排序方式: 共有180条查询结果,搜索用时 15 毫秒
171.
Dagmara Baraniak Daniel Baranowski Piotr Ruszkowski Jerzy Boryski 《Nucleosides, nucleotides & nucleic acids》2013,32(11):807-835
AbstractThe fluorinated nucleoside dimers with a 1,2,3-triazole linkage are novel compounds within the field of bioorganic chemistry. We report on the synthesis and properties of two groups of nucleoside dimers analogs possessing a different arrangement of the 1,4-disubstituted 1,2,3-triazole linkage. Based on analysis of the 3JHH, 3JH1′C2, and 3JH1′C6 we estimated conformational preferences of sugar part and orientation around glycosidic bond. These compounds show moderate anticancer activity, with cytostatic studies in three different cancer cell lines. 相似文献
172.
Baltasar Lucendo-Villarin Kate Cameron Dagmara Szkolnicka Paul Travers Ferdous Khan Jeffrey G. Walton John Iredale Mark Bradley David C. Hay 《Journal of visualized experiments : JoVE》2014,(91)
Currently, one of the major limitations in cell biology is maintaining differentiated cell phenotype. Biological matrices are commonly used for culturing and maintaining primary and pluripotent stem cell derived hepatocytes. While biological matrices are useful, they permit short term culture of hepatocytes, limiting their widespread application. We have attempted to overcome the limitations using a synthetic polymer coating. Polymers represent one of the broadest classes of biomaterials and possess a wide range of mechanical, physical and chemical properties, which can be fine-tuned for purpose. Importantly, such materials can be scaled to quality assured standards and display batch-to-batch consistency. This is essential if cells are to be expanded for high through-put screening in the pharmaceutical testing industry or for cellular based therapy. Polyurethanes (PUs) are one group of materials that have shown promise in cell culture. Our recent progress in optimizing a polyurethane coated surface, for long-term culture of human hepatocytes displaying stable phenotype, is presented and discussed. 相似文献
173.
A Radwanska M Litwin D Nowak D Baczynska Y Wegrowski FX Maquart M Malicka-Blaszkiewicz 《Experimental cell research》2012,318(18):2312-2323
Cell migration is a multistep process initiated by extracellular matrix components that leads to cytoskeletal changes and formation of different protrusive structures at the cell periphery. Lumican, a small extracellular matrix leucine-rich proteoglycan, has been shown to inhibit human melanoma cell migration by binding to α2β1 integrin and affecting actin cytoskeleton organization. The aim of this study was to determine the effect of lumican overexpression on the migration ability of human colon adenocarcinoma LS180 cells. The cells stably transfected with plasmid containing lumican cDNA were characterized by the increased chemotactic migration measured on Transwell filters. Lumican-overexpressing cells presented the elevated filamentous to monomeric actin ratio and gelsolin up-regulation. This was accompanied by a distinct cytoskeletal actin rearrangement and gelsolin subcellular relocation, as observed under laser scaning confocal microscope. Moreover, LS180 cells overexpressing lumican tend to form podosome-like structures as indicated by vinculin redistribution and its colocalization with gelsolin and actin at the submembrane region of the cells. In conclusion, the elevated level of lumican secretion to extracellular space leads to actin cytoskeletal remodeling followed by an increase in migration capacity of human colon LS180 cells. These data suggest that lumican expression and its presence in ECM has an impact on colon cancer cells motility and may modulate invasiveness of colon cancer. 相似文献
174.
175.
