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21.
Prostaglandin-like material was released from finely cut guinea-pig ileum or human intestinal mucosa during incubation with Krebs solution. The tissue inactivated some significant change in release of prostaglandin-like material when pure cholera toxin was incubated with guinea-pig ileum or human intestinal mucosa. The work is discussed in relation to the action of cholera toxin in vivo. 相似文献
22.
Identification, characterization, and nucleotide sequence of the F17-G gene, which determines receptor binding of Escherichia coli F17 fimbriae. 总被引:4,自引:0,他引:4 下载免费PDF全文
P F Lintermans A Bertels C Schlicker F Deboeck G Charlier P Pohl M Norgren S Normark M van Montagu H De Greve 《Journal of bacteriology》1991,173(11):3366-3373
Enterotoxigenic Escherichia coli strains express fimbriae which mediate binding to intestinal mucosal cells. The F17 fimbriae mediate binding to N-acetylglucosamine-containing receptors present on calf intestinal mucosal cells. These fimbriae consist of F17-A subunit peptides. Analysis of the F17 gene cluster indicated that at least the F17-A, F17-C, F17-D, and F17-G genes are indispensable to obtain adhesive F17 fimbriae (unpublished data). Genetic evidence is presented that the F17-G protein, a minor fimbrial component, is required for the binding of the F17 fimbriae to the intestinal villi. The F17-G gene was cloned and sequenced. An open reading frame of 1,032 bp encoding a polypeptide of 344 amino acids, starting with a signal sequence of 22 residues, was localized. The F17-G mutant strain produced F17 fimbriae which were morphologically identical to the fimbriae purified from strains which contained the intact F17 gene cluster. However, this F17-G mutant could no longer adhere to calf villi. The F17-G locus was shown to act in trans: transformation of the F17-G mutant strain, still expressing the genes F17-A, F17-C, and F17-D, with a vector expressing the F17-G gene restored the binding activity of this mutant strain. 相似文献
23.
Patricia Maurer Corinne Royer Bernard Mauchamp Patrick Porcheron Danile Debieu Guy Riba 《Archives of insect biochemistry and physiology》1991,16(1):1-9
The major ecdysteroids in large worker pupae of the leaf-cutting ant Acromyrmex octospinosus were characterized at the peak ecdysteroid concentration by using high-performance liquid chromatography, enzyme immunoassay, and mass spectrometry. In decreasing amounts, they were determined to be makisterone A, an unidentified C28 ecdysteroid bearing a molecular weight of 494, 20-hydroxyecdysone (ratio of 1 to 6 as compared to makisterone A), and putative but negligible ecdysone. The presence of both C28 and C27 ecdysteroids is discussed in relation to the content of 4-desmethylsterols determined by gas chromatography and mass spectrometry to be ergosta-5,7,24 (28)-trien-3β-ol, ergosterol, ergosta-5,7-dien-3β-ol and ergosta-7,24(28)-dien-3β-ol for the main sterols, and with a small amount of cholesterol. 相似文献
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Aaron Mendez-Bermudez Liudmyla Lototska Melanie Pousse Florent Tessier Oliver Croce Chrysa
M Latrick Veronica Cherdyntseva Joe Nassour Jiang Xiaohua Yiming Lu Corinne Abbadie Sarantis Gagos Jing Ye Eric Gilson 《Nucleic acids research》2022,50(13):7493
Cellular senescence triggers various types of heterochromatin remodeling that contribute to aging. However, the age-related mechanisms that lead to these epigenetic alterations remain elusive. Here, we asked how two key aging hallmarks, telomere shortening and constitutive heterochromatin loss, are mechanistically connected during senescence. We show that, at the onset of senescence, pericentromeric heterochromatin is specifically dismantled consisting of chromatin decondensation, accumulation of DNA breakages, illegitimate recombination and loss of DNA. This process is caused by telomere shortening or genotoxic stress by a sequence of events starting from TP53-dependent downregulation of the telomere protective protein TRF2. The resulting loss of TRF2 at pericentromeres triggers DNA breaks activating ATM, which in turn leads to heterochromatin decondensation by releasing KAP1 and Lamin B1, recombination and satellite DNA excision found in the cytosol associated with cGAS. This TP53–TRF2 axis activates the interferon response and the formation of chromosome rearrangements when the cells escape the senescent growth arrest. Overall, these results reveal the role of TP53 as pericentromeric disassembler and define the basic principles of how a TP53-dependent senescence inducer hierarchically leads to selective pericentromeric dismantling through the downregulation of TRF2. 相似文献
26.
