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  • 1
    Electronic Resource
    Electronic Resource
    Linked Genes for Calmodulin and E2 Ubiquitin-Conjugating Enzyme in Trichomonas vaginalis (1996)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 43 (1996), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In searching the genomes of early-diverging protists to study whether the possession of calmodulin is ancestral to all eukaryotes, the gene for calmodulin was identified in Trichomonas vaginalis. This flagellate is a member of the Parabasalia, one of the earliest lineages of recognized eukaryotes to have diverged. This sequence was used to isolate a homologous 1.250-kb fragment from the T. vaginalis genome by inverse polymerase chain reaction. This fragment was also completely sequenced and shown to contain the 3′ end of the single-copy calmodulin gene and the 3′ end of a gene encoding a protein with high similarity to E2 ubiquitin-conjugating enzymes, a family which has previously only been identified in animals, plants, and fungi. Phylogenetic analysis of 50 members of the E2 family distinguishes at least nine separate subfamilies one of which includes the T. vaginalis E2-homologue and an uncharacterized gene from yeast chromosome XII.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1996.tb04506.x
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  • 2
    Electronic Resource
    Electronic Resource
    Phylogenetic Diversity of Parabasalian Symbionts from Termites, Including the Phylogenetic Position of Pseudotrypanosoma and Trichonympha (1998)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 45 (1998), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The phylogenetic diversity of parabasalian flagellates from termite hindguts has been examined by small subunit ribosomal RNA (rRNA) amplification and sequencing. Two species of particular interest, the giant trichomonad Pseudotrypanosoma giganteum and the hypermastigote Trichonympha magna, were isolated from the gut of Porotermes adamsoni by micropipetting. and the rRNA genes from these small populations amplified and sequenced. rRNA genes representing Hypermastigida and the Trichomonadida families Devescovinidae and Trichomonadidae. were also recovered by amplification from whole hindguts of three termites, P. adamsoni, Cryptotermes brevis, and Cryptotermes dudleyi. The parabasalian rRNA genes from C. brevis were found to comprise a unique and extremely heterogeneous lineage with no clear affinities to any known parabasalian rRNAs. In addition, one of the sequences isolated from P. Adamsoni was found to be similar to another uncharacterised rRNA gene from Reticulitermes flavipes. The phylogeny of all known parabasalian small subunit rRNAs was examined with these new sequences. We find many taxonomic groups to be supported by rRNA, but not all. We have found the root of parabasalia to be very difficult to discern accurately, but have nevertheless identified several possible positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1998.tb04561.x
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  • 3
    Electronic Resource
    Electronic Resource
    MICROSPORIDIA: Biology and Evolution of Highly Reduced Intracellular Parasites (2002)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 56 (2002), S. 93-116 
    Details
    ISSN: 0066-4227
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract Microsporidia are a large group of microbial eukaryotes composed exclusively of obligate intracellular parasites of other eukaryotes. Almost 150 years of microsporidian research has led to a basic understanding of many aspects of microsporidian biology, especially their unique and highly specialized mode of infection, where the parasite enters its host through a projectile tube that is expelled at high velocity. Molecular biology and genomic studies on microsporidia have also drawn attention to many other unusual features, including a unique core carbon metabolism and genomes in the size range of bacteria. These seemingly simple parasites were once thought to be the most primitive eukaryotes; however, we now know from molecular phylogeny that they are highly specialized fungi. The fungal nature of microsporidia indicates that microsporidia have undergone severe selective reduction permeating every level of their biology: From cell structures to metabolism, and from genomics to gene structure, microsporidia are reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.micro.56.012302.160854
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  • 4
    Electronic Resource
    Electronic Resource
