Multilocus sequence analysis of Porphyromonas gingivalis indicates frequent recombination

Microbiology ◽  
2003 ◽  
Vol 149 (9) ◽  
pp. 2407-2415 ◽  
Author(s):  
Andreas Koehler ◽  
Helge Karch ◽  
Thomas Beikler ◽  
Thomas. F. Flemmig ◽  
Sebastian Suerbaum ◽  
...  

In this study, the genetic relationship of 19 Porphyromonas gingivalis isolates from patients with periodontitis was investigated by multilocus sequence analysis. Internal 400–600 bp DNA fragments of the 10 chromosomal genes ef-tu, ftsQ, hagB, gpdxJ, pepO, mcmA, dnaK, recA, pga and nah were amplified by PCR and sequenced. No two isolates were identical at all 10 loci. Phylogenetic analyses indicated a panmictic population structure of P. gingivalis. Split decomposition analysis, calculation of homoplasy ratios and analyses of clustered polymorphisms all indicate that recombination plays a major role in creating the genetic heterogeneity of P. gingivalis. A standardized index of association of 0·0898 indicates that the P. gingivalis genes analysed are close to linkage equilibrium.

2004 ◽  
Vol 46 (3) ◽  
pp. 145-152 ◽  
Author(s):  
Cecília Luiza S. Santos ◽  
Maria Anice M. Sallum ◽  
Peter G. Foster ◽  
Iray Maria Rocco

The genomic sequences of the Envelope-Non-Structural protein 1 junction region (E/NS1) of 84 DEN-1 and 22 DEN-2 isolates from Brazil were determined. Most of these strains were isolated in the period from 1995 to 2001 in endemic and regions of recent dengue transmission in São Paulo State. Sequence data for DEN-1 and DEN-2 utilized in phylogenetic and split decomposition analyses also include sequences deposited in GenBank from different regions of Brazil and of the world. Phylogenetic analyses were done using both maximum likelihood and Bayesian approaches. Results for both DEN-1 and DEN-2 data are ambiguous, and support for most tree bipartitions are generally poor, suggesting that E/NS1 region does not contain enough information for recovering phylogenetic relationships among DEN-1 and DEN-2 sequences used in this study. The network graph generated in the split decomposition analysis of DEN-1 does not show evidence of grouping sequences according to country, region and clades. While the network for DEN-2 also shows ambiguities among DEN-2 sequences, it suggests that Brazilian sequences may belong to distinct subtypes of genotype III.


2011 ◽  
Vol 78 (5) ◽  
pp. 1385-1396 ◽  
Author(s):  
Jennifer K. Parker ◽  
Justin C. Havird ◽  
Leonardo De La Fuente

ABSTRACTIsolates of the plant pathogenXylella fastidiosaare genetically very similar, but studies on their biological traits have indicated differences in virulence and infection symptomatology. Taxonomic analyses have identified several subspecies, and phylogenetic analyses of housekeeping genes have shown broad host-based genetic differences; however, results are still inconclusive for genetic differentiation of isolates within subspecies. This study employs multilocus sequence analysis of environmentally mediated genes (MLSA-E; genes influenced by environmental factors) to investigateX. fastidiosarelationships and differentiate isolates with low genetic variability. Potential environmentally mediated genes, including host colonization and survival genes related to infection establishment, were identifieda priori. The ratio of the rate of nonsynonymous substitutions to the rate of synonymous substitutions (dN/dS) was calculated to select genes that may be under increased positive selection compared to previously studied housekeeping genes. Nine genes were sequenced from 54X. fastidiosaisolates infecting different host plants across the United States. Results of maximum likelihood (ML) and Bayesian phylogenetic (BP) analyses are in agreement with knownX. fastidiosasubspecies clades but show novel within-subspecies differentiation, including geographic differentiation, and provide additional information regarding host-based isolate variation and specificity.dN/dSratios of environmentally mediated genes, though <1 due to high sequence similarity, are significantly greater than housekeeping genedN/dSratios and correlate with increased sequence variability. MLSA-E can more precisely resolve relationships between closely related bacterial strains with low genetic variability, such asX. fastidiosaisolates. Discovering the genetic relationships betweenX. fastidiosaisolates will provide new insights into the epidemiology of populations ofX. fastidiosa, allowing improved disease management in economically important crops.


