Physical and functional interactions between human mitochondrial single-stranded DNA-binding protein and tumour suppressor p53

Single-stranded DNA-binding proteins (SSB) form a class of proteins that bind preferentially single-stranded DNA with high affinity. They are involved in DNA metabolism in all organisms and serve a vital role in replication, recombination and repair of DNA. In this report, we identify human mitochondrial SSB (HmtSSB) as a novel protein-binding partner of tumour suppressor p53, in mitochondria. It binds to the transactivation domain (residues 1–61) of p53 via an extended binding interface, with dissociation constant of 12.7 (± 0.7) μM. Unlike most binding partners reported to date, HmtSSB interacts with both TAD1 (residues 1–40) and TAD2 (residues 41–61) subdomains of p53. HmtSSB enhances intrinsic 3′-5′ exonuclease activity of p53, particularly in hydrolysing 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) present at 3′-end of DNA. Taken together, our data suggest that p53 is involved in DNA repair within mitochondria during oxidative stress. In addition, we characterize HmtSSB binding to ssDNA and p53 N-terminal domain using various biophysical measurements and we propose binding models for both

Transition à la Parentalité et Fonctionnement Conjugal chez les Couples Infertiles en Tunisie

Objectif.-Evaluer l’impact de l’adoption sur le fonctionnement conjugal des couples infertiles. Méthode.-L’échantillon est composé de 146 participants hétérosexuels (73 couples) répartis en un groupe avec enfant adoptif (GAEA) composé de 30 couples infertiles vivant une parentalité adoptive et deux groupes contrôles ; le groupe avec enfant biologique (GAEB) composé de 30 couples fertiles ayant accès à la parentalité biologique et le groupe sans enfant (GSE) qui comprend 13 couples infertiles sans enfants. Résultats : Le GAEA semble éviter moins la proximité que les deux groupes contrôles et apparaît plus anxieux face à l’abandon uniquement par rapport au GAEB. Il utilise significativement plus la communication mutuelle mais uniquement par rapport au GSE et rapporte davantage des comportements de "Demande-Retrait" par rapport aux deux groupes témoins. De plus, Il est plus satisfait sur le plan conjugal que les deux groupes contrôles. Conclusion: L’étude offre une meilleure compréhension des changements au sein des couples infertiles devenant parents par voie d’adoption et ouvre plusieurs pistes d’investigation.   The aim of this study is to assess the impact of adoption on the marital functioning of infertile couples. The sample is composed of 146 heterosexual participants (73 couples) divided into a group with adopted children (GWAC) made up of 30 infertile couples living in adoptive parenthood and two control groups; the group with biological child (GWBC) made up of 30 fertile couples with access to biological parenthood and the childless group (GWC) which includes 13 infertile couples without children. The GWAC seems to avoid proximity less than the two control groups and appears more anxious about abandonment only in relation to the GWBC. He used mutual communication significantly more but only in relation to the GWC and reported more "Request-Withdrawal" behaviors compared to the two control groups. In addition, he is more marital satisfaction than the two control groups. The study offers a better understanding of the changes in infertile couples becoming parents by adoption and opens several tracks of investigation

Effects of salt on lipid peroxidation and antioxidant enzyme activities of Catharanthus roseus suspension cells

Cells of Catharanthus roseus (L.) G. Don were maintained and sub-cultured in the absence of NaCl (control) or were sub-cultured for 7 days in the presence of 50 mM (“50”) or 100 mM (“100”) NaCl, or were maintained and sub-cultured for 8 months in the continuous presence of 50 mM NaCl (“50T” or salt-adapted cells). Exposure of cells to salt treatment reduced growth in a concentration-dependent manner. Salt-treated cells strongly accumulated Na+ and, to a lesser extent, Cl−. However, no significant change in Cl− accumulation was observed in 50T cells. Salt progressively increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities whereas a strong increase in catalase (CAT) activity was only obtained in 50 and 50T cells. SOD activity was lower in 50T than in 50 cells, whereas the opposite was observed for APX activity. After native polyacrylamide gel electrophoresis (PAGE) analysis, five SOD isoenzymes were detected and the increase in SOD activity observed in salt-treated cells seemed to be mainly due to isoenzymes (SOD 1, 2 and 3). Three APX isoenzymes (APX 1, 2 and 3) were detected markedly, especially in salt-adapted cells. Salt strongly induced CAT 2 isoenzyme in 50 cells and CAT 1 isoenzyme in 50T cells. These data suggest that salt treatment provoked an oxidative stress in C. roseus cells, as shown by the increase in lipid peroxidation, in spite of the induction of antioxidant enzymes. This increase in lipid peroxidation was paralleled by a rise in lipoxygenase (LOX) activity. Increases in antioxidant activities could also be a response to the cellular damage provoked by NaCl. Probably, this increase could not stop the deleterious effects of salt, but reduced stress severity thus allowing cell growth to occur.The Sécrétariat d’état à la recherche Scientifique et à la Technologie of Tunisia is gratefully acknowledged for supporting this research.Peer reviewe

