- Volume 54, Issue 3, 2004
Volume 54, Issue 3, 2004
- Evolution, Phylogeny And Biodiversity
-
-
-
Phylogenetic analysis of gastric and enterohepatic Helicobacter species based on partial HSP60 gene sequences
More LessAnalysis of 16S rRNA gene sequences has been the method generally used to study the evolution and phylogeny of bacteria. Phylogenetic analysis of the 16S rRNA gene has shown the position of the genus Helicobacter in the ε-subclass of the Proteobacteria. Because 16S rRNA-based phylogeny does not always correspond to the results of polyphasic taxonomy, and the related species cannot always be separated, new phylogenetic markers for Helicobacter species are needed. In this study, conserved partial (600 bp) 60 kDa heat-shock protein (HSP60) sequences were used to study the phylogeny of 37 strains of gastric and enterohepatic Helicobacter species, including type strains of 15 Helicobacter species with validly published names, reference strains of flexispira taxa and Helicobacter felis, Helicobacter bizzozeronii and Helicobacter salomonis and canine flexispira strains. The partial HSP60 gene sequence proved to be a useful phylogenetic marker for the genus Helicobacter, providing a means of differentiating all 15 Helicobacter species analysed. In the resulting phylogenetic tree, gastric Helicobacter species and enterohepatic species with flexispira morphology formed tight, separate clusters. In general, HSP60 sequence similarities between Helicobacter species were significantly lower than the corresponding 16S rRNA gene sequence similarities, indicating a better resolution for species identification. In addition, a specific PCR method for identifying H. salomonis was developed based on the partial HSP60 sequence.
-
-
-
-
Repeat-type distribution in trnL intron does not correspond with species phylogeny: comparison of the genetic markers 16S rRNA and trnL intron in heterocystous cyanobacteria
More LesstRNALeu UAA (trnL) intron sequences are used as genetic markers for differentiating cyanobacteria and for constructing phylogenies, since the introns are thought to be more variable among close relatives than is the 16S rRNA gene, the conventional phylogenetic marker. The evolution of trnL intron sequences and their utility as a phylogenetic marker were analysed among heterocystous cyanobacteria with maximum-parsimony, maximum-likelihood and Bayesian inference by comparing their evolutionary information to that of the 16S rRNA gene. Trees inferred from the 16S rRNA gene and the distribution of two repeat classes in the P6b stem–loop of the trnL intron were in clear conflict. The results show that, while similar heptanucleotide repeat classes I and II in the P6b stem–loop of the trnL intron could be found among distant relatives, some close relatives harboured different repeat classes with a high sequence difference. Moreover, heptanucleotide repeat class II and other sequences from the P6b stem–loop of the trnL intron interrupted several other intergenic regions in the genomes of heterocystous cyanobacteria. Cluster analyses based on conserved intron sequences without loops P6b, P9 and parts of P5 corresponded in most clades to the 16S rRNA gene phylogeny, although the relationships were not resolved well, according to low bootstrap support. Thus, the hypervariable loop sequences of the trnL intron, especially the P6b stem–loop, cannot be used for phylogenetic analysis and conclusions cannot be drawn about species relationships on the basis of these elements. Evolutionary scenarios are discussed considering the origin of the repeats.
-
-
-
Evaluation of the phylogenetic position of the planctomycete ‘Rhodopirellula baltica’ SH 1 by means of concatenated ribosomal protein sequences, DNA-directed RNA polymerase subunit sequences and whole genome trees
More LessIn recent years, the planctomycetes have been recognized as a phylum of environmentally important bacteria with habitats ranging from soil and freshwater to marine ecosystems. The planctomycetes form an independent phylum within the bacterial domain, whose exact phylogenetic position remains controversial. With the completion of sequencing of the genome of ‘Rhodopirellula baltica’ SH 1, it is now possible to re-evaluate the phylogeny of the planctomycetes based on multiple genes and genome trees in addition to single genes like the 16S rRNA or the elongation factor Tu. Here, evidence is presented based on the concatenated amino acid sequences of ribosomal proteins and DNA-directed RNA polymerase subunits from ‘Rhodopirellula baltica’ SH 1 and more than 90 other publicly available genomes that support a relationship of the Planctomycetes and the Chlamydiae. Affiliation of ‘Rhodopirellula baltica’ SH 1 and the Chlamydiae was reasonably stable regarding site selection since, during stepwise filtering of less-conserved sites from the alignments, it was only broken when rigorous filtering was applied. In a few cases, ‘Rhodopirellula baltica’ SH 1 shifted to a deep branching position adjacent to the Thermotoga/Aquifex clade. These findings are in agreement with recent publications, but the deep branching position was dependent on site selection and treeing algorithm and thus not stable. A genome tree calculated from normalized blastp scores did not confirm a close relationship of ‘Rhodopirellula baltica’ SH 1 and the Chlamydiae, but also indicated that the Planctomycetes do not emerge at the very root of the Bacteria. Therefore, these analyses rather contradict a deep branching position of the Planctomycetes within the bacterial domain and reaffirm their earlier proposed relatedness to the Chlamydiae.