2012 ◽  
Vol 62 (Pt_9) ◽  
pp. 2286-2295 ◽  
Author(s):  
Tulu Degefu ◽  
Endalkachew Wolde-meskel ◽  
Åsa Frostegård

The diversity of 71 rhizobial strains belonging to the genus Ensifer , isolated from root nodules of woody legumes growing in southern Ethiopia, was studied using multilocus sequence analysis (MLSA) and phenotypic approaches. Phylogenetic analyses based on core genes revealed that 43 strains were clustered in seven distinct and consistent positions (genospecies I–VII), while another 25 strains were also distinct but were discrepant in their placement on the different gene trees. The remaining three strains occupied the same phylogenetic branches as defined Ensifer species and thus were not distinct. Irrespective of their chromosomal background, the majority of the test strains were highly related with respect to their nifH and nodC gene sequences, suggesting that these symbionts might have acquired these genes recently from a common origin. On the nifH phylogenetic tree, the branch containing the test strains and reference species isolated from woody legumes in Africa was clearly separate from those isolated outside the continent, suggesting that these symbionts have a long history of separate evolution within Ensifer for this gene. A cross-inoculation study showed that our strains were capable of eliciting effective nodulation on the homologous host and on other host species. This suggests a potential to improve nitrogen fixation by selecting for broad-host-range inoculants. Our study confirms the presence of a wide diversity of Ensifer in East Africa and, while contributing to the general knowledge of the biodiversity within the genus, also highlights the need to focus on previously less-well-explored biogeographical regions to unravel as-yet-unidentified rhizobial resources.


2015 ◽  
Vol 65 (Pt_11) ◽  
pp. 3788-3793 ◽  
Author(s):  
Wei Fang ◽  
Min-wei Guo ◽  
Zhi-yong Ruan ◽  
Han Xue ◽  
Lai-fa Wang ◽  
...  

Four novel bacterial strains belonging to the genus Kurthia were isolated from the surface of a weevil of the family Curculionidae (strain 10y-14T), and from bark samples of hybrid poplar, Populus × euramericana (strains 6-3, 2-5 and 06C10-3-14), in Puyang, Henan Province, China. Phylogenetic analyses of the 16S rRNA gene and multilocus sequence analysis (MLSA) data showed that the four strains form a distinct cluster in the genus Kurthia, indicating that they all belong to a single taxon within the genus. DNA–DNA hybridization levels between strain 10y-4T and Kurthia huakuii LAM0618T and Kurthia massiliensis DSM 24639T were 58.31 and 53.92 %, respectively. This indicates that the four novel strains represent a species distinct from these two closely related species. The DNA G+C content of the novel strains was 42.1–42.6 %. The major fatty acids were iso-C15 : 0 and anteiso-C15 : 0.The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unknown phospholipid and unidentified aminophospholipids. The predominant menaquinones were MK-7 (90 %) and MK-6 (10 %). The major cell-wall amino acids were lysine, alanine, glutamic acid and glycine. On the basis of the MLSA and 16S rRNA gene sequence phylogenetic analyses, DNA–DNA reassociation values, DNA base composition, and biochemical and phenotypic characteristics, the four strains are considered to represent a novel species within the genus Kurthia, for which the name Kurthia populi sp. nov. is proposed. The type strain is 10y-14T ( = CFCC 11600T = KCTC 33522T).


Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 995-1010 ◽  
Author(s):  
Rafael Zardoya ◽  
Axel Meyer

The complete nucleotide sequence of the 16,407-bp mitochondrial genome of the coelacanth (Latimeria chalumnae) was determined. The coelacanth mitochondrial genome order is identical to the consensus vertebrate gene order which is also found in all ray-finned fishes, the lungfish, and most tetrapods. Base composition and codon usage also conform to typical vertebrate patterns. The entire mitochondrial genome was PCR-amplified with 24 sets of primers that are expected to amplify homologous regions in other related vertebrate species. Analyses of the control region of the coelacanth mitochondrial genome revealed the existence of four 22-bp tandem repeats close to its 3′ end. The phylogenetic analyses of a large data set combining genes coding for rRNAs, tRNA, and proteins (16,140 characters) confirmed the phylogenetic position of the coelacanth as a lobe-finned fish; it is more closely related to tetrapods than to ray-finned fishes. However, different phylogenetic methods applied to this largest available molecular data set were unable to resolve unambiguously the relationship of the coelacanth to the two other groups of extant lobe-finned fishes, the lungfishes and the tetrapods. Maximum parsimony favored a lungfish/coelacanth or a lungfish/tetrapod sistergroup relationship depending on which transversion:transition weighting is assumed. Neighbor-joining and maximum likelihood supported a lungfish/tetrapod sistergroup relationship.


