A P-type ATPase importer that discriminates between essential and toxic transition metals

Transition metals, although being essential cofactors in many physiological processes, are toxic at elevated concentrations. Among the membrane-embedded transport proteins that maintain appropriate intracellular levels of transition metals are ATP-driven pumps belonging to the P-type ATPase superfamily. These metal transporters may be differentiated according to their substrate specificities, where the majority of pumps can extrude either silver and copper or zinc, cadmium, and lead. In the present report, we have established the substrate specificities of nine previously uncharacterized prokaryotic transition-metal P-type ATPases. We find that all of the newly identified exporters indeed fall into one of the two above-mentioned categories. In addition to these exporters, one importer, Pseudomonas aeruginosa Q9I147, was also identified. This protein, designated HmtA (heavy metal transporter A), exhibited a different substrate recognition profile from the exporters. In vivo metal susceptibility assays, intracellular metal measurements, and transport experiments all suggest that HmtA mediates the uptake of copper and zinc but not of silver, mercury, or cadmium. The substrate selectivity of this importer ensures the high-affinity uptake of essential metals, while avoiding intracellular contamination by their toxic counterparts

Efecto de tres m?todos de amamantamiento sobre el crecimiento de los terneros, Producci?n y reProducci?n de sus madres.

Tesis (M. Sc) -- CATIE; UCR, Turrialba (Costa Rica), 1983Se compararon dos formas de amamantamiento restringido de terneros, con la pr?ctica m?s generalizada que llevan a cabo los ganaderos en sus fincas, para determinar el mejor m?todo considerando el efecto que causa sobre el crecimiento del ternero y el comportamiento productivo y reproductivo de sus madres. Los tratamientos consistieron en: (T1) orde?o de 3/4 reservando un ?? para el ternero en rotaci?n diaria y amamantamiento de la cr?a por 6 horas (T2) orde?o de los 4/4 y amamantamiento por 6 horas, (T3) orde?o de los 4/4 y amamantamiento de la cr?a por una hora despu?s del orde?o y otra hora al medio d?a. Las vacas se mantuvieron alimentadas ?nicamente mediante el pastoreo de forrajes sin fertilizar, proporcion?ndoles suplementaci?n mineral los terneros se mantuvieron en igual forma despu?s del m?todo de amamantamiento restringido por 180 d?as seg?n tratamiento asignado. En los terneros se midi? el efecto del tratamiento sobre el aumento de peso del nacimiento, al destete (APND) y la mortalidad (M) en las madres, Producci?n de leche vendible en 180 d?as de lactancia (PLV/L), cambios de peso entre el inicio y el final de la lactancia (CPIFL), incidencia de mastitis (IM) y pre?ez (P). Se concluy? que el T1, es un buen m?todo de amamantamiento. Sin embargo, ninguno de los tratamientos promovi? un aumento de peso satisfactorio en los terneros, por lo que se recomienda una suplementaci?n en pastoreo, lo cual unido a la Producci?n de leche vendible (PLV/L) producir? una relaci?n adecuada en la Producci?n bovina de las explotaciones de doble prop?sit

Viabilidad del aumento de la produccion y comercializaci?n de biofertilizantes y bioplaguicidas en la zona alta de los municipios de San Ignacio y La Palma en El Salvador