    Re-examining Alveolate Evolution Using Multiple Protein Molecular Phylogenies (2002)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 49 (2002), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Alveolates are a diverse group of protists that includes three major lineages: ciliates, apicomplexa, and dinoflagellates. Among these three, it is thought that the apicomplexa and dinoflagellates are more closely related to one another than to ciliates. However, this conclusion is based almost entirely on results from ribosomal RNA phylogeny because very few morphological characters address this issue and scant molecular data are available from dinoflagellates. To better examine the relationships between the three major alveolate groups, we have sequenced six genes from the non-photosynthetic dinoflagellate, Ciyptlzecodinium cohnii: actin, beta-tubulin, hsp70, BiP, hsp90, and mitochondria1 hspl0. Beta-tubulin, hsp70, BIP, and hsp90 were found to be useful for intra-alveolate phylogeny, and trees were inferred from these genes individually and in combination. Trees inferred from individual genes generally supported the apicomplexa-dinoflagellate grouping, as did a combined analysis of all four genes. However, it was also found that the outgroup had a significant effect on the topology within alveolates when using certain methods of phylogenetic reconstruction, and an alternative topology clustering dinoflagellates and ciliates could not be rejected by the combined data. Altogether, these results support the sisterhood of apicomplexa and dinoflagellates, but point out that the relationship is not as strong as is often assumed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2002.tb00336.x
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  • 5
    Electronic Resource
    Electronic Resource
    Genome evolution in Microsporidia (2005)
    Oxford, UK : Blackwell Science Inc
    The @journal of eukaryotic microbiology 52 (2005), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Microsporidia are eukaryotic intracellular parasites that evolved from fungi. However, they are highly derived and specialized, and lack several typical eukaryotic features, such as canonical mitochondria, flagella and peroxisomes. They also exhibit seemingly “primitive” traits, probably due to their extreme sequence divergence and reductive evolution, which long obscured their true phylogenetic affinity. Gene content and genomic architecture in Microsporidia are known from E. cuniculi, the only species whose complete genome has been sequenced. A genomic sequence survey of A. locustae, a second and distantly related species, carried out in our laboratory provided valuable data for many studies that improved our knowledge on the biology and evolution of Microsporidia. We present here the latest results of our survey, emphasizing comparative analyses between A. locustae and E. cuniculi in order to explore the dynamics of genome evolution and compaction in this intriguing group of parasites. We found that, in spite of their extreme rates of sequence evolution, microsporidian genome structure evolves slowly compared to other eukaryotic groups and we propose that it is a consequence of compaction. We also report the discovery and characterization of a photolyase in A. locustae that protects the spore from DNA damage. In addition, comparative analysis allows the identification of several important genes that would otherwise not be recognised due to the extreme level of sequence evolution. Finally, we compared intergenic DNA between both species aiming to understand the structure of regulatory sequences in these highly compacted genomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_70.x
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  • 6
    Electronic Resource
    Electronic Resource
    The Phylogenetic Position of Alpha- and Beta-Tubulins from the Chlorarachnion Host and Cercomonas (Cercozoa) (1998)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 45 (1998), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Alpha and beta-tubulin genes from Chlorarachnion and an alpha-tubulin gene from Cercomonas have been characterised. We found the Cercomonas and Chlorarachnion alpha-tubulins to be closely related to one another, confirming the proposed relationship of these genera. In addition, the Chlorarachnion host and Cercomonas also appear to be more distantly related to Heterolobosea. Euglenozoa, chlorophytes. Heterokonts, and alveolates. Chlorarachnion was also found to have two distinctly different types of both alpha- and beta-tubulin. one type being highly-divergent. Chlorarachnion contains a secondary endosymbiont of green algal origin, raising the possibility that one type of Chlorarachnion tubulins comes from the host and the other from the endosymbiont. Probing pulsed field-separated chromosomes showed that the highly-divergent genes are encoded by the host genome, and neither alpha- nor beta-tubulin cDNAs were found to include 5′ extensions that might serve as targeting peptides. It appears that Chlorarachnion has distinct and divergent tubulin paralogues that are all derived from the host lineage. One Chlorarachnion beta-tubulin was also found to be a pseudogene, which is still expressed but aberrantly processed. Numerous unspliced introns and deletions resulting from mis-splicing are contained in the mRNAs from this gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1998.tb05117.x
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  • 7
    Electronic Resource
    Electronic Resource
