The Experts below are selected from a list of 720 Experts worldwide ranked by ideXlab platform

Mavis Hendson - One of the best experts on this subject based on the ideXlab platform.

  • genetic characteristics of borrelia coriaceae isolates from the soft tick ornithodoros coriaceus acari argasidae
    Journal of Clinical Microbiology, 2000
    Co-Authors: Mavis Hendson, Robert S Lane
    Abstract:

    Two Borrelia isolates (CA434 and CA435) cultured from the soft tick Ornithodoros coriaceus were analyzed by contour-clamped homogeneous electric field gel electrophoresis of unrestricted and ApaI-restricted DNA, standard electrophoresis of BamHI- and HindIII-restricted DNA, Southern hybridization, restriction fragment length polymorphism and sequencing of the 16S rRNA gene, and amplification of the 5S-23S intergenic spacer region. These isolates were compared with Borrelia coriaceae type strain Co53, B. burgdorferi sensu stricto strain CA4, and the relapsing-fever spirochete B. parkeri (undesignated). The 16S rRNA region of CA434 and CA435 differed from that of B. coriaceae type strain Co53 by the presence of 1 base (C) at position 367 (GenBank accession no. U42286). The linear plasmid profile of CA434 was similar to that of Co53, and the ApaI, BamHI, and HindIII restriction fingerprints of the total cellular DNA of CA434 and Co53 were similar. In contrast, CA435 differed somewhat from CA434 and Co53, which demonstrates that B. coriaceae is genetically diverse. Southern hybridization showed that the DNAs of CA434 and CA435 hybridized strongly with the digoxigeninlabeled DNA of Co53. Low homology was found between the DNA of Co53 and that of B. parkeri. The 16S rRNA sequence of B. parkeri was identical to previously published results for B. parkeri strain M3001 (GenBank accession number U42296). CA434 and CA435 represent only the second and third isolates of B. coriaceae obtained from any source since its initial isolation from an O. coriaceus tick in 1985. All three B. coriaceae isolates were derived from adult ticks collected from the same locality in northwestern California. Difficulties encountered in detecting B. coriaceae in, and isolating this spirochete from, the tissues of O. coriaceus are discussed. The lack of concordance between different detection or isolation methods suggests that reliance upon a single technique may grossly underestimate the true prevalence of spirochetal infection in wild-caught O. coriaceus ticks. In 1985, a previously unrecognized Borrelia-like spirochete was detected in all three trophic stages of the human-biting soft tick Ornithodoros coriaceus from northern California, and a single isolate from a male tick was partially characterized morphologically and immunochemically (15). Shortly thereafter, this isolate, designated Co53, was characterized genetically and phenotypically and named Borrelia coriaceae after its tick vector (14, 19). B. coriaceae was found to be passed transstadially and occasionally via eggs in its tick vector (15, 17), and the Columbian black-tailed deer (Odocoileus hemionus columbianus) was implicated as a probable natural host of the spirochete (16). Furthermore, circumstantial evidence suggested that B. coriaceae is the cause of epizootic bovine abortion (EBA), a significant disease of rangeland cattle in some areas of the far-western United States, particularly California (15). Subsequent studies, while not ruling out the possibility that B. coriaceae or another spirochete is involved in the epizoology of EBA, have not established a firm link between the presence of spirochetes and bovine abortion (28, 29, 37, 38, 41). To our knowledge, no more isolates of B. coriaceae have been isolated since 1985. Here we genetically characterize two more recently acquired isolates of B. coriaceae that were derived from O. coriaceus ticks and compare them with the Co53 type strain of B. coriaceae, the relapsing-fever spirochete B. parkeri, and the Lyme disease spirochete B. burgdorferi sensu stricto (s.s.). These new isolates of B. coriaceae, designated CA434 and CA435, represent only the second and third iso

  • genetic characteristics of borrelia coriaceae isolates from the soft tick ornithodoros coriaceus acari argasidae
    Journal of Clinical Microbiology, 2000
    Co-Authors: Mavis Hendson
    Abstract:

