A low-voltage activated, transient calcium current is responsible for the time-dependent depolarizing inward rectification of rat neocortical neurons in vitro

Intracellular recordings were obtained from rat neocortical neurons in vitro. The current-voltage-relationship of the neuronal membrane was investigated using current- and single-electrode-voltage-clamp techniques. Within the potential range up to 25 mV positive to the resting membrane potential (RMP: –75 to –80 mV) the steady state slope resistance increased with depolarization (i.e. steady state inward rectification in depolarizing direction). Replacement of extracellular NaCl with an equimolar amount of choline chloride resulted in the conversion of the steady state inward rectification to an outward rectification, suggesting the presence of a voltage-dependent, persistent sodium current which generated the steady state inward rectification of these neurons. Intracellularly injected outward current pulses with just subthreshold intensities elicited a transient depolarizing potential which invariably triggered the first action potential upon an increase in current strength. Single-electrode-voltage-clamp measurements reveled that this depolarizing potential was produced by a transient calcium current activated at membrane potentials 15–20 mV positive to the RMP and that this current was responsible for the time-dependent increase in the magnitude of the inward rectification in depolarizing direction in rat neocortical neurons. It may be that, together with the persistent sodium current, this calcium current regulates the excitability of these neurons via the adjustment of the action potential threshold

An improved method for constructing and selectively silanizing double-barreled, neutral liquid-carrier, ion-selective microelectrodes

We describe an improved, efficient and reliable method for the vapour-phase silanization of multi-barreled, ion-selective microelectrodes of which the silanized barrel(s) are to be filled with neutral liquid ion-exchanger (LIX). The technique employs a metal manifold to exclusively and simultaneously deliver dimethyldichlorosilane to only the ion-selective barrels of several multi-barreled microelectrodes. Compared to previously published methods the technique requires fewer procedural steps, less handling of individual microelectrodes, improved reproducibility of silanization of the selected microelectrode barrels and employs standard borosilicate tubing rather than the less-conventional theta-type glass. The electrodes remain stable for up to 3 weeks after the silanization procedure. The efficacy of a double-barreled electrode containing a proton ionophore in the ion-selective barrel is demonstrated in situ in the leaf apoplasm of pea (Pisum) and sunflower (Helianthus). Individual leaves were penetrated to depth of ~150 μm through the abaxial surface. Microelectrode readings remained stable after multiple impalements without the need for a stabilizing PVC matrix

Effects of Hydrogen Peroxide on Wound Healing in Mice in Relation to Oxidative Damage

10.1371/journal.pone.0049215PLoS ONE711

Cytisus scoparius link - A natural antioxidant

BACKGROUND: Recent investigations have shown that the antioxidant properties of plants could be correlated with oxidative stress defense and different human diseases. In this respect flavonoids and other polyphenolic compounds have gained the greatest attention. The plant Cytisus scoparius contains the main constituent of flavone and flavonals. The present study was undertaken to evaluate the in vitro antioxidant activities of extract of aerial part of Cytisus scoparius. METHODS: The plant extract was tested for DPPH (1, 1-diphenyl, 2-picryl hydrazyl) radical scavenging, nitric oxide radical scavenging, superoxide anion radical scavenging, hydroxyl radical scavenging, antilipid peroxidation assay, reducing power and total phenol content. RESULTS: The extract exhibited scavenging potential with IC(50 )value of 1.5 μg/ml, 116.0 μg/ml and 4.7 μg/ml for DPPH, nitric oxide and superoxide anion radicals. The values were found to lesser than those of vitamin C, rutin, and curcumin, as standards. The extract showed 50% protection at the dose of 104.0 μg/ml in lipid peroxidation induced by Fe(2+)/ ascorbate system in rat liver microsomal preparation. There is decrease in hydroxyl radical generation with IC(50 )value of 27.0 μg/ml when compared with standard vitamin E. The reducing power of the extract depends on the amount of extract. A significant amount of polyphenols could be detected by the equivalent to 0.0589 μg of pyrocatechol from 1 mg of extract. CONCLUSION: The results obtained in the present study indicate that hydro alcoholic extract of aerial part of Cytisus scoparius is a potential source of natural antioxidants

