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331.
Background
In black-background-adapted Xenopus laevis, the intermediate pituitary melanotrope cells are hyperactive, producing large amounts of their major secretory cargo proopiomelanocortin (POMC, representing ~80% of all newly synthesised proteins), whereas in white-adapted frogs these cells are only basally active. Here we explored in the hyperactive and basally active melanotrope cells the capacity for posttranslational POMC processing events in the secretory pathway. 相似文献332.
Roelofsen H Dijkstra M Weening D de Vries MP Hoek A Vonk RJ 《Molecular & cellular proteomics : MCP》2009,8(2):316-324
Adipose tissue is an endocrine organ involved in regulation of whole-body energy metabolism via storage of lipids and secretion of various peptide hormones (adipokines). We previously characterized the adipose tissue secretome and showed that [(13)C]lysine incorporation into secreted proteins can be used to determine the origin of identified proteins. In the present study we determined the effect of insulin on the secretome by comparing incorporation rates of (13)C-labeled lysine in the presence and absence of insulin. Human visceral adipose tissue from one patient was divided over six dishes. After subsequent washes to remove serum proteins, [(13)C]lysine-containing medium was added. Three dishes also received 60 nm insulin. The other three were controls. After 72 h of culture, media were collected and processed separately, involving concentration by ultrafiltration and fractionation by SDS-PAGE followed by in-gel digestion of excised bands and LC-MS/MS analyses. The obtained spectra were used for database searching and calculation of heavy/light ratios. The three control data sets shared 342 proteins of which 156 were potentially secreted and contained label. The three insulin-derived data sets shared 361 proteins of which 141 were potentially secreted and contained label. After discarding secreted proteins with very low label incorporation, 121 and 113 proteins remained for control and insulin data sets, respectively. The average coefficient of variation for control triplicates was 10.0% and for insulin triplicates was 18.3%. By comparing heavy/light ratios in the absence and presence of insulin we found 24 up-regulated proteins and four down-regulated proteins, and 58 proteins showed no change. Proteins involved in the endoplasmic reticulum stress response and in extracellular matrix remodeling were up-regulated by insulin. In conclusion, comparison of isotope-labeled amino acid incorporation rates (CILAIR) allows quantitative assessment of changes in protein secretion without the need for 100% label incorporation, which cannot be reached in differentiated tissues or cells. 相似文献
333.
Background
Biological data resources have become heterogeneous and derive from multiple sources. This introduces challenges in the management and utilization of this data in software development. Although efforts are underway to create a standard format for the transmission and storage of biological data, this objective has yet to be fully realized. 相似文献334.
Artem?CherkasovEmail author Shannan?J?Ho Sui Robert?C?Brunham Steven?JM?Jones 《BMC bioinformatics》2004,5(1):101
Background
We establish that the occurrence of protein folds among genomes can be accurately described with a Weibull function. Systems which exhibit Weibull character can be interpreted with reliability theory commonly used in engineering analysis. For instance, Weibull distributions are widely used in reliability, maintainability and safety work to model time-to-failure of mechanical devices, mechanisms, building constructions and equipment. 相似文献335.
Nell MJ Tjabringa GS Vonk MJ Hiemstra PS Grote JJ 《FEMS immunology and medical microbiology》2004,42(2):225-231
The respiratory epithelium plays a major role in the primary defense of the airways against infection. It has been demonstrated that bacterial products are involved in the induction of inflammatory reactions of the upper airways. Little is known about the effects of bacterial products on expression of the antimicrobial peptide hCAP-18/LL-37, the only human cathelicidin identified so far. The aim of this study was to investigate the effects of bacterial products from both gram-positive and gram-negative bacteria on the expression of hCAP-18/LL-37 by sinus epithelial cells using an air-exposed tissue culture model. Lipopolysaccharide and lipoteichoic acid both increased hCAP-18/LL-37 expression in cultured sinus epithelium as assessed by immunohistochemistry, where maximal stimulation occurred at 100 ng ml(-1) lipopolysaccharide or 10 microg ml(-1) lipoteichoic acid. The stimulatory effect of lipopolysaccharide and lipoteichoic acid was not restricted to expression of hCAP-18/LL-37, since also mucin expression and IL-8 release from cultured sinus epithelium cells were increased by lipopolysaccharide and lipoteichoic acid. This suggests that bacterial products may stimulate innate immunity in the upper airways. 相似文献
336.
Agnes?SchuurmansEmail author Rob?RouwetteEmail author Nico?Vonk Joris?Broers Hester?Rijnsburger Hans?Pietersen 《The International Journal of Life Cycle Assessment》2005,10(2):131-135
Goal, Scope and Background Due to the limited spatial possibilities for the extraction of coarse sand available from land sources, and the abundant availability of finer sands in land and marine sources, the Dutch government aims to allow for the use of finer sand used in the Netherlands. The application of finer sand in concrete requires adaptations in the concrete composition (additional cement, additional superplasticiser, or other aggregates) to maintain workability. In order to examine if these adaptations result in shifts from (the expected) land use effects to other environmental effects, an LCA of finer sand in concrete was carried out.Methods Besides the common CML-method, an experimental characterisation method for land use, was applied.Results and Discussion, Conclusion The results show that the application of finer sand indeed results in lower land use effects. Compositions with additional cement and other aggregates result in somewhat higher scores on the usual CML impact categories. Compositions with extra superplasticiser result in roughly similar environmental effects as the current compositions.Recommendation and Perspective The conclusions were used to formulate recommendations for the national policy on fine sand in concrete. Due to a change in priorities, it is not sure if and which organisation will use the conclusions. 相似文献
337.
