In severe environments, the presence of arbuscular mycorrhlzai fungi (AMF) Is essential for plant survival and a balanced ecosystem e. The aim of this work was to characterize the arbuscular mycorrhizal fungi present in algarrobales (Frosopis alba) areas of contrasting humid and semi-arid climatic conditions, Colonia Benitez and Padre Lozano respectively, both in the Parque Chaqueño region in Argentina. The Colonia Benitez and Padre Lozano sites showed significant edaphological differences, the most important being the lower content of organic matter and phosphorus, and the higher percentage of exchangeable sodium in Colonia Benitez, associated with a higher infective capacity and greater mycorrhizal potential of inoculum. Only one species was found in both soils: Acaulospora laevis, typical of arid environments. In the inocula, three species were identified in both sites: Funneliformis mosseae, Rhizophagus intraradices, Claroideoglomus etunicatum; two species were only identified in Colonia Benítez: Septoglomus constrictum and Rhizophagus clarus; and two species were only identified in Padre Lozano: Claroideoglomus claroideum and Diversispora spurca. This is the first study in Argentina to analyze AMF diversity in Frosopis alba areas (algarrobales) and their infectivity in the soils and their inocula.

En ambientes severos, la presencia de hongos micorrícicos arbusculares (HMA) es clave para la supervivencia de las plantas y el balance ecosistémico. El objetivo de este trabajo fue caracterizar los hongos micorrícicos arbusculares presentes en sitios de algarrobales (Frosopis alba) del Parque Chaqueño argentino de condiciones climáticas contrastantes: húmedo, Colonia Benítez, y semiárido, Padre Lozano. Los sitios de Colonia Benítez y Padre Lozano presentaron diferencias edafológicas significativas, destacándose el menor contenido de materia orgánica y fósforo, y el mayor porcentaje de sodio intercambiable en Colonia Benítez, asociados a una mayor capacidad infectiva y mayor potencial micorrícico de inóculo. En los suelos sólo se encontró una especie común: Acaulospora laevis, propia de ambientes áridos. En los inóculos se registraron tres especies en común: Funneliformis mosseae, Rhizophagus intraradices, Claroideoglomus etunicatum; dos especies exclusivas de Colonia Benítez, Septoglomus constrictum y Rhizophagus clarus; y dos especies exclusivas de Padre Lozano, Claroideoglomus claroideum y Diversispora spurca. Este es el primer estudio en Argentina en el cual se reporta la diversidad de HMA en suelos de algarrobales y se mide la infectividad de los suelos y de los inóculos obtenidos a partir de esos suelos.

Three superoxide dismutase isoenzymes of different cellular location were detected in an homogenate of Thrichuris ovis. Each of these molecular forms was purified by differential centrifugation and precipitation with ammonium sulphate, followed by chromatography on DEAE-cellulose and Sephadex G-75 columns. The activity levels of the two molecular forms detected in the mitochondrial (one cyanide sensitive Cu-Zn-SOD and the other cyanide intensitive Mn-Sod were higher than that of the superoxide dismutase detected in the cytoplasmic fraction (cyanid sensitive Cu-Zn-SOD). All the mollecular forms present evident differences to the SODs contained in the host liver. Molecular mass and some of the physical and chemical aproperties of the enzyme was determined for all three molecular forms. An inhibitory effect on the SOD of the parasite an the host was detected with a series of compounds, some of wich markedly inhibited parasite ensyme but not host enzyme.

The inhibitor effect on the Glycogen synthetase (E.C.2.4.1.11) activity by four anthelmintics: Mebendazole, Parbendazole, Albendazole and Thiabendazole was determinated. The most inhibitor effect of Parbendazole on A. suum, F. hepatica and M. expansa, was observed. The lowest inhibitor effect of Thiabendazole, on all cases, was also observed. The aim of our study, and further studies on the same line, are to provide new reports about the unknown locus of actuation of these anthelmintics.

Se ha determinado el effecto inhibidor sobre la actividad Glucogeno sintetasa (E.C.2.41.11) por parte de cuatro antihelminticos: Albendazol, Mebendazol, Parbendazol y Tiabendazol. Observandose que en todos los casos, es el Parbendazol quien ha demostrado un mayor poder inhibidor sobre la glucógeno sintetasa de Ascaris suum, Fasciola hepatica y Moniezia expansa. El Tiabendazol es el anti-helmintico que menor efecto inhibidor ha presentado sobre la enzima en los tres parasitos objeto de nuestro estudio. Con el presente trabajo y otros previstos en la misma linea, se pretende aportar nuevos datos acerca del aun desconocido locus de acción de estos antihelminticos.