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281.
Natali Rianika Mustafa Hye Kyong Kim Young Hae Choi Robert Verpoorte 《Biotechnology letters》2009,31(12):1967-1974
The effect of salicylic acid (SA) on the metabolic profile of Catharanthus roseus suspension cells throughout a time course (0, 6, 12, 24, 48 and 72 h after treatment) was investigated using NMR spectroscopy
and multivariate data analysis. When compared to control cell lines, SA-treated cells showed a high level of sugars (glucose
and sucrose) up to 48 h after treatment, followed by a dynamic change in amino acids, phenylpropanoids, and tryptamine. Additionally,
one compound—2,5-dihydroxybenzoic-5-O-glucoside—was detected solely in SA-treated cells. 相似文献
282.
M2 transmembrane domain channel (M2‐TMD) permeation properties are studied using molecular dynamics simulations of M2‐TMD (1NYJ) embedded in a lipid bilayer (DMPC) with 1 mol/kg NaCl or KCl saline solution. This study allows examination of spontaneous cation and anion entry into the selectivity filter. Three titration states of the M2‐TMD tetramer are modeled for which the four His37 residues, forming the selectivity filter, are net uncharged, +2 charged, or +3 charged. M2‐TMD structural properties from our simulations are compared with the properties of other models extracted from NMR and X‐ray studies. During 10 ns simulations, chloride ions occasionally occupy the positively‐charged selectivity filter region, and from umbrella sampling simulations, Cl? has a lower free‐energy barrier in the selectivity‐filter region than either Na+ or NH, and NH has a lower free‐energy barrier than Na+. For Na+ and Cl?, the free‐energy barriers are less than 5 kcal/mol, suggesting that the 1NYJ conformation would probably not be exquisitely proton selective. We also point out a rotameric configuration of Trp41 that could fully occlude the channel. Proteins 2009. © 2009 Wiley‐Liss, Inc. 相似文献
283.
284.
Ö. Şimşek A. H. Çon N. Akkoç P. E. J. Saris Mustafa Akçelik 《Journal of industrial microbiology & biotechnology》2009,36(4):481-490
Nisin production of three bioengineered strains, (LAC338, LAC339 and LAC340) with immunity (nisFEG) and/or regulation (nisRK) genes of nisin biosynthesis on plasmids in the Lactococcus lactis LL27 nisin producer, was evaluated under pH-controlled and pH-uncontrolled batch fermentations. Optimization studies showed
that fructose and yeast extract yielded the highest nisin activity. The strains LAC338, LAC339, and LAC340 produced 24, 45,
and 44% more nisin, respectively, than wild-type L. lactis LL27 after 12-h incubation. However, sharp decreases in the yield of nisin were observed at the late phase of fermentation
with LAC339 and LL27 in contrast to LAC340 and LAC338 strains for which the high level of nisin could be maintained longer.
Obviously, increasing the copy number of the regulation genes together with immunity genes in the nisin producers retarded
the loss of nisin in the late phase of the fermentation. 相似文献
285.
Salmonella Typhimurium contains 13 operons coding for fimbriae with unique binding specificities to host epithelial surfaces. stj operon is only detected in S. Typhimurium genome suggesting that Stj fimbria may effect serovarspecific virulence characteristics. In this study, the
role of stj fimbrial operon in the long-term persistence of S. Typhimurium was identified by competitive infection experiment in genetically resistant mouse (CBA) model system. Knock-out
mutation of stjA (major subunit of the Stj fimbria) gene reduced recovery of S. Typhimurium from fecal samples and its colonization to spleen, cecum and mesenteric lymph nodes over a 34-day time period
(p < 0.05). This data indicate that stj fimbrial operon has a role in long-term intestinal persistence of S. Typhimurium in CBA mice. 相似文献
286.
The predator beetle Rhizophagus grandis Gyll. (Coleoptera, Rhizophaginae) is one of the most important biological control agents, mass-bred and used to suppress populations of an important pest: the great spruce bark beetle, Dendroctonus micans. The achlorophyllous alga Helicosporidium sp. was first discovered in the pest. Later it was also found in the predator, but only in the adults. In this study, the pathogenic alga Helicosporidium sp. was discovered in larvae and early pupae of R. grandis for the first time. The morphological characteristics of the pathogenic alga were revealed by light and electron microscopy. Infection rates of Helicosporidium sp. in the larvae and pupae of R. grandis were 23.5% and 6.25%, respectively. 相似文献
287.
