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123.
Lucia Panzella Paola Manini Giuseppe Monfrecola Marco D'Ischia Alessandra Napolitano 《Pigment cell & melanoma research》2007,20(2):128-133
A procedure for analysis of melanin‐pigmented tissues based on alkaline hydrogen peroxide degradation coupled with high‐performance liquid chromatography (HPLC) ultraviolet determination of pyrrole‐2,3,5‐tricarboxylic acid (PTCA) for eumelanin and 6‐(2‐amino‐2‐carboxyethyl)‐2‐carboxy‐4‐hydroxybenzothiazole (BTCA) and 1,3‐thiazole‐2,4,5‐tricarboxylic acid for pheomelanin was recently developed. Despite advantages related to the degradation conditions and sample handling, a decrease of the reproducibility and resolution was observed after several chromatographic runs. We report herein an improved chromatographic methodology for simultaneous determination of PTCA and BTCA as representative markers of eumelanin and pheomelanin, respectively, based on the use of an octadecylsilane column with polar end‐capping with 1% formic acid (pH 2.8)/methanol as the eluant. The method requires conventional HPLC equipments and gives very good peak shapes and resolution, without need of ion pair reagents or high salt concentrations in the mobile phase. The intra‐assay precision of the analytical runs was satisfactory with CV values ≤4.0% (n = 5) for the two markers which did not exceed 8% after 50 consecutive injections on the column over 1 week. The peak area ratios at 254 and 280 nm (A280/A254: PTCA = 1.1, BTCA = 0.6) proved a valuable parameter for reliable identification of the structural markers even in the most complex degradation mixtures. The method can be applied to various eumelanin and pheomelanin pigmented tissues, including mammalian hair, skin and irides, and is amenable to be employed in population screening studies. 相似文献
124.
Wang-Sattler R Blandin S Ning Y Blass C Dolo G Touré YT delle Torre A Lanzaro GC Steinmetz LM Kafatos FC Zheng L 《PloS one》2007,2(11):e1249
Background
Attempts over the last three decades to reconstruct the phylogenetic history of the Anopheles gambiae species complex have been important for developing better strategies to control malaria transmission.Methodology
We used fingerprint genotyping data from 414 field-collected female mosquitoes at 42 microsatellite loci to infer the evolutionary relationships of four species in the A. gambiae complex, the two major malaria vectors A. gambiae sensu stricto (A. gambiae s.s.) and A. arabiensis, as well as two minor vectors, A. merus and A. melas.Principal Findings
We identify six taxonomic units, including a clear separation of West and East Africa A. gambiae s.s. S molecular forms. We show that the phylogenetic relationships vary widely between different genomic regions, thus demonstrating the mosaic nature of the genome of these species. The two major malaria vectors are closely related and closer to A. merus than to A. melas at the genome-wide level, which is also true if only autosomes are considered. However, within the Xag inversion region of the X chromosome, the M and two S molecular forms are most similar to A. merus. Near the X centromere, outside the Xag region, the two S forms are highly dissimilar to the other taxa. Furthermore, our data suggest that the centromeric region of chromosome 3 is a strong discriminator between the major and minor malaria vectors.Conclusions
Although further studies are needed to elucidate the basis of the phylogenetic variation among the different regions of the genome, the preponderance of sympatric admixtures among taxa strongly favor introgression of different genomic regions between species, rather than lineage sorting of ancestral polymorphism, as a possible mechanism. 相似文献125.
The renewal and differentiation of Isl1+ cardiovascular progenitors are controlled by a Wnt/beta-catenin pathway 总被引:3,自引:0,他引:3
Qyang Y Martin-Puig S Chiravuri M Chen S Xu H Bu L Jiang X Lin L Granger A Moretti A Caron L Wu X Clarke J Taketo MM Laugwitz KL Moon RT Gruber P Evans SM Ding S Chien KR 《Cell Stem Cell》2007,1(2):165-179
Isl1(+) cardiovascular progenitors and their downstream progeny play a pivotal role in cardiogenesis and lineage diversification of the heart. The mechanisms that control their renewal and differentiation are largely unknown. Herein, we show that the Wnt/beta-catenin pathway is a major component by which cardiac mesenchymal cells modulate the prespecification, renewal, and differentiation of isl1(+) cardiovascular progenitors. This microenvironment can be reconstituted by a Wnt3a-secreting feeder layer with ES cell-derived, embryonic, and postnatal isl1(+) cardiovascular progenitors. In vivo activation of beta-catenin signaling in isl1(+) progenitors of the secondary heart field leads to their massive accumulation, inhibition of differentiation, and outflow tract (OFT) morphogenic defects. In addition, the mitosis rate in OFT myocytes is significantly reduced following beta-catenin deletion in isl1(+) precursors. Agents that manipulate Wnt signals can markedly expand isl1(+) progenitors from human neonatal hearts, a key advance toward the cloning of human isl1(+) heart progenitors. 相似文献
126.
