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31.
We used scaled factorial moments to search for intermittency in the log expression ratios (LERs) for thousands of genes spotted on cDNA microarrays (gene chips). Results indicate varying levels of intermittency in gene expression. The observation of intermittency in the data analyzed provides a complimentary handle on moderately expressed genes, generally not tackled by conventional techniques. 相似文献
32.
Characterization of the endogenous plasmid from Pseudomonas alcaligenes NCIB 9867: DNA sequence and mechanism of transfer 下载免费PDF全文
The endogenous plasmid pRA2 from Pseudomonas alcaligenes NCIB 9867 was determined to have 32,743 bp with a G+C content of 59.8%. Sequence analysis predicted a total of 29 open reading frames, with approximately half of them contributing towards the functions of plasmid replication, mobilization, and stability. The Pac25I restriction-modification system and two mobile elements, Tn5563 and IS1633, were physically localized. An additional eight open reading frames with unknown functions were also detected. pRA2 was genetically tagged with the OmegaStr(r)/Spc(r) gene cassette by homologous recombination. Intrastrain transfer of pRA2-encoded genetic markers between isogenic mutants of P. alcaligenes NCIB 9867 were observed at high frequencies (2.4 x 10(-4) per donor). This transfer was determined to be mediated by a natural transformation process that required cell-cell contact and was completely sensitive to DNase I (1 mg/ml). Efficient transformation was also observed when pRA2 DNA was applied directly onto the cells, while transformation with foreign plasmid DNAs was not observed. pRA2 could be conjugally transferred into Pseudomonas putida RA713 and KT2440 recipients only when plasmid RK2/RP4 transfer functions were provided in trans. Plasmid stability analysis demonstrated that pRA2 could be stably maintained in its original host, P. alcaligenes NCIB 9867, as well as in P. putida RA713 after 100 generations of nonselective growth. Disruption of the pRA2 pac25I restriction endonuclease gene did not alter plasmid stability, while the pRA2 minireplicon exhibited only partial stability. This indicates that other pRA2-encoded determinants could have significant roles in influencing plasmid stability. 相似文献
33.
34.
Hörig H Lee DS Conkright W Divito J Hasson H LaMare M Rivera A Park D Tine J Guito K Tsang KW Schlom J Kaufman HL 《Cancer immunology, immunotherapy : CII》2000,49(9):504-514
The generation of cytotoxic effector T cells requires delivery of two signals, one derived from a specific antigenic epitope
and one from a costimulatory molecule. A phase I clinical trial was conducted with a non-replicating canarypoxvirus (ALVAC)
constructed to express both human carcinoembryonic antigen (CEA) and the B7.1 costimulatory molecule. This was the first study
in cancer patients to determine if the delivery of costimulation with a tumor vaccine was feasible and improved immune responses.
Three cohorts of six patients, each with advanced CEA-expressing adenocarcinomas, were treated with increasing doses of an
ALVAC-CEA-B7.1 vaccine (4.5 × 106, 4.5 × 107, and 4.5 × 108 plaque-forming units, PFU). Patients were vaccinated by intramuscular injection every 4 weeks for 3 months and monitored
for side-effects, tumor growth and anti-CEA immune responses. ALVAC-CEA- B7.1 at doses up to 4.5 × 108 PFU was given without evidence of significant toxicity or autoimmune reactions. Three patients experienced clinically stable
disease that correlated with increasing CEA-specific precursor T cells, as shown by in vitro interferon-γ enzyme-linked immunoassay
spot tests (ELISPOT). These three patients underwent repeated vaccination resulting in augmented CEA-specific T cell responses.
This study represents the first use of costimulation to enhance antitumor vaccines in cancer patients. This approach resulted
in CEA-specific immunity associated with stable diseases in three patients. This study also demonstrated that CEA-specific
T cell responses could be sustained by repeated vaccinations. Although the number of patients was small, the addition of B7.1
to virus-based vaccines may improve immunological and stable diseases to vaccination against tumor-associated antigens with
tolerable toxicity.
Received: 6 May 2000 / Accepted: 13 July 2000 相似文献
35.
High rate of DNA loss in the Drosophila melanogaster and Drosophila virilis species groups 总被引:6,自引:3,他引:3
We recently proposed that patterns of evolution of non-LTR
retrotransposable elements can be used to study patterns of spontaneous
mutation. Transposition of non-LTR retrotransposable elements commonly
results in creation of 5' truncated, "dead-on-arrival" copies. These
inactive copies are effectively pseudogenes and, according to the neutral
theory, their molecular evolution ought to reflect rates and patterns of
spontaneous mutation. Maximum parsimony can be used to separate the
evolution of active lineages of a non-LTR element from the fate of the
"dead-on-arrival" insertions and to directly assess the relative
frequencies of different types of spontaneous mutations. We applied this
approach using a non-LTR element, Helena, in the Drosophila virilis group
and have demonstrated a surprisingly high incidence of large deletions and
the virtual absence of insertions. Based on these results, we suggested
that Drosophila in general may exhibit a high rate of spontaneous large
deletions and have hypothesized that such a high rate of DNA loss may help
to explain the puzzling dearth of bona fide pseudogenes in Drosophila. We
also speculated that variation in the rate of spontaneous deletion may
contribute to the divergence of genome size in different taxa by affecting
the amount of superfluous "junk" DNA such as, for example, pseudogenes or
long introns. In this paper, we extend our analysis to the D. melanogaster
subgroup, which last shared a common ancestor with the D. virilis group
approximately 40 MYA. In a different region of the same transposable
element, Helena, we demonstrate that inactive copies accumulate deletions
in species of the D. melanogaster subgroup at a rate very similar to that
of the D. virilis group. These results strongly suggest that the high rate
of DNA loss is a general feature of Drosophila and not a peculiar property
of a particular stretch of DNA in a particular species group.