MCW Chan CY Cheung WH Chui SW Tsao JM Nicholls YO Chan RWY Chan HT Long LLM Poon Y Guan JSM Peiris 《Respiratory research》2005,6(1):135
Background
Fatal human respiratory disease associated with influenza A subtype H5N1 has been documented in Hong Kong, and more recently in Vietnam, Thailand and Cambodia. We previously demonstrated that patients with H5N1 disease had unusually high serum levels of IP-10 (interferon-gamma-inducible protein-10). Furthermore, when compared with human influenza virus subtype H1N1, the H5N1 viruses in 1997 (A/Hong Kong/483/97) (H5N1/97) were more potent inducers of pro-inflammatory cytokines (e.g. tumor necrosis factor-a) and chemokines (e.g. IP-10) from primary human macrophages in vitro, which suggests that cytokines dysregulation may play a role in pathogenesis of H5N1 disease. Since respiratory epithelial cells are the primary target cell for replication of influenza viruses, it is pertinent to investigate the cytokine induction profile of H5N1 viruses in these cells.Methods
We used quantitative RT-PCR and ELISA to compare the profile of cytokine and chemokine gene expression induced by H5N1 viruses A/HK/483/97 (H5N1/97), A/Vietnam/1194/04 and A/Vietnam/3046/04 (both H5N1/04) with that of human H1N1 virus in human primary alveolar and bronchial epithelial cells in vitro.Results
We demonstrated that in comparison to human H1N1 viruses, H5N1/97 and H5N1/04 viruses were more potent inducers of IP-10, interferon beta, RANTES (regulated on activation, normal T cell expressed and secreted) and interleukin 6 (IL-6) in primary human alveolar and bronchial epithelial cells in vitro. Recent H5N1 viruses from Vietnam (H5N1/04) appeared to be even more potent at inducing IP-10 than H5N1/97 virus.Conclusion
The H5N1/97 and H5N1/04 subtype influenza A viruses are more potent inducers of proinflammatory cytokines and chemokines in primary human respiratory epithelial cells than subtype H1N1 virus. We suggest that this hyper-induction of cytokines may be relevant to the pathogenesis of human H5N1 disease. 相似文献338.
339.
340.
Evolution of the secondary structures and compensatory mutations of the ribosomal RNAs of Drosophila melanogaster 总被引:10,自引:0,他引:10
This paper examines the effects of DNA sequence evolution on RNA secondary
structures and compensatory mutations. Models of the secondary structures
of Drosophila melanogaster 18S ribosomal RNA (rRNA) and of the complex
between 2S, 5.8S, and 28S rRNAs have been drawn on the basis of comparative
and energetic criteria. The overall AU richness of the D. melanogaster
rRNAs allows the resolution of some ambiguities in the structures of both
large rRNAs. Comparison of the sequence of expansion segment V2 in D.
melanogaster 18S rRNA with the same region in three other Drosophila
species and the tsetse fly (Glossina morsitans morsitans) allows us to
distinguish between two models for the secondary structure of this region.
The secondary structures of the expansion segments of D. melanogaster 28S
rRNA conform to a general pattern for all eukaryotes, despite having highly
divergent sequences between D. melanogaster and vertebrates. The 70 novel
compensatory mutations identified in the 28S rRNA show a strong (70%) bias
toward A-U base pairs, suggesting that a process of biased mutation and/or
biased fixation of A and T point mutations or AT-rich slippage-generated
motifs has occurred during the evolution of D. melanogaster rDNA. This
process has not occurred throughout the D. melanogaster genome. The
processes by which compensatory pairs of mutations are generated and spread
are discussed, and a model is suggested by which a second mutation is more
likely to occur in a unit with a first mutation as such a unit begins to
spread through the family and concomitantly through the population.
Alternatively, mechanisms of proofreading in stem-loop structures at the
DNA level, or between RNA and DNA, might be involved. The apparent
tolerance of noncompensatory mutations in some stems which are otherwise
strongly supported by comparative criteria within D. melanogaster 28S rRNA
must be borne in mind when compensatory mutations are used as a criterion
in secondary-structure modeling. Noncompensatory mutation may extend to the
production of unstable structures where a stem is stabilized by RNA-
protein or additional RNA-RNA interactions in the mature ribosome. Of
motifs suggested to be involved in rRNA processing, one (CGAAAG) is
strongly overrepresented in the 28S rRNA sequence. The data are discussed
both in the context of the forces involved with the evolution of multigene
families and in the context of molecular coevolution in the rDNA family in
particular.
相似文献