i-Motif formation and spontaneous deletions in human cells

Concatemers of d(TCCC) that were first detected through their association with deletions at the RACK7 locus, are widespread throughout the human genome. Circular dichroism spectra show that d(GGGA)_n sequences form G-quadruplexes when n > 3, while i-motif structures form at d(TCCC)_n sequences at neutral pH when n ≥ 7 in vitro. In the PC3 cell line, deletions are observed only when the d(TCCC)_n variant is long enough to form significant levels of unresolved i-motif structure at neutral pH. The presence of an unresolved i-motif at a representative d(TCCC)_n element at RACK7 was suggested by experiments showing that that the region containing the d(TCCC)₉ element was susceptible to bisulfite attack in native DNA and that d(TCCC)₉ oligo formed an i-motif structure at neutral pH. This in turn suggested that that the i-motif present at this site in native DNA must be susceptible to bisulfite mediated deamination even though it is a closed structure. Bisulfite deamination of the i-motif structure in the model oligodeoxynucleotide was confirmed using mass spectrometry analysis. We conclude that while G-quadruplex formation may contribute to spontaneous mutation at these sites, deletions actually require the potential for i-motif to form and remain unresolved at neutral pH.     

Dasatinib ameliorates thioacetamide-induced liver fibrosis: modulation of miR-378 and miR-17 and their linked Wnt/β-catenin and TGF-β/smads pathways

Hepatic stellate cells activation (HSCs) plays a crucial role in the pathogenesis of liver fibrosis. Specific microRNAs have been suggested to affect the activation of HSCs via various signalling pathways including TGF-β/smads and Wnt/β-catenin pathways. Dasatinib is a multitarget inhibitor of many tyrosine kinases has recently studied for its anti-fibrotic effects in a variety of fibrous diseases. This study investigated the role of modulation of miRNA-378 and miRNA-17 in the pathogenesis of liver fibrosis through altering Wnt/β-catenin and TGF-β/smads pathways and evaluated the beneficial effect of the tyrosine kinase inhibitor, dasatinib, in thioacetamide-induced liver fibrosis model in mice. Treatment with dasatinib down-regulated miRNA-17 expression, leading to the restoration of WiF-1 and smad-7 which cause the inhibition of both Wnt/β-catenin and TGF-β/smads signalling. In addition, it upregulated miRNA-378 leading to the decrease of Wnt-10 which contributes to the suppression of activated HSCs.     

Synthesis of New Furanone Derivatives with Potent Anticancer Activity

Russian Journal of Bioorganic Chemistry - New compounds based on Furanone derivatives were synthesized by reaction of 3-(4-nitrobezylidine)-5-phenylfuran-2(3H)-one with various reagents as...     

Mutations in CYC1, Encoding Cytochrome c1 Subunit of Respiratory Chain Complex III,Cause Insulin-Responsive Hyperglycemia

Many individuals with abnormalities of mitochondrial respiratory chain complex III remain genetically undefined. Here, we report mutations (c.288G>T [p.Trp96Cys] and c.643C>T [p.Leu215Phe]) in CYC1, encoding the cytochrome c₁ subunit of complex III, in two unrelated children presenting with recurrent episodes of ketoacidosis and insulin-responsive hyperglycemia. Cytochrome c₁, the heme-containing component of complex III, mediates the transfer of electrons from the Rieske iron-sulfur protein to cytochrome c. Cytochrome c₁ is present at reduced levels in the skeletal muscle and skin fibroblasts of affected individuals. Moreover, studies on yeast mutants and affected individuals’ fibroblasts have shown that exogenous expression of wild-type CYC1 rescues complex III activity, demonstrating the deleterious effect of each mutation on cytochrome c₁ stability and complex III activity.     

Fatty acid composition of two Tunisian pine seed oils

Oils were extracted from fully ripen Pinus pinea L. and Pinus halepensis Mill seeds and fatty acid composition has been established by capillary gas chromatography. Seeds are rich in lipids, 34.63-48.12% on a dry weight basis. Qualitatively, fatty acid composition of both species is identical. For P. halepensis linoleic acid is the major fatty acid (56.06% of total fatty acids) followed by oleic (24.03%) and palmitic (5.23%) acids. For P. pinea, the same fatty acids are found with the proportions 47.28%, 36.56%, and 6.67%, respectively. Extracted fatty acids from both species are mainly unsaturated, respectively, 89.87% and 88.01%. Pinus halepensis cis-5 olefinic acids are more abundant (7.84% compared to 2.24%). Results will be important as a good indication of the potential nutraceutical value of Pinus seeds as new sources of fruit oils rich in polyunsaturated fatty acids and cis-5 olefinic acids.     