2011 ◽  
Vol 81 (1-2) ◽  
pp. 32-42 ◽  
Author(s):  
Yoshiyuki Ishitani ◽  
Sohta A. Ishikawa ◽  
Yuji Inagaki ◽  
Masashi Tsuchiya ◽  
Kozo Takahashi ◽  
...  

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Susanne Vogeler ◽  
Stefano Carboni ◽  
Xiaoxu Li ◽  
Alyssa Joyce

Abstract Background Apoptosis is an important process for an organism’s innate immune system to respond to pathogens, while also allowing for cell differentiation and other essential life functions. Caspases are one of the key protease enzymes involved in the apoptotic process, however there is currently a very limited understanding of bivalve caspase diversity and function. Results In this work, we investigated the presence of caspase homologues using a combination of bioinformatics and phylogenetic analyses. We blasted the Crassostrea gigas genome for caspase homologues and identified 35 potential homologues in the addition to the already cloned 23 bivalve caspases. As such, we present information about the phylogenetic relationship of all identified bivalve caspases in relation to their homology to well-established vertebrate and invertebrate caspases. Our results reveal unexpected novelty and complexity in the bivalve caspase family. Notably, we were unable to identify direct homologues to the initiator caspase-9, a key-caspase in the vertebrate apoptotic pathway, inflammatory caspases (caspase-1, − 4 or − 5) or executioner caspases-3, − 6, − 7. We also explored the fact that bivalves appear to possess several unique homologues to the initiator caspase groups − 2 and − 8. Large expansions of caspase-3 like homologues (caspase-3A-C), caspase-3/7 group and caspase-3/7-like homologues were also identified, suggesting unusual roles of caspases with direct implications for our understanding of immune response in relation to common bivalve diseases. Furthermore, we assessed the gene expression of two initiator (Cg2A, Cg8B) and four executioner caspases (Cg3A, Cg3B, Cg3C, Cg3/7) in C. gigas late-larval development and during metamorphosis, indicating that caspase expression varies across the different developmental stages. Conclusion Our analysis provides the first overview of caspases across different bivalve species with essential new insights into caspase diversity, knowledge that can be used for further investigations into immune response to pathogens or regulation of developmental processes.


Zootaxa ◽  
2021 ◽  
Vol 4974 (2) ◽  
pp. 333-360
Author(s):  
KOJI TOJO ◽  
KEN MIYAIRI ◽  
YUTO KATO ◽  
AYANA SAKANO ◽  
TOMOYA SUZUKI

A new mayfly species, Bleptus michinokuensis sp. nov. (Ephemeroptera: Heptageniidae) is described on the basis of specimens of male and female adults and mature nymphs collected at a seepage zone of a small freshwater branch of the ‘Tachiya-zawa-gawa’ River located amongst the northern foothills of Mt. Gassan (Shonai-machi Town, Yamagata Prefecture, Japan). This new Bleptus species is characterized by its clear fore and hind wings. That is, they neither exhibit the distinct black band on the fore wings, nor the characteristic darkened margins along the edges of both the fore and hind wings. Rather it has a blackish colored terminal half of its fore legs (i.e., tibial, tarsal and pretarsal segments). These features differ clearly when comparing them to the other known species, Bleptus fasciatus Eaton. The information and data describing the habitat and distribution range of this new species are also noted. We also examined and discussed the genetic relationship of two Bleptus mayflies to settle the taxonomic status, inferred from the partially sequenced cytochrome c oxidase subunit I (COI) and large mitochondrial ribosomal subunit (16S rRNA) genes, and also the nuclear internal transcribed spacer 2 (ITS2) gene sequences. Consequently, phenetic and molecular phylogenetic analyses agreed well in terms of clustering. 


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