Optimization of laccase production by two strains of Ganoderma lucidum using phenolic and metallic inducers / Optimización de la producción de lacasa por dos cepas de Ganoderma lucidum utilizando inductores fenólicos y metálicos

Ganoderma lucidum (Curtis) P. Karst es un hongo causante de pudrición blanca, capaz de degradar la lignina de la madera y otros sustratos en los que crece. En este trabajo se evaluó la capacidad de dos cepas de esta especie de producir la enzima ligninolítica lacasa. Asimismo, se ensayó la inducción de esta enzima con diferentes compuestos fenólicos e iones metálicos, y se encontró que el ácido ferúlico y el cobre fueron los mejores inductores de la lacasa entre los agentes evaluados. También se encontró que los dos tipos de inductores (fenólicos y metálicos) producen distintos patrones electroforéticos de actividad lacasa. Las concentraciones óptimas de los inductores fueron establecidas mediante un diseño factorial. Se estimó la estabilidad térmica de la lacasa en un amplio rango de pH ácidos, y se comprobó que a pH más altos la enzima es más termoestable.

Ganoderma lucidum (Curtis) P. Karst is a white rot fungus that is able to degrade the lignin component in wood. The ability of two strains of this species to produce the ligninolytic enzyme laccase was assessed. After the evaluation of induction with heavy metals and phenolic compounds, it was found that among the tested substances, copper and ferulic acid are the best laccase inducers. It was also observed that the two types of inducers (phenolic and metallic) produce different electrophoretic patterns of laccase activity. Optimized concentrations of inducers were obtained through a factorial design and the thermal stability of optimized supernatants was studied at a wide range of acidic pH. We found that the enzyme is more thermostable at higher pH values.

Effects of manganese (Mn2+) on neurotoxic and myotoxic activities induced by Crotalus durissus terrificus and Bothrops jararacussu venoms in chick biventer cervicis preparations

In the present study, manganese (Mn2+), a neuromuscular blocker with pre and postsynaptic actions, was used to verify the neurotoxicity and myotoxicity induced by Crotalus durissus terrificus (Cdt) and Bothrops jararacussu (Bjssu) venoms in biventer cervicis preparations (BCp). Preparations pretreated with 0.66 and 1.6mM Mn2+ did not affect Cdt venom-induced blockage nor change KCl-induced contracture but partially reduced ACh-induced contracture. However, both Mn2+ concentrations partially hindered Bjssu venom-induced blockage after washing the preparations with Krebs solution, and only 1.6mM Mn2+ preparations significantly recovered ACh-induced contracture. The effect of Cdt venom myotoxicity on contractile responses was different from that of Bjssu venom myotoxicity. Pretreatment with 1.6mM Mn2+ partially reduced muscle damage percentage and creatine kinase (CK) activity (U/l) induced by both venoms. In conclusion, Mn2+ interfered in ACh-induced contracture of the nicotinic receptor; did not prevent Cdt venom neurotoxicity but partially reduced its myotoxicity in vitro due to the stabilizing action of this venom on the sarcolemmal membrane; and partially attenuated myotoxicity and neuromuscular blockage induced by Bjssu venom. The Mn2+ dual action (pre and postsynaptic) is useful to study snake venoms since most of them present one or both of these actions; besides, Mn2+ allowed recovering coherent interpretation of experimental versus clinical results.

Regulation of glucose utilization and lipogenesis in adipose tissue of diabetic and fat fed animals: effects of insulin and manganese.

In order to evaluate the modulatory effects of manganese, high fat diet fed and alloxan diabetic rats were taken and the changes in the glucose oxidation, glycerol release and effects of manganese on these parameters were measured from adipose tissue. An insulin-mimetic effect of manganese was observed in the adipose tissue in the controls and an additive effect of insulin and manganese on glucose oxidation was seen when Mn2+ was added in vitro. The flux of glucose through the pentose phosphate pathway and glycolysis was significantly decreased in high fat fed animals. Although the in vitro addition of Mn2+ was additive with insulin when 14CO2 was measured from control animals, it was found neither in young diabetic animals (6-8 weeks old) nor in the old (16 weeks old). Both insulin and manganese caused an increased oxidation of carbon-1 of glucose and an increase of its incorporation into 14C-lipids in the young control animals; the additive effect of insulin and manganese suggests separate site of action. This effect was decreased in fat fed animals, diabetic animals and old animals. Manganese alone was found to decrease glycerol in both the control and diabetic adipose tissue in in vitro incubations. The results of the effects of glucose oxidation, lipogenesis, and glycerol release in adipose tissue of control and diabetic animals of different ages are presented together with the effect of manganese on adipose tissue from high fat milk diet fed animals.

Amelioration of mercurial toxicity by manganese. I. A case study in mung bean seedling.

Mercury, a non essential element renders inhibitory effect on many physiological activities of plants even at a low concentration. Plants absorb "Hg" from soil through root system. Manganese, an essential element has been found to counter the inhibitory effect of mercury mostly by preventing it's uptake from soil. Mung bean (Vigna radiata L. Wilczek) cv. Pusa Baisakhi grown in individual (1, 10, 100 and 1000 ppm) solution of Hg and Mn showed varied uptake of these heavy metals. However, in combined solutions (1 : 1, 10 : 1 and 1 : 10 ppm Hg : Mn), mercury uptake was mostly prevented in presence of 10 ppm Mn, indicating it's ameliorating effect.