Phytochemical Analysis and Evaluation of the Antioxidant,Anti-Inflammatory,and Antinociceptive Potential of Phlorotannin-Rich Fractions from Three Mediterranean Brown Seaweeds

Phlorotannins, phenolic compounds produced exclusively by seaweeds, have been reported to possess various pharmacological properties. However, there have been few works on these compounds from Mediterranean seaweeds. In this study, we investigated the phytochemical analysis and pharmacological potential of phlorotannin-rich fractions from three brown seaweeds collected along the Tunisia coast: Cystoseira sedoides (PHT-SED), Cladostephus spongeosis (PHT-CLAD), and Padina pavonica (PHT-PAD). Phytochemical determinations showed considerable differences in total phenolic content (TPC) and phlorotannin content (PHT). The highest TPC level (26.45 mg PGE/g dry material (Dm)) and PHT level (873.14 μg PGE/g Dm) were observed in C. sedoides. The antioxidant properties of these three fractions assessed by three different methods indicated that C. sedoides displayed the highest total antioxidant activity among the three species (71.30 mg GAE/g Dm), as well as the free radical scavenging activity with the lowest IC₅₀ value in both DPPH (27.7 μg/mL) and ABTS (19.1 μg/mL) assays. Furthermore, the pharmacological screening of the anti-inflammatory potential of these fractions using in vivo models, in comparison to reference drugs, established a remarkable activity of PHT-SED at the dose of 100 mg/kg; the inhibition percentages of ear edema in mice model and paw edema in rats model were of 82.55 and 81.08%, respectively. The content of malondialdehyde (MDA) in liver tissues has been quantified, and PHT-SED was found to remarkably increase the lipid peroxidation in rat liver tissues. In addition, in two pain mice models, PHT-SED displayed a profound antinociceptive activity at 100 mg/kg and has proved a better analgesic activity when used in combination with the opioid drug, tramadol.     

Cadmium-induced ovarian pathophysiology is mediated by change in gene expression pattern of zinc transporters in zebrafish (Danio rerio)

This study explored the potential for expression pattern of genes encoding zinc (Zn) transporters to be involved in the cadmium (Cd)-induced reproductive toxicity in female of zebrafish. For this purpose, oocytes maturity and ovarian histology as well as Cd, Zn and metallothioneins (MTs) accumulation and expression of genes encoding Zrt-,Irt-related protein 10 (ZIP10), Zn transporter 1 (ZnT1) and zebrafish metallothionein (zMT) were examined in ovaries of adult zebrafish exposed to 0.4 mg/L Cd in water and supplemented with Zn (5 mg kg⁻¹) in their diet for 21 days. Cd-exposure decreased the expression of ZnT1 and caused up-regulation of ZIP10 and zMT gene expression. These changes were accompanied by increased Cd and MTs accumulation, decreased Zn contents as well as by histopathological damages in ovarian tissues. The co-exposure of fish to Cd and Zn abolished ZnT1 down-regulation and rendered a persistently increased ZIP10 mRNA level. This treatment also decreased Cd and MTs accumulation, reversed Cd-induced Zn depletion and partially restored Cd-induced histological changes in ovarian tissues. These results imply that the downregulation of ZnT1 as well as the overexpression of ZIP10, in responses to the ovarian Zn depletion induced by Cd, play a major role in Cd accumulation and consequently in its toxicity. The protective effect of dietary Zn supplementation against Cd-induced toxicity is mediated, at least in part, by the increase of Zn availability and subsequently the induction of ZnT1 gene expression.     

Immobilization of rhodopsin on a self-assembled multilayer and its specific detection by electrochemical impedance spectroscopy

Rhodopsin, the G protein-coupled receptor (GPCR) which mediates the sense of vision, was prepared from calf eyes and used as receptor enriched membrane fraction. In this study it was immobilized onto gold electrode by two different techniques: Langmuir-Blodgett (LB) and a strategy based on a self-assembled multilayer. We demonstrated that Langmuir and LB films of rhodopsin are not stable. Thus, in this study a new protein multilayer was prepared on gold electrode by building up layer-by-layer a self-assembled multilayer. It is composed of a mixed self-assembled monolayer formed by MHDA and biotinyl-PE, followed by a biotin-avidin system which allows binding of biotinylated antibody specific to rhodopsin. The immobilization of rhodopsin in membrane fraction, by the specific antibody bound previously on self-assembled multilayer, was monitored with electrochemical impedance spectroscopy (EIS). In addition, the specificity and sensitivity of this self-assembled multilayer system to the presence of rhodopsin were investigated. No effect was observed when the system was in contact with olfactory receptor I7 in membrane fraction used for control measurements. All these results demonstrate that rhodopsin can be immobilized efficiently, specifically, quantitatively and stably on gold electrode through the self-assembled multilayer.     

Enzymatic activity of immobilized yeast phosphoglycerate kinase

This work reports the first evidence that recombinant yeast phosphoglycerate kinase (PGK) is still significantly active when immobilized on glass and muscovite mica. Using previous work to improve the sensitivity of the existing setup, Tapping Mode atomic force microscopy (AFM) was used in a liquid environment to determine the surface enzyme coverage of derivatized mica and glass slides. When associated to spectrophotometric measurements, the AFM data allows assessing the catalytic constant of surface enzymes and comparing it to bulk values. The validity of the Michaelis-Menten model for surface reactions is discussed, supported by spectroscopic measurements of the surface consumption of 1,3-bis-phosphoglycerate (1,3-BPG). Only a few percent of the enzyme material maintains its initial bulk activity. This value could constitute a guideline for biosensors made with the method used here whenever a rapid assessment of the remaining surface activity is needed.