    Two Borrelia isolates (CA434 and CA435) cultured from the soft tick Ornithodoros coriaceus were analyzed by contour-clamped homogeneous electric field gel electrophoresis of unrestricted and ApaI-restricted DNA, standard electrophoresis of BamHI- and HindIII-restricted DNA, Southern hybridization, restriction fragment length polymorphism and sequencing of the 16S rRNA gene, and amplification of the 5S-23S intergenic spacer region. These isolates were compared with Borrelia coriaceae type strain Co53, B. burgdorferi sensu stricto strain CA4, and the relapsing-fever spirochete B. parkeri (undesignated). The 16S rRNA region of CA434 and CA435 differed from that of B. coriaceae type strain Co53 by the presence of 1 base (C) at position 367 (GenBank accession no. U42286). The linear plasmid profile of CA434 was similar to that of Co53, and the ApaI, BamHI, and HindIII restriction fingerprints of the total cellular DNA of CA434 and Co53 were similar. In contrast, CA435 differed somewhat from CA434 and Co53, which demonstrates that B. coriaceae is genetically diverse. Southern hybridization showed that the DNAs of CA434 and CA435 hybridized strongly with the digoxigenin-labeled DNA of Co53. Low homology was found between the DNA of Co53 and that of B. parkeri. The 16S rRNA sequence of B. parkeri was identical to previously published results for B. parkeri strain M3001 (GenBank accession number U42296). CA434 and CA435 represent only the second and third isolates of B. coriaceae obtained from any source since its initial isolation from an O. coriaceus tick in 1985. All three B. coriaceae isolates were derived from adult ticks collected from the same locality in northwestern California. Difficulties encountered in detecting B. coriaceae in, and isolating this spirochete from, the tissues of O. coriaceus are discussed. The lack of concordance between different detection or isolation methods suggests that reliance upon a single technique may grossly underestimate the true prevalence of spirochetal infection in wild-caught O. coriaceus ticks.

Robert S Lane - One of the best experts on this subject based on the ideXlab platform.

  • genetic characteristics of borrelia coriaceae isolates from the soft tick ornithodoros coriaceus acari argasidae
    Journal of Clinical Microbiology, 2000
    Co-Authors: Mavis Hendson, Robert S Lane
    Abstract:

    Two Borrelia isolates (CA434 and CA435) cultured from the soft tick Ornithodoros coriaceus were analyzed by contour-clamped homogeneous electric field gel electrophoresis of unrestricted and ApaI-restricted DNA, standard electrophoresis of BamHI- and HindIII-restricted DNA, Southern hybridization, restriction fragment length polymorphism and sequencing of the 16S rRNA gene, and amplification of the 5S-23S intergenic spacer region. These isolates were compared with Borrelia coriaceae type strain Co53, B. burgdorferi sensu stricto strain CA4, and the relapsing-fever spirochete B. parkeri (undesignated). The 16S rRNA region of CA434 and CA435 differed from that of B. coriaceae type strain Co53 by the presence of 1 base (C) at position 367 (GenBank accession no. U42286). The linear plasmid profile of CA434 was similar to that of Co53, and the ApaI, BamHI, and HindIII restriction fingerprints of the total cellular DNA of CA434 and Co53 were similar. In contrast, CA435 differed somewhat from CA434 and Co53, which demonstrates that B. coriaceae is genetically diverse. Southern hybridization showed that the DNAs of CA434 and CA435 hybridized strongly with the digoxigeninlabeled DNA of Co53. Low homology was found between the DNA of Co53 and that of B. parkeri. The 16S rRNA sequence of B. parkeri was identical to previously published results for B. parkeri strain M3001 (GenBank accession number U42296). CA434 and CA435 represent only the second and third isolates of B. coriaceae obtained from any source since its initial isolation from an O. coriaceus tick in 1985. All three B. coriaceae isolates were derived from adult ticks collected from the same locality in northwestern California. Difficulties encountered in detecting B. coriaceae in, and isolating this spirochete from, the tissues of O. coriaceus are discussed. The lack of concordance between different detection or isolation methods suggests that reliance upon a single technique may grossly underestimate the true prevalence of spirochetal infection in wild-caught O. coriaceus ticks. In 1985, a previously unrecognized Borrelia-like spirochete was detected in all three trophic stages of the human-biting soft tick Ornithodoros coriaceus from northern California, and a single isolate from a male tick was partially characterized morphologically and immunochemically (15). Shortly thereafter, this isolate, designated Co53, was characterized genetically and phenotypically and named Borrelia coriaceae after its tick vector (14, 19). B. coriaceae was found to be passed transstadially and occasionally via eggs in its tick vector (15, 17), and the Columbian black-tailed deer (Odocoileus hemionus columbianus) was implicated as a probable natural host of the spirochete (16). Furthermore, circumstantial evidence suggested that B. coriaceae is the cause of epizootic bovine abortion (EBA), a significant disease of rangeland cattle in some areas of the far-western United States, particularly California (15). Subsequent studies, while not ruling out the possibility that B. coriaceae or another spirochete is involved in the epizoology of EBA, have not established a firm link between the presence of spirochetes and bovine abortion (28, 29, 37, 38, 41). To our knowledge, no more isolates of B. coriaceae have been isolated since 1985. Here we genetically characterize two more recently acquired isolates of B. coriaceae that were derived from O. coriaceus ticks and compare them with the Co53 type strain of B. coriaceae, the relapsing-fever spirochete B. parkeri, and the Lyme disease spirochete B. burgdorferi sensu stricto (s.s.). These new isolates of B. coriaceae, designated CA434 and CA435, represent only the second and third iso

