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991.
Helena Raquel Tiago Lourenço Catarina Moita M. Margarida Oliveira 《Plant biotechnology reports》2008,2(1):75-85
Prune dwarf virus (PDV) is an Ilarvirus systemically infecting almond trees and other Prunus species and spreading through pollen, among other means. We have studied strategies based on coat protein (cp) gene to block
PDV replication in host plant cells. A Portuguese isolate of PDV was obtained from infected almond leaves and used to produce
the cDNA of the cp gene. Various constructs were prepared based on this sequence, aiming for the transgenic expression of
the original or modified PDV coat protein (cpPDVSense and cpPDVMutated) or for the expression of cpPDV RNA (cpPDVAntisense
and cpPDVwithout start codon). All constructs were tested in a PDV host model, Nicotiana benthamiana, and extensive molecular characterization and controlled infections were performed on transformants and their progenies.
Transgenic plants expressing the coat protein RNA were able to block the proliferation of a PDV isolate sharing only 91% homology
with the isolate used for cpPDV cloning, as evaluated by DAS-ELISA on newly developed leaves. With cp expression, the blockage
of PDV proliferation in newly developed leaves was only achieved with the construct cpPDV Mutated, where the coat protein
has a substitution in the 14th aa residue, with arginine replaced by alanine. This result points to a possible role of the
mutated amino acid in the virus ability to replicate and proliferate. This work reveals the possibility of achieving protection
against PDV through either coat protein RNA or mutated cp sequence. 相似文献
992.
Carlos R. Oliveira Fábio D. Nascimento Marília B. Meneghin Edgar J. Paredes-Gamero Tiago Rodrigues Antonio C.F. Caires Claudia Bincoletto 《Chemico-biological interactions》2009,177(3):181-189
Previous studies reported by our group have introduced a new antitumoural drug called Biphosphinic Palladacycle Complex (BPC). In this paper we show that BPC causes apoptosis in leukaemia cells (HL60 and Jurkat), but not in normal human lymphocytes. IC50 values obtained for both cell lines using the MTT and trypan blue exclusion assays 5 h after BPC treatment were lower than 8.0 μM. Using metachromatic fluorophore, acridine orange, we observed that BPC elicited lysosomal rupture of leukaemic cells. Furthermore, BPC triggered caspase-3 and caspase-6 activation and apoptosis in cell lines, inducing chromatin condensation, apoptotic bodies, and DNA fragmentation. Interestingly, the lysosomal cathepsin B inhibitor CA074 markedly decreased BPC-induced caspase-3 and caspase-6 activation as well as cell death. Lysosomal BPC-induced membrane destabilisation was not dependent on reactive oxygen species generation, which was consistent with the absence of cellular HL60 and Jurkat membrane lipid peroxidation. We conclude that, following BPC treatment, lysosomal membrane rupture precedes cell death and the apoptotic signalling pathway is initiated by the release of cathepsin B in the cytoplasm of leukaemia cells. As no toxic effects for human lymphocytes were observed, we suggest that BPC is more selective for transformed cells, mainly due to their exacerbated lysosome expression. 相似文献
993.
Lucia Libanez Bessa Campelo Braga Maria Aparecida Alves de Oliveira Maria Helane Rocha Batista Gon?alves Fernando Kennedy Chaves Tiago Gomes da Silva Benigno Adriana Dias Gomes Cícero Igor Sim?es Moura Silva Charles Anacleto Sérgio de Assis Batista Dulciene Maria Magalh?es Queiroz 《Memórias do Instituto Oswaldo Cruz》2014,109(8):1045-1049
Helicobacter pylori infection is one of the most common infections
worldwide and is associated with gastric diseases. Virulence factors such as VacA and
CagA have been shown to increase the risk of these diseases. Studies have suggested a
causal role of CagA EPIYA-C in gastric carcinogenesis and this factor has been shown
to be geographically diverse. We investigated the number of CagA EPIYA motifs and the
vacA i genotypes in H. pylori strains from
asymptomatic children. We included samples from 40 infected children (18 females and
22 males), extracted DNA directly from the gastric mucus/juice (obtained using the
string procedure) and analysed the DNA using polymerase chain reaction and DNA
sequencing. The vacA i1 genotype was present in 30 (75%) samples,
the i2 allele was present in nine (22.5%) samples and both alleles were present in
one (2.5%) sample. The cagA-positive samples showed distinct
patterns in the 3’ variable region of cagA and 18 of the 30 (60%)
strains contained 1 EPIYA-C motif, whereas 12 (40%) strains contained two EPIYA-C
motifs. We confirmed that the studied population was colonised early by the most
virulent H. pylori strains, as demonstrated by the high frequency of
the vacA i1 allele and the high number of EPIYA-C motifs. Therefore,
asymptomatic children from an urban community in Fortaleza in northeastern Brazil are
frequently colonised with the most virulent H. pylori
strains. 相似文献
994.
