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101.
In nature, ribosomally synthesized proteins can contain at least 22 different amino acids: the 20 common amino acids as well as selenocysteine and pyrrolysine. Each of these amino acids is inserted into proteins codon-specifically via an aminoacyl-transfer RNA (aa-tRNA). In most cases, these aa-tRNAs are biosynthesized directly by a set of highly specific and accurate aminoacyl-tRNA synthetases (aaRSs). However, in some cases aaRSs with relaxed or novel substrate specificities cooperate with other enzymes to generate specific canonical and non-canonical aminoacyl-tRNAs. 相似文献
102.
CD39 is the cell surface-located prototypic member of the ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase) family. Biological actions of CD39 are a consequence (at least in part) of the regulated phosphohydrolytic activity on extracellular nucleotides. This ecto-enzymatic cascade in tandem with CD73 (ecto-5–nucleotidase) also generates adenosine and has major effects on both P2 and adenosine receptor signalling. Despite the early recognition of CD39 as a B lymphocyte activation marker, little is known of the role of CD39 in humoral or cellular immune responses. There is preliminary evidence to suggest that CD39 may impact upon antibody affinity maturation. Pericellular nucleotide/nucleoside fluxes caused by dendritic cell expressed CD39 are also involved in the recruitment, activation and polarization of naïve T cells. We have recently explored the patterns of CD39 expression and the functional role of this ecto-nucleotidase within quiescent and activated T cell subsets. Our data indicate that CD39, together with CD73, efficiently distinguishes T regulatory cells (Treg) from other resting or activated T cells in mice (and humans). Furthermore, CD39 serves as an integral component of the suppressive machinery of Treg, acting, at least in part, through the modulation of pericellular levels of adenosine. We have also shown that the coordinated regulation of CD39/CD73 expression and of the adenosine receptor A2A activates an immunoinhibitory loop that differentially regulates Th1 and Th2 responses. The in vivo relevance of this network is manifest in the phenotype of Cd39-null mice that spontaneously develop features of autoimmune diseases associated with Th1 immune deviation. These data indicate the potential of CD39 and modulated purinergic signalling in the co-ordination of immunoregulatory functions of dendritic and Treg cells. Our findings also suggest novel therapeutic strategies for immune-mediated diseases. 相似文献
103.
Genome sequence of Babesia bovis and comparative analysis of apicomplexan hemoprotozoa 总被引:1,自引:0,他引:1
Brayton KA Lau AO Herndon DR Hannick L Kappmeyer LS Berens SJ Bidwell SL Brown WC Crabtree J Fadrosh D Feldblum T Forberger HA Haas BJ Howell JM Khouri H Koo H Mann DJ Norimine J Paulsen IT Radune D Ren Q Smith RK Suarez CE White O Wortman JR Knowles DP McElwain TF Nene VM 《PLoS pathogens》2007,3(10):1401-1413
104.
Günther S Wallace L Patzewitz EM McMillan PJ Storm J Wrenger C Bissett R Smith TK Müller S 《PLoS pathogens》2007,3(12):e189
Lipoic acid (LA) is an essential cofactor of alpha-keto acid dehydrogenase complexes (KADHs) and the glycine cleavage system. In Plasmodium, LA is attached to the KADHs by organelle-specific lipoylation pathways. Biosynthesis of LA exclusively occurs in the apicoplast, comprising octanoyl-[acyl carrier protein]: protein N-octanoyltransferase (LipB) and LA synthase. Salvage of LA is mitochondrial and scavenged LA is ligated to the KADHs by LA protein ligase 1 (LplA1). Both pathways are entirely independent, suggesting that both are likely to be essential for parasite survival. However, disruption of the LipB gene did not negatively affect parasite growth despite a drastic loss of LA (>90%). Surprisingly, the sole, apicoplast-located pyruvate dehydrogenase still showed lipoylation, suggesting that an alternative lipoylation pathway exists in this organelle. We provide evidence that this residual lipoylation is attributable to the dual targeted, functional lipoate protein ligase 2 (LplA2). Localisation studies show that LplA2 is present in both mitochondrion and apicoplast suggesting redundancy between the lipoic acid protein ligases in the erythrocytic stages of P. falciparum. 相似文献
105.