-
-
-
Phylogeny of Firmicutes with special reference to Mycoplasma (Mollicutes) as inferred from phosphoglycerate kinase amino acid sequence data
More LessThe phylogenetic position of the Mollicutes has been re-examined by using phosphoglycerate kinase (Pgk) amino acid sequences. Hitherto unpublished sequences from Mycoplasma mycoides subsp. mycoides, Mycoplasma hyopneumoniae and Spiroplasma citri were included in the analysis. Phylogenetic trees based on Pgk data indicated a monophyletic origin for the Mollicutes within the Firmicutes, whereas Bacilli (Firmicutes) and Clostridia (Firmicutes) appeared to be paraphyletic. With two exceptions, i.e. Thermotoga (Thermotogae) and Fusobacterium (Fusobacteria), which clustered within the Firmicutes, comparative analyses show that at a low taxonomic level, the resolved phylogenetic relationships that were inferred from both the Pgk protein and 16S rRNA gene sequence data are congruent.
-
-
-
The genus Spiroplasma and its non-helical descendants: phylogenetic classification, correlation with phenotype and roots of the Mycoplasma mycoides clade
The genus Spiroplasma (helical mollicutes: Bacteria: Firmicutes: Mollicutes: Entomoplasmatales: Spiroplasmataceae) is associated primarily with insects. The Mycoplasma mycoides cluster (sensu Weisburg et al. 1989 and Johansson and Pettersson 2002 ) is a group of mollicutes that includes the type species – Mycoplasma mycoides – of Mycoplasmatales, Mycoplasmataceae and Mycoplasma. This cluster, associated solely with ruminants, contains five other species and subspecies. Earlier phylogenetic reconstructions based on partial 16S rDNA sequences and a limited sample of Spiroplasma and Mycoplasma sequences suggested that the genus Mycoplasma was polyphyletic, as the M. mycoides cluster and the grouping that consisted of the hominis and pneumoniae groups of Mycoplasma species were widely separated phylogenetically and the M. mycoides cluster was allied with Spiroplasma. It is shown here that the M. mycoides cluster arose from Spiroplasma through an intermediate group of non-helical spiroplasmal descendants – the Entomoplasmataceae. As this conclusion has profound implications in the taxonomy of Mollicutes, a detailed phylogenetic study of Spiroplasma and its non-helical descendants was undertaken. These analyses, done with maximum-parsimony, provide cladistic status; a new nomenclature is introduced here, based on ‘bottom-up’ rather than ‘top-down’ clade classification. The order Entomoplasmatales consists of four major clades: (i) the Mycoides–Entomoplasmataceae clade, which contains M. mycoides and its allies and Entomoplasma and Mesoplasma species and is a sister lineage to (ii) the Apis clade of Spiroplasma. Spiroplasma and the Entomoplasmataceae are paraphyletic, but this status does not diminish their phylogenetic usefulness. Five species that were previously unclassified phylogenetically are basal to the Apis clade sensu strictu and to the Mycoides clade. One of these species, Spiroplasma sp. TIUS-1, has very poor helicity and a very small genome (840 kbp); this putative species can be envisioned as a ‘missing link’ in the evolution of the Mycoides–Entomoplasmataceae clade. The other two Spiroplasma clades are: (iii) the Citri–Chrysopicola–Mirum clade (serogroups I, II, V and VIII) and (iv) the ixodetis clade (serogroup VI). As Mesoplasma lactucae represents a basal divergence within the Mycoides–Entomoplasmataceae clade, and as Entomoplasma freundtii is basal to the Mycoides clade, M. mycoides and its allies must have arisen from an ancestor in the Entomoplasmataceae. The paraphyletic grouping that consists of the Hominis and Pneumoniae groups (sensu Johansson & Pettersson 2002 ) of Mycoplasma species contains the ancestral roots of Ureaplasma spp. and haemoplasmas. This clade is a sister lineage to the Entomoplasmatales clade. Serological classifications of spiroplasma are very highly supported by the trees presented. Genome size and G+C content of micro-organismal DNA were moderately conserved, but there have been frequent and polyphyletically distributed genome reductions. Sterol requirements were polyphyletic, as was the ability to grow in the presence of polyoxyethylene sorbitan-supplemented, but not serum-supplemented, media. As this character is not phylogenetically distributed, Mesoplasma and Entomoplasma should be combined into a single genus. The phylogenetic trees presented here confirm previous reports of polyphyly of the genus Mycoplasma. As both clades of Mycoplasma contain several species of great practical importance, a change of the genus name for species in either clade would have immense practical implications. In addition, a change of the genus name for M. mycoides would have to be approved by the Judicial Commission. For these reasons, the Linnaean and phylogenetic classifications of Mycoplasma must for now be discrepant.