Jack B Fisher - One of the best experts on this subject based on the ideXlab platform.

  • branching principles governing the architecture of cornus kousa Cornaceae
    Annals of Botany, 1999
    Co-Authors: Hiroaki Hatta, Hisao Honda, Jack B Fisher
    Abstract:

    Abstract The complex structure of the crown of Cornus kousa, generally five-forked in vegetative branching and two-forked in reproductive branching, is analysed quantitatively and described by two basic branching principles: decussate phyllotaxy and the resetting rule for planes of branching. Most Cornus species have opposite, decussate phyllotaxis. The leaf pair (with axillary buds) defines the branching plane of a node. Because of regular phyllotaxis, the fundamental branching pattern is that every branching plane along an axis is perpendicular to the preceding one. However, the first node of a lateral horizontal shoot always has a horizontal branching plane; we term this the resetting rule. We observed that resetting occurs when the first nodes initiated in the vertical plane are repositioned by a twisting of their first internodes. All later nodes alternate directions, i.e. show usual decussate alternation. Foliage leaf nodes usually produce three-forked branchings. When vegetative winter buds are formed, a foliar node and adjacent scale leaf node produce a five-forked branching. When reproductive winter buds with a terminal inflorescence are formed, the last foliar node and two adjacent scale leaf nodes can produce a variety of branchings but usually produce an equal two-forked branching. To understand better the architecture in C. kousa, we contrast it with C. capitata which does not produce buds with scale leaves and whose vegetative nodes are clearly separated.

  • branch geometry in cornus kousa Cornaceae computer simulations
    American Journal of Botany, 1997
    Co-Authors: Hisao Honda, Hiroaki Hatta, Jack B Fisher
    Abstract:

    Computer simulations similar to actual trees were constructed using simple branching rules. Branch orientation with respect to the direction of gravity was a fundamental consideration. In Cornus kousa BUERG. ex HANCE, several types of branches develop from winter buds, varying from orthotropic shoots to plagiotropic ones. Based on actual observations and measurements of branching structures with a wide range of orientations, we made a flexible geometrical model consisting of five forking branches that varied in outgrowth depending on the direction of the shoot with respect to gravity. Repetition of the branching by computer generated a realistic tree pattern, which was close to the shape of a young C. kousa tree. Reproductive shoots seem to be under a branching rule that was a modification of vegetative branching, although the reproductive branch size was considerably smaller than the vegetative one, and reproductive branching was bifurcated instead of five-forked. We conclude that all branchings in orthotropic and plagiotropic shoots in the vegetative phase and shoots in the reproductive phase are formed under the same branching rule, but each has different parameter values.

Qiuyun Xiang - One of the best experts on this subject based on the ideXlab platform.

  • heterogeneous evolution of the myc like anthocyanin regulatory gene and its phylogenetic utility in cornus l Cornaceae
    Molecular Phylogenetics and Evolution, 2004
    Co-Authors: Chuanzhu Fan, Michael D Purugganan, David T Thomas, Brian M Wiegmann, Qiuyun Xiang
    Abstract:

    Anthocyanin is a major pigment in vegetative and floral organs of most plants and plays an important role in plant evolution. The anthocyanin regulatory genes are responsible for regulating transcription of genes in the anthocyanin synthetic pathway. To assess evolutionary significance of sequence variation and evaluate the phylogenetic utility of an anthocyanin regulatory gene, we compared nucleotide sequences of the myc-like anthocyanin regulatory gene in the genus of dogwoods (Cornus: Cornaceae). Phylogenetic analyses demonstrate that the myc-like anthocyanin regulatory gene has potential as an informative phylogenetic marker at different taxonomic levels, depending on the data set considered (DNA or protein sequences) and regions applied (exons or introns). Pairwise nonsynonymous and synonymous substitution rate tests and codon-based substitution models were applied to characterize variation and to identify sites under diversifying selection. Mosaic evolution and heterogeneous rates among different domains and sites were detected.

