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1.
The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
相似文献
2.
PARP-1 Regulates Metastatic Melanoma through Modulation of Vimentin-induced Malignant Transformation
María Isabel Rodríguez Andreína Peralta-Leal Francisco O'Valle José Manuel Rodriguez-Vargas Ariannys Gonzalez-Flores Jara Majuelos-Melguizo Laura López Santiago Serrano Antonio García de Herreros Juan Carlos Rodríguez-Manzaneque Rubén Fernández Raimundo G. del Moral José Mariano de Almodóvar F. Javier Oliver 《PLoS genetics》2013,9(6)
PARP inhibition can induce anti-neoplastic effects when used as monotherapy or in combination with chemo- or radiotherapy in various tumor settings; however, the basis for the anti-metastasic activities resulting from PARP inhibition remains unknown. PARP inhibitors may also act as modulators of tumor angiogenesis. Proteomic analysis of endothelial cells revealed that vimentin, an intermediary filament involved in angiogenesis and a specific hallmark of EndoMT (endothelial to mesenchymal transition) transformation, was down-regulated following loss of PARP-1 function in endothelial cells. VE-cadherin, an endothelial marker of vascular normalization, was up-regulated in HUVEC treated with PARP inhibitors or following PARP-1 silencing; vimentin over-expression was sufficient to drive to an EndoMT phenotype. In melanoma cells, PARP inhibition reduced pro-metastatic markers, including vasculogenic mimicry. We also demonstrated that vimentin expression was sufficient to induce increased mesenchymal/pro-metastasic phenotypic changes in melanoma cells, including ILK/GSK3-β-dependent E-cadherin down-regulation, Snail1 activation and increased cell motility and migration. In a murine model of metastatic melanoma, PARP inhibition counteracted the ability of melanoma cells to metastasize to the lung. These results suggest that inhibition of PARP interferes with key metastasis-promoting processes, leading to suppression of invasion and colonization of distal organs by aggressive metastatic cells. 相似文献
3.
A wide-ranging examination of plastid (pt)DNA sequence homologies within
higher plant nuclear genomes (promiscuous DNA) was undertaken. Digestion
with methylation-sensitive restriction enzymes and Southern analysis was
used to distinguish plastid and nuclear DNA in order to assess the extent
of variability of promiscuous sequences within and between plant species.
Some species, such as Gossypium hirsutum (cotton), Nicotiana tabacum
(tobacco), and Chenopodium quinoa, showed homogenity of these sequences,
while intraspecific sequence variation was observed among different
cultivars of Pisum sativum (pea), Hordeum vulgare (barley), and Triticum
aestivum (wheat). Hypervariability of plastid sequence homologies was
identified in the nuclear genomes of Spinacea oleracea (spinach) and Beta
vulgaris (beet), in which individual plants were shown to possess a unique
spectrum of nuclear sequences with ptDNA homology. This hypervariability
apparently extended to somatic variation in B. vulgaris. No sequences with
ptDNA homology were identified by this method in the nuclear genome of
Arabidopsis thaliana.
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4.
Jonathan N. Gonzalez-Flores Nirupama Gupta Louise W. DeMong Paul R. Copeland 《The Journal of biological chemistry》2012,287(46):38936-38945
The selenocysteine (Sec)-specific eukaryotic elongation factor (eEFSec) delivers the aminoacylated selenocysteine-tRNA (Sec-tRNASec) to the ribosome and suppresses UGA codons that are upstream of Sec insertion sequence (SECIS) elements bound by SECIS-binding protein 2 (SBP2). Multiple studies have highlighted the importance of SBP2 forming a complex with the SECIS element, but it is not clear how this regulates eEFSec during Sec incorporation. Compared with the canonical elongation factor eEF1A, eEFSec has a unique C-terminal extension called Domain IV. To understand the role of Domain IV in Sec incorporation, we examined a series of mutant proteins for all of the known molecular functions for eEFSec: GTP hydrolysis, Sec-tRNASec binding, and SBP2/SECIS binding. In addition, wild-type and mutant versions of eEFSec were analyzed for Sec incorporation activity in a novel eEFSec-dependent translation extract. We have found that Domain IV is essential for both tRNA and SBP2 binding as well as regulating GTPase activity. We propose a model where the SBP2/SECIS complex activates eEFSec by directing functional interactions between Domain IV and the ribosome to promote Sec-tRNASec binding and accommodation into the ribosomal A-site. 相似文献
5.
JN Matthiessen 《Australian Journal of Entomology》1999,38(4):348-353
In field and laboratory studies, mortality of African black beetle, Heteronychus arator, in the winter-rainfall, Mediterranean-type climate region of south-western Australia was higher in the late immature stages during summer than in the early immature stages that occur during spring, a contrast to summer-rainfall climatic regions. Greatest mortality occurred around the pupal stage in contrasting soil types, despite drying differences in summer and supplementary watering in some plots. Sampling of natural populations confirmed experimental results that mortality in late immature stages is the major factor limiting H. arator populations under a Mediterranean-type climate. Inter-generation increase in H. arator abundance was uncommon, explaining the consistent abundance typically observed between years in south-western Australia. Random dispersal of newly emerged adults in autumn was inferred to restore uniformity in adult abundance between areas of varying favourability for immature survival. 相似文献
6.