-
-
-
Use of recA as an alternative phylogenetic marker in the family Vibrionaceae
More LessThis study analysed the usefulness of recA gene sequences as an alternative phylogenetic and/or identification marker for vibrios. The recA sequences suggest that the genus Vibrio is polyphyletic. The high heterogeneity observed within vibrios was congruent with former polyphasic taxonomic studies on this group. Photobacterium species clustered together and apparently nested within vibrios, while Grimontia hollisae was apart from other vibrios. Within the vibrios, Vibrio cholerae and Vibrio mimicus clustered apart from the other genus members. Vibrio harveyi- and Vibrio splendidus-related species formed compact separated groups. On the other hand, species related to Vibrio tubiashii appeared scattered in the phylogenetic tree. The pairs Vibrio coralliilyticus and Vibrio neptunius, Vibrio nereis and Vibrio xuii and V. tubiashii and Vibrio brasiliensis clustered completely apart from each other. There was a correlation of 0·58 between recA and 16S rDNA pairwise similarities. Strains of the same species have at least 94 % recA sequence similarity. recA gene sequences are much more discriminatory than 16S rDNA. For 16S rDNA similarity values above 98 % there was a wide range of recA similarities, from 83 to 99 %.
-
- International Committee On Systematics Of Prokaryotes
-
- Minutes
- Taxonomic Note
-
-
Proposal of Nakamurella gen. nov. as a substitute for the bacterial genus Microsphaera Yoshimi et al. 1996 and Nakamurellaceae fam. nov. as a substitute for the illegitimate bacterial family Microsphaeraceae Rainey et al. 1997
More LessThe bacterial genus Microsphaera Yoshimi et al. 1996 is illegitimate because of priority of the fungal genus Microsphaera (Wallr.) Lév. [Principle 2, Rule 51b(4) of the Bacteriological Code]. Therefore, a new genus name, Nakamurella, is proposed for the bacterial genus. The type species Microsphaera multipartita Yoshimi et al. 1996 becomes Nakamurella multipartita gen. nov., comb. nov. Due to the illegitimacy of the only genus in the family Microsphaeraceae Rainey et al. 1997, this family name is replaced by the new bacterial family name Nakamurellaceae.
-
Volumes and issues
-
Volume 74 (2024)
-
Volume 73 (2023)
-
Volume 72 (2022 - 2023)
-
Volume 71 (2020 - 2021)
-
Volume 70 (2020)
-
Volume 69 (2019)
-
Volume 68 (2018)
-
Volume 67 (2017)
-
Volume 66 (2016)
-
Volume 65 (2015)
-
Volume 64 (2014)
-
Volume 63 (2013)
-
Volume 62 (2012)
-
Volume 61 (2011)
-
Volume 60 (2010)
-
Volume 59 (2009)
-
Volume 58 (2008)
-
Volume 57 (2007)
-
Volume 56 (2006)
-
Volume 55 (2005)
-
Volume 54 (2004)
-
Volume 53 (2003)
-
Volume 52 (2002)
-
Volume 51 (2001)
-
Volume 50 (2000)
-
Volume 49 (1999)
-
Volume 48 (1998)
-
Volume 47 (1997)
-
Volume 46 (1996)
-
Volume 45 (1995)
-
Volume 44 (1994)
-
Volume 43 (1993)
-
Volume 42 (1992)
-
Volume 41 (1991)
-
Volume 40 (1990)
-
Volume 39 (1989)
-
Volume 38 (1988)
-
Volume 37 (1987)
-
Volume 36 (1986)
-
Volume 35 (1985)
-
Volume 34 (1984)
-
Volume 33 (1983)
-
Volume 32 (1982)
-
Volume 31 (1981)
-
Volume 30 (1980)
-
Volume 29 (1979)
-
Volume 28 (1978)
-
Volume 27 (1977)
-
Volume 26 (1976)
-
Volume 25 (1975)
-
Volume 24 (1974)
-
Volume 23 (1973)
-
Volume 22 (1972)
-
Volume 21 (1971)
-
Volume 20 (1970)
-
Volume 19 (1969)
-
Volume 18 (1968)
-
Volume 17 (1967)
-
Volume 16 (1966)
-
Volume 15 (1965)
-
Volume 14 (1964)
-
Volume 13 (1963)
-
Volume 12 (1962)
-
Volume 11 (1961)
-
Volume 10 (1960)
-
Volume 9 (1959)
-
Volume 8 (1958)
-
Volume 7 (1957)
-
Volume 6 (1956)
-
Volume 5 (1955)
-
Volume 4 (1954)
-
Volume 3 (1953)
-
Volume 2 (1952)
-
Volume 1 (1951)