Amino terminal sequence of the mitochondrial protein mtDBP-C: similarity with nonhistone chromosomal proteins HMG I and 2

International audienceWe have previously reported the characterization of a DNA-binding protein isolated from Xenopus !aevis mitochondfia (mtDBP-C). The amino terminal sequence of this protein (26 residues) has been determined by automated Edman degradation and used to search for sequence similarity with the NBRF library. A segment of 17 amino acids displays 47. 1% of identity with proteins HMG-1 and 2 of various vertebrate species. amino acid sequence / mitochondria / DNA-binding protein / HMG protein

Study of the involvement of H+-ATPase and osmotic adjustment in the resistance of Catharanthus roseus suspension cells to salt stress

The salt-induced H+-ATPase activity and osmotic adjustment responses of Catharanthus roseus (L.) G. Don suspension cultures were studied. Cells were treated with 0, 50 or 100mM NaCl for 7days or were maintained for 8 months with 50 mM NaCl (50T cells). Growth, osmotic potential (), ions content, soluble sugars, proline and total amino acids were determined in the sap of control and salt-treated cells. Salinity reduced cell growth and . The higher decrease in the in salt-treated cells was due to higher accumulation of Na+ and Cl–. The levels of organic solutes, such as soluble sugars, free proline and total amino acids, increased with salt treatment. These results suggest that salt-tolerant cells are able to osmotically adjust. Salinity treatments stimulated H+-ATPase activity. Immunodetection of the enzyme showed that the increased activity was due to an increased amount of protein in the plasmalemma. The induction by NaCl, especially at 100 mM NaCl and for 50T cells, could account for the K+ and Cl– uptake but not for higher or lower tolerance.The Secretariat of State for Scientific Research and Technology from Tunisia is gratefully acknowledged for supporting this research.Peer reviewe

Endurcissement à la sécheresse et accumulation de glucides solubles et d'acides aminés libres dans les phyllodes d'Acacia cyanophylla Lindl

Drought hardening, soluble carbohydrates and free amino acid accumulation in Acacia cyanophylla Lindl phyllodes. Two plots of 8-month-old plants of Acacia cyanophylla Lindl grown in the greenhouse have been subjected to two contrasting water feedings. The first was nearly maximum evapotranspiration (D) and the second was D/6. Three plants of each water feeding were subjected to a drying cycle by water withholding after 1, 3, 5 and 13 months in order to allow the emergence of adaptive mechanisms in hard drought. At the beginning of each drying cycle, water potential component had been measured at 1 Pm in order to evaluate the effect of drought preconditioning duration on the D/6 plants. At the end of each cycle, marked by zero turgor, the same measures had been made and the remaining phyllodes were used to determine the concentration of free amino acids, soluble sugars and starch. We noted at the beginning of the cycles that D plants had a slight decrease in osmotic potential and a slight increase in the turgor; these variations seemed to be related to age. The response of D/6 plants varied with the duration of preconditioning. After 1 month, at the beginning of the cycle, their turgor was less than that of D plants. At the end of the cycle, they had a less negative osmotic potential and lower contents of free amino acids as compared to D plants. This suggests that a 1 month preconditioning to D/6 treatment was insufficient to induce hardening mechanisms. After 3 months and at the beginning of the cycles, we noted a higher turgor and a lower osmotic potential in the D/6 plants with an increasing difference in osmotic potential between D and D/6 over time (from 0.15 to 0.47 MPa). At the end of the fourth cycle, D/6 plants maintained a positive turgor at water potentials near -4.50 MPa. The difference of osmotic potential between D and D/6 plants was significant (from 0.40 to 1.60 MPa) and was accompanied by an increasing accumulation of soluble sugars and free amino acids, especially proline. Concomitantly, a reduction in starch concentration was observed. This could in part explain the accumulation of soluble sugars. These results attest to an acquired hardening by D/6 plants subsequent to a preconditioning of more than 3 months. This hardening was expressed at the end of the drying cycles by increasing osmotic adjustment ability over time.Deux lots d'Acacia cyanophylla Lindl cultivés en pots, sous serre, ont été soumis à l'âge de 8 mois à deux alimentations hydriques très contrastées : une dose d'irrigation proche de l'évapotranspiration maximale (D) et D/6. Au bout de 1, 3, 5 et 13 mois, trois plants de chaque lot ont été soumis à un cycle de dessèchement par privation d'eau afin de permettre aux mécanismes adaptatifs de s'exprimer en condition de sécheresse extrême. Au début de chaque cycle, les composantes du potentiel hydrique du phyllode ont été mesurées à 13 heures, afin d'évaluer l'effet de la durée du préconditionnement à la sécheresse sur les plants D/6. À la fin de chaque cycle, marquée par une turgescence nulle, des mesures analogues ont été effectuées et les phyllodes restants ont servi à la détermination des acides aminés libres, des sucres solubles et de l'amidon. Chez les plants D, on a noté au début des cycles une légère baisse du potentiel osmotique et une légère augmentation de la turgescence au cours du temps; ces variations semblent être liées à l'âge. La réponse des plants D/6 a varié selon la durée du préconditionnement. Après 1 mois, leur potentiel de turgescence, au début du cycle, a été inférieur à celui des plants D; à la fin du cycle, ils ont eu un potentiel osmotique moins négatif et des teneurs plus faibles en acides aminés libres en comparaison avec les plants D. Cela semble indiquer que 1 mois de préconditionnement à la dose D/6 a été insuffisant pour induire des mécanismes d'endurcissement. À partir du troisième mois, on a noté, au début des cycles, une turgescence plus élevée et un potentiel osmotique plus bas chez les plants D/6 avec une différence de potentiel osmotique entre D et D/6 croissante dans le temps (de 0,15 à 0,47 MPa). À la fin du quatrième cycle, les plants D/6 ont conservé une turgescence positive à des potentiels hydriques voisins de -4,50 MPa. La différence de potentiel osmotique entre D et D/6 s'est accentuée (de 0,40 à 1,60 MPa) et a été accompagnée d'une accumulation croissante de sucres solubles et d'acides aminés libres, essentiellement de proline. Parallèlement, on a enregistré une diminution de la teneur en amidon qui n'explique qu'en partie l'accumulation des sucres solubles. Ces résultats témoignent d'un endurcissement acquis par les plants D/6 suite à un préconditionnement de 3 mois ou plus. Cet endurcissement s'est traduit à la fin des cycles de dessèchement par une capacité d'ajustement osmotique croissante au cours du temps

