Mejoramiento en avena: resistencia genética a pulgón

La avena, con una superficie sembrada estimada en 1.400.000 ha, se utiliza como integrante de mezclas forrajeras o verdeos, modalidad de uso que representa más del 70% de dicha superficie. El pulgón verde , schizaphis graminum (rond), la plaga de mayor incidencia en los cereales de invierno, afecta especialmente siembras tempranas de verdeo, tal como ocurre en avena. El control de este áfido es posible mediante el logro de variedades con resistencia genética, la utilización de dichas variedades, disminuye notablemente las pérdidas de producción, resulta compatible con otras estrategias de control biológico, cultural e incluso químico. Simplifica el manejo, reduce costos y resulta acorde con los actuales criterios de sustentabilidad: sistemas productivos de bajos insumos, que limiten el impacto ambiental. Objetivo: obtención de cultivares con resistencia genética al pulgón verde, que incluyan además cualidades agronómicas, como rendimiento en pasto y en grano, sanidad y calidad

Activation by calcium of AMP deaminase from the human red cell

AbstractWe have investigated the effects of Ca2+ on AMP deaminase from human red cells. At variance with the other known modulators, Ca2+ increased the apparent affinity for AMP without modifying the characteristic positive cooperativity of the enzyme towards the substrate. Ca2+ sensitivity was not modified by dialysis, but dilution of the haemolysate produced an activation of the enzyme similar to that induced by Ca2+. Simultaneously, the Ca2+ dependence was lost. The sensitivity to other modulators, such as ATP, diphosphoglycerate or phosphate, was not modified by dilution. Partial purification of the enzyme produced the same effects as haemolysate dilution. These results may be interpreted to mean that Ca2+ acts by antagonizing an endogenous inhibitor present in red cell lysates

Efectos de la Compresión Neumática Intermitente (IPC) sobre la fatiga muscular tras una carga excéntrica

28 páginas.Trabajo Fin de Máster en Actividad Física y Salud. Tutor: Dr. D. Antonio Martínez Amat. El objetivo del presente estudio fue valorar la conveniencia de la IPC para la recuperación de la fatiga muscular, para lo que 25 sujetos (18 ♂ 7♀) realizaron un ejercicio inductor de la fatiga y tras ello, fueron sometidos a tres sesiones de presoterapia o simulación en días consecutivos y durante los que se recogieron valores de las pruebas de baropodometría (estabilometría, Sway y marcha dinámica), perímetro muscular y de la algometría. El estudio fue repetido tiempo después para realizar un crossover y finalmente los resultados obtenidos, refutarán la hipótesis inicial de que la IPC ayuda a disminuir la fatiga muscular después de un ejercicio excéntrico.The purpose of the present study was tu value the convenence of the IPC for the recovery of muscle fatigue, for which 25 subjects (18 ♂ 7♀) performed a fatigue-inducing exercise and after that, they recived three pressotherapy sessions or simulation on consecutive days and during which values of the baropodometry tests (stabilometry, Sway and dynamic gait), muscle perimeter and algometry were collected. The study was repeated some time later to carry out a crossover and finally the results obtained will refute the initial hypothesis that IPC helps to decrease muscle fatigue after eccentric exercise

Potentiation by cyclooxygenase inhibitors of the release of catecholamines from the rabbit carotid body and its reversal by prostaglandin E2

Producción CientíficaSalicylates, at the high therapeutic doses used in the treatment of rheumatoid arthritis, produce an increase in ventilation and augment the carotid body reactivity to hypoxic stimulus, leading to an exaggerated hyperventilation during hypoxia. These effects had been related to the action of salicylates as uncouplers of oxidative phosphorylation. In the present study, carried out in an in vitro preparation of the rabbit carotid body, we show that acetylsalicylic acid and indomethacin, two anti-inflammatory drugs that are also powerful inhibitors of cyclooxygenase, the prostaglandinsynthetizing enzyme, produce an increase in the [3H]catecholamine release evoked by low oxygen stimulation. The drugs did not affect basal normoxic release, a finding that suggests that at the concentration used these anti-inflammatory agents do not have uncoupling actions, and that their effects on hypoxic-induced release of [3H]catecholamines is mediated by their specific action as cyclooxygenase inhibitors. In agreement with this suggestion we found that prostaglandin E~ completely prevented the effects of both anti-inflammatory agents. In addition, our data indicate that endogenously synt hetized prostaglandins are powerful modulators of chemoreceptor cell function

Mejoramiento en avena: resistencia genética a pulgón

La avena, con una superficie sembrada estimada en 1.400.000 ha, se utiliza como integrante de mezclas forrajeras o verdeos, modalidad de uso que representa más del 70% de dicha superficie. El pulgón verde , schizaphis graminum (rond), la plaga de mayor incidencia en los cereales de invierno, afecta especialmente siembras tempranas de verdeo, tal como ocurre en avena. El control de este áfido es posible mediante el logro de variedades con resistencia genética, la utilización de dichas variedades, disminuye notablemente las pérdidas de producción, resulta compatible con otras estrategias de control biológico, cultural e incluso químico. Simplifica el manejo, reduce costos y resulta acorde con los actuales criterios de sustentabilidad: sistemas productivos de bajos insumos, que limiten el impacto ambiental. Objetivo: obtención de cultivares con resistencia genética al pulgón verde, que incluyan además cualidades agronómicas, como rendimiento en pasto y en grano, sanidad y calidad.Facultad de Ciencias Agrarias y Forestale

