Abstract:

Cysteines possess a unique property among the 20 naturally occurring amino acids: it can be present in proteins in either the reduced or oxidized form, and can regulate the activity of some proteins. Consequently, to augment our previous treatment of the other types of residues, the 13Cα13Cα and 13Cβ13Cβ chemical shifts of 837 cysteines in disulfide-bonded cystine from a set of seven non-redundant proteins, determined by X-ray crystallography and NMR spectroscopy, were computed at the DFT level of theory. Our results indicate that the errors between observed and computed 13Cα13Cα chemical shifts of such oxidized cysteines can be attributed to several effects such as: (a) the quality of the NMR-determined models, as evaluated by the conformational-average (ca) rmsd value; (b) the existence of high B-factor or crystal-packing effects for the X-ray-determined structures; (c) the dynamics of the disulfide bonds in solution; and (d) the differences in the experimental conditions under which the observed 13Cα13Cα chemical shifts and the protein models were determined by either X-ray crystallography or NMR-spectroscopy. These quantum-chemical-based calculations indicate the existence of two, almost non-overlapped, basins for the oxidized and reduced −SH 13Cβ13Cβ , but not for the 13Cα13Cα , chemical shifts, in good agreement with the observation of 375 13Cα13Cα and 337 13Cβ13Cβ resonances from 132 proteins by Sharma and Rajarathnam (2000). Overall, our results indicate that explicit consideration of the disulfide bonds is a necessary condition for an accurate prediction of 13Cα13Cα and 13Cβ13Cβ chemical shifts of cysteines in cystines.

Author affiliation: Martín, Osvaldo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Matemática Aplicada de San Luis; Argentina

Author affiliation: Villegas, Myriam E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Matemática Aplicada de San Luis; Argentina

Author affiliation: Vila, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Matemática Aplicada de San Luis; Argentina. Cornell University; Estados Unidos

Author affiliation: Scheraga, Harold A.. Cornell University; Estados Unidos

Abstract:

Heat stress (HS) combined with water stress (WS) negatively impact soybean [Glycine max (L.) Merr.] production. The aims of this research were to quantify the combined effect of HS and WS during grain filling (GF) on grain yield, and to identify physiological-biochemical traits strongly associated to crop performance and yield determination processes under these stressful field environments. Two soybean cultivars were exposed during GF to ambient temperature or to HS (>32 °C for 6 h per d) during 21 d; and to field capacity or to WS (20% of available soil water content) during 35 d. Yield, grain number and weight (GN and GW) were significantly reduced under HS combined with WS. In irrigated HS yield and GN were also reduced, albeit final GW was similar to that of control, highlighting compensation mechanisms. Chlorophyll fluorescence analysis indicated that detrimental effects of HS and WS on photosynthesis were via structural capacity aspects but also through damage to photosystem II. The HS × WS decreased the availability of assimilate to grains, but also impaired the sink-grain metabolization of the remobilized products from leaves. A multivariate analysis highlighted strong correlations between quantum efficiency of photosystem II photochemistry, chlorophyll content (SPAD value), and the antioxidant state of leaves, which were all positively correlated with yield. Canopy temperature throughout grain filling (CTGF) was negatively associated with GN and GW, the latter also positively associated with SPAD. Explaining these physiological traits 81, 50, and 82% of the total variability of yield, GN and GW, respectively. To our knowledge this is the first report that integrating different scales of study, demonstrates the potential of physiological-biochemical parameters to explain yield variations in field-grown soybean under HS and WS conditions.

Author affiliation: Ergo, Verónica Vanesa. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina

Author affiliation: Lascano, Hernan Ramiro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Author affiliation: Vega, Claudia Rosa Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Manfredi; Argentina

Author affiliation: Parola, Rodrigo. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Author affiliation: Carrera, Constanza Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Instituto de Fisiología y Recursos Genéticos Vegetales; Argentina

Abstract:

The present study investigates the effects of hypothyroidism on both the redox state and the thyroid hormone receptors expression in the heart ventricle of virgin and pregnant rats. Hypothyroid state was induced by 6-n-propyl-2-thiouracil in drinking water given to Wistar rats starting 8 days before mating until day 21 of pregnancy or for 30 days in virgin rats. Serum paraoxonase-1 (PON-1) activity, serum and heart nitrites, and thiobarbituric acid-reactive substances (TBARS) were analyzed. Heart protein oxidation, as carbonyls, and copper-zinc superoxide dismutase (CuZnSOD), glutathione peroxidase (GPx), and catalase (CAT) activities, were determined. In addition, heart expressions of NADPH oxidase (NOX-2), CAT, SOD, GPx, and thyroid receptors (TRα and TRβ) mRNA were assessed by RT-PCR. Inducible and endothelial Nitric Oxide Synthase (iNOS and eNOS) were determined by Western blot. Hypothyroidism in the heart of virgin rats decreased TRα and TRβ expressions, and induced oxidative stress, leading to a decrease of nitrites and an increase of carbonyls, NOX-2 mRNA, and GPx activity. A decreased PON-1 activity suggested low protection against oxidative stress in blood circulation. Pregnancy reduced TRα and TRβ mRNA expressions and induced oxidative stress by increasing nitrite and TBARS levels, SOD and CAT activities and NOX-2, eNOS and iNOS expressions, while hypothyroidism, emphasized the decreases of TRα mRNA levels and did not alter the redox state in the heart. TR expressions and redox balance of rat hearts depend on the physiological state. Pregnancy per se seems to protect the heart against oxidative stress induced by hypothyroidism.

