The effect of two planting dates on the physiological age and yielding potential of seed potatoes grown in a warm temperate climate in Argentina

The effect of two planting dates upon the physiological age of seed tubers, measured by their incubation period, and their yielding potential was studied during a three-year period with two medium-early and one medium-late cultivar. Although seed tubers of the December planting were physiologically significantly younger than those obtained from the November planting in two of the three seasons studied, no reliable effect upon tuber yield was found. Reasons for this lack of relation are discussed. The accumulated day-degrees above 17°C (daily mean temperature) during the bulking period of the seed crop modified the incubation period of the tubers clearly.Der Einfluss zweier Pflanztermine auf das physiologische Alter von Pflanzkartoffeln und ihr Ertragspotential wurde während einer Dreijahresperiode an zwei mittelfrühen Sorten, Spunta und Kennebec, und einer mittelspäten Sorte, Bonaerense la Ballenera MAA, in warmer gemässigter Klimazone in Argentinien geprüft. Saatbestände aus November- und Dezemberpflanzungen von 1979, 1980 und 1981 wurden im November 1980, 1981 und 1982 in vergleichenden Ertragsversuchen gepflanzt. Das physiologische Alter der Knollen wurde bei der Pflanzung durch die Inkubationsperiode (Claver, 1973, 1975) gemessen. Abb. 1 zeigt die meteorologischen Daten der vier Vegetationsperioden. Es ergaben sich signifikante Unterschiede im physiologischen Alter zwischen den Sorten und den Pflanzterminen (Tab. 1). Bei Lagerung der Saatkartoffeln in Mieten im Feld beschleunigte sich das physiologische Alter (Tab. lc). Die Gesamtknollenerträge schwankten zwischen den Sorten in 1980/81 und 1982/83 (Tab. 2a und 2c), es ergaben sich jedoch keine signifikanten Unterschiede zwischen Pflanzgut der beiden Pflanztermine, obwohl sich zwischen beiden Pflanzterminen Unterschiede im physiologischen Alter ergaben. Der Gesamtknollenertrag war 1982/83 am höchsten (Tab. 2c), obwohl die Pflanzknollen physiologisch die Ältesten waren. Es ist unwahrscheinlich, dass eine hohe prozentuale Infektionsrate mit PLRV und PVY der Pflanzknollen von Spunta und Kennebec aus der Dezemberflanzung den Einfluss des physiologischen Alters auf den Ertrag derart überdeckte, dass keine signifikanten Unterschiede mehr gefunden werden konnten (Abb. 2). Weil die Unterschiede im physiologischen Alter innerhalb einer Sorte jedoch klein waren, waren andere ertragsbestimmende Faktoren offensichtlich wichtiger als die Unterschiede im Alter. Die akkumulierten Tagesgrade über einer täglichen Temperatur von 17°C während der Periode des Knollenansatzes hatten eine klare Änderung der Inkubationsperiode zur Folge.L'effet de deux dates de plantation sur l'âge physiologique de tubercules de semence et sur leur rendement potentiel a été étudié durant une période de trois années avec deux variétés demi-hâtives, Spunta et Kennebec, et une demi-tardive, Bonaerense la Ballenera MAA, cultivées dans un climat chaud d'Argentine. Les plants récoltés en novembre et décembre des années 1979, 1980 et 1981 ont été plantés en novembre 1980, 1981 et 1982 selon des essais comparables de rendement. L'âge physiologique des tubercules était évalué à la plantation par la période d'incubation (Claver, 1973, 1975). Les relevés météorologiques pour les quatres saisons sont donnés dans la fig. 1. On observait des différences significatives dans l'âge physiologique entre les variétés et les dates de plantation (tabl. 1). Quand les tubercules de semence étaient conservés en silo au champ, l'âge physiologique était avancé (tabl. lc). Le rendement total en tubercules était différent entre variétés pour 1980/81 et 1982/83 (tabl. 2a et 2c) mais il n'y avait pas de différences significatives entre les plants des deux dates de plantation bien qu'il y ait des différences significatives dans leur âge physiologique. Le rendement total en tubercules était plus élevé en 1982/83 (tabl. 2c) malgré des tubercules de semence physiologiquement plus vieux. Il est peu probable que le taux important d'infection par les virus de l'enroulement et Y des semences de Spunta et Kennebec observé de l'âge physiologique des plants sur les rendements, ceux-ci ne présentant aucune différence significative (fig. 2). De plus, parce que les différences d'âge physiologique des semences au sein d'une variété sont-faibles, d'autres facteurs déterminants que le rendement doivent avoir été plus importants que la différence d'âge. Le cumul jour-degrés au-dessus de la température journalière de 17°C durant la période de tubérisation des tubercules de semence modifie sensiblement la durée d'incubation des plants (fig. 3).Instituto de Fisiología Vegeta

