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  • 1
    Electronic Resource
    Electronic Resource
    The First Sexual Lineage and the Relevance of Facultative Sex (1999)
    Springer
    Journal of molecular evolution 48 (1999), S. 779-783 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Oxymonad — Parabasalid — Eukaryote phylogeny — Melosis — Origin of sex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Models for the origin of the sex incorporate either obligate or facultative sexual cycles. The relevance of each assumption to the ancestral sexual population can be examined by surveying the sexual cycles of eukaryotes, and by determining the first lineage to diverge after sexuality evolved. Two protistan groups, the parabasalids and the oxymonads, have been suggested to be early-branching sexual lineages. A maximum-likelihood analysis of elongation factor-1α sequences shows that the parabasalids diverged prior to the oxymonads and thus represent the earliest sexual lineage of eukaryotes. Since both of these protist lineages and most other eukaryotes are facultatively sexual, it is likely that the common ancestor of all known eukaryotes was facultatively sexual as well. This finding has important implications for the ``Best-Man hypothesis'' and other models for the origin of sex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013156
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  • 2
    Electronic Resource
    Electronic Resource
    Primary Structure and Phylogenetic Relationships of a Malate Dehydrogenase Gene from Giardia lamblia (1999)
    Springer
    Journal of molecular evolution 48 (1999), S. 750-755 
    Details
    ISSN: 1432-1432
    Keywords: Key words:Giardia lamblia— Diplomonads — Malate dehydrogenase — Protein phylogeny — Amitochondriate protist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The lactate and malate dehydrogenases comprise a complex protein superfamily with multiple enzyme homologues found in eubacteria, archaebacteria, and eukaryotes. In this study we describe the sequence and phylogenetic relationships of a malate dehydrogenase (MDH) gene from the amitochondriate diplomonad protist, Giardia lamblia. Parsimony, distance, and maximum-likelihood analyses of the MDH protein family solidly position G. lamblia MDH within a eukaryote cytosolic MDH clade, to the exclusion of chloroplast, mitochondrial, and peroxisomal homologues. Furthermore, G. lamblia MDH is specifically related to a homologue from Trichomonas vaginalis. This MDH topology, together with published phylogenetic analyses of β-tubulin, chaperonin 60, valyl-tRNA synthetase, and EF-1α, suggests a sister-group relationship between diplomonads and parabasalids. Since these amitochondriate lineages contain genes encoding proteins which are characteristic of mitochondria and α-proteobacteria, their shared ancestry suggests that mitochondrial properties were lost in the common ancestor of both groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006519
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  • 3
    Electronic Resource
    Electronic Resource
    Sequence Analysis of the Mitochondrial Genome of Sarcophyton glaucum: Conserved Gene Order Among Octocorals (1998)
    Springer
    Journal of molecular evolution 47 (1998), S. 697-708 
    Details
    ISSN: 1432-1432
    Keywords: Key words:Sarcophyton glaucum— Cnidaria — Mitochondrial DNA — Nucleotide sequence — Genetic code — Gene order
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The nucleotide sequence for an 11,715-bp segment of the mitochondrial genome of the octocoral Sarcophyton glaucum is presented, completing the analysis of the entire genome for this anthozoan member of the phylum Cnidaria. The genome contained the same 13 protein-coding and 2 ribosomal RNA genes as in other animals. However, it also included an unusual mismatch repair gene homologue reported previously and codes for only a single tRNA gene. Intermediate in length compared to two other cnidarians (17,443 and 18,911 bp), this organellar genome contained the smallest amount of noncoding DNA (428, compared to 1283 and 781 nt, respectively), making it the most compact one found for the phylum to date. The mitochondrial genes of S. glaucum exhibited an identical arrangement to that found in another octocoral, Renilla kolikeri, with five protein-coding genes in the same order as has been found in insect and vertebrate mitochondrial genomes. Although gene order appears to be highly conserved among octocorals, compared to the hexacoral, Metridium senile, few similarities were found. Like other metazoan mitochondrial genomes, the A + T composition was elevated and a general bias against codons ending in G or C was observed. However, an exception to this was the infrequent use of TGA compared to TGG to code for tryptophan. This divergent codon bias is unusual but appears to be a conserved feature among two rather distantly related anthozoans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006429
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  • 4