Effect of dietary supplementation of zinc and/or manganese on growth and reproductive performance of Japanese quail

This work was conducted to study the effect of dietary supplementation of zinc and /or manganese on growth and reproductive performance of Japanese quail. A total of 270 one-day old Japanese quail were used and allotted into 9 equal groups. Zinc and manganese were supplemented to the basal diet at different levels: 0 + 0, 0 + 90, 0 + 180, 25 + 0, 25 + 90, 25 + 180, 50 + 0, 50 + 90, 50 + 180 ppm in the starting and growing periods and at levels: 0 +0, 0 + 70, 0 + 140, 50 + 0, 50 + 70, 50 + 140, 100 + 0, 100 + 70, 100 + 140 ppm in the laying period. Addition of zinc and /or manganese improved the final body weight [at 6 weeks], total body gain, daily gain, body weight gain% relative to the control group and feed conversion ratio. The dressing%, organ weight and blood picture showed some variations in different quail groups. During the laying period, average egg production, egg mass and feed conversion ratio showed an improvement in treated groups when compared to the control one. Hatchability% of fertile eggs showed some variations in different quail groups. Eggs, yolk and albumen weights, shell thickness, shell weight and ash percentage of quail eggs in different treated groups showed a slight improvement when compared to the control one. It can be concluded that, addition of zinc and /or manganese to the ordinary diets of quail improves their growth performance and also slightly improves reproductive performance

Post-rest contractions of amphibian cardiac muscle

Post-rest potentiated contractions have been reported to be more dependent on Ca2+ stored in intracellular sites than on transmembrana Ca2+ influx. The phenomenon was examined using toad ventricular strips contracting isometrically and superfused with Ringer solution. Toad ventricular strips did not present post-rest potentiation, a fact that may be explained be the reduced volume of the sarcoplasmic reticulum in the amphibian myocardium. Potentiated post-res contractins were obtained after calcium influx blockade with 10 µM verapamil or 2mM Mn2+ and the slow reduction of extracellular Ca2+ concentration obtained by slowly exchanging the bath fluid was accompanied by a progressive decrease of both steady-state and post-rest contractions. These data suggestion of the dependende of post-rest potentiation on activator calcium liberated from intracellular stores

Efeito pós-natal do manganês na retençäo de flúor em tecidos mineralizados de ratos: II. Ossos / Post-natal effect of manganese on fluorine retention in mineralized tissues of rats: II. Bones

Visando determinar a influência do manganês na fixaçäo de flúor, 96 ratos albinos recém-desmamados foram distribuídos em grupos, recebendo dieta de caseína "ad libitum" e água conforme segue: G 1 - 10 ppm F; G 2 - 10 ppm F + 15 ppm Mn; G-3 - 10 ppm F + 50 ppm Mn; G 4 - 10 ppm F + 100 ppm Mn; G 5 - 1 ppm F; G 6 - 1 ppm F + 1,5 ppm Mn; G 7 - 1 ppm F + 5,0 ppm Mn; G 8 - 1 ppm F + 10 ppm Mn. Decorridos 60 dias do período experimental os animais foram sacrificados e o flúor retido nos diferentes osso determinado. Os resultados obtidos mostraram que a administraçäo simultânea de flúor e manganês reduziu significativamente a concentraçäo de flúor nos ossos longos, quando o excesso de manganês com relaçäo ao flúor foi superior a 50 por cento . Este efeito foi mas acentuado nos grupos que receberam maiores níveis dos elementos na água. Além disso, verificou-se que a açäo inibitória do mang ânes na retençäo de flúor em tecidos mineralizados foi dependente näo apenas da quantidade absoluta dos elementos na água mas também na proporçäo F:Mn

Influence of divalent cations on rabbit atria and modification of catecholamine response on pacemaker cells.

Spontaneously beating isolated atria of rabbits responded to Mn++ and Co++ with a progressively increasing negative chronotropism and inotropism, which was reversible by washout and by elevating the bath concentration of Ca++. The cumulative dose response curve for adrenaline for chronotropic response was markedly shifted to the right in the presence of Mn++ or Co++. This effect was also reversible. Verapamil produced only a moderate decline in spontaneous rate and contractility and did not block the chronotropic response to adrenaline. It is concluded that Mn++ and Co++ block the action of catecholamine on the pacemaker cells and they differ at least in part from organic calcium channel antagonists in their mechanism of action.

Effect of Mn++ on blood sugar level in rats.

Mn++ produced hypoglycemia in normal rats. The effect was dose-dependent. However, Mn++ did not produce hypoglycemia in alloxan-treated rats. There was a rise in liver glycogen following Mn++ treatment which was correlated with fall in blood sugar at 1 1/2 and 3 hr. There was also increase in the glucose uptake by rat diaphragm upto 47% between 2 and 3 hr. The results suggest that functioning, intact pancreatic beta-cells are necessary for the action of Mn++ and that Mn++ may have a peripheral effect on glucose entry into the cells.