Aldosterone stimulates the cardiac Na +/H + exchanger via transactivation of the epidermal growth factor receptor

The use of antagonists of the mineralocorticoid receptor in the treatment of myocardial hypertrophy and heart failure has gained increasing importance in the last years. The cardiac Na/H exchanger (NHE-1) upregulation induced by aldosterone could account for the genesis of these pathologies. We tested whether aldosterone-induced NHE-1 stimulation involves the transactivation of the epidermal growth factor receptor (EGFR). Rat ventricular myocytes were used to measure intracellular pH with epifluorescence. Aldosterone enhanced the NHE-1 activity. This effect was canceled by spironolactone or eplerenone (mineralocorticoid receptor antagonists), but not by mifepristone (glucocorticoid receptor antagonist) or cycloheximide (protein synthesis inhibitor), indicating that the mechanism is mediated by the mineralocorticoid receptor triggering nongenomic pathways. Aldosterone-induced NHE-1 stimulation was abolished by the EGFR kinase inhibitor AG1478, suggesting that is mediated by transactivation of EGFR. The increase in the phosphorylation level of the kinase p90 RSK and NHE-1 serine703 induced by aldosterone was also blocked by AG1478. Exogenous epidermal growth factor mimicked the effects of aldosterone on NHE-1 activity. Epidermal growth factor was also able to increase reactive oxygen species production, and the epidermal growth factor-induced activation of the NHE-1 was abrogated by the reactive oxygen species scavenger N-2-mercaptopropionyl glycine, indicating that reactive oxygen species are participating as signaling molecules in this mechanism. Aldosterone enhances the NHE-1 activity via transactivation of the EGFR, formation of reactive oxygen species, and phosphorylation of the exchanger. These results call attention to the consideration of the EGFR as a new potential therapeutic target of the cardiovascular pathologies involving the participation of aldosterone.Facultad de Ciencias Médica

Aldosterone stimulates the cardiac Na +/H + exchanger via transactivation of the epidermal growth factor receptor

The use of antagonists of the mineralocorticoid receptor in the treatment of myocardial hypertrophy and heart failure has gained increasing importance in the last years. The cardiac Na/H exchanger (NHE-1) upregulation induced by aldosterone could account for the genesis of these pathologies. We tested whether aldosterone-induced NHE-1 stimulation involves the transactivation of the epidermal growth factor receptor (EGFR). Rat ventricular myocytes were used to measure intracellular pH with epifluorescence. Aldosterone enhanced the NHE-1 activity. This effect was canceled by spironolactone or eplerenone (mineralocorticoid receptor antagonists), but not by mifepristone (glucocorticoid receptor antagonist) or cycloheximide (protein synthesis inhibitor), indicating that the mechanism is mediated by the mineralocorticoid receptor triggering nongenomic pathways. Aldosterone-induced NHE-1 stimulation was abolished by the EGFR kinase inhibitor AG1478, suggesting that is mediated by transactivation of EGFR. The increase in the phosphorylation level of the kinase p90 RSK and NHE-1 serine703 induced by aldosterone was also blocked by AG1478. Exogenous epidermal growth factor mimicked the effects of aldosterone on NHE-1 activity. Epidermal growth factor was also able to increase reactive oxygen species production, and the epidermal growth factor-induced activation of the NHE-1 was abrogated by the reactive oxygen species scavenger N-2-mercaptopropionyl glycine, indicating that reactive oxygen species are participating as signaling molecules in this mechanism. Aldosterone enhances the NHE-1 activity via transactivation of the EGFR, formation of reactive oxygen species, and phosphorylation of the exchanger. These results call attention to the consideration of the EGFR as a new potential therapeutic target of the cardiovascular pathologies involving the participation of aldosterone.Facultad de Ciencias Médica