    Transfer of Nosema locustae (Microsporidia) to Antonospora locustae n. comb. Based on Molecular and Ultrastructural Data (2004)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . Nosema locustae is a microsporidian parasite of grasshopper pesthd that is used as a biological control agent, and is one of the emerging model systems for microsporidia. Due largely to its diplokaryotic nuclei, N. locustae has been classified in the genus Nosema, a large genus with members that infect a wide variety of insects. However, some molecular studies have cast doubt on the validity of certain Nosema species, and on the taxonomic position of N. locustae. To clarify the affinities of this important insect parasite we sequenced part of the rRNA operon of N. locustae and conducted a phylogenetic analysis using the complete small subunit rRNA gene. Nosema locustae is only distantly related to the nominotypic N. bombycis, and is instead closely related to Antonospora scoticae, a recently described parasite of bees. We examined the ultrastructure of mature N. locustae spores, and found the spore wall to differ from true Nosema species in having a multi-layered exospore resembling that of Antonospora (one of the distinguishing features of that genus). Based on both molecular and morphological evidence, therefore, we propose transferring N. locustae to the genus Antonospora, as Antonospora locustae n. comb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00547.x
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  • 8
    Electronic Resource
    Electronic Resource
    Plastid-Targeting Peptides from the Chlorarachniophyte Bigelowiella natans (2004)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Chlorarachniophytes are marine amoeboflagellate protists that have acquired their plastid (chloroplast) through secondary endosymbiosis with a green alga. Like other algae, most of the proteins necessary for plastid function are encoded in the nuclear genome of the secondary host. These proteins are targeted to the organelle using a bipartite leader sequence consisting of a signal peptide (allowing entry in to the endomembrane system) and a chloroplast transit peptide (for transport across the chloroplast envelope mem branes). We have examined the leader sequences from 45 full-length predicted plastid-targeted proteins from the Chlorarachniophyte Bigelowiella natans with the goal of understanding important features of these sequences and possible conserved motifs. The chemical characteristics of these sequences were compared with a set of 10 B. natans endomembrane-targeted proteins and 38 cytosolic or nuclear proteins, which show that the signal peptides are similar to those of most other eukaryotes, while the transit peptides differ from those of other algae in some characteristics. Consistent with this, the leader sequence from one B. natans protein was tested for function in the apicomplexan parasite, Toxoplasma gondii, and shown to direct the secretion of the protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00288.x
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  • 9
    Electronic Resource
    Electronic Resource
    Symbiotic Innovation in the Oxymonad Streblomastix strix (2004)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 51 (2004), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . 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 5. strix from a long slender cell to a teardrop-shaped cell, where the axostyle was compacted and became bifurcated near the posterior end.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00569.x
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  • 10
    Electronic Resource
    Electronic Resource
    An Evaluation of Hsp90 as a Mediator of Cortical Patterning in Tetrahymena (2001)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 48 (2001), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: . This study asks two questions: 1) whether Hsp90 is involved in the regulation of cortical patterning in Tetrahymena, and 2) if it is, whether specific defects in this regulation can be attributed to functional insufficiency of the Hsp90 molecule. To address question I, we compared the effects of a specific inhibitor of Hsp90, geldanamycin, on population growth and on development of the oral apparatus in two Tetrahymena species, T. pyriformis and T. thermophila. We observed that geldanamycin inhibits population growth in both species at very low concentrations, and that it has far more severe effects on oral patterning in T. pyriformis than in T. thermophila. These effects are parallel to those of high temperature in the same two species, and provide a tentative affirmative answer to the first question. To address question 2, we ascertained the base sequence of the genes that encode the Hsp90 molecules which are induced at high temperatures in both Tetrahymena species, as well as corresponding sequences in Paramecium tetraurelia. Extensive comparative analyses of the deduced amino acid sequences of the Hsp90 molecules of the two Tetrahymena species indicate that on the basis of what we currently know about Hsp90 both proteins are equally likely to be functional. Phylogenetic analyses of Hsp90 amino acid sequences indicate that the two Tetrahymena Hsp90 molecules have undergone a similar number of amino acid substitutions from their most recent common ancestor, with none of these corresponding to any known functionally critical region of the molecule. Thus there is no evidence that the Hsp90 molecule of T. pyriformis is functionally impaired; the flaw in the control of cortical patterning is more likely to be caused by defects in mechanism(s) that mediate the response to Hsp90, as would be expected from the “Hsp90 capacitor” model of Rutherford and Lindquist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2001.tb00297.x
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