Toscani T Moseriti A Dossena A Dall'Asta C Simoncini N Virgili R 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,855(2):242-248
A fast and sensitive method for the quantification of the mycotoxin ochratoxin A (OTA) in dry-cured meat products has been developed, which does not require a clean-up step, by HPLC with an alkaline mobile phase (pH 9.8). Validation procedures for specificity, trueness, ruggedness, stability, recovery and repeatability were performed. The decision limit (CC alpha) and the decision capability (CC beta) were calculated at 1.10 and 1.23 microg/kg, respectively. The procedure was applied to representative dehydration levels of dry-cured meat samples. 相似文献
127.
Proteomics analysis of cytokine-induced dysfunction and death in insulin-producing INS-1E cells: new insights into the pathways involved 总被引:1,自引:0,他引:1
D'Hertog W Overbergh L Lage K Ferreira GB Maris M Gysemans C Flamez D Cardozo AK Van den Bergh G Schoofs L Arckens L Moreau Y Hansen DA Eizirik DL Waelkens E Mathieu C 《Molecular & cellular proteomics : MCP》2007,6(12):2180-2199
Cytokines released by islet-infiltrating immune cells play a crucial role in beta-cell dysfunction and apoptotic cell death in the pathogenesis of type 1 diabetes and after islet transplantation. RNA studies revealed complex pathways of genes being activated or suppressed during this beta-cell attack. The aim of the present study was to analyze protein changes in insulin-producing INS-1E cells exposed to inflammatory cytokines in vitro using two-dimensional DIGE. Within two different pH ranges we observed 2214 +/- 164 (pH 4-7) and 1641 +/- 73 (pH 6-9) spots. Analysis at three different time points (1, 4, and 24 h of cytokine exposure) revealed that the major changes were taking place only after 24 h. At this time point 158 proteins were altered in expression (4.1%, n = 4, p < or = 0.01) by a combination of interleukin-1beta and interferon-gamma, whereas only 42 and 23 proteins were altered by either of the cytokines alone, giving rise to 199 distinct differentially expressed spots. Identification of 141 of these by MALDI-TOF/TOF revealed proteins playing a role in insulin secretion, cytoskeleton organization, and protein and RNA metabolism as well as proteins associated with endoplasmic reticulum and oxidative stress/defense. We investigated the interactions of these proteins and discovered a significant interaction network (p < 1.27e-05) containing 42 of the identified proteins. This network analysis suggests that proteins of different pathways act coordinately in a beta-cell dysfunction/apoptotic beta-cell death interactome. In addition the data suggest a central role for chaperones and proteins playing a role in RNA metabolism. As many of these identified proteins are regulated at the protein level or undergo post-translational modifications, a proteomics approach, as performed in this study, is required to provide adequate insight into the mechanisms leading to beta-cell dysfunction and apoptosis. The present findings may open new avenues for the understanding and prevention of beta-cell loss in type 1 diabetes. 相似文献
128.
Handisurya A Gilch S Winter D Shafti-Keramat S Maurer D Schätzl HM Kirnbauer R 《The FEBS journal》2007,274(7):1747-1758
Prion diseases are fatal neurodegenerative disorders caused by proteinaceous infectious pathogens termed prions (PrP(Sc)). To date, there is no prophylaxis or therapy available for these transmissible encephalopathies. Passive immunization with monclonal antibodies recognizing the normal host-encoded prion protein (PrP(C)) has been reported to abolish PrP(Sc) infectivity and to delay onset of disease. Because of established immunologic tolerance against the widely expressed PrP(C), active immunization appears to be difficult to achieve. To overcome this limitation, papillomavirus-like particles were generated that display a nine amino acid B-cell epitope, DWEDRYYRE, of the murine/rat prion protein in an immunogenic capsid surface loop, by insertion into the L1 major capsid protein of bovine papillomavirus type 1. The PrP peptide was selected on the basis of its previously suggested central role in prion pathogenesis. Immunization with PrP-virus-like particles induced high-titer antibodies to PrP in rabbit and in rat, without inducing overt adverse effects. As determined by peptide-specific ELISA, rabbit immune sera recognized the inserted murine/rat epitope and also cross-reacted with the homologous rabbit/human epitope differing in one amino acid residue. In contrast, rat immune sera recognized the murine/rat peptide only. Sera of both species reacted with PrP(C) in its native conformation in mouse brain and on rat pheochromocytoma cells, as determined by immunoprecipitation and fluorescence-activated cell sorting analysis. Importantly, rabbit anti-PrP serum contained high-affinity antibody that inhibited de novo synthesis of PrP(Sc) in prion-infected cells. If also effective in vivo, PrP-virus-like particle vaccination opens a unique possibility for immunologic prevention of currently fatal and incurable prion-mediated diseases. 相似文献
129.
Slate Mandy L. Matallana-Mejia Nicolas Aromin Alessandra Callaway Ragan M. 《Biological invasions》2022,24(10):3109-3118
Biological Invasions - Temporally dynamic resource supplies may alter or lead to fluctuations in competitive outcomes. Resource pulses have been theorized to promote incursion by exotic species... 相似文献
130.
Castagneri Daniele Vacchiano Giorgio Hacket-Pain Andrew DeRose R. Justin Klein Tamir Bottero Alessandra 《Ecosystems》2022,25(1):30-43
Ecosystems - Drought will increasingly threaten forest ecosystems worldwide. Understanding how competition influences tree growth response to drought is essential for forest management aiming at... 相似文献