Centro Agron?mico Tropical de Investigaci?n y Ense?anza (CATIE)-MA

Potential of the clean development mechanism in the forestplantations of Panama

Tesis (M. Sc) -- CATIE, Turrialba (Costa Rica),2007El objetivo del presente trabajo es determinar el potencial para proyectos de plantaci?n forestal bajo el mecanismo de desarrollo limpio (MDL) en Panam? a nivel de corregimientos. Se estudiaron la adicionalidad y la elegibilidad de tierras para ubicar las ?reas m?s potenciales de Panam?. Para demostrar la potencialidad se realiz? un an?lisis financiero en el cual se desarroll? una ecuaci?n general. Esta ecuaci?n general se utiliz? para representar la rentabilidad de las plantaciones por corregimiento a trav?s del indicador financiero valor esperado de la tierra (VET). En el trabajo se utilizaron variables fuzzy, para representar la variabilidad de los par?metros y de los resultados. Para la elaboraci?n de este trabajo se seleccion? a la especie teca representativa de las plantaciones forestales de Panam?. Se concluy? que aquellas ?reas con mayor potencial, teniendo en cuenta la adicionalidad y elegibilidad de tierras, se encuentran en las regiones de Veraguas, Panam?, Herrera y Dari?n. The objective of the present work is to determine the potential of the clean development mechanism (CDM) for forest plantation projects in Panama. The additionality and the eligibility of lands are the two most restrictive issues for afforestation/reforestation projects under the CDM. Additionality and land eligibility were assessed to locate the areas with more potential in Panama. A financial analysis was applied with a general equation representing the profit value of the plantations by districts. This equation used the land expected value (LEV) as financial indicator. Fuzzy variables were used to represent the variability and ambiguity of the parameters and their values. Teak was selected as the representative species for forest plantations in Panama. Results showed that areas with greater potential of additionality and land eligibility were located in the regions of Veraguas, Panama, Herrera and Darien

Mechanism of Cu+-transporting ATPases: Soluble Cu+ chaperones directly transfer Cu+ to transmembrane transport sites

As in other P-type ATPases, metal binding to transmembrane metal-binding sites (TM-MBS) in Cu+-ATPases is required for enzyme phosphorylation and subsequent transport. However, Cu+ does not access Cu+-ATPases in a free (hydrated) form but is bound to a chaperone protein. Cu+ transfer from Cu+ chaperones to regulatory cytoplasmic metal-binding domains (MBDs) present in these ATPases has been described, but there is no evidence of a proposed subsequent Cu+ movement from the MBDs to the TM-MBS. Alternatively, we postulate the parsimonious Cu+ transfer by the chaperone directly to TM-MBS. Testing both models, the delivery of Cu+ by Archaeoglobus fulgidus Cu+ chaperone CopZ to the corresponding Cu+-ATPase, CopA, was studied. As expected, CopZ interacted with and delivered the metal to CopA MBDs. Cu+-loaded MBDs, acting as metal donors, were unable to activate CopA or a truncated CopA lacking MBDs. Conversely, Cu+-loaded CopZ activated the CopA ATPase and CopA constructs in which MBDs were rendered unable to bind Cu+. Furthermore, under nonturnover conditions, CopZ transferred Cu+ to the TM-MBS of a CopA lacking MBDs. These data are consistent with a model where MBDs serve a regulatory function without participating in metal transport and the chaperone delivers Cu+ directly to transmembrane transport sites of Cu+-ATPases

A unique virus complex causes Ageratum yellow vein disease

Ageratum conyzoides L., a weed species widely distributed throughout southeast Asia, frequently exhibits striking yellow vein symptoms associated with infection by Ageratum yellow vein virus (AYVV), a member of the Geminiviridae (genus Begomovirus). Most begomoviruses have bipartite genomes (DNAs A and B), but only a DNA A has been identified for AYVV. We demonstrate that yellow vein disease of A. conyzoides results from co-infection by AYVV DNA A (2,741 nt) and a circular DNA that is approximately half its size (1,347 nt) that we designate DNA β. Apart from the sequence TAATATTAC, common to all geminiviruses and containing the initiation site of rolling circle replication, DNA β shows negligible sequence homology either to AYVV DNA A or to DNA B associated with bipartite begomoviruses. DNA β depends on DNA A for replication and is encapsidated by DNA A-encoded coat protein and so has characteristics of a DNA satellite. However, systemic infection of A. conyzoides by DNA A alone is sporadic and asymptomatic, and DNA A accumulation is reduced to 5% or less of its accumulation in the presence of DNA β. Therefore, DNA A and DNA β together form a previously unrecognized disease-inducing complex. Our data also demonstrate that the nanovirus-like DNA 1 component associated with infected A. conyzoides plays no essential role in the disease and represents a satellite-like DNA. Furthermore, the satellite DNA previously found associated with tomato leaf curl virus is probably a defective DNA β homologue