scholarly journals Sequence Diversity and Molecular Evolution of the Leukotoxin (lktA) Gene in Bovine and Ovine Strains ofMannheimia (Pasteurella)haemolytica

2001 ◽  
Vol 183 (4) ◽  
pp. 1394-1404 ◽  
Author(s):  
Robert L. Davies ◽  
Thomas S. Whittam ◽  
Robert K. Selander
Keyword(s):  
Molecular Evolution ◽  
Allelic Diversity ◽  
Pasteurella Haemolytica ◽  
Intragenic Recombination ◽  
Allelic Variants ◽  
Amino Acid Divergence ◽  
History Of ◽  
Nucleotide Divergence ◽  
Pasteurella Trehalosi ◽  
Different Sources

ABSTRACT The molecular evolution of the leukotoxin structural gene (lktA) of Mannheimia (Pasteurella)haemolytica was investigated by nucleotide sequence comparison of lktA in 31 bovine and ovine strains representing the various evolutionary lineages and serotypes of the species. Eight major allelic variants (1.4 to 15.7% nucleotide divergence) were identified; these have mosaic structures of varying degrees of complexity reflecting a history of horizontal gene transfer and extensive intragenic recombination. The presence of identical alleles in strains of different genetic backgrounds suggests that assortative (entire gene) recombination has also contributed to strain diversification in M. haemolytica. Five allelic variants occur only in ovine strains and consist of recombinant segments derived from as many as four different sources. Four of these alleles consist of DNA (52.8 to 96.7%) derived from the lktA gene of the two related species Mannheimia glucosida andPasteurella trehalosi, and four contain recombinant segments derived from an allele that is associated exclusively with bovine or bovine-like serotype A2 strains. The two major lineages of ovine serotype A2 strains possess lktA alleles that have very different evolutionary histories and encode divergent leukotoxins (5.3% amino acid divergence), but both contain segments derived from the bovine allele. Homologous segments of donor and recipient alleles are identical or nearly identical, indicating that the recombination events are relatively recent and probably postdate the domestication of cattle and sheep. Our findings suggest that host switching of bovine strains from cattle to sheep, together with inter- and intraspecies recombinational exchanges, has played an important role in generating leukotoxin diversity in ovine strains. In contrast, there is limited allelic diversity of lktA in bovine strains, suggesting that transmission of strains from sheep to cattle has been less important in leukotoxin evolution.

scholarly journals Mosaic Structure and Molecular Evolution of the Leukotoxin Operon (lktCABD) in Mannheimia (Pasteurella) haemolytica, Mannheimia glucosida, and Pasteurella trehalosi

2002 ◽  
Vol 184 (1) ◽  
pp. 266-277 ◽  
Author(s):  
Robert L. Davies ◽  
Susan Campbell ◽  
Thomas S. Whittam
Keyword(s):  
Amino Acid ◽  
Molecular Evolution ◽  
Antigenic Variation ◽  
Amino Acid Replacement ◽  
Pasteurella Haemolytica ◽  
Mosaic Structure ◽  
Common Mechanism ◽  
Intragenic Recombination ◽  
Evolutionary Constraint ◽  
Pasteurella Trehalosi

ABSTRACT The mosaic structure and molecular evolution of the leukotoxin operon (lktCABD) was investigated by nucleotide sequence comparison of the lktC, lktB, and lktD genes in 23 Mannheimia (Pasteurella) haemolytica, 6 Mannheimia glucosida, and 4 Pasteurella trehalosi strains. Sequence variation in the lktA gene has been described previously (R. L. Davies et al., J. Bacteriol. 183:1394–1404, 2001). The leukotoxin operon of M. haemolytica has a complex mosaic structure and has been derived by extensive inter- and intraspecies horizontal DNA transfer and intragenic recombination events. However, the pattern of recombination varies throughout the operon and among the different evolutionary lineages of M. haemolytica. The lktA and lktB genes have the most complex mosaic structures with segments derived from up to four different sources, including M. glucosida and P. trehalosi. In contrast, the lktD gene is highly conserved in M. haemolytica. The lktC, lktA, and lktB genes of strains representing the major ovine lineages contain recombinant segments derived from bovine or bovine-like serotype A2 strains. These findings support the previous conclusion that host switching of bovine A2 strains from cattle to sheep has played a major role in the evolution of the leukotoxin operon in ovine strains of M. haemolytica. Homologous segments of donor and recipient alleles are identical, or nearly identical, indicating that the recombinational exchanges occurred relatively recent in evolutionary terms. The 5′ and 3′ ends of the operon are highly conserved in M. haemolytica, which suggests that multiple horizontal exchanges of the complete operon have occurred by a common mechanism such as transduction. Although the lktA and lktB genes both have complex mosaic structures and high nucleotide substitution rates, the amino acid diversity of LktB is significantly lower than that of LktA due to a higher degree of evolutionary constraint against amino acid replacement. The recombinational exchanges within the leukotoxin operon have had greatest effect on LktA and probably provide an adaptive advantage against the host antibody response by generating novel antigenic variation at surface-exposed sites.