    Electronic Resource
    Electronic Resource
    Eukaryotic evolution Early origin of canonical introns (2002)
    [s.l.] : Nature Publishing Group
    Nature 419 (2002), S. 270-270 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Spliceosomal introns, one of the hallmarks of eukaryotic genomes, were thought to have originated late in evolution and were assumed not to exist in eukaryotes that diverged early — until the discovery of a single intron with an aberrant splice boundary in the primitive 'protozoan' ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/419270a
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  • 5
    Electronic Resource
    Electronic Resource
    Can commercial protection be good for research? (2002)
    [s.l.] : Nature Publishing Group
    Nature 419 (2002), S. 111-111 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sir Ari Patrinos and Dan Drell (Nature 417, 589–590; 2002) recommend that journals embrace the commercial realities facing science, suggesting that arrangements such as Science allowing some data restriction are ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/419111a
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  • 6
    Electronic Resource
    Electronic Resource
    Cell evolution Mitochondria in hiding (2002)
    [s.l.] : Nature Publishing Group
    Nature 418 (2002), S. 827-829 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] At some point in the history of life, certain bacteria took up residence in other cells, starting a symbiotic relationship that led to their establishment as the mitochondria found within most eukaryotic cells. Eukaryotes are organisms whose cells contain a nucleus, a cytoskeleton, internal ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/418827a
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  • 7
    Electronic Resource
    Electronic Resource
    Primary Structure and Phylogenetic Relationships of Glyceraldehyde-3-Phosphate Dehydrogenase Genes of Free-Living and Parasitic Diplomonad Flagellates (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: . Complete nucleotide sequences have been established for two genes (gap1 and gap2) coding for glyceraldehyde-3-phosphate dehydrogenase (GAPDH, EC 1.2.1.12) homologs in the diplomonad Giardia lamblia. In addition, almost complete sequences of the GAPDH open reading frames were obtained from PCR products for two free-living diplomonad species, Trepomonas agilis and Hexamita inflata, and a parasite of Atlantic salmon, an as yet unnamed species with morphological affinities to Spironucleus. Giardia lamblia gap 1 and the genes from the three other diplomonad species show high similarity to each other and to other glycolytic GAPDH genes. All amino-acyl residues known to be highly conserved in this enzyme are also conserved in these sequences. Giardia lamblia gap2 gene is more divergent and its putative translation reveals the presence of a cysteine and serine-rich insertion resembling a metal binding finger. This motif has not yet been noted in other GAPDH molecules. All sequences contain an S-loop signature with characteristics close to those of eukaryotes. In phylogenetic reconstructions based on the derived amino acid sequences with neighborjoining, parsimony and maximum-likelihood methods the four typical GAPDH sequences of diplomonads cluster into a single clade. Within this clade, G. lamblia gap1 shares a common ancestor with the rest of the genes. The latter are more closely related to each other, indicating an early separation of the lineage leading to the genus Giardia from the lineage encompassing the morphologically less differentiated genera, Trepomonas, Hexamita and that of the unnamed species. This result is discordant with the orthogonal evolution of diplomonads suggested on the basis of comparative morphology. In neighbor-joining reconstructions G. lamblia gap2 occupies a variable position, due to its great divergence. In parsimony and maximum likelihood analysis however, it shares a most recent common ancestor with the typical G. lamblia gap1 gene, suggesting that it diverged after the separation of the Giardia lineage. The position of the diplomonad clade in broader phylogenetic reconstructions is firmly within the typical cytosolic glycolytic representatives of GAPDH of eukaryotes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1996.tb03997.x
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  • 8
    Electronic Resource
    Electronic Resource