Tumor cell plasticity is an event that has been observed in several malignancies. In fact, most of the solid tumors are characterized by cellular heterogeneity and undergo constant changes as the tumor develops. The increased plasticity displayed by these cells allows them to acquire additional properties, enabling epithelial-mesenchymal transitions, dedifferentiation and the acquisition of stem cell-like properties. Here we discuss the particular importance of an inflammatory microenvironment for the bidirectional control of cellular plasticity and the potential for therapeutic intervention. 相似文献
995.
Tiago Villanueva 《CMAJ》2010,182(18):E825-E826
996.
Knowledge of the rate and fitness effects of mutations is essential for understanding the process of evolution. Mutations are inherently difficult to study because they are rare and are frequently eliminated by natural selection. In the ciliate Tetrahymena thermophila, mutations can accumulate in the germline genome without being exposed to selection. We have conducted a mutation accumulation (MA) experiment in this species. Assuming that all mutations are deleterious and have the same effect, we estimate that the deleterious mutation rate per haploid germline genome per generation is U = 0.0047 (95% credible interval: 0.0015, 0.0125), and that germline mutations decrease fitness by s = 11% when expressed in a homozygous state (95% CI: 4.4%, 27%). We also estimate that deleterious mutations are partially recessive on average (h = 0.26; 95% CI: –0.022, 0.62) and that the rate of lethal mutations is <10% of the deleterious mutation rate. Comparisons between the observed evolutionary responses in the germline and somatic genomes and the results from individual-based simulations of MA suggest that the two genomes have similar mutational parameters. These are the first estimates of the deleterious mutation rate and fitness effects from the eukaryotic supergroup Chromalveolata and are within the range of those of other eukaryotes. 相似文献
997.
Larissa Krüger Christina Herzberg Hermann Rath Tiago Pedreira Till Ischebeck Anja Poehlein Jan Gundlach Rolf Daniel Uwe Vlker Ulrike Mder Jrg Stülke 《PLoS genetics》2021,17(1)
In order to adjust to changing environmental conditions, bacteria use nucleotide second messengers to transduce external signals and translate them into a specific cellular response. Cyclic di-adenosine monophosphate (c-di-AMP) is the only known essential nucleotide second messenger. In addition to the well-established role of this second messenger in the control of potassium homeostasis, we observed that glutamate is as toxic as potassium for a c-di-AMP-free strain of the Gram-positive model bacterium Bacillus subtilis. In this work, we isolated suppressor mutants that allow growth of a c-di-AMP-free strain under these toxic conditions. Characterization of glutamate resistant suppressors revealed that they contain pairs of mutations, in most cases affecting glutamate and potassium homeostasis. Among these mutations, several independent mutations affected a novel glutamate transporter, AimA (Amino acid importer A, formerly YbeC). This protein is the major transporter for glutamate and serine in B. subtilis. Unexpectedly, some of the isolated suppressor mutants could suppress glutamate toxicity by a combination of mutations that affect phospholipid biosynthesis and a specific gain-of-function mutation of a mechanosensitive channel of small conductance (YfkC) resulting in the acquisition of a device for glutamate export. Cultivation of the c-di-AMP-free strain on complex medium was an even greater challenge because the amounts of potassium, glutamate, and other osmolytes are substantially higher than in minimal medium. Suppressor mutants viable on complex medium could only be isolated under anaerobic conditions if one of the two c-di-AMP receptor proteins, DarA or DarB, was absent. Also on complex medium, potassium and osmolyte toxicity are the major bottlenecks for the growth of B. subtilis in the absence of c-di-AMP. Our results indicate that the essentiality of c-di-AMP in B. subtilis is caused by the global impact of the second messenger nucleotide on different aspects of cellular physiology. 相似文献
998.
999.
Lisiane G. Londero Débora K. Rieger Fernanda Hansen Simone L. Silveira Tiago L. Martins Francisco Lulhier Roselis S. da Silva Diogo O. Souza Adriano M. de Assis 《Cell biochemistry and function》2013,31(8):636-642
Long‐chain polyunsaturated n‐3 fatty acids (n‐3 LCPUFAs) have hypolipidemic effects and modulate intermediary metabolism to prevent or reverse insulin resistance in a way that is not completely elucidated. Here, effects of these fatty acids on the lipid profile, phosphoenolpyruvate carboxykinase (PEPCK) activity, lipid synthesis from glucose in epididymal adipose tissue (Ep‐AT) and liver were investigated. Male rats were fed a high‐sucrose diet (SU diet), containing either sunflower oil or a mixture of sunflower and fish oil (SU–FO diet), and the control group was fed a standard diet. After 13 weeks, liver, adipose tissue and blood were harvested and analysed. The dietary n‐3 LCPUFAs prevented sucrose‐induced increase in adiposity and serum free fat acids, serum and hepatic triacylglycerol and insulin levels. Furthermore, these n‐3 LCPUFAs decreased lipid synthesis from glucose and increased PEPCK activity in the Ep‐AT of rats fed the SU–FO diet compared to those fed the SU diet, besides reducing lipid synthesis from glucose in hepatic tissue. Thus, the inclusion of n‐3 LCPUFAs in the diet may be beneficial for the prevention or attenuation of dyslipidemia and insulin resistance, and for reducing the risk of related chronic diseases. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
1000.