scholarly journals Molecular Evolution of the dotA Gene in Legionella pneumophila

2003 ◽  
Vol 185 (21) ◽  
pp. 6269-6277 ◽  
Author(s):  
Kwan Soo Ko ◽  
Seong Karp Hong ◽  
Hae Kyung Lee ◽  
Mi-Yeoun Park ◽  
Yoon-Hoh Kook
Keyword(s):  
Amino Acid ◽  
Molecular Evolution ◽  
Legionella Pneumophila ◽  
Decomposition Analysis ◽  
Amino Acid Sequences ◽  
Intragenic Recombination ◽  
Heterogeneous Structure ◽  
Gene Encoding ◽  
Synonymous And Nonsynonymous Substitutions ◽  
Different Sources

ABSTRACT The molecular evolution of dotA, which is related to the virulence of Legionella pneumophila, was investigated by comparing the sequences of 15 reference strains (serogroups 1 to 15). It was found that dotA has a complex mosaic structure. The whole dotA gene of Legionella pneumophila subsp. pneumophila serogroups 2, 6, and 12 has been transferred from Legionella pneumophila subsp. fraseri. A discrepancy was found between the trees inferred from the nucleotide and deduced amino acid sequences of dotA, which suggests that multiple hits, resulting in synonymous substitutions, have occurred. Gene phylogenies inferred from three different segments (the 5′-end region, the central, large periplasmic domain, and the 3′-end region) showed impressively dissimilar topologies. This was concordant with the sequence polymorphisms, indicating that each region has experienced an independent evolutionary history, and was evident even within the same domain of each strain. For example, the PP2 domain was found to have a heterogeneous structure, which led us hypothesize that the dotA gene of L. pneumophila may have originated from two or more different sources. Comparisons of synonymous and nonsynonymous substitutions demonstrated that the PP2 domain has been under strong selective pressure with respect to amino acid change. Split decomposition analysis also supported the intragenic recombination of dotA. Multiple recombinational exchange within the dotA gene, encoding an integral cytoplasmic membrane protein that is secreted, probably provided increased fitness in certain environmental niches, such as within a particular biofilm community or species of amoebae.

scholarly journals Sequence Diversity and Molecular Evolution of the Heat-Modifiable Outer Membrane Protein Gene (ompA) of Mannheimia(Pasteurella) haemolytica, Mannheimia glucosida, and Pasteurella trehalosi

2004 ◽  
Vol 186 (17) ◽  
pp. 5741-5752 ◽  
Author(s):  
Robert L. Davies ◽  
Inkyoung Lee
Keyword(s):  
Molecular Evolution ◽  
Host Species ◽  
Cell Receptor ◽  
Dna Transfer ◽  
Class I ◽  
Nucleotide Sequence Analysis ◽  
Intragenic Recombination ◽  
Class Iii ◽  
Recombination Class ◽  
Pasteurella Trehalosi