    Evidence for the Heterolobosea from Phylogenetic Analysis of Genes Encoding Glyceraldehyde-3-Phosphate Dehydrogenase (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: The phylogenetic relationships between major slime mould groups and the identification of their unicellular relatives has been a subject of controversy for many years. Traditionally, it has been assumed that two slime mould groups, the acrasids and the dictyostelids were related by virtue of their cellular slime mould habit; a view still endorsed by at least one current classification scheme, However, a decade ago, on the basis of detailed ultrastructural resemblances, it was proposed that acrasids of the family Acrasidae were not relatives of other slime moulds but instead related to a group of mostly free-living unicellular amoebae, the Schizopyrenida. The class Heterolobosea was created to contain these organisms and has since figured in many discussions of protist evolution. We sought to test the validity of Heterolobosea by characterizing homologs of the highly conserved glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from an acrasid, Acrasis rosea; a dictyostelid, Dictyostelium discoideum; and the schizopyrenid Naegleria andersoni. Phylogenetic analysis of these and other GAPDH sequences, using maximum parsimony, neighbour-joining distance and maximum likelihood methods strongly supports the Heterolobosea hypothesis and discredits the concept of a cellular slime mould grouping. Moreover, all of our analyses place Dictyostelium discoideum as a relatively recently originating lineage, most closely related to the Metazoa, similar to other recently published phylogenies of protein-coding genes. However, GAPDH phylogenies do not show robust branching orders for most of the relationships between major groups. We propose that several of the incongruencies observed between GAPDH and other molecular phylogenies are artifacts resulting from substitutional saturation of this enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1996.tb04507.x
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  • 9
    Electronic Resource
    Electronic Resource
    Ellobiopsids of the Genus Thalassomyces are Alveolates (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: . Ellobiopsids are multinucleate protist parasites of aquatic crustaceans that possess a nutrient absorbing ‘root’ inside the host and reproductive structures that protrude through the carapace. Ellobiopsids have variously been affiliated with fungi, ‘colorless algae’, and dinoflagellates, although no morphological character has been identified that definitively alh'es them with any particular eukaryotic lineage. The arrangement of the trailing and circumferential flagella of the rarely observed bi-flagellated ‘zoospore’ is reminiscent of dinoflagellate flagellation, but a well-organized ‘dinokaryotic nucleus’ has never been observed. Using small subunit ribosomal RNA gene sequences from two species of Thalassomyces, phylogenetic analyses robustly place these ellobiopsid species among the alveolates (ciliates, apicomplexans, dinoflagellates and relatives) though without a clear affiliation to any established alveolate lineage. Our trees demonstrate that Thalassomyces fall within a dinoflagellate + apicomplexa + Perkinsidae +“marine alveolate group 1” clade, clustering most closely with dinoflagellates. However, the poor statistical support for branches within this region indicates that additional data will be needed to resolve relationships among these taxa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2004.tb00555.x
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  • 10
    Electronic Resource
    Electronic Resource
    The evolutionary relationships amongst excavates: a concatened protein analysis (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: Morphological studies and phylogenies of ribosomal RNA, taken together, suggest that excavate protists may be related to each other, but many of the deepest level relationships amongt these organisms remain poorly understood. We have assembled a data set of six slowly evolving nuclear-encoded protein genes that include nine of the 10 recognized excavate groups. Maximum likelihood analyses demonstrate that diplomonads and Carpediemonas than parabasalids are related to each other. They also confirm that Trimastix is specifically related to oxymonads, forming the taxon Preaxostyla. There is strong support for a clade of Euglenozoa, Heterolobsea and jakobids, but, unexpectedly, jakobids and Heterolobosea are robustly recovered as sister taxa. Malawimonas is placed either as sister to Preaxostyla or as sister to the (Euglenozoa, Heterolobosea, jakobid) clade. The original data set strongly supports an association between the (diplomonad, Carpediemonas, parabasalid) clade and Opisthokonts. However, this grouping is not recovered when α-tubulin is excluded from the analysis, suggesting that the signal for this relationship lies within this one protein and might be suspect. All other important nodes in the tree are, by contrast, robust to the removal of any one gene. With α-tubulin excluded, excavates tend to form just two clades, with no strong nodes separating them. Jakobids, with their apparently ancestral bacterial-type mitrochondrial RNA polymerase are nonetheless nested within a clade with normal phage-type RNA polymerases, complicating any understanding of deep-level mitochondrial evolution The position of jakobids also seriously challenges the now well-accepted concept of a taxon Discicristata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.2005.05202003_1_68.x
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