Bioacumulación de Hg atmosférico utilizando líquenes fruticosos

El mercurio (Hg) está incluido en la lista de los diez principales productos químicos de mayor preocupación para la salud pública, y por este motivo se promueven programas para monitorear el Hg atmosférico en todo el mundo. Este elemento se transporta largas distancias desde su emisión, depositándose en lugares tan remotos como el Ártico y la Antártida. Una vez en la litosfera, el Hg puede acumularse en la biota hasta alcanzar concentraciones tóxicas. En pos del resguardo de la calidad del medio ambiente, el nivel del Hg se monitorea por distintos medios: artificiales, los que pueden ser pasivos como filtros/trampas o