相似文献
36.
Targeted disruption of the ubiquitous CNC-bZIP transcription factor, Nrf-1, results in anemia and embryonic lethality in mice. 总被引:1,自引:0,他引:1
The CNC-basic leucine zipper (CNC-bZIP) family is a subfamily of bZIP proteins identified from independent searches for factors that bind the AP-1-like cis-elements in the beta-globin locus control region. Three members, p45-Nf-e2, Nrf-1 and Nrf-2 have been identified in mammals. Expression of p45-Nf-e2 is largely restricted to hematopoietic cells while Nrf-1 and Nrf-2 are expressed in a wide range of tissues. To determine the function of Nrf-1, targeted disruption of the Nrf-1 gene was carried out. Homozygous Nrf-1 mutant mice are anemic due to a non-cell autonomous defect in definitive erythropoiesis and die in utero. 相似文献
37.
38.
Melissa M. Page Kurtis D. Salway Yuen Kwong Ip Shit F. Chew Sarah A. Warren James S. Ballantyne Jeffrey A. Stuart 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(3):361-369
The African slender lungfish, Protopterus dolloi, is highly adapted to withstand periods of drought by secreting a mucous cocoon and estivating for periods of months to years. Estivation is similar to the diapause and hibernation of other animal species in that it is characterized by negligible activity and a profoundly depressed metabolic rate. As is typically observed in quiescent states, estivating P. dolloi are resistant to environmental stresses. We tested the hypothesis that P. dolloi enhances stress resistance during estivation by upregulating intracellular antioxidant defences in brain and heart tissues. We found that most of the major intracellular antioxidant enzymes, including the mitochondrial superoxide dismutase, cytosolic superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, were upregulated in brain tissue of lungfish that had estivated for 60 days. Several of these enzymes were also elevated in heart tissue of estivators. These changes were not due to food deprivation, as they did not occur in a group of fish that were deprived of food but maintained in water for the same period of time. We found little evidence of tissue oxidative damage in estivators. Products of lipid peroxidation (4-hydroxynonenal adducts) and oxidative protein damage (carbonylation) were similar in estivating and control lungfish. However, protein nitrotyrosine levels were elevated in brain tissue of estivators. Taken together, these data indicate that estivating P. dolloi have enhanced oxidative stress resistance in brain and heart due to a significant upregulation of intracellular antioxidant capacity. 相似文献
39.
Experiments were conducted in a continuous flow reactor at room temperature to evaluate the elimination of low-concentration toluene in the gas phase to verify if fly-ash products from biomass combustion in an ozonation system could be used in the removal of volatile organic compounds. The fly-ash products from pure biomass combustion (Ash100) demonstrated the highest ozonation activities upon the removal of low-concentration toluene (1.5 ppmv), followed by the fly-ash products from co-combustion (Ash30) and the coal combustion (Ash0). Kinetic experiments showed that the activation energy of the toluene elimination process was substantially reduced with the use of ozone and the reaction intermediates, such as formic acids, aldehydes, etc. Results also showed that the intermediates were reduced with increasing humidity level. The combined use of fly-ash products and zeolite 13X enhanced the removal of toluene to above 90% and suppressed the release of residual ozone and intermediates by holding them in the adsorbed phase. 相似文献
40.
Zhongcai Ma Kenny Y.C. Kwong David Paek 《Biochemical and biophysical research communications》2010,400(4):569-574
Plaminogen activator inhibitor-1 (PAI-1), the key physiological inhibitor of the plasmin fibrinolytic system, plays important roles in the pathogenesis of asthma. Mast cells (MCs) are crucial effector cells and a major source of PAI-1 for asthma. Cyclic adenosine monophosphate (cAMP) is the important regulator of MCs; however, its effects on PAI-1 expression in MCs remain unknown. We reported cAMP/protein kinase A pathway positively regulates PAI-1 expression through cAMP-response element binding protein binding to hypoxia response element-1 at −158 to −153 bp of human PAI-1 promoter in human MCs. Moreover, cAMP synergistically augments PAI-1 expression with ionomycin- or IgE receptor cross-linking-mediated stimulation. 相似文献