Author affiliation: Carmona Viglianco, Yamila Virginia. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina

Author affiliation: Coria, Mariela Janet. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina

Author affiliation: Oliveros, L. B.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; Argentina

Author affiliation: Gimenez, Maria Sofia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; Argentina. Universidad Nacional de San Luis. Facultad de Quimica, Bioquimica y Farmacia. Departamento de Bioquímica y Ciencias Biológicas; Argentina

Abstract:

Polyhydroxyalkanoates (PHAs) are highly reduced bacterial storage compounds that increase fitness in changing environments. We have previously shown that phaRBAC genes from the Antarctic bacterium Pseudomonas sp. 14-3 are located in a genomic island containing other genes probably related with its adaptability to cold environments. In this paper, Pseudomonas sp. 14-3 and its PHA synthase-minus mutant (phaC) were used to asses the effect of PHA accumulation on the adaptability to cold conditions. The phaC mutant was unable to grow at 10°C and was more susceptible to freezing than its parent strain. PHA was necessary for the development of the oxidative stress response induced by cold treatment. Addition of reduced compounds cystine and gluthathione suppressed the cold sensitive phenotype of the phaC mutant. Cold shock produced very rapid degradation of PHA in the wild type strain. The NADH/NAD ratio and NADPH content, estimated by diamide sensitivity, decreased strongly in the mutant after cold shock while only minor changes were observed in the wild type. Accordingly, the level of lipid peroxidation in the mutant strain was 25-fold higher after temperature downshift. We propose that PHA metabolism modulates the availability of reducing equivalents, contributing to alleviate the oxidative stress produced by low temperature. © 2008 Springer.

Author affiliation: Ayub, Nicolás Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina

Author affiliation: Tribelli, Paula Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina

Author affiliation: López, Nancy Irene. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina

Abstract:

We report here an . in-vivo, non-invasive, depth profiling study on an electrically-active biofilm by Confocal Raman Microscopy. Films based on . Geobacter sulfurreducens bacteria were grown onto an indium tin oxide (ITO) conducting glass, where the ITO piece plays a double role: it acts as a supporting polarized electrode for the bacteria population but also as a transparent window that gives direct access to the biofilm body. A confocal Raman microscope was used to examine the biofilm redox state at increasing distances from the ITO surface, upon variable polarization and under the presence or not of a chemical electron donor or acceptor. Resonant Raman effect allowed to selectively probe the redox response of biofilm cytochromes to the applied potential and chemicals, revealing internal connectivity details of the bacterial population. Full methodological details for this application case are given, while the importance of confocal Raman for the analysis of biological or electrochemically active systems in non-invasive way is highlighted.

Author affiliation: Robuschi, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Author affiliation: Tomba, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Author affiliation: Busalmen, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina

Abstract:

The developmental competence of cumulus oocyte complexes (COCs) can be increased during in vitro oocyte maturation with the addition of exogenous oocyte-secreted factors, such as bone morphogenetic protein 15 (BMP15), in combination with hormones. FSH and BMP15, for example, induce different metabolic profiles within COCs—namely, FSH increases glycolysis while BMP15 stimulates FAD and NAD(P)H accumulation within oocytes, without changing the redox ratio. The aim of this study was to investigate if this BMP15-induced NAD(P)H increase was due to de novo NADPH production. Cattle COCs were cultured with FSH and/or recombinant human BMP15, resulting in a significant decrease in glucose-6-phosphate dehydrogenase activity (P < 0.05). Inhibition of isocitrate dehydrogenase (IDH) during this process decreased NAD(P)H intensity threefold in BMP15-treated oocytes, suggesting that BMP15 stimulates IDH and NADPH production via the tricarboxylic acid cycle. As NADPH is a reducing agent, reduced glutathione (GSH), H2O2, and mitochondrial activity were also measured to assess the general redox status of the oocyte. FSH alone decreased GSH levels whereas the combination of BMP15 and FSH sustained higher levels. Expression of genes encoding glutathione-reducing enzymes were also lower in oocytes cultured in the presence of FSH alone. BMP15 supplementation further promoted mitochondrial localization patterns that are consistent with enhanced developmental competence. Metabolomics revealed significant consumption of glutamine and production of alanine by COCs matured with both FSH and BMP15 compared to the control (P < 0.05). Hence, BMP15 supplementation differentially modulates reductive metabolism and mitochondrial localization within the oocyte. In comparison, FSH-stimulation alone decreases the oocytes’ ability to regulate cellular stress, and therefore utilizes other mechanisms to improve developmental competence.

Author affiliation: Sutton Mcdowall, Melanie L.. University Of Adelaide; Australia. Australian Research Council; Australia

Author affiliation: Purdey, Malcom. Australian Research Council; Australia

Author affiliation: Brown, Hannah. University Of Adelaide; Australia

Author affiliation: Abell, Andrew D.. Australian Research Council; Australia

Author affiliation: Mottershead, David G.. University Of Adelaide; Australia

Author affiliation: Cetica, Pablo Daniel. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Instituto de Investigacion y Tecnología en Reproducción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Produccion Animal; Argentina

Author affiliation: Dalvit, Gabriel C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Produccion Animal; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentina

Author affiliation: Goldys, Ewa M.. Australian Research Council; Australia. Macquarie University; Australia

Author affiliation: Gilchrist, Robert B.. University Of Adelaide; Australia. University Of New South Wales; Australia

Author affiliation: Gardner, David K.. The University Of Melbourne; Australia

Author affiliation: Thompson, Jeremy G.. University Of Adelaide; Australia. Australian Research Council; Australia