ABSTRACT The OmpA (or heat-modifiable) protein is a major structural component of the outer membranes of gram-negative bacteria. The protein contains eight membrane-traversing β-strands and four surface-exposed loops. The genetic diversity and molecular evolution of OmpA were investigated in 31 Mannheimia (Pasteurella) haemolytica, 6 Mannheimia glucosida, and 4 Pasteurella trehalosi strains by comparative nucleotide sequence analysis. The OmpA proteins of M. haemolytica and M. glucosida contain four hypervariable domains located at the distal ends of the surface-exposed loops. The hypervariable domains of OmpA proteins from bovine and ovine M. haemolytica isolates are very different but are highly conserved among strains from each of these two host species. Fourteen different alleles representing four distinct phylogenetic classes, classes I to IV, were identified in M. haemolytica and M. glucosida. Class I, II, and IV alleles were associated with bovine M. haemolytica, ovine M. haemolytica, and M. glucosida strains, respectively, whereas class III alleles were present in certain M. haemolytica and M. glucosida isolates. Class I and II alleles were associated with divergent lineages of bovine and ovine M. haemolytica strains, respectively, indicating a history of horizontal DNA transfer and assortative (entire gene) recombination. Class III alleles have mosaic structures and were derived by horizontal DNA transfer and intragenic recombination. Our findings suggest that OmpA is under strong selective pressure from the host species and that it plays an important role in host adaptation. It is proposed that the OmpA protein of M. haemolytica acts as a ligand and is involved in binding to specific host cell receptor molecules in cattle and sheep. P. trehalosi expresses two OmpA homologs that are encoded by different tandemly arranged ompA genes. The P. trehalosi ompA genes are highly diverged from those of M. haemolytica and M. glucosida, and evidence is presented to suggest that at least one of these genes was acquired by horizontal DNA transfer.

scholarly journals Application of Multilocus Sequence Typing To Study the Genetic Structure of Megaplasmids in Medicago-Nodulating Rhizobia

2010 ◽  
Vol 76 (12) ◽  
pp. 3967-3977 ◽  
Author(s):  
Peter van Berkum ◽  
Patrick Elia ◽  
Bertrand D. Eardly
Keyword(s):  
Genetic Structure ◽  
Multilocus Sequence Typing ◽  
Sinorhizobium Meliloti ◽  
Natural Populations ◽  
Allelic Diversity ◽  
Intragenic Recombination ◽  
Symbiotic Gene ◽  
Close Proximity ◽  
History Of ◽  
Genetic Structure And Diversity

ABSTRACT A multilocus sequence typing (MLST) analysis was used to examine the genetic structure and diversity within the two large extrachromosomal replicons in Medicago-nodulating rhizobia (Sinorhizobium meliloti and Sinorhizobium medicae). The allelic diversity within these replicons was high compared to the reported diversity within the corresponding chromosomes of the same strains (P. van Berkum et al., J. Bacteriol. 188:5570-5577, 2006). Also, there was strong localized linkage disequilibrium (LD) between certain pSymA loci: e.g., nodC and nifD. Although both of these observations could be explained by positive (or diversifying) selection by plant hosts, results of tests for positive selection did not provide consistent support for this hypothesis. The strong LD observed between the nodC and nifD genes could also be explained by their close proximity on the pSymA replicon. Evidence was obtained that some nodC alleles had a history of intragenic recombination, while other alleles of this locus had a history of intergenic recombination. Both types of recombination were associated with a decline in symbiotic competence with Medicago sativa as the host plant. The combined observations of LD between the nodC and nifD genes and intragenic recombination within one of these loci indicate that the symbiotic gene region on the pSymA plasmid has evolved as a clonal segment, which has been laterally transferred within the natural populations.

The perils and dangers of these knights (and undead peasants): Interpreting English and Scottish Extent Rolls of 1297–1305

2016 ◽  
Vol 36 (1) ◽  
pp. 13-39 ◽  
Author(s):  
J. Donnelly
Keyword(s):  
Social History ◽  
Economic History ◽  
Time Frame ◽  
Compte Rendu ◽  
History Of ◽  
Different Sources

Medieval Scottish economic and social history has held little interest for a unionist establishment but, just when a recovery of historic independence begins to seem possible, this paper tackles a (perhaps the) key pre-1424 source. It is compared with a Rutland text, in a context of foreign history, both English and continental. The Berwickshire text is not, as was suggested in 2014, a ‘compte rendu’ but rather an ‘extent’, intended to cross-check such accounts. Read alongside the Rutland roll, it is not even a single ‘compte’ but rather a palimpsest of different sources and times: a possibility beyond earlier editorial imaginings. With content falling (largely) within the time-frame of the PoMS project (although not actually included), when the economic history of Scotland in Europe is properly explored, the sources discussed here will be key and will offer an interesting challenge to interpretation. And some surprises about their nature and date.