Oxidative Stress Mediates Physiological Costs of Begging in Magpie (Pica pica) Nestlings

[Background] Theoretical models predict that a cost is necessary to guarantee honesty in begging displays given by offspring to solicit food from their parents. There is evidence for begging costs in the form of a reduced growth rate and immunocompetence. Moreover, begging implies vigorous physical activity and attentiveness, which should increase metabolism and thus the releasing of pro-oxidant substances. Consequently, we predict that soliciting offspring incur a cost in terms of oxidative stress, and growth rate and immune response (processes that generate pro-oxidants substances) are reduced in order to maintain oxidative balance. [Methodology/Principal Findings] We test whether magpie (Pica pica) nestlings incur a cost in terms of oxidative stress when experimentally forced to beg intensively, and whether oxidative balance is maintained by reducing growth rate and immune response. Our results show that begging provokes oxidative stress, and that nestlings begging for longer bouts reduce growth and immune response, thereby maintaining their oxidative status. [Conclusions/Significance] These findings help explaining the physiological link between begging and its associated growth and immunocompetence costs, which seems to be mediated by oxidative stress. Our study is a unique example of the complex relationships between the intensity of a communicative display (begging), oxidative stress, and life-history traits directly linked to viability.GM-R was supported by the Spanish Government (Ministerio de Ciencia y Tecnología, “Juan de la Cierva” program), and TR was supported by the Consejo Superior de Investigaciones Científicas (CSIC; Proyectos Intramurales Especiales)

Environmentally induced changes in antioxidant phenolic compounds levels in wild plants

