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241.
242.
Paul V. Bernhardt Gregory J. Wilson Philip C. Sharpe Danuta S. Kalinowski Des R. Richardson 《Journal of biological inorganic chemistry》2008,13(1):107-119
2-Pyridinecarbaldehyde isonicotinoyl hydrazone (HPCIH) and di-2-pyridylketone isonicotinoyl hydrazone (HPKIH) are two Fe chelators
with contrasting biological behavior. HPCIH is a well-tolerated Fe chelator with limited antiproliferative activity that has
potential applications in the treatment of Fe-overload disease. In contrast, the structurally related HPKIH ligand possesses
significant antiproliferative activity against cancer cells. The current work has focused on understanding the mechanisms
of the Fe mobilization and antiproliferative activity of these hydrazone chelators by synthesizing new analogs (based on 2-acetylpyridine
and 2-benzoylpyridine) that resemble both series and examining their Fe coordination and redox chemistry. The Fe mobilization
activity of these compounds is strongly dependent on the hydrophobicity and solution isomeric form of the hydrazone (E or Z). Also, the antiproliferative activity of the hydrazone ligands was shown to be influenced by the redox properties of the
Fe complexes. This indicated that toxic Fenton-derived free radicals are important for the antiproliferative activity for
some hydrazone chelators. In fact, we show that any substitution of the H atom present at the imine C atom of the parent HPCIH
analogs leads to an increase in antiproliferative efficacy owing to an increase in redox activity. These substituents may
deactivate the imine R–C=N–Fe (R is Me, Ph, pyridyl) bond relative to when a H atom is present at this position preventing
nucleophilic attack of hydroxide anion, leading to a reversible redox couple. This investigation describes novel structure–activity
relationships of aroylhydrazone chelators that will be useful in designing new ligands or fine-tuning the activity of others.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
243.
Influence of cholesterol on electroporation of bilayer lipid membranes: chronopotentiometric studies
This paper presents the results of constant-current (chronopotentiometric) measurements of the egg yolk phosphatidylcholine (PC) bilayer membrane without and with cholesterol. The experiments were performed on planar bilayer lipid membrane (BLM) formed by the Mueller-Rudin method. It is demonstrated that the constant-intensity current flow through bilayer membranes generated fluctuating pores in their structure. The presence of cholesterol in the membrane caused an increase in the value of the breakdown potential. It is postulated that greater stability of the bilayer with cholesterol can result from an increased critical pore radius (at which the bilayer would undergo irreversible rupture). This confirms that cholesterol has a stabilizing effect on BLM. Besides, our results suggest that addition of cholesterol causes shift in the distribution of pore conductance towards a smaller value. It is suggested that this can be connected with the phenomenon of domain formation in the membranes containing high concentration of cholesterol. Moreover, it is shown that chronopotentiometry with programmable current intensity is a promising method for observation of the membrane recovery process. 相似文献
244.
Lythrum salicaria, now a widespread invasive species, exhibits tristyly, a form of heteromorphic selfincompatibility. In tristyly, each plant
exhibits one (and only one) of three morphologically different floral forms. Moreover, each flower produces two types of stamens,
and these two exhibit different incompatibility reactions. Differences between stamens of a single flower must be the result
of epigenetic phenomena and for that reason, we performed two-dimensional gel electrophoresis (2-DE) to analyze fractions
of soluble proteins derived from the pollen coat and protoplast including three hydrolytic enzymes from the six different
stamen types (two from each of three floral forms). There were significant differences in the 2-D protein profiles both between
pollen from the same flower and between the same type of pollen from two different flowers, in the pollen coat as well as
in the protoplast extracts. In five of the six samples of pollen fractions, characteristic peptides were found. Quantitative
differences between pollen from the same flower were observed in case of esterases. Furthermore, analysis of proteases and
acid phosphatases revealed also qualitative differences between these enzymes in pollen from the same flower. 相似文献
245.