scholarly journals Linking morphological and molecular sources to disentangle the case of Xylodon australis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Javier Fernández-López ◽  
M. Teresa Telleria ◽  
Margarita Dueñas ◽  
Mara Laguna-Castro ◽  
Klaus Schliep ◽  
...  
Keyword(s):  
New Zealand ◽  
Phylogenetic Analyses ◽  
Single Species ◽  
R Package ◽  
Molecular Data ◽  
Historical Collections ◽  
Close Relationship ◽  
Kinship Relations ◽  
History Of ◽  
Different Sources

AbstractThe use of different sources of evidence has been recommended in order to conduct species delimitation analyses to solve taxonomic issues. In this study, we use a maximum likelihood framework to combine morphological and molecular traits to study the case of Xylodon australis (Hymenochaetales, Basidiomycota) using the locate.yeti function from the phytools R package. Xylodon australis has been considered a single species distributed across Australia, New Zealand and Patagonia. Multi-locus phylogenetic analyses were conducted to unmask the actual diversity under X. australis as well as the kinship relations respect their relatives. To assess the taxonomic position of each clade, locate.yeti function was used to locate in a molecular phylogeny the X. australis type material for which no molecular data was available using morphological continuous traits. Two different species were distinguished under the X. australis name, one from Australia–New Zealand and other from Patagonia. In addition, a close relationship with Xylodon lenis, a species from the South East of Asia, was confirmed for the Patagonian clade. We discuss the implications of our results for the biogeographical history of this genus and we evaluate the potential of this method to be used with historical collections for which molecular data is not available.

scholarly journals Recombination and Selection at Brassica Self-Incompatibility Loci

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 413-425 ◽  
Author(s):  
Philip Awadalla ◽  
Deborah Charlesworth
Keyword(s):  
Linkage Disequilibrium ◽  
Balancing Selection ◽  
Brassica Species ◽  
Selective Constraint ◽  
Intragenic Recombination ◽  
Self Incompatibility ◽  
History Of ◽  
Unknown Gene ◽  
Slg Gene ◽  
High Diversity

Abstract In Brassica species, self-incompatibility is controlled genetically by haplotypes involving two known genes, SLG and SRK, and possibly an as yet unknown gene controlling pollen incompatibility types. Alleles at the incompatibility loci are maintained by frequency-dependent selection, and diversity at SLG and SRK appears to be very ancient, with high diversity at silent and replacement sites, particularly in certain “hypervariable portions of the genes. It is important to test whether recombination occurs in these genes before inferences about function of different parts of the genes can be made from patterns of diversity within their sequences. In addition, it has been suggested that, to maintain the relationship between alleles within a given S-haplotype, recombination is suppressed in the S-locus region. The high diversity makes many population genetic measures of recombination inapplicable. We have analyzed linkage disequilibrium within the SLG gene of two Brassica species, using published coding sequences. The results suggest that intragenic recombination has occurred in the evolutionary history of these alleles. This is supported by patterns of synonymous nucleotide diversity within both the SLG and SRK genes, and between domains of the SRK gene. Finally, clusters of linkage disequilibrium within the SLG gene suggest that hypervariable regions are under balancing selection, and are not merely regions of relaxed selective constraint.

scholarly journals Independent origins of the Golgi phosphoprotein 3 oncoprotein gene

2021 ◽  
Author(s):  
Juan C. Opazo ◽  
Michael W. Vandewege ◽  
Javier Gutierrez ◽  
Kattina Zavala ◽  
Luis Vargas-Chacoff ◽  
...  
Keyword(s):  
Gene Family ◽  
Transcript Abundance ◽  
Single Copy ◽  
Model Systems ◽  
Deep Roots ◽  
Starting Point ◽  
Amino Acid Divergence ◽  
Evolutionarily Conserved ◽  
History Of ◽  
Divergence Estimates