[EN] Different adverse environmental conditions cause oxidative stress in plants by generation of reactive oxygen species (ROS). Accordingly, a general response to abiotic stress is the activation of enzymatic and non-enzymatic antioxidant systems. Many phenolic compounds, especially flavonoids, are known antioxidants and efficient ROS scavengers in vitro, but their exact role in plant stress responses in nature is still under debate. The aim of our work is to investigate this role by correlating the degree of environmental stress with phenolic and flavonoid levels in stress-tolerant plants. Total phenolic and antioxidant flavonoid contents were determined in 19 wild species. Meteorological data and plant and soil samples were collected in three successive seasons from four Mediterranean ecosystems: salt marsh, dune, semiarid and gypsum habitats. Changes in phenolic and flavonoid levels were correlated with the environmental conditions of the plants and were found to depend on both the taxonomy and ecology of the investigated species. Despite species-specific differences, principal component analyses of the results established a positive correlation between plant phenolics and several environmental parameters, such as altitude, and those related to water stress: temperature, evapotranspiration, and soil water deficit. The correlation with salt stress was, however, very weak. The joint analysis of all the species showed the lowest phenolic and flavonoid levels in the halophytes from the salt marsh. This finding supports previous data indicating that the halophytes analysed here do not undergo oxidative stress in their natural habitat and therefore do not need to activate antioxidant systems as a defence against salinity.This work has been funded by the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund. Thanks to Dr. Rafael Herrera for critical reading of the manuscript.Bautista, I.; Boscaiu, M.; Lidón, A.; Llinares Palacios, JV.; Lull, C.; Donat-Torres, MP.; Mayoral García-Berlanga, O.... (2016). Environmentally induced changes in antioxidant phenolic compounds levels in wild plants. Acta Physiologiae Plantarum. 38(1):1-15. https://doi.org/10.1007/s11738-015-2025-2S115381Agati G, Biricolti S, Guidi L, Ferrini F, Fini A, Tattini M (2011) The biosynthesis of flavonoids is enhanced similarly by UV radiation and root zone salinity in L. vulgare leaves. J Plant Physiol 168:204–212Agati G, Brunetti C, Di Ferdinando M, Ferrini F, Pollastri S, Tattini M (2013) Functional roles of flavonoids in photoprotection: new evidence, lessons from the past. Plant Physiol Biochem 72:35–45Albert A, Sareedenchai V, Heller W, Seidlitz HK, Zidorn C (2009) Temperature is the key to altitudinal variation of phenolics in Arnica montana L. cv. ARBO. Oecologia 160:1–8Appel K, Hirt H (2004) Reactive oxygen species: metabolism, oxidative stress, and signal transduction. Annu Rev Plant Biol 55:373–399Bachereau F, Marigo G, Asta J (1998) Effect of solar radiation (UV and visible) at high altitude on CAM-cycling and phenolic compounds biosynthesis in Sedum album. Physiol Plant 104:203–210Ballizany WL, Hofmann RV, Jahufer MZZ, Barrett BB (2012) Multivariate associations of flavonoid and biomass accumulation in white clover (Trifolium repens) under drought. Funct Plant Biol 39:167–177Bieza K, Lois R (2001) An Arabidopsis mutant tolerant to lethal ultraviolet-B levels shows constitutively elevated accumulation of flavonoids and other phenolics. Plant Physiol 126:1105–1115Bilger W, Rolland M, Nybakken L (2007) UV screening in higher plants induced by low temperature in the absence of UV-B radiation. Photochem Photobiol Sci 6:190–195Blumthaler M, Ambach M, Ellinger R (1997) Increase in solar UV radiation with altitude. J Photochem Photobiol B 39:130–134Boscaiu M, Lull C, Llinares J, Vicente O, Boira H (2013) Proline as a biochemical marker in relation to the ecology of two halophytic Juncus species. J Plant Ecol 