Aldosterone stimulates the cardiac Na +/H + exchanger via transactivation of the epidermal growth factor receptor

The use of antagonists of the mineralocorticoid receptor in the treatment of myocardial hypertrophy and heart failure has gained increasing importance in the last years. The cardiac Na/H exchanger (NHE-1) upregulation induced by aldosterone could account for the genesis of these pathologies. We tested whether aldosterone-induced NHE-1 stimulation involves the transactivation of the epidermal growth factor receptor (EGFR). Rat ventricular myocytes were used to measure intracellular pH with epifluorescence. Aldosterone enhanced the NHE-1 activity. This effect was canceled by spironolactone or eplerenone (mineralocorticoid receptor antagonists), but not by mifepristone (glucocorticoid receptor antagonist) or cycloheximide (protein synthesis inhibitor), indicating that the mechanism is mediated by the mineralocorticoid receptor triggering nongenomic pathways. Aldosterone-induced NHE-1 stimulation was abolished by the EGFR kinase inhibitor AG1478, suggesting that is mediated by transactivation of EGFR. The increase in the phosphorylation level of the kinase p90 RSK and NHE-1 serine703 induced by aldosterone was also blocked by AG1478. Exogenous epidermal growth factor mimicked the effects of aldosterone on NHE-1 activity. Epidermal growth factor was also able to increase reactive oxygen species production, and the epidermal growth factor-induced activation of the NHE-1 was abrogated by the reactive oxygen species scavenger N-2-mercaptopropionyl glycine, indicating that reactive oxygen species are participating as signaling molecules in this mechanism. Aldosterone enhances the NHE-1 activity via transactivation of the EGFR, formation of reactive oxygen species, and phosphorylation of the exchanger. These results call attention to the consideration of the EGFR as a new potential therapeutic target of the cardiovascular pathologies involving the participation of aldosterone.Facultad de Ciencias Médica

Estrés oxidativo: nexo entre aldosterona y el daño del miocardio mediado por el NHE1

En los estudios clínicos RALES, EPHESUS y EMPHASIS se demostraron los efectos beneficiosos del antagonismo de la aldosterona (Aldo) en la insuficiencia cardíaca (IC), aunque no se conocen los mecanismos implicados. Por otro lado, el estrés oxidativo, aumentado en la IC, resulta deletéreo por diferentes mecanismos, siendo uno de ellos la activación de quinasas redox-sensibles que fosforilan y estimulan al NHE1. Además, la inhibición del NHE1 es beneficiosa en modelos experimentales de hipertrofia e IC.Facultad de Ciencias Médica

Sustainability and biodiversity: from policy to implementation, with examples from Swedish forests

The implementation of the Rio protocol and the preservation of biodiversity at national and regional level is an important step in achieving a sustainable forestry. This is indeed a challenging task since our knowledge of the ecology and habitat demands for but a few species is severely restricted. Research in the last years show that forest species have very different qualitative and spatial demands on their environment which requires complex and broad solutions. This poses a great problem for conservation and often forces societies/decision-makers to take decisions based on assumptions rather than on empirical data. With assumptions follow uncertainty, a factor thatwhich is necessary to controltake account of. We identify and discuss the uncertainties of steps that are considered to be important for preserving biodiversity on a regional level and exemplify this with cases from southern Sweden. We argue that there is no universal solution for the conservation of biodiversity. In strongly fragmented and transformed regions like southern Sweden, a mix of species approaches and ecosystem approaches is necessary for biodiversity conservation. Programs for preserving biodiversity should be flexible, not rigid for allowing modifications due to a constantly increasing body of knowledge and ambiental changes. Prominent gaps in our knowledge include species dispersal ability and propensity, extinction rates and the species dependence on fragmentation and landscape history. It is possible that the question of responsibility species may gain in importance, an issue with far-reaching implications for economy and inter-regional compensatory system