martin Kolisko, Vladimír HamplAbstract:Lower termites harbor in their hindgut complex microbial communities that are involved in the digestion of cellulose. Among these are protists, which are usually associated with specific bacterial symbionts found on their surface or inside their cells. While these form the foundations of a classic system in symbiosis research, we still know little about the functional basis for most of these relationships. Here, we describe the complex functional relationship between one protist, the oxymonad Streblomastix Strix, and its ectosymbiotic bacterial community using single-cell genomics. We generated partial assemblies of the host S. Strix genome and Candidatus Ordinivivax streblomastigis, as well as a complex metagenome assembly of at least 8 other Bacteroidetes bacteria confirmed by ribosomal (r)RNA fluorescence in situ hybridization (FISH) to be associated with S. Strix. Our data suggest that S. Strix is probably not involved in the cellulose digestion, but the bacterial community on its surface secretes a complex array of glycosyl hydrolases, providing them with the ability to degrade cellulose to monomers and fueling the metabolism of S. Strix. In addition, some of the bacteria can fix nitrogen and can theoretically provide S. Strix with essential amino acids and cofactors, which the protist cannot synthesize. On the contrary, most of the bacterial symbionts lack the essential glycolytic enzyme enolase, which may be overcome by the exchange of intermediates with S. Strix. This study demonstrates the value of the combined single cell (meta)genomic and FISH approach for studies of complicated symbiotic systems.
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Symbiotic Innovation in the Oxymonad Streblomastix Strix
The Journal of eukaryotic microbiology, 2004Co-Authors: Brian S. Leander, Patrick J. KeelingAbstract:Streblomastix Strix is an enigmatic oxymonad found exclusively in the hindgut of the damp-wood termite Zootermopsis. Streblomastix has a number of unusual morphological characters and forms a complex but poorly understood symbiosis with epibiotic bacteria. Here we described the ultrastructure of S. Strix, with emphasis on the axial cytoskeleton and cell-cell associations, in its normal state and when treated with antibiotics. In untreated cells, epibiotic bacteria were orderly arranged end-to-end on six or seven longitudinal vanes, giving S. Strix a stellate appearance in transverse section. The epibiotic bacteria were unusually long bacilli of at least three different morphotypes. Bacteria adhered to the oxymonad host by distinct cell-cell junctions that protruded between the poles of adjacent epibiotic bacteria. Treating termites with the antibiotic carbenicillin led to the loss of most (but not all) of the bacteria and the transformation of S. Strix from a long slender cell to a teardrop-shaped cell, where the axostyle was compacted and became bifurcated near the posterior end.
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Characterisation of a non-canonical genetic code in the oxymonad Streblomastix Strix.
Journal of molecular biology, 2003Co-Authors: Patrick J. Keeling, Brian S. LeanderAbstract:The genetic code is one of the most highly conserved characters in living organisms. Only a small number of genomes have evolved slight variations on the code, and these non-canonical codes are instrumental in understanding the selective pressures maintaining the code. Here, we describe a new case of a non-canonical genetic code from the oxymonad flagellate Streblomastix Strix. We have sequenced four protein-coding genes from S. Strix and found that the canonical stop codons TAA and TAG encode the amino acid glutamine. These codons are retained in S. Strix mRNAs, and the legitimate termination codons of all genes examined were found to be TGA, supporting the prediction that this should be the only true stop codon in this genome. Only four other lineages of eukaryotes are known to have evolved non-canonical nuclear genetic codes, and our phylogenetic analyses of α-tubulin, β-tubulin, elongation factor-1 α (EF-1 alpha), heat-shock protein 90 (HSP90), and small subunit rRNA all confirm that the variant code in S. Strix evolved independently of any other known variant. The independent origin of each of these codes is particularly interesting because the code found in S. Strix, where TAA and TAG encode glutamine, has evolved in three of the four other nuclear lineages with variant codes, but this code has never evolved in a prokaryote or a prokaryote-derived organelle. The distribution of non-canonical codes is probably the result of a combination of differences in translation termination, tRNAs, and tRNA synthetases, such that the eukaryotic machinery preferentially allows changes involving TAA and TAG.
Brian S. Leander - One of the best experts on this subject based on the ideXlab platform.
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Symbiotic Innovation in the Oxymonad Streblomastix Strix
The Journal of eukaryotic microbiology, 2004Co-Authors: Brian S. Leander, Patrick J. KeelingAbstract:Streblomastix Strix is an enigmatic oxymonad found exclusively in the hindgut of the damp-wood termite Zootermopsis. Streblomastix has a number of unusual morphological characters and forms a complex but poorly understood symbiosis with epibiotic bacteria. Here we described the ultrastructure of S. Strix, with emphasis on the axial cytoskeleton and cell-cell associations, in its normal state and when treated with antibiotics. In untreated cells, epibiotic bacteria were orderly arranged end-to-end on six or seven longitudinal vanes, giving S. Strix a stellate appearance in transverse section. The epibiotic bacteria were unusually long bacilli of at least three different morphotypes. Bacteria adhered to the oxymonad host by distinct cell-cell junctions that protruded between the poles of adjacent epibiotic bacteria. Treating termites with the antibiotic carbenicillin led to the loss of most (but not all) of the bacteria and the transformation of S. Strix from a long slender cell to a teardrop-shaped cell, where the axostyle was compacted and became bifurcated near the posterior end.