Chris T. McAllister Dagmara Motriuk-Smith Catherine M. Kerr 《Systematic parasitology》2018,95(2-3):271-279
Three new species of coccidians (Apicomplexa: Eimeriidae) are described from eastern moles, Scalopus aquaticus (Linnaeus) from Arkansas. Oöcysts of Cyclospora duszynskii n. sp. are subspheroidal with a smooth bi-layered wall, measure 11.4 × 10.0 µm, and have a length/width (L/W) ratio of 1.1; both micropyle and oöcyst residuum are absent, but a single polar granule is present. Sporocysts are ellipsoidal and measure 7.2 × 5.4 µm, L/W 1.3; an indistinct Stieda body is present, but the sub-Stieda and para-Stieda bodies are absent and the sporocyst residuum is composed of medium to large granules of different sizes along the edge of the sporocyst. Oöcysts of Cyclospora yatesi n. sp. are subspheroidal to ovoidal with an ornate outer wall, measure 17.0 × 15.2 µm, L/W 1.1; both micropyle and oöcyst residuum are absent, but a single polar granule is present. Sporocysts are ellipsoidal and measure 9.7 × 7.3 µm, L/W 1.3; an indistinct Stieda body is present, but sub-Stieda and para-Stieda bodies are absent and the sporocyst residuum is composed of medium to large granules of different sizes along the edge of the sporocyst. Oöcysts of Eimeria paulettefordae n. sp. are ovoidal to ellipsoidal with an ornate outer wall, measure 30.0 × 25.4 µm, L/W 1.2; both micropyle and oöcyst residuum are absent, but a single polar granule is present. Sporocysts are ellipsoidal and measure 12.6 × 9.2 µm, L/W 1.4; a button-like Stieda body is present, but sub-Stieda and para-Stieda bodies are absent and the sporocyst residuum is composed of medium to large granules of different sizes along the edge of the sporocyst. These are the first coccidians described from Arkansas populations of S. aquaticus. In addition, a summary is provided on the cyclosporans and eimerians from North American talpids. 相似文献
176.
Jörg Schaber Miquel Àngel Adrover Emma Eriksson Serge Pelet Elzbieta Petelenz-Kurdziel Dagmara Klein Francesc Posas Mattias Goksör Mathias Peter Stefan Hohmann Edda Klipp 《European biophysics journal : EBJ》2010,39(11):1547-1556
Parameterized models of biophysical and mechanical cell properties are important for predictive mathematical modeling of cellular processes. The concepts of turgor, cell wall elasticity, osmotically active volume, and intracellular osmolarity have been investigated for decades, but a consistent rigorous parameterization of these concepts is lacking. Here, we subjected several data sets of minimum volume measurements in yeast obtained after hyper-osmotic shock to a thermodynamic modeling framework. We estimated parameters for several relevant biophysical cell properties and tested alternative hypotheses about these concepts using a model discrimination approach. In accordance with previous reports, we estimated an average initial turgor of 0.6 ± 0.2 MPa and found that turgor becomes negligible at a relative volume of 93.3 ± 6.3% corresponding to an osmotic shock of 0.4 ± 0.2 Osm/l. At high stress levels (4 Osm/l), plasmolysis may occur. We found that the volumetric elastic modulus, a measure of cell wall elasticity, is 14.3 ± 10.4 MPa. Our model discrimination analysis suggests that other thermodynamic quantities affecting the intracellular water potential, for example the matrix potential, can be neglected under physiological conditions. The parameterized turgor models showed that activation of the osmosensing high osmolarity glycerol (HOG) signaling pathway correlates with turgor loss in a 1:1 relationship. This finding suggests that mechanical properties of the membrane trigger HOG pathway activation, which can be represented and quantitatively modeled by turgor. 相似文献
177.
Marcin Szafran Patrycja Skut Bartosz Ditkowski Katarzyna Ginda Govind Chandra Jolanta Zakrzewska-Czerwińska Dagmara Jakimowicz 《Journal of bacteriology》2013,195(19):4445-4455
Streptomyces species are bacteria that resemble filamentous fungi in their hyphal mode of growth and sporulation. In Streptomyces coelicolor, the conversion of multigenomic aerial hyphae into chains of unigenomic spores requires synchronized septation accompanied by segregation of tens of chromosomes into prespore compartments. The chromosome segregation is dependent on ParB protein, which assembles into an array of nucleoprotein complexes in the aerial hyphae. Here, we report that nucleoprotein ParB complexes are bound in vitro and in vivo by topoisomerase I, TopA, which is the only topoisomerase I homolog found in S. coelicolor. TopA cannot be eliminated, and its depletion inhibits growth and blocks sporulation. Surprisingly, sporulation in the TopA-depleted strain could be partially restored by deletion of parB. Furthermore, the formation of regularly spaced ParB complexes, which is a prerequisite for proper chromosome segregation and septation during the development of aerial hyphae, has been found to depend on TopA. We hypothesize that TopA is recruited to ParB complexes during sporulation, and its activity is required to resolve segregating chromosomes. 相似文献
178.