6:177–186Bose J, Rodrigo-Moreno A, Shabala S (2013) ROS homeostasis in halophytes in the context of salinity stress tolerance. J Exp Bot 65:1241–1257Brown DE, Rashotte AM, Murphy AS, Normanly J, Tague BW, Peer WA, Taiz L, Muday GK (2001) Flavonoids act as a negative regulators of auxin transport in vivo in Arabidopsis. Plant Physiol 126:524–535Burchard P, Bilger W, Weissenböck G (2000) Contribution of hydroxycinnamates and flavonoids to epidermal shielding of UV-A and UV-B radiation in developing rye primary leaves as assessed by ultraviolet-induced chlorophyll fluorescence measurements. Plant Cell Environ 23:1373–1380Burriel F, Hernando V (1947) Nuevo método para determinar el fósforo asimilable en los suelos. Anales de Edafología Fisiología Vegetal 9:611–622Cheynier V, Comte G, Davies KM, Lattanzio V, Martens S (2013) Plant phenolics: recent advances on their biosynthesis, genetics, and ecophysiology. Plant Physiol Biochem 72:1–20Coman C, Rugina OD, Socaciu C (2012) Plants and natural compounds with antidiabetic action. Not Bot Horti Agrobo 40:314–325Di Ferdinando M, Brunetti C, Fini A, Tattini M (2012) Flavonoids as antioxidants in plants under abiotic stresses. In: Ahmad P, Prasad MNV (eds) Abiotic stress responses in plants: metabolism, productivity and sustainability. Springer, New York, pp 159–179Di Ferdinando M, Brunetti C, Agati G, Tattini M (2014) Multiple functions of polyphenols in plants inhabiting unfavourable Mediterranean areas. Environ Exper Bot 103:107–116FAO (1990) Management of gypsiferous soils. FAO Soils Bull, p 62Fini A, Brunetti C, Di Ferdinando M, Ferrini F, Tattini M (2011) Stress-induced flavonoid biosynthesis and the antioxidant machinery of plants. Plant Signal Behav 6:709–711Gil R, Lull C, Boscaiu M, Bautista I, Lidón A, Vicente O (2011) Soluble carbohydrates as osmolytes in several halophytes from a Mediterranean salt marsh. Not Bot Horti Agrobo 39:9–17Gil R, Bautista I, Boscaiu M, Lidón A, Wankhade S, Sánchez H, Llinares J, Vicente O (2014) Responses of five Mediterranean halophytes to seasonal changes in environmental conditions. AoB Plants 6: plu049Gould KS, Lister C (2006) Flavonoid function in plants. In: Andersen ØM, Marham KR (eds) Flavonoids, chemistry, biochemistry and application. CRC Press, Boca Raton, pp 397–442Hajimahmoodi M, Moghaddam G, Ranjbar AM, Khazani H, Sadeghi N, Oveisi MR, Jannat B (2013) Total phenolic, flavonoids, tannin content and antioxidant power of some Iranian pomegranate flower cultivars (Punica granatum L.). Am J Plant Sci 4:1815–1820Halliwell B (2006) Reactive species and antioxidants. Redox biology is a fundamental theme of aerobic life. Plant Physiol 141:312–322Harborne JB, Williams C (2000) Advances in flavonoid research since 1992. Phytochemistry 55:481–504Hernández I, Alegre L, Munné-Bosch S (2004) Drought-induced changes in flavonoids and other low molecular weight antioxidants in Cistus clusii grown under Mediterranean field conditions. Tree Physiol 24:1303–1311Hernández I, Alegre L, Van Breusegem F, Munné-Bosch S (2008) How relevant are flavonoids as antioxidants in plants? Trends Plant Sci 14:125–132Iwashina T (2000) The structure and distribution of the flavonoids in plants. J Plant Res 113:287–299Jaakola L, Määttä-Riihinen K, Kärenlampi S, Hohtola A (2004) Activation of flavonoid biosynthesis by solar radiation in bilberry (Vaccinium myrtillus L.) leaves. Planta 218:721–728Jenkins GI (2009) Signal transduction in responses to UB-B radiation. Annu Rev Plant Biol 60:407–431Jenkins GI, Long JC, Wade HK, Shenton MR, Bibikova TN (2001) UV and blue light signalling: pathways regulating chalcone synthase gene expression in Arabidopsis. New Phytol 151:121–131Kaulen H, Schell J, Kreuzaler F (1986) Light-induced expression of the chimeric chalcone synthase-NPTII gene in tobacco cells. EMBO J 5:1–8Kim DO, Jeong SW, Lee CY (2003) Antioxidant capacity of phenolic phytochemicals from various cultivars of plums. Food Chem 