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41.
Halinen K Fewer DP Sihvonen LM Lyra C Eronen E Sivonen K 《FEMS microbiology ecology》2008,64(2):199-208
Late summer cyanobacterial blooms in the Baltic Sea contain Anabaena sp. together with Nodularia spumigena and Aphanizomenon flos-aquae. Although Anabaena is common especially in the Gulf of Finland, very little is known about its genetic diversity. Here we undertook a molecular phylogenetic study of 68 Anabaena strains isolated from the brackish Gulf of Finland. We sequenced the 16S rRNA genes from 54 planktonic and 14 benthic Anabaena strains, and rbcL and rpoC1 genes from a subset of these strains. Phylogenetic trees showed that Anabaena strains, from both planktonic and benthic habitats, were genetically diverse. Although the Anabaena strains were morphologically diverse, in our study only one genetically valid species was found to exist in the plankton. Evolutionary distances between benthic Anabaena strains were greater than between planktonic strains, suggesting that benthic habitats allow for the maintenance of greater genetic diversity than planktonic habitats. A number of novel lineages containing only sequences obtained in this study were compiled in the phylogenetical analyses. Thus, it seemed that novel lineages of the genus Anabaena may be present in the Baltic Sea. Our results demonstrate that the Baltic Sea Anabaena strains show surprisingly high genetic diversity. 相似文献
42.
Thomas?Fett Laurent?LM?Zecchinon Etienne?A?Baise Daniel?JM?DesmechtEmail author 《BMC veterinary research》2005,1(1):4
Background
Lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18, alpha L beta 2) is required for many cellular adhesive interactions during the immune response.Results
The Capra hircus CD11a-encoding cDNA was sequenced and compared with its human, murine, rat, bovine and ovine counterparts. Despite some focal differences, it shares all the main characteristics of its known mammalian homologues.Conclusion
Therefore, along with the caprine CD18-encoding cDNA, which has been available for a few months, the sequence data revealed here will allow the Capra hircus LFA-1 expression in vitro as a tool to explore the specificities of inflammation in the caprine species.43.
The movement protein of cucumber mosaic virus traffics into sieve elements in minor veins of nicotiana clevelandii 总被引:5,自引:2,他引:3 下载免费PDF全文
The location of the 3a movement protein (MP) of cucumber mosaic virus (CMV) was studied by quantitative immunogold labeling of the wild-type 3a MP in leaves of Nicotiana clevelandii infected by CMV as well as by using a 3a-green fluorescent protein (GFP) fusion expressed from a potato virus X (PVX) vector. Whether expressed from CMV or PVX, the 3a MP targeted plasmodesmata and accumulated in the central cavity of the pore. Within minor veins, the most extensively labeled plasmodesmata were those connecting sieve elements and companion cells. In addition to targeting plasmodesmata, the 3a MP accumulated in the parietal layer of mature sieve elements. Confocal imaging of cells expressing the 3a-GFP fusion protein showed that the 3a MP assembled into elaborate fibrillar formations in the sieve element parietal layer. The ability of 3a-GFP, expressed from PVX rather than CMV, to enter sieve elements demonstrates that neither the CMV RNA nor the CMV coat protein is required for trafficking of the 3a MP into sieve elements. CMV virions were not detected in plasmodesmata from CMV-infected tissue, although large CMV aggregates were often found in the parietal layer of sieve elements and were usually surrounded by 3a MP. These data suggest that CMV traffics into minor vein sieve elements as a ribonucleoprotein complex that contains the viral RNA, coat protein, and 3a MP, with subsequent viral assembly occurring in the sieve element parietal layer. 相似文献
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Yuliy A. Ratiner Leila M. Sihvonen Yanqun Liu Lei Wang Anja Siitonen 《Archives of microbiology》2010,192(4):267-278
A practically important phenomenon, resulting in the loss of the original flagellar phenotype (genotype) of bacteria, is described
in the Escherichia coli H17 type strain P12b possessing two distinct genes for H17 and H4 flagellins, respectively. By PCR, sequencing, and phylogenetic
investigation, the H17 gene (originally expressed) was considered a new non-fliC flagellin gene and assigned flnA, while the H4 gene (originally cryptic) was reaffirmed as fliC. H17 and H4 flagella differed morphologically. The phenomenon consisted in the replacement of H17 cells by H4 cells during
subculturing through certain semisolid media and resulted from the excision of flnA
H17 entirely or in part. The substitution rate depended on the density and nutrient composition of media and reached 100% even
after a single passage through 0.3% LB agar. Such phenomenon can lead to an unexpected loss of original H17 phenotype. Our
review of the literature showed that the loss of the original flagellar genotype (phenotype) of P12b has occurred in some
laboratories while the authors continued to consider their cultures H17. We showed how to distinguish these alternative flagellin
genotypes using popular fliC primers. Attention was also paid to possible discrepancies between serological and molecular results in flagellar typing
of E. coli. 相似文献
47.