Sheppard TL 《Nature chemical biology》2007,3(8):451
A new division of The Scripps Research Institute that is dedicated to biomedical research and drug discovery is taking shape on the shores of southern Florida. 相似文献
106.
Current literature related to the impact of probiotics on the incidence of gastrointestinal tract infections (GITIs) has shown mixed results and no systematic review available with pooled analysis exists. Thus, the aim of this systematic review was to provide contemporary evidence regarding the overall and strain-specific influence of probiotics in preventing GITIs among infants and children attending childcare centres. The review shortlisted 18 RCTs after screening through the initial search results of 779 articles. However, only 15 trials were deemed eligible, addressing at least one outcome in the pooled analysis. It is concluded that the supplementation of probiotics (overall effect) may reduce the risk of GITI episode by 26%, with Lacticaseibacillus paracasei, Limosilactobacillus reuteri and Lacticaseibacillus rhamnosus GG being specifically potent probiotic strains in reducing GITI episode, duration of infection and absence from childcare respectively. There is insufficient evidence to determine the effect of Bifidobacterium animalis subsp. lactis BB-12 based on the findings of the trials included in this review. 相似文献
107.
Claassens Anders Rose Michael T. Van Zwieten Lukas Weng Zhe Rose Terry J. 《Plant and Soil》2019,439(1-2):393-404
Plant and Soil - Some studies have shown that an increasing atmospheric CO2 concentration reduces plant transpiration while others have demonstrated that it interacts with nutrients in soil to... 相似文献
108.
109.
Tracy S. Replogle-Schwab Robert H. Getzenberg Terry L. Donat Kenneth J. Pienta 《Journal of cellular biochemistry》1996,62(1):132-141
The nuclear matrix has been linked to several important cellular functions within cells, such as DNA organization and replication, as well as regulation of gene expression. It has been reported that the nuclear matrix protein composition is altered in cells grown on different extracellular matrices in vitro. This study examined the nuclear matrix protein composition of tumors produced by MAT-LyLu (MLL) rat prostate tumor cells implanted at different organ sites within the rat. When high resolution two-dimensional gels were utilized to compare nuclear matrix protein composition to the prostate orthotopic tumor, it was found that there were distinct protein differences depending upon where the tumor grew. In particular, there were 14 proteins found in the lung, six proteins found in intramuscular, 17 proteins is the heart, and five proteins in the tail vein tumor tissue that were not present in the prostate orthotopic tumor tissue. Therefore, this study adds evidence to support that the nuclear matrix composition of a cell is dependent, at least in part, by the extracellular matrix and/or different cellular environments and may have a role in site-specific differences in tumor properties. © 1996 Wiley-Liss, Inc. 相似文献
110.
Elizabeth A. Wilson Eric N. Powell M. Alison Craig Terry L. Wade James M. Brooks 《International Review of Hydrobiology》1990,75(4):533-550
Oysters from 48 Gulf of Mexico sites were examined for presence and infection intensity of the endoparasite, Perkinsus (= Dermocystidium) marinus (Mackin, Owen and Collier, 1950) as part of NOAA's Status and Trends Mussel Watch Program. Prevalence exceeded 75% at 25 sites. Infection intensity did not vary with sex or reproductive stage. Latitude, total polynuclear aromatic hydrocarbon (PAH) content and industrial and agricultural land use significantly affected the parasite's distribution. PAH and pesticide concentrations were latitudinally dependent, suggesting an impact of spawning frequency on uptake and depuration. P. marinus analysis complements the use of pollutant body burden for determining change in environmental quality because it responds differently than pollutant body burden to the biology and ecology of the oyster. 相似文献