81:321–326Kirakosyan A, Seymour E, Kaufman PB, Warber S, Bolling S, Chang SC (2003) Antioxidant capacity of polyphenolic extracts from leaves of Crataegus laevigata and Crataegus monogyna (Hawthorn) subjected to drought and cold stress. J Agr Food Chem 51:3973–3976Knudssen D, Peterson GA, Pratt PF (1982) Lithium, Sodium and Potassium. In: Page AL et al (eds) Methods of soil analysis, chemical and microbiological properties. American Society of Agronomy, Madison, pp 225–246Koes RE, Spelt CE, Mol JNM (1989) The chalcone synthase multigene family of Petunia hybrida (V30): differential, light-regulated expression during flower development and UV light induction. Plant Mol Biol 12:213–225Körner C (1999) Alpine plant life. Functional plant ecology of high mountain ecosytems, BerlinKumar S, Pandey AK (2013) Chemistry and biological activities of flavonoids: an overview. Sci World J 2013:1–16Kuo S (1996) Phosphorus. In: Spark D (ed) Methods of soil analysis: chemical methods, part 3. American Society of Agronomy, Madison, pp 869–919Lavola A (1998) Accumulation of flavonoids and related compounds in birch induced by UV-B irradiance. Tree Physiol 18:53–58Li J, Ou-Lee TM, Raba R, Amundson RG, Last RL (1993) Arabidopsis flavonoid mutants are hypersensitive to UV-B radiation. Plant Cell 5:171–179Llinares JV, Bautista I, Donat MP, Lidón A, Lull C, Mayoral O, Wankhade S, Boscaiu M, Vicente O (2015) Responses to environmental stress in plants adapted to Mediterranean gypsum habitats. Not Sci Biol 7:34–44Marinova D, Ribarova F, Atanassova M (2005) Total phenolics and total flavonoids in Bulgarian fruits and vegetables. J Univ Chem Technol Metall 40:255–260Martens H, Naes T (1989) Multivariate calibration. Wiley, New YorkMurai Y, Takemura S, Takeda K, Kitajima K, Iwashina T (2009) Altitudinal variation of UV-absorbing compounds in Plantago asiatica. Biochem Syst Ecol 37:78–384Nakabayashi R, Yonekura-Sakakibara K, Urano K, Suzuki M, Yamada Y, Nishizawa T, Matsuda F, Kojima M, Sakakibara H, Shinozaki K, Michael AJ, Tohge T, Yamazaki M, Saito K (2014) Enhancement of oxidative and drought tolerance in Arabidopsis by overaccumulation of antioxidant flavonoids. Plant J 77:367–379Napoli CA, Fahy D, Wang HY, Taylor LP (1999) white anther: a petunia mutant that abolishes pollen flavonoid accumulation, induces male sterility, and is complemented by a chalcone synthase transgene. Plant Physiol 120:615–622Nechita A, Cotea VV, Nechita CB, Pincu RR, Mihai CT, Colibaba CL (2012) Study of cytostatic and cytotoxic activity of several polyphenolic extracts obtained from Vitis vinifera. Not Bot Horti Agrobo 40:216–221Nelson DW, Sommers LE (1982) Total carbon, organic carbon, and organic matter. In: Page AL et al (eds) Methods of soil analysis, chemical and microbiological properties. Soil Science Society of America, Madison, pp 539–577Nelson RE, Klameth LC, Nettleton WD (1978) Determining soil gypsum content and expressing properties of gypsiferous soils. Soil Sci Soc Am J 42:659–661Nile SH, Khobragade CN (2010) Antioxidant activity and flavonoid derivatives of Plumbago zeylanica. J Nat Prod 3:130–133Park HL, Lee SW, Jung KH, Hahn TR, Cho MH (2013) Transcriptomic analysis of UV-treated rice leaves reveals UV-induced phytoalexin biosynthetic pathways and their regulatory networks in rice. Phytochemistry 96:57–71Pękal A, Pyrzynska K (2014) Evaluation of aluminium complexation reaction for flavonoid content assay. Food Anal Method 7:1776–1782Pollastri S, Tattini M (2011) Flavonols: old compounds for old roles. Ann Bot 108:1225–1233Ravishankar D, Rajora AK, Greco F, Osborn HM (2013) Flavonoids as prospective compounds for anti-cancer therapy. Int J Biochem Cell B 45:2821–2831Rice-Evans CA, Miller NJ, Paganga G (1996) Structure-antioxidant activity relationships of flavonoids and phenolic acids. Free Radical Bio Med 20:933–956Rieger G, Müller M, Guttenberger H, Bucar F (2008) Influence of altitudinal variation on the content of