Phylogenetic analysis of the outer-membrane-protein genes of Chlamydiae, and its implication for vaccine development 总被引:9,自引:0,他引:9
Examination of 18 complete and 6 partial sequences of the major outer-
membrane protein from 24 chlamydiae isolates was used to reconstruct their
evolutionary relationships. From this analysis, assuming that the clades
with 100% bootstrap support are correct, come the following conclusions:
(1) The tree of these sequences is not congruent with the phylogeny of the
hosts, and thus host switching would seem to have occurred, thereby
limiting the extent to which there has been coevolution of parasite and
host. (2) The tree is also noncongruent with clustering by type of cell
infected, thereby limiting the extent to which there has been coevolution
of parasite and the cell type that it infects. (3) The tree is also
noncongruent with clustering by the organ infected (eyes or genitalia),
thereby limiting the extent to which there has been coevolution of parasite
and the organ that it infects. (4) The tree is also noncongruent with
genital strains arising from lymphogranuloma venereum strains. (5) The tree
is also noncongruent with the geographic site at which the isolates were
obtained, thereby limiting the extent of divergence explained by geographic
separation. (6) There are estimated to be 185 amino acid positions that are
invariable (as opposed to unvaried) in the major outer-membrane protein.
There are 10 unvaried positions in the variable domains, of which 9 appear
to be invariable, giving some reason to hope that development of a vaccine
might be possible. (7) The rate of change of this protein is too small to
see increased divergence over the time span of isolation of these genes,
giving hope to any vaccine having longevity. Bootstrapping supports those
portions of the tree on which the first five conclusions above depend. The
picture that these results provide is more one of pathogen versatility than
one of coevolutionary constraints. In addition, we examined 10 60-KDa,
outer-membrane protein- 2 genes, all but one of which were from these same
strains. The tree was not, among the trachomatis strains, congruent with
the major-outer- membrane protein tree, suggesting that gene exchange could
be occurring among strains. Moreover, there is an apparent slowdown in
divergence in this gene, among the trachomatis strains.
相似文献
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49.
PÉTER BIHARI BOTOND SIPOS GEORGE MELIKA BALÁZS FEHÉR KÁLMÁN SOMOGYI GRAHAM N. STONE ZSOLT PÉNZES 《Biological journal of the Linnean Society. Linnean Society of London》2011,102(4):750-764
Insect‐induced galls on plants comprise species‐rich but self‐contained communities of herbivores and natural enemies. In the present study, we focus on galls induced by cynipid gall wasps on oaks, and on the least‐known trophic level that these galls contain: inquilines. These insects, also cynipids, feed on gall tissue and are an abundant but taxonomically poorly understood part of an otherwise well‐studied system. We used DNA sequence data to examine spatial patterns in the genetic diversity of Synergus umbraculus Olivier 1791 (Hymenoptera: Cynipidae: Synergini), a widespread species attacking many host galls across the Western Palaearctic. Analysis of 239 cytochrome b sequences revealed eight haplogroups showing significant phylogeographic pattern across the Western Palaearctic, corresponding to putative glacial refugia in Iberia, Central Europe, Turkey, and Iran. There were significant genetic discontinuities across the Pyrenees and the Anatolian diagonal but no impact of the Alps, suggesting that significant discontinuities have biotic rather than physical causes. Detailed analysis of sites in the Carpathian Basin reveal a high diversity and low spatial structure, and identify Central Europe as the source of colonists for Quaternary colonization of Germany, France, and Britain. We found no evidence for host‐associated differentiation of S. umbraculus lineages associated with the most common cynipid host galls, suggesting frequent shifts within the host gall assemblage by inquiline lineages. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 750–764. 相似文献
50.