AbstractGolgi phosphoprotein 3 (GOLPH3) is considered the first oncoprotein of the Golgi apparatus. It was identified as an evolutionarily conserved protein upon its discovery about 20 years ago, but its function remains puzzling in normal and cancer cells. The GOLPH3 gene is part of a group of genes that also includes the GOLPH3L gene. Because cancer has deep roots in multicellular evolution, studying the evolution of the GOLPH3 gene family in non-model species represents an opportunity to identify new model systems that could help better understand the biology behind this group of genes. The main goal of this study is to explore the evolution of the GOLPH3 gene family in birds as a starting point to understand the evolutionary history of this oncoprotein. We identified a repertoire of three GOLPH3 genes in birds. We found duplicated copies of the GOLPH3 gene in all main groups of birds other than paleognaths, and a single copy of the GOLPH3L gene. We suggest there were at least three independent origins for GOLPH3 duplicates. Amino acid divergence estimates show that most of the variation is located in the N-terminal region of the protein. Our transcript abundance estimations show that one paralog is highly and ubiquitously expressed, and the others were variable. Our results are an example of the significance of understanding the evolution of the GOLPH3 gene family, especially for unraveling its structural and functional attributes.

scholarly journals The Anti-Bogomil Anathemas in the Synodikon of Tsar Boril and in the Discourse of Kosmas the Presbyter against the Bogomils

2019 ◽  
Vol 9 ◽  
pp. 107-122
Author(s):  
Anna-Maria Totomanova
Keyword(s):  
Original Form ◽  
Greek Version ◽  
Substantial Evidence ◽  
National Library ◽  
Additional Information ◽  
History Of ◽  
Romanian Academy ◽  
Points Of View ◽  
Academy Of Sciences ◽  
Different Sources

During the last dеcade the history of the Synodikon of the Оrthodoxy in Medieval Bulgaria has been tackled upon from different points of view. The author of this paper provided substantial evidence proving that the Synodikon of Tsar Boril did not survive in its original form. By the end of the 14th c. the original translation was amended and edited in order to be installed in a canonical-liturgical compilation (archieratikon) that includes texts and services related to the Feast of Orthodoxy. The compilation is kept in the National Library in Palauzov’s collection No 289. Additional information about the different sources of some rubrics of the Synodikon, which do not correspond to its Greek version, was also provided. Recently we have discovered that the text, preserved in a collection of Damasckin type from the beginning of 16th c. (Drinov’s copy) represents indeed a compilation: its first part (the canonical one) contains the translation of the Palaeologan version of the Synodikon, which survived also in a triodion from the Library of the Romanian Academy of Sciences. The second part of the compilation however coincides with the text of the Synodikon of Tsar Boril with all amendments related to the Bulgarian history – rulers, patriarchs, bishops and nobles. This “Bulgarian” part of the Synodikon includes a series of anathemas against Bogomils, that do not have Greek correspondences and generally repeat the anti-Bogomils anathemas taken from the Letter of Patriarch Kosmas in a simpler language more understandable to the faithful. This paper is tracing the connection between these anathemas and the Anti-Bogomils anathemas in the Discourse of Kosmas the Presbyter against the Bogomils.

Internationalising Arts, Gaining Visibility: Internationalisation of the National Art Gallery through the Promulgation of the Malayan Identity and Commonwealth Ideals

2021 ◽  
pp. 1-15
Author(s):  
Sarena Abdullah
Keyword(s):  
World War Ii ◽  
Art Gallery ◽  
Exhibition History ◽  
International Visibility ◽  
History Of ◽  
Commonwealth Institute ◽  
British Commonwealth ◽  
Post War ◽  
Relationship Of ◽  
Different Sources

Abstract The early history of the Malaysian National Art Gallery has been thoroughly elucidated through many different sources but its role as promoter of Malaysia’s art in the first ten years of its early formation have never been critically examined. This paper will trace the transnational relationship of the National Art Gallery through its exhibitions co-organised with the Commonwealth Institute in London within the larger context of the post-World War II period and the British decolonisation in Malaya. This paper will situate and contextualise its research on Malaya’s early exhibition history on multiculturalism and the Malayan identity framework, and later draw the link and connection between the Commonwealth Institute and the context of its establishment in Britain and the establishment of the National Art Gallery in Malaya. Subsequently, this paper will trace and demonstrate the importance of these early exhibitions to be understood in the larger context of (a) the need to exert international visibility during the period of Confrontation and (b) the exhibition as a platform that mooted the Malayan identity that aligns with the core values and principles of the Commonwealth. As such, this paper demonstrates that the transnational relations between the National Art Gallery and the Commonwealth Institute in the realm of Malaysia’s exhibition history must be analysed in tandem with the issues that are faced by a new British Commonwealth country, i.e., Malaysia during the immediate post-war period.

Sign in / Sign up

Export Citation Format

Share Document