phenolic compounds in wild populations of Calluna vulgaris, Sambucus nigra, and Vaccinium myrtillus. J Agric Food Chem 58:9080–9086Rivas-Martínez S, Rivas-Saenz S (1996–2009) Worldwide bioclimatic classification system. Phytosociological Research Center, Spain. http://www.globalbioclimatics.org . Accessed 1 July 2013Rohman A, Riyanto S, Yuniarti N, Saputra WR, Utami R, Mulatsih W (2010) Antioxidant activity, total phenolic, and total flavonoid of extracts and fractions of red fruit (Pandanus conoideus Lam). Int Food Res J 17:97–106Romano B, Pagano E, Montanaro V, Fortunato AL, Milic N, Borrelli F (2013) Novel insights into the pharmacology of flavonoids. Phytother Res 27:1588–1596Rozema J, van de Staaij J, Björn LO, Caldwell MM (1997) UV-B as an environmental factor in plant life: stress and regulation. Trends Ecol Evol 12:22–28Rozema J, Bjorn LO, Bornman JF, Gaberščik A, Häder DP, Trošt T, Germ M, Klisch M, Gröniger A, Sinha RP, Lebert M, He YY, Buffoni-Hall R, de Bakker NVJ, van de Staaij J, Meijkamp BB (2002) The role of UV-B radiation in aquatic and terrestrial ecosystems—an experimental and functional analysis of the evolution of UV-absorbing compounds. Photochem Photobiol B Biol 66:2–12Schulze-Lefert P, Dangl JL, Becker-André M, Hahlbrock K, Schulz W (1989) Inducible in vivo DNA footprints define sequences necessary for UV light activation of the parsley chalcone synthase gene. EMBO J 8:651–656Sena MM, Frighetto RTS, Valarini PJ, Tokeshi H, Poppi RJ (2002) Discrimination of management effects on soil parameters by using principal component analysis: a multivariate analysis case study. Soil Till Res 67:171–181Shulaev V, Oliver DJ (2006) Metabolic and proteomic markers for oxidative stress. New tools for reactive oxygen species research. Plant Physiol 141:367–372Singleton VL, Rossi JA Jr (1965) Colorimetry of total phenolics with phosphomolybdic phosphotungstic acid reagents. Am J EnolVitic 16:144–158Spitaler R, Winkler A, Lins I, Yanar S, Stuppner H, Zidorn C (2008) Altitudinal variation of phenolic contents in flowering heads of Arnica montana cv. ARBO: a 3-year comparison. J Chem Ecol 34:369–375Stapleton AE, Walbot V (1994) Flavonoids can protect maize DNA from the induction of UV radiation damage. Plant Physiol 105:881–889Takahashi M, Asada K (1988) Superoxide production in aprotic interior of chloroplast thylakoids. Arch Biochem Biophys 267:714–722Tattini M, Gravano E, Pinelli P, Mulinacci N, Romani A (2000) Flavonoids accumulate in leaves and glandular trichomes of Phillyrea latifolia exposed to excess solar radiation. New Phytol 148:69–77Tattini M, Galardi C, Pinelli P, Massai R, Remorini D, Agati G (2004) Differential accumulation of flavonoids and hydroxycinnamates in leaves of Ligustrum vulgare under excess light and drought stress. New Phytol 163:547–561Treutter D (2005) Significance of flavonoids in plant resistance and enhancement of their biosynthesis. Plant Biol 7:581–591Treutter D (2006) Significance of flavonoids in plant resistance: a review. Environ Chem Lett 4:147–157Van Breusegem F, Dat JF (2006) Reactive oxygen species in plant cell death. Plant Physiol 141:384–390Williams CA, Grayer RJ (2004) Anthocyanins and other flavonoids. Nat Prod Rep 21:539–573Winkel-Shirley B (2002) Biosynthesis of flavonoids and effect of stress. Curr Opin Plant Biol 5:218–223Ylstra B, Touraev A, Benito Moreno RM, Stöger E, van Tunen AA, Vicente O, Mol JNM, Heberle-Bors E (1992) Flavonols stimulate development, germination and tube growth of tobacco pollen. Plant Physiol 100:902–907Zhishen J, Mengcheng T, Jianming W (1999) The determination of flavonoid contents in mulberry and their scavenging effects on superoxide radicals. Food Chem 64:555–559Zidorn C, Schubert B, Stuppner H (2005) Altitudinal differences in the contents of phenolics in flowering heads of three members of the tribe Lactuceae (Asteraceae) occurring as introduced species in New Zealand. Biochem Syst Ecol 33:855–87