  • phylogenetic relationships within cornus Cornaceae based on 26s rdna sequences
    American Journal of Botany, 2001
    Co-Authors: Chuanzhu Fan, Qiuyun Xiang
    Abstract:

    Phylogenetic relationships within the dogwood genus Cornus have been highly controversial due to the great morphological heterogeneity. Earlier phylogenetic analyses of Cornus using chloroplast DNA (cpDNA) data (including rbcL and matK sequences, as well as restriction sites) and morphological characters suggested incongruent relationships within the genus. The present study generated sequence data from the nuclear gene 26S rDNA for Cornus to test the phylogenetic hypotheses based on cpDNA and morphological data. The 26S rDNA sequence data obtained represent 16 species, 13 from Cornus and three from outgroups, having an aligned length of 3380 bp. Both parsimony and maximum likelihood analyses of these sequences were conducted. Trees resulting from these analyses suggest relationships among subgroups of Cornus consistent with those inferred from cpDNA data. That is, the dwarf dogwood (subg. Arctocrania) and the big-bracted dogwood (subg. Cynoxylon and subg. Syncarpea) clades are sisters, which are, in turn, sister to the cornelian cherries (subg. Cornus and subg. Afrocrania). This red-fruited clade is sister to the blue- or white-fruited dogwoods (subg. Mesomora, subg. Kraniopsis, and subg. Yinquania). Within the blue- or white-fruited clade, C. oblonga (subg. Yinquania) is sister to the remainder, and subg. Mesomora is sister to subg. Kraniopsis. These relationships were also suggested by the combined 26S rDNA and cpDNA data, but with higher bootstrap and Bremer support in the combined analysis. The 26S rDNA sequence data of Cornus consist of 12 expansion segments spanning 1034 bp. These expansion segments evolve approximately four times as fast as the conserved core regions. The study provides an example of phylogenetic utility of 26S rDNA sequences below the genus level.

  • cornus Cornaceae based on 26s rdna sequences1
    2001
    Co-Authors: Chuanzhu Fan, Qiuyun Xiang
    Abstract:

    Phylogenetic relationships within the dogwood genus Cornus have been highly controversial due to the great morphological heterogeneity. Earlier phylogenetic analyses of Cornus using chloroplast DNA (cpDNA) data (including rbcL and matK sequences, as well as restriction sites) and morphological characters suggested incongruent relationships within the genus. The present study generated sequence data from the nuclear gene 26S rDNA for Cornus to test the phylogenetic hypotheses based on cpDNA and morphological data. The 26S rDNA sequence data obtained represent 16 species, 13 from Cornus and three from outgroups, having an aligned length of 3380 bp. Both parsimony and maximum likelihood analyses of these sequences were conducted. Trees resulting from these analyses suggest relationships among subgroups of Cotnus consistent with those inferred from cpDNA data. That is, the dwarf dogwood (subg. Arctocrania) and the big-bracted dogwood (subg. Cynoxylon and subg. Syncarpea) clades are sisters, which are, in turn, sister to the cornelian cherries (subg. Cornus and subg. Afrocrania). This red-fruited clade is sister to the blue- or white-fruited dogwoods (subg. Mesomora, subg. Kraniopsis, and subg. Yinquania). Within the blue- or white-fruited clade, C. oblonga (subg. Yinquania) is sister to the remainder, and subg. Mesomora is sister to subg. Kraniopsis. These relationships were also suggested by the combined 26S rDNA and cpDNA data, but with higher bootstrap and Bremer support in the combined analysis. The 26S rDNA sequence data of Cornus consist of 12 expansion segments spanning 1034 bp. These expansion segments evolve approximately four times as fast as the conserved core regions. The study provides an example of phylogenetic utility of 26S rDNA sequences below the genus level.

Hugh D. Wilson - One of the best experts on this subject based on the ideXlab platform.