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排序方式: 共有78条查询结果,搜索用时 15 毫秒
1.
Andrei Diakin Kevin C. Wakeman Andrea Valigurová 《The Journal of eukaryotic microbiology》2017,64(1):56-66
A novel species of aseptate eugregarine, Ganymedes yurii sp. n., is described using microscopic and molecular approaches. It inhabits the intestine of Gondogeneia sp., a benthic amphipod found along the shore of James Ross Island, Weddell Sea, Antarctica. The prevalence of the infection was very low and only a few caudo‐frontal syzygies were found. Morphologically, the new species is close to a previously described amphipod gregarine, Ganymedes themistos, albeit with several dissimilarities in the structure of the contact zone between syzygy partners, as well as other characteristics. Phylogenetic analysis of the 18S rDNA from G. yurii supported a close relationship between these species. These two species were grouped with other gregarines isolated from crustaceans hosts (Cephaloidophoroidea); however, statistical support throughout the clade of Cephaloidophoroidea gregarines was minimal using the available dataset. 相似文献
2.
AV Shevchenko IG Budzanivska TP Shevchenko VP Polischuk D Spaar 《Archives Of Phytopathology And Plant Protection》2013,46(2):139-146
The work was focused on the investigation of possible dependencies between the development of viral infection in plants and the presence of high heavy metal concentrations in soil. Field experiments have been conducted in order to study the development of systemic tobacco mosaic virus (TMV) infection in Lycopersicon esculentum L. cv. Miliana plants under effect of separate salts of heavy metals Cu, Zn and Pb deposited in soil. As it is shown, simultaneous effect of viral infection and heavy metals in tenfold maximum permissible concentration leads to decrease of total chlorophyll content in experiment plants mainly due to the degradation of chlorophyll a. The reduction of chlorophyll concentration under the combined influence of both stress factors was more serious comparing to the separate effect of every single factor. Plants' treatment with toxic concentrations of lead and zinc leaded to slight delay in the development of systemic TMV infection together with more than twofold increase of virus content in plants that may be an evidence of synergism between these heavy metal's and virus' effects. Contrary, copper although decreased total chlorophyll content but showed protective properties and significantly reduced amount of virus in plants. 相似文献
3.
Javier del Campo Maria J. Pons Maria Herranz Kevin C. Wakeman Juana del Valle Mark J. A. Vermeij Brian S. Leander Patrick J. Keeling 《Environmental microbiology》2019,21(10):3855-3861
The application of metabarcoding to study animal-associated microeukaryotes has been restricted because the universal barcode used to study microeukaryotic ecology and distribution in the environment, the Small Subunit of the Ribosomal RNA gene (18S rRNA), is also present in the host. As a result, when host-associated microbial eukaryotes are analysed by metabarcoding, the reads tend to be dominated by host sequences. We have done an in silico validation against the SILVA 18S rRNA database of a non-metazoan primer set (primers that are biased against the metazoan 18S rRNA) that recovers only 2.6% of all the metazoan sequences, while recovering most of the other eukaryotes (80.4%). Among metazoans, the non-metazoan primers are predicted to amplify 74% of Porifera sequences, 4% of Ctenophora, and 15% of Cnidaria, while amplifying almost no sequences within Bilateria. In vivo, these non-metazoan primers reduce significantly the animal signal from coral and human samples, and when compared against universal primers provide at worst a 2-fold decrease in the number of metazoan reads and at best a 2800-fold decrease. This easy, inexpensive, and near-universal method for the study of animal-associated microeukaryotes diversity will contribute to a better understanding of the microbiome. 相似文献
4.
Catherine A. Wakeman 《Journal of molecular biology》2009,392(3):723-13405
Riboswitches are regulatory RNAs that control downstream gene expression in response to direct association with intracellular metabolites or metals. Typically, riboswitch aptamer domains bind to a single small-molecule metabolite. In contrast, an X-ray crystallographic structural model for the M-box riboswitch aptamer revealed the absence of an organic metabolite ligand but the presence of at least six tightly associated magnesiums. This observation agrees well with the proposed role of the M-box riboswitch in functioning as a sensor of intracellular magnesium, although additional nonspecific metal interactions are also undoubtedly required for these purposes. To gain greater functional insight into the metalloregulatory capabilities of M-box RNAs, we sought to determine whether all or a subset of the RNA-chelated magnesium ions were required for riboswitch function. To accomplish this task, each magnesium-binding site was simultaneously yet individually perturbed through random incorporation of phosphorothioate nucleotide analogues, and RNA molecules were investigated for their ability to fold in varying levels of magnesium. These data revealed that all of the magnesium ions observed in the structural model are important for magnesium-dependent tertiary structure formation. Additionally, these functional data revealed a new core of potential metal-binding sites that are likely to assist formation of key tertiary interactions and were previously unobserved in the structural model. It is clear from these data that M-box RNAs require specific binding of a network of metal ions for partial fulfillment of their metalloregulatory functions. 相似文献
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Rad17 recruits the MRE11‐RAD50‐NBS1 complex to regulate the cellular response to DNA double‐strand breaks 下载免费PDF全文
Qinhong Wang Michael Goldstein Peter Alexander Timothy P Wakeman Tao Sun Junjie Feng Zhenkun Lou Michael B Kastan Xiao‐Fan Wang 《The EMBO journal》2014,33(8):862-877
The MRE11‐RAD50‐NBS1 (MRN) complex is essential for the detection of DNA double‐strand breaks (DSBs) and initiation of DNA damage signaling. Here, we show that Rad17, a replication checkpoint protein, is required for the early recruitment of the MRN complex to the DSB site that is independent of MDC1 and contributes to ATM activation. Mechanistically, Rad17 is phosphorylated by ATM at a novel Thr622 site resulting in a direct interaction of Rad17 with NBS1, facilitating recruitment of the MRN complex and ATM to the DSB, thereby enhancing ATM signaling. Repetition of these events creates a positive feedback for Rad17‐dependent activation of MRN/ATM signaling which appears to be a requisite for the activation of MDC1‐dependent MRN complex recruitment. A point mutation of the Thr622 residue of Rad17 leads to a significant reduction in MRN/ATM signaling and homologous recombination repair, suggesting that Thr622 phosphorylation is important for regulation of the MRN/ATM signaling by Rad17. These findings suggest that Rad17 plays a critical role in the cellular response to DNA damage via regulation of the MRN/ATM pathway. 相似文献
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Clones of human ribosomal DNA containing the complete 18 S-rRNA and 28 S-rRNA genes. Characterization, a detailed map of the human ribosomal transcription unit and diversity among clones. 总被引:13,自引:1,他引:12 下载免费PDF全文
B E Maden C L Dent T E Farrell J Garde F S McCallum J A Wakeman 《The Biochemical journal》1987,246(2):519-527
10.
A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
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