Bidirectional action of extracellular ATP on intracapillary volume of isolated rat renal glomeruli. 总被引:2,自引:0,他引:2
M Jankowski M Szczepańska-Konkel L Kalinowski S Angielski 《Journal of physiology and pharmacology》2000,51(3):491-496
Receptors for extracellular nucleotides (P2-purinoceptors) are expressed in renal glomerulus; both on mesangial and endothelial cells. In the present study we have evaluated the potential role of ATP in the regulation of glomerular contraction and relaxation. Using [3H]-inulin we measured the Glomerular Inulin Space (GIS), (that reflects mainly glomerular intracapillary volume), in the presence of ATP and its analogues e.g. 2-methylthio-ATP (P2Y-receptor agonist) and beta,gamma-methylene-ATP (P2X-receptor agonist). Incubation of the intact glomeruli with ATP or 2-methylthio-ATP or beta,gamma-methylene-ATP induced a decrease of GIS in similar magnitude as angiotensin II e.g.: about 10% of the basal value. When glomeruli were precontracted with angiotensin II it was observed that both ATP and 2-methylthio-ATP induced an increase of GIS to the basal value, similarly to atrial natriuretic factor. Furthermore, there was no relaxing effect with beta,gamma-methylene-ATP. We suggest that, these bidirectional changes of the intracapillary volume induced by the extracellular ATP may contribute to regulation of glomerular dynamics. 相似文献
246.
A new method and a new apparatus for capacitance measurements on bilayer lipid membranes are described. The membrane is charged and discharged with a constant current during the measurement. The charge-discharge cycle duration, which is proportional to the membrane capacitance, is measured. The measured time period is converted into a binary number by digital systems and then this number is either further converted into a constant capacity-proportional voltage or read out by the computer. The apparatus makes it possible to measure the capacitances of voltage-polarized membranes. Application of the apparatus to capacitance measurements of bilayer lipid membranes during their potential on the capacitance is presented. The capacitances of membranes stimulated by rectangular voltage pulses and of those stimulated by a linearly varying potential were reported. 相似文献
247.
248.
Steven T. Kalinowski Clint C. Muhlfeld Christopher S. Guy Benjamin Cox 《Conservation Genetics》2010,11(5):2049-2053
Non-native species of fish threaten native fishes throughout North America, and in the Rocky Mountains, introduced populations
of lake trout threaten native populations of bull trout. Effective management of lake trout and other exotic species require
understanding the dynamics of invasion in order to either suppress non-native populations or to prevent their spread. In this
study, we used microsatellite genetic data to estimate the number of lake trout that invaded a population of bull trout in
Swan Lake, MT. Examination of genetic diversity and allele frequencies within the Swan Lake populations showed that most of
the genes in the lake trout population are descended from two founders. This emphasizes the importance of preventing even
a few lake trout from colonizing new territory. 相似文献
249.
Sofia Medvedeva David Brandt Virginija Cvirkaite-Krupovic Ying Liu Konstantin Severinov Sonoko Ishino Yoshizumi Ishino David Prangishvili Jörn Kalinowski Mart Krupovic 《Environmental microbiology》2021,23(8):4612-4630
Saccharolobus (formerly Sulfolobus) shibatae B12, isolated from a hot spring in Beppu, Japan in 1982, is one of the first hyperthermophilic and acidophilic archaeal species to be discovered. It serves as a natural host to the extensively studied spindle-shaped virus SSV1, a prototype of the Fuselloviridae family. Two additional Sa. shibatae strains, BEU9 and S38A, sensitive to viruses of the families Lipothrixviridae and Portogloboviridae, respectively, have been isolated more recently. However, none of the strains has been fully sequenced, limiting their utility for studies on archaeal biology and virus–host interactions. Here, we present the complete genome sequences of all three Sa. shibatae strains and explore the rich diversity of their integrated mobile genetic elements (MGE), including transposable insertion sequences, integrative and conjugative elements, plasmids, and viruses, some of which were also detected in the extrachromosomal form. Analysis of related MGEs in other Sulfolobales species and patterns of CRISPR spacer targeting revealed a complex network of MGE distributions, involving horizontal spread and relatively frequent host switching by MGEs over large phylogenetic distances, involving species of the genera Saccharolobus, Sulfurisphaera and Acidianus. Furthermore, we characterize a remarkable case of a virus-to-plasmid transition, whereby a fusellovirus has lost the genes encoding for the capsid proteins, while retaining the replication module, effectively becoming a plasmid. 相似文献