Synthesis,binding affinities and metabolic stability of dimeric dermorphin analogs modified with β3‐homo‐amino acids 下载免费PDF全文
Oliwia Frączak Anika Lasota Dagmara Tymecka Piotr Kosson Adriana Muchowska Aleksandra Misicka Aleksandra Olma 《Journal of peptide science》2016,22(4):222-227
In this study, proteinogenic amino acids residues of dimeric dermorphin pentapeptides were replaced by the corresponding β3‐homo‐amino acids. The potency and selectivity of hybrid α/β dimeric dermorphin pentapeptides were evaluated by competetive receptor binding assay in the rat brain using [3H]DAMGO (a μ ligand) and [3H]DELT (a δ ligand). Tha analog containing β3‐homo‐Tyr in place of Tyr (Tyr‐d ‐Ala‐Phe‐Gly‐β3‐homo‐Tyr‐NH‐)2 showed good μ receptor affinity and selectivity (IC50 = 0.302, IC50 ratio μ/δ = 68) and enzymatic stability in human plasma. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
179.
We studied the influence of habitat and increased mineral phosphorus and nitrogen loading on the extracellular activity of
five selected hydrolases and pH in the trap fluid of the aquatic carnivorous plants, Utricularia vulgaris, U. australis, and U. foliosa (Lentibulariaceae). Enzyme activities in the trap fluid were determined using fluorometry. Phosphatase exhibited the highest
activities in the traps of the European species as well as field-grown tropical U. foliosa. Trap enzyme production appeared to be uninfluenced by elevated dissolved mineral N or P concentrations both in the trap
and ambient environment and thus, it seems to be constitutive. Enzyme activity in the trap fluid was determined by species
and environmental conditions and varied significantly among sites within a single species. Trap fluid pH was between 4.2–5.1
in U. vulgaris and U. australis but between 5.7–7.3 in U. foliosa and seems to be regulated by the traps. 相似文献
180.
Carina Conceicao Nazia Thakur Stacey Human James T. Kelly Leanne Logan Dagmara Bialy Sushant Bhat Phoebe Stevenson-Leggett Adrian K. Zagrajek Philippa Hollinghurst Michal Varga Christina Tsirigoti Matthew Tully Chris Chiu Katy Moffat Adrian Paul Silesian John A. Hammond Helena J. Maier Erica Bickerton Holly Shelton Isabelle Dietrich Stephen C. Graham Dalan Bailey 《PLoS biology》2020,18(12)
SARS Coronavirus 2 (SARS-CoV-2) emerged in late 2019, leading to the Coronavirus Disease 2019 (COVID-19) pandemic that continues to cause significant global mortality in human populations. Given its sequence similarity to SARS-CoV, as well as related coronaviruses circulating in bats, SARS-CoV-2 is thought to have originated in Chiroptera species in China. However, whether the virus spread directly to humans or through an intermediate host is currently unclear, as is the potential for this virus to infect companion animals, livestock, and wildlife that could act as viral reservoirs. Using a combination of surrogate entry assays and live virus, we demonstrate that, in addition to human angiotensin-converting enzyme 2 (ACE2), the Spike glycoprotein of SARS-CoV-2 has a broad host tropism for mammalian ACE2 receptors, despite divergence in the amino acids at the Spike receptor binding site on these proteins. Of the 22 different hosts we investigated, ACE2 proteins from dog, cat, and cattle were the most permissive to SARS-CoV-2, while bat and bird ACE2 proteins were the least efficiently used receptors. The absence of a significant tropism for any of the 3 genetically distinct bat ACE2 proteins we examined indicates that SARS-CoV-2 receptor usage likely shifted during zoonotic transmission from bats into people, possibly in an intermediate reservoir. Comparison of SARS-CoV-2 receptor usage to the related coronaviruses SARS-CoV and RaTG13 identified distinct tropisms, with the 2 human viruses being more closely aligned. Finally, using bioinformatics, structural data, and targeted mutagenesis, we identified amino acid residues within the Spike–ACE2 interface, which may have played a pivotal role in the emergence of SARS-CoV-2 in humans. The apparently broad tropism of SARS-CoV-2 at the point of viral entry confirms the potential risk of infection to a wide range of companion animals, livestock, and wildlife.A study using a combination of surrogate entry assays and live virus suggests that SARS-CoV-2 may have a broad host-range, revealing that the virus''s spike protein can use a broad range of host ACE2 receptors to enter cells and that the sequence of this protein might have changed during the zoonotic jump into humans. 相似文献