Effects of 2-Deoxy-D-Glucose on In Vitro Cat Carotid Body

Producción CientíficaThe process of chemosensory transduction in the arterial chemoreceptors is not well understood. According to the metabolic hypothesis of chemoreception, a decrease in arterial pO 2 will produce a decrease in the adenosine triphosphate (ATP) content in the chcmosensory type I cells, leading to release of a neurotransmitter and increased sensory neural activity. There is a paucity of direct experimental support for this hypothesis, and in the present work, we have tested the postulates of the metabolic hypothesis in an in vitro preparation of cat carotid body using 2-deoxy-D-glucose as an ATP-depleting agent. This preparation, when superfused with Tyrode containing 5 mM Na+-pyruvate instead of glucose, responds normally to hypoxia, low pH and acetylcholinc, and maintains normal ATP levels. Under these conditions, 2-deoxy-D-glucose is a chemostimulant, i.e. electrical activity in the carotid sinus nerve is increased, with a threshold concentration of 0.25 mM and a maximum response at about 2-4 raM. These concentrations of 2-deoxyglucose evoke a dose-dependent release of [3H]dopamine (synthesized from pH]tyrosine) from the carotid bodies which parallels the electrical activity. The 2-deoxy-D-glucose-evoked release and electrical activity is dependent on the presence of extracellular Ca 2+ . These same concentrations of 2-deoxy-D-glucose significantly reduce the ATP content of the carotid bodies. The events postulated bv the metabolic hypothesis, i.e. decrease in ATP content, release of a putative neurotransminer and activation of the sensory nerve endings are found to occur simultaneously. A possible cause-effect relationship between these three events is discussed

Correlation Between Adenosine Triphosphate Levels, Dopamine Release and Electrical Activity in the Carotid Body: Support for the Metabolic Hypothesis of Chemoreception

Producción CientíficaAn unsolved issue for the arterial chemoreceptors is the mechanism by which hypoxia and other natural stimuli lead to an increase of activity in the carotid sinus nerve. According to the 'metabolic hypothesis', the hypoxic activation of the carotid body (CB) is mediated by a decrease of the ATP levels in the type I cells, which then release a neurotransmitter capable of exciting the sensory nerve endings. Using an in vitro preparation of cat CB, we report that ATP levels in the CB do in fact decrease when the organs are exposed to moderate, short lasting hypoxia (5 min 20% 02). Additionally, we found that decreases in ATP levels induced by 2-deoxyglucose (2 mM) or sodium cyanide (0.1 raM) are closely correlated with dopamine release from type I cells and electrical activity in the carotid sinus nerve elicited by these agents. The possible cause-effect relationship of these events is discusse

Evaluación de líneas y cultivares de avena para doble propósito y grano

Objetivos: Evaluar el comportamiento de líneas de avena pertenecientes al plan de mejoramiento de Cerealicultura en rendimiento en materia verde y seca y grano en comparación con cultivares comerciales y su comportamiento con tratamientos con fungicidas y fertilización nitrogenada

Muscarinic receptor localization and function in rabbit carotid body

Producción CientíficaAcetylcholine and muscarinic agonists inhibit chemosensory activity in the rabbit carotid sinus nerve (CSN). Because the mechanism of this inhibition is poorly understood, we have investigated the kinetics and distribution of muscarinic receptors in the rabbit carotid body with the specific muscarinic antagonist [SH]quinuclidinylbenzitate ([3H]QNB). Equilibrium binding experiments identified displaceable binding sites (1/~M atropine) with a K d = 71.46 pM and a Bm~ x = 9.23 pmol/g tissue. These binding parameters and the pharmacology of the displaceable [SH]QNB binding sites are similar to specific muscannic receptors identified in numerous other nervous, muscular and glandular tissues. Comparisons of specific binding in normal and chronic CSN-denervated carotid bodies suggest that musearinic receptors are absent on afferent terminals in the carotid body; however, nearly 50% of the specific [3H]QNB binding is lost following chronic sympathectomy, suggesting the presence of presynaptic muscarinic receptors on the sympathetic innervation supplying the carotid body vasculature. Autoradiographic studies have localized the remainder of [3H]QNB binding sites to Iobules of type I and type II parenchymal cells. In separate experiments, the muscarinic agonists, oxotremorine (100/~M) and bethanechol (100 ~tM) were shown to inhibit both the release of catecholamines and the increased CSN activity evoked by nicotine (50/~M) stimulation of the in vitro carotid body, Our data suggest that muscarinic inhibition in the rabbit carotid body is mediated by receptors located on type I cells which are able to modulate the excitatory actions of acetylcholine at nicotinic sites

Evidence for two types of nicotinic receptors in the cat carotid body chemoreceptor cells

Producción CientíficaCurrent concepts on the location and functional significance of nicotinic receptors in the carotid body rest on a-bungarotoxin binding and autoradiographic studies. Using an in vitro preparation of the cat carotid body whose catecholamine deposits have been labeled by prior incubation with the tritiated natural precursor w3Hxtyrosine, we have found that nicotine induces release of w3Hxcatecholamines in a dose-dependent manner IC50s9.81 mM.. We also found that mecamylamine 50 mM. completely abolished the nicotine-induced release, while a-bungarotoxin 100 nM; f20 times its binding Kd. only reduced the release by 56%. These findings indicate that chemoreceptor cells, and perhaps other carotid body structures, contain nicotinic receptors that are not sensitive to a-bungarotoxin and force a revision of the current concepts on cholinergic mechanisms in the carotid body chemoreception