Olivier Mercey Corinne Kostic Eloïse Bertiaux Alexia Giroud Yashar Sadian David C. A. Gaboriau Ciaran G. Morrison Ning Chang Yvan Arsenijevic Paul Guichard Virginie Hamel 《PLoS biology》2022,20(6)
Inherited retinal degeneration due to loss of photoreceptor cells is a leading cause of human blindness. These cells possess a photosensitive outer segment linked to the cell body through the connecting cilium (CC). While structural defects of the CC have been associated with retinal degeneration, its nanoscale molecular composition, assembly, and function are barely known. Here, using expansion microscopy and electron microscopy, we reveal the molecular architecture of the CC and demonstrate that microtubules are linked together by a CC inner scaffold containing POC5, CENTRIN, and FAM161A. Dissecting CC inner scaffold assembly during photoreceptor development in mouse revealed that it acts as a structural zipper, progressively bridging microtubule doublets and straightening the CC. Furthermore, we show that Fam161a disruption in mouse leads to specific CC inner scaffold loss and triggers microtubule doublet spreading, prior to outer segment collapse and photoreceptor degeneration, suggesting a molecular mechanism for a subtype of retinitis pigmentosa.Inherited retinal degeneration due to loss of photoreceptor cells is a leading cause of human blindness. Ultrastructure expansion microscopy on mouse retina reveals the presence of a novel structure inside the photoreceptor connecting cilium, the inner scaffold, that protects the outer segment against degeneration. 相似文献
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Bouyssié D Gonzalez de Peredo A Mouton E Albigot R Roussel L Ortega N Cayrol C Burlet-Schiltz O Girard JP Monsarrat B 《Molecular & cellular proteomics : MCP》2007,6(9):1621-1637
Proteomics strategies based on nanoflow (nano-) LC-MS/MS allow the identification of hundreds to thousands of proteins in complex mixtures. When combined with protein isotopic labeling, quantitative comparison of the proteome from different samples can be achieved using these approaches. However, bioinformatics analysis of the data remains a bottleneck in large scale quantitative proteomics studies. Here we present a new software named Mascot File Parsing and Quantification (MFPaQ) that easily processes the results of the Mascot search engine and performs protein quantification in the case of isotopic labeling experiments using either the ICAT or SILAC (stable isotope labeling with amino acids in cell culture) method. This new tool provides a convenient interface to retrieve Mascot protein lists; sort them according to Mascot scoring or to user-defined criteria based on the number, the score, and the rank of identified peptides; and to validate the results. Moreover the software extracts quantitative data from raw files obtained by nano-LC-MS/MS, calculates peptide ratios, and generates a non-redundant list of proteins identified in a multisearch experiment with their calculated averaged and normalized ratio. Here we apply this software to the proteomics analysis of membrane proteins from primary human endothelial cells (ECs), a cell type involved in many physiological and pathological processes including chronic inflammatory diseases such as rheumatoid arthritis. We analyzed the EC membrane proteome and set up methods for quantitative analysis of this proteome by ICAT labeling. EC microsomal proteins were fractionated and analyzed by nano-LC-MS/MS, and database searches were performed with Mascot. Data validation and clustering of proteins were performed with MFPaQ, which allowed identification of more than 600 unique proteins. The software was also successfully used in a quantitative differential proteomics analysis of the EC membrane proteome after stimulation with a combination of proinflammatory mediators (tumor necrosis factor-alpha, interferon-gamma, and lymphotoxin alpha/beta) that resulted in the identification of a full spectrum of EC membrane proteins regulated by inflammation. 相似文献
29.
Germline transformation of the silkworm Bombyx mori L. using a piggyBac transposon-derived vector 总被引:21,自引:0,他引:21
Tamura T Thibert C Royer C Kanda T Abraham E Kamba M Komoto N Thomas JL Mauchamp B Chavancy G Shirk P Fraser M Prudhomme JC Couble P Toshiki T Chantal T Corinne R Toshio K Eappen A Mari K Natuo K Jean-Luc T Bernard M Gérard C Paul S Malcolm F Jean-Claude P Pierre C 《Nature biotechnology》2000,18(1):81-84
We have developed a system for stable germline transformation in the silkworm Bombyx mori L. using piggyBac, a transposon discovered in the lepidopteran Trichoplusia ni. The transformation constructs consist of the piggyBac inverted terminal repeats flanking a fusion of the B. mori cytoplasmic actin gene BmA3 promoter and the green fluorescent protein (GFP). A nonautonomous helper plasmid encodes the piggyBac transposase. The reporter gene construct was coinjected into preblastoderm eggs of two strains of B. mori. Approximately 2% of the individuals in the G1 broods expressed GFP. DNA analyses of GFP-positive G1 silkworms revealed that multiple independent insertions occurred frequently. The transgene was stably transferred to the next generation through normal Mendelian inheritance. The presence of the inverted terminal repeats of piggyBac and the characteristic TTAA sequence at the borders of all the analyzed inserts confirmed that transformation resulted from precise transposition events. This efficient method of stable gene transfer in a lepidopteran insect opens the way for promising basic research and biotechnological applications. 相似文献
30.
Sb(III) oxidation was documented in an Agrobacterium tumefaciens isolate that can also oxidize As(III). Equivalent Sb(III) oxidation rates were observed in the parental wild-type organism and in two well-characterized mutants that cannot oxidize As(III) for fundamentally different reasons. Therefore, despite the literature suggesting that Sb(III) and As(III) may be biochemical analogs, Sb(III) oxidation is catalyzed by a pathway different than that used for As(III). Sb(III) and As(III) oxidation was also observed for an eukaryotic acidothermophilic alga belonging to the order Cyanidiales, implying that the ability to oxidize metalloids may be phylogenetically widespread. 相似文献