BRCA1 C-terminal (BRCT) domains are integral signaling modules in the DNA damage response (DDR). Aside from their established roles as phospho-peptide binding modules, BRCT domains have been implicated in phosphorylation-independent protein interactions, DNA binding and poly(ADP-ribose) (PAR) binding. These numerous functions can be attributed to the diversity in BRCT domain structure and architecture, where domains can exist as isolated single domains or assemble into higher order homo- or hetero-domain complexes. In this review, we incorporate recent structural and biochemical studies to demonstrate how structural features allow single and tandem BRCT domains to attain a high degree of functional diversity.Key words: BRCT domain, DNA repair, phosphorylation, phospho-peptide interaction, protein interaction, DNA binding, DNA damage response 相似文献
7.
A novel protein domain induces high affinity selenocysteine insertion sequence binding and elongation factor recruitment 总被引:1,自引:0,他引:1
Donovan J Caban K Ranaweera R Gonzalez-Flores JN Copeland PR 《The Journal of biological chemistry》2008,283(50):35129-35139
Selenocysteine (Sec) is incorporated at UGA codons in mRNAs possessing a Sec insertion sequence (SECIS) element in their 3'-untranslated region. At least three additional factors are necessary for Sec incorporation: SECIS-binding protein 2 (SBP2), Sec-tRNA(Sec), and a Sec-specific translation elongation factor (eEFSec). The C-terminal half of SBP2 is sufficient to promote Sec incorporation in vitro, which is carried out by the concerted action of a novel Sec incorporation domain and an L7Ae RNA-binding domain. Using alanine scanning mutagenesis, we show that two distinct regions of the Sec incorporation domain are required for Sec incorporation. Physical separation of the Sec incorporation and RNA-binding domains revealed that they are able to function in trans and established a novel role of the Sec incorporation domain in promoting SECIS and eEFSec binding to the SBP2 RNA-binding domain. We propose a model in which SECIS binding induces a conformational change in SBP2 that recruits eEFSec, which in concert with the Sec incorporation domain gains access to the ribosomal A site. 相似文献
8.
Florian Ryffel Eric JN Helfrich Patrick Kiefer Lindsay Peyriga Jean-Charles Portais J?rn Piel Julia A Vorholt 《The ISME journal》2016,10(3):632-643
The phyllosphere, which is defined as the parts of terrestrial plants above the ground, is a large habitat for different microorganisms that show a high extent of adaption to their environment. A number of hypotheses were generated by culture-independent functional genomics studies to explain the competitiveness of specialized bacteria in the phyllosphere. In contrast, in situ data at the metabolome level as a function of bacterial colonization are lacking. Here, we aimed to obtain new insights into the metabolic interplay between host and epiphytes upon colonization of Arabidopsis thaliana leaves in a controlled laboratory setting using environmental metabolomics approaches. Quantitative nuclear magnetic resonance (NMR) and imaging high-resolution mass spectrometry (IMS) methods were used to identify Arabidopsis leaf surface compounds and their possible involvement in the epiphytic lifestyle by relative changes in compound pools. The dominant carbohydrates on the leaf surfaces were sucrose, fructose and glucose. These sugars were significantly and specifically altered after epiphytic leaf colonization by the organoheterotroph Sphingomonas melonis or the phytopathogen Pseudomonas syringae pv. tomato, but only to a minor extent by the methylotroph Methylobacterium extorquens. In addition to carbohydrates, IMS revealed surprising alterations in arginine metabolism and phytoalexin biosynthesis that were dependent on the presence of bacteria, which might reflect the consequences of bacterial activity and the recognition of not only pathogens but also commensals by the plant. These results highlight the power of environmental metabolomics to aid in elucidating the molecular basis underlying plant–epiphyte interactions in situ. 相似文献
9.
Background
During the development of the central nervous system (CNS), patterning processes along the dorsoventral (DV) axis of the neural tube generate different neuronal subtypes. As development progresses these neurons are arranged into functional units with varying cytoarchitecture, such as laminae or nuclei for efficient relaying of information. Early in development ventral and dorsal regions are similar in size and structure. Different proliferation rates and cell migration patterns are likely to result in the formation of laminae or nuclei, eventually. However, the underlying molecular mechanisms that establish these different structural arrangements are not well understood. 相似文献10.
Efficient four fragment cloning for the construction of vectors for targeted gene replacement in filamentous fungi 总被引:2,自引:0,他引:2
Rasmus JN Frandsen Jens A Andersson Matilde B Kristensen Henriette Giese 《BMC molecular biology》2008,9(1):70