The amino-terminal sequence of the Xenopus laevis mitochondrial SSB is homologous to that of the Escherichia coli protein

International audienceTwo closely related forms of the single-stranded DNA binding protein purified from Xenopus laevis oocytes mitochondria have been identified. Their amino terminal sequences exhibit homology with the Escherichia co/i SSB protein

Characterization and utilization of fly ash of heavy fuel oil generated in power stations

Unlike coal fly ash, fly ash of heavy fuel oil has received much less attention in the literature. In this work, detailed physicochemical characterization of heavy fuel oil fly ash (FA) is provided. The ash has a carbonaceous matrix and contains V, Ni, Zn, Cr, Cu, and Pb with variable amounts. V was the most abundant heavy metal with enrichment factor of 277 in the FA. The presence of V in the FA is attributed to the formation of Mg 3V2O8 oxides at high combustion temperature as confirmed by XRD. Particle size distribution showed that the mean particle diameter of the FA was 70.5 ?m. Extraction recovery up to 85% of metals was achieved using 1.0 M HNO3 and at room temperature. Standard metal-leaching tests confirmed that the elution of the toxic metals and the level of eluted Zn were much higher than the regulated value for the solid residues. Five stable geopolymers GPs containing 41.7 wt.% FA were prepared. All GPs showed high compressive strength and low water absorption which support their application as lightweight construction composites. Most importantly, adding FA to GP had significantly reduced metal migration into the environment as confirmed by the synthetic precipitation leaching procedure.Higher Council for Science and Technology, JordanScopu

Lebetin 2, a Snake Venom-Derived B-Type Natriuretic Peptide, Provides Immediate and Prolonged Protection against Myocardial Ischemia-Reperfusion Injury via Modulation of Post-Ischemic Inflammatory Response

International audienceMyocardial infarction (MI) followed by left ventricular (LV) remodeling is the most frequent cause of heart failure. Lebetin 2 (L2), a snake venom-derived natriuretic peptide, exerts cardioprotection during acute myocardial ischemia-reperfusion (IR) ex vivo. However, its effects on delayed consequences of IR injury, including post-MI inflammation and fibrosis have not been defined. Here, we determined whether a single L2 injection exerts cardioprotection in IR murine models in vivo, and whether inflammatory response to ischemic injury plays a role in L2-induced effects. We quantified infarct size (IS), fibrosis, inflammation, and both endothelial cell and cardiomyocyte densities in injured myocardium and compared these values with those induced by B-type natriuretic peptide (BNP). Both L2 and BNP reduced IS, fibrosis, and inflammatory response after IR, as evidenced by decreased leukocyte and proinflammatory M1 macrophage infiltrations in the infarcted area compared to untreated animals. However, only L2 increased anti-inflammatory M2-like macrophages. L2 also induced a higher density of endothelial cells and cardiomyocytes. Our data show that L2 has strong, acute, prolonged cardioprotective effects in post-MI that are mediated, at least in part, by the modulation of the post-ischemic inflammatory response and especially, by the enhancement of M2-like macrophages, thus reducing IR-induced necrotic and fibrotic effects