Gul HI Cizmecioglu M Zencir S Gul M Canturk P Atalay M Topcu Z 《Journal of enzyme inhibition and medicinal chemistry》2009,24(3):804-807
Chalcones (1,3-diaryl-2-propen-1-ones) are alpha, beta-unsaturated ketones with cytotoxic and anticancer properties. Several reports have shown that compounds with cytotoxic properties may also interfere with DNA topoisomerase functions. Five derivatives of 4'-hydroxychalcones were examined for cytotoxicity against transformed human T (Jurkat) cells as well as plasmid supercoil relaxation experiments using mammalian DNA topoisomerase I. The compounds were 3-phenyl-1-(4'-hydroxyphenyl)-2-propen-1-one (I), 3-(p-methylphenyl)-1-(4'-hydroxyphenyl)-2-propen-1-one (II), 3-(p-methoxyphenyl)-1-(4'-hydroxyphenyl)-2-propen-1-one (III), 3-(p-chlorophenyl)-1-(4'-hydroxyphenyl)-2-propen-1-one (IV), and 3-(2- thienyl)-1-(4'-hydroxyphenyl)-2-propen-1-one (V). The order of the cytotoxicity of the compounds was; IV > III > II > I > V. Compound IV, had the highest Hammett and log P values (0.23 and 4.21, respectively) and exerted both highest cytotoxicity and strongest DNA topoisomerase I inhibition. Compounds I and II gave moderate interference with the DNA topoisomerase I while III & V did not interfere with the enzyme. 相似文献
288.
Athina-Myrto Chioni Dongmin Shao Richard Grose Mustafa B.A. Djamgoz 《The international journal of biochemistry & cell biology》2010,42(2):346-358
Voltage-gated Na+ channels (VGSCs) are expressed in excitable cells (e.g. neurons and muscles), as well as in some classically ‘non-excitable’ cells (e.g. fibroblasts), and in carcinomas. In general, functional expression of VGSCs in plasma membrane (PM) is hierarchical and dynamic. Previously, we have shown that an activity-dependent positive feedback mechanism involving cAMP-dependent protein kinase A (PKA) plays a significant role in upregulation of VGSCs in strongly metastatic rat prostate cancer Mat-LyLu cells expressing Nav1.7. Here, we investigated the possible role of PKA in VGSC regulation and its functional consequences in strongly metastatic human breast cancer (BCa) MDA-MB-231 cells, where the neonatal splice form of Nav1.5 (nNav1.5) is the predominant VGSC present. Treatment with the PKA activator forskolin for 24 h increased mRNA and PM protein levels of nNav1.5, without changing the total VGSC protein level. Opposite effects were obtained by application of the PKA inhibitor KT5720 or the highly specific VGSC blocker tetrodotoxin (TTX), the latter implying activity-dependent upregulation. We tested the possibility, therefore, that the activity dependence of VGSC (nNav1.5) expression involved PKA. Indeed, TTX pretreatment reduced the level of phosphorylated PKA and eliminated basal and PKA-stimulated cellular migration. These data suggested that activity-dependent positive feedback mediated by PKA plays an important role in the functional expression of nNav1.5 in BCa, and in turn, this enhances the cells’ metastatic potential. 相似文献
289.
290.
Arican N Kaya M Kalayci R Uzun H Ahishali B Bilgic B Elmas I Kucuk M Gurses C Uzun M 《Life sciences》2006,79(1):1-7
We investigated the effects of lipopolysachharide (LPS) on functional and structural properties of the blood-brain barrier (BBB) during pentylenetetrazole (PTZ)-induced epileptic seizures in rats. Arterial blood pressure was significantly elevated during epileptic seizures irrespective of LPS pretreatment. Plasma levels of interleukin (IL)-1, interleukin (IL)-6, nitric oxide (NO) and malondialdehyde (MDA) increased while catalase concentrations decreased in animals treated with LPS, PTZ and LPS plus PTZ. The significantly increased BBB permeability to Evans blue (EB) dye in the cerebral cortex, diencephalon and cerebellum regions of rats by PTZ-induced seizures was markedly reduced upon LPS pretreatment. Immunoreactivity for tight junction proteins, zonula occludens-1 and occludin, did not change in brain vessels of animals treated with PTZ and LPS plus PTZ. Glial fibrillary acidic protein immunoreactivity was increased in LPS, but not in PTZ and LPS plus PTZ. These results indicate that LPS pretreatment reduces the passage of EB dye bound to albumin into the brain, at least partly, by increasing plasma NO and IL-6 levels during PTZ-induced epileptic seizures. We suggest that LPS may provide protective effects on the BBB integrity during epileptic seizures through transcellular pathway, since the paracellular route remained unaffected by LPS and LPS plus PTZ. 相似文献