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Characterisation of a non-canonical genetic code in the oxymonad Streblomastix Strix.
Journal of molecular biology, 2003Co-Authors: Patrick J. Keeling, Brian S. LeanderAbstract:The genetic code is one of the most highly conserved characters in living organisms. Only a small number of genomes have evolved slight variations on the code, and these non-canonical codes are instrumental in understanding the selective pressures maintaining the code. Here, we describe a new case of a non-canonical genetic code from the oxymonad flagellate Streblomastix Strix. We have sequenced four protein-coding genes from S. Strix and found that the canonical stop codons TAA and TAG encode the amino acid glutamine. These codons are retained in S. Strix mRNAs, and the legitimate termination codons of all genes examined were found to be TGA, supporting the prediction that this should be the only true stop codon in this genome. Only four other lineages of eukaryotes are known to have evolved non-canonical nuclear genetic codes, and our phylogenetic analyses of α-tubulin, β-tubulin, elongation factor-1 α (EF-1 alpha), heat-shock protein 90 (HSP90), and small subunit rRNA all confirm that the variant code in S. Strix evolved independently of any other known variant. The independent origin of each of these codes is particularly interesting because the code found in S. Strix, where TAA and TAG encode glutamine, has evolved in three of the four other nuclear lineages with variant codes, but this code has never evolved in a prokaryote or a prokaryote-derived organelle. The distribution of non-canonical codes is probably the result of a combination of differences in translation termination, tRNAs, and tRNA synthetases, such that the eukaryotic machinery preferentially allows changes involving TAA and TAG.
Susan M. Haig - One of the best experts on this subject based on the ideXlab platform.
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Microsatellite loci for distinguishing spotted owls (Strix occidentalis), barred owls (Strix varia), and their hybrids
Molecular Ecology Notes, 2006Co-Authors: W. Chris Funk, Thomas D. Mullins, Eric D. Forsman, Susan M. HaigAbstract:We identified four diagnostic microsatellite loci that distinguish spotted owls (Strix occidentalis), barred owls (Strix varia), F 1 hybrids and backcrosses. Thirty-four out of 52 loci tested (65.4%) successfully amplified, and four of these loci (11.8%) had allele sizes that did not overlap between spotted and barred owls. The probability of correctly identifying a backcross with these four loci is 0.875. Genotyping potential hybrid owls with these markers revealed that field identifications were often wrong. Given the difficulty of identifying hybrids in the field, these markers will be useful for hybrid identification, law enforcement and spotted owl conservation.
Vladimír Hampl - One of the best experts on this subject based on the ideXlab platform.
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revealing the metabolic capacity of streblomastix Strix and its bacterial symbionts using single cell metagenomics
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Sebastian C Treitli, Filip Husnik, Patrick J. Keeling, Martin Kolisko, Vladimír HamplAbstract:Lower termites harbor in their hindgut complex microbial communities that are involved in the digestion of cellulose. Among these are protists, which are usually associated with specific bacterial symbionts found on their surface or inside their cells. While these form the foundations of a classic system in symbiosis research, we still know little about the functional basis for most of these relationships. Here, we describe the complex functional relationship between one protist, the oxymonad Streblomastix Strix, and its ectosymbiotic bacterial community using single-cell genomics. We generated partial assemblies of the host S. Strix genome and Candidatus Ordinivivax streblomastigis, as well as a complex metagenome assembly of at least 8 other Bacteroidetes bacteria confirmed by ribosomal (r)RNA fluorescence in situ hybridization (FISH) to be associated with S. Strix. Our data suggest that S. Strix is probably not involved in the cellulose digestion, but the bacterial community on its surface secretes a complex array of glycosyl hydrolases, providing them with the ability to degrade cellulose to monomers and fueling the metabolism of S. Strix. In addition, some of the bacteria can fix nitrogen and can theoretically provide S. Strix with essential amino acids and cofactors, which the protist cannot synthesize. On the contrary, most of the bacterial symbionts lack the essential glycolytic enzyme enolase, which may be overcome by the exchange of intermediates with S. Strix. This study demonstrates the value of the combined single cell (meta)genomic and FISH approach for studies of complicated symbiotic systems.
W. Chris Funk - One of the best experts on this subject based on the ideXlab platform.
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Microsatellite loci for distinguishing spotted owls (Strix occidentalis), barred owls (Strix varia), and their hybrids
Molecular Ecology Notes, 2006Co-Authors: W. Chris Funk, Thomas D. Mullins, Eric D. Forsman, Susan M. HaigAbstract:We identified four diagnostic microsatellite loci that distinguish spotted owls (Strix occidentalis), barred owls (Strix varia), F 1 hybrids and backcrosses. Thirty-four out of 52 loci tested (65.4%) successfully amplified, and four of these loci (11.8%) had allele sizes that did not overlap between spotted and barred owls. The probability of correctly identifying a backcross with these four loci is 0.875. Genotyping potential hybrid owls with these markers revealed that field identifications were often wrong. Given the difficulty of identifying hybrids in the field, these markers will be useful for hybrid identification, law enforcement and spotted owl conservation.
