Caracterización físico-química de ambientes acuáticos permanentes y temporarios del Chaco Oriental

Physico-chemical characteristies of 17 strearas and 3 tropical swamps-so called "esteros"- were studied in the provinces of Santa Fe, Chaco and Formosa in the esastern Chaco (Argentine). This study was done in order to gather suitable information about the availability of regional hydric re-sources, to determine the possible utilization and to contribute to the improvement of the landscape management. In the initial stage, samples were analyzed in three different opportunities during the hydrologic cycle, including dry and flooded seasons. The paper describes seasonal variations of the salinity, major ion composition, expressed as the porcentage of equivalent sum of total cations or anions, their geographical distribution and some other features, as the nutrient levels,hardness and aptitude for irrigation. On this basis, a characterization of the differents habitats is given also considering the most distinctive physico-chemical features. Analysis have been made according with the methodology described in Standard Methods (APHA, 1975) and Golterman and Clymo (IBP, 1978). Among the obtained records, the most relevant was the one concerning with the salinization phenomena being frequent in the Salado, Saladito, Saladillo and Palometa streams. In low water periods, they increased the conductivity to 103 uS.cm-1, with the correlative increment in the sodium, chloride and sulfate concentration which determined changes in the ionic typology.Physico-chemical characteristies of 17 strearas and 3 tropical swamps-so called "esteros"- were studied in the provinces of Santa Fe, Chaco and Formosa in the esastern Chaco (Argentine). This study was done in order to gather suitable information about the availability of regional hydric re-sources, to determine the possible utilization and to contribute to the improvement of the landscape management. In the initial stage, samples were analyzed in three different opportunities during the hydrologic cycle, including dry and flooded seasons. The paper describes seasonal variations of the salinity, major ion composition, expressed as the porcentage of equivalent sum of total cations or anions, their geographical distribution and some other features, as the nutrient levels,hardness and aptitude for irrigation. On this basis, a characterization of the differents habitats is given also considering the most distinctive physico-chemical features. Analysis have been made according with the methodology described in Standard Methods (APHA, 1975) and Golterman and Clymo (IBP, 1978). Among the obtained records, the most relevant was the one concerning with the salinization phenomena being frequent in the Salado, Saladito, Saladillo and Palometa streams. In low water periods, they increased the conductivity to 103 uS.cm-1, with the correlative increment in the sodium, chloride and sulfate concentration which determined changes in the ionic typology

Chemical composition of four essential oils from Eupatorium spp: Biological activities toward Tribolium castaneum (Coleoptera: Tenebrionidae) Composición química de cuatro aceites esenciales provenientes de Eupatorium spp. y su toxicidad para Tribolium castaneum (Coleoptera: Tenebrionidae)

Toxic and repellent properties of whole essential oils from four Eupatorium (Asteraceae) species (E. buniifolium Hook. et Arn, E. inulaefolium Kunth, E. arnottii Baker, and E. viscidum Hook. & Arn) were investigated in different concentrations toward Tribolium castaneum Herbst adults. The essential oils were isolated by hydrodistillation techniques from the aerial parts. The analysis was performed by GC-FID and GC-MS methods. Contact toxicity assays showed that all the evaluated essential oils were toxic. Furthermore, in all the cases mortality was dose dependent. The main repellency was observed for the essential oil recovered from E. buniifolium.<br>Se evaluaron las propiedades tóxicas y repelentes de los aceites esenciales de cuatro especies del género Eupatorium (Asteraceae): E. buniifolium Hook. et Arn, E. inulaefolium Kunth, E. arnottii Baker y E. viscidum Hook. & Arn, en diferentes concentraciones frente a adultos de Tribolium castaneum Herbst. Los aceites esenciales se aislaron de las partes aéreas de las plantas, mediante técnicas de hidrodestilación y se analizaron por los métodos GC-FID y GC-MS. Los ensayos de toxicidad por contacto demostraron que todos los aceites fueron tóxicos y la mortalidad fue, en todos los casos, dependiente de la dosis. El aceite esencial de E. buniifolium presentó la mayor actividad repelente

Chemical composition of four essential oils from Eupatorium spp: Biological activities toward Tribolium castaneum (Coleoptera: Tenebrionidae)

Se evaluaron las propiedades tóxicas y repelentes de los aceites esenciales de cuatro especies del género Eupatorium (Asteraceae): E. buniifolium Hook. et Arn, E. inulaefolium Kunth, E. arnottii Baker y E. viscidum Hook. & Arn, en diferentes concentraciones frente a adultos de Tribolium castaneum Herbst. Los aceites esenciales se aislaron de las partes aéreas de las plantas, mediante técnicas de hidrodestilación y se analizaron por los métodos GC-FID y GC-MS. Los ensayos de toxicidad por contacto demostraron que todos los aceites fueron tóxicos y la mortalidad fue, en todos los casos, dependiente de la dosis. El aceite esencial de E. buniifolium presentó la mayor actividad repelente

Ultrastructural study of the relationship between generative and vegetative cells inMagnolia ×soulangeana Soul.-Bod. pollen grains

Summary InMagnolia ×soulangeana pollen grains the generative cell (GC) does not become totally free within the vegetative cell (VC), at least until the pollen tube emergence. Due to a deviation in its detachment process from the sporoderm, the opposing ends of the VC plasmalemma do not fuse themselves when the GC moves away from the intine. Consequently, the interplasmalemmic space surrounding the GC does not become isolated but rather maintains continuity with the sporoderm through a complex formation that we have called plasmalemmic cord. The real existence of this formation was confirmed through serial sectioning showing the plasmalemmic cord to consist of the VC plasmalemma. In its initial portion it is occupied by a reasonably accentuated wall ingrowth of the inner layer of the intine (intine 3). In the remainder portion, neither of the cytochemical tests used in this work have revealed the presence of a significant amount of wall material. However, ultrathin sections of samples processed either chemically or by cryofixation showed the existence of an intricate system of tubules and vesicles, some of which are evaginations of the VC plasmalemma. The hypothesis that the plasmalemmic cord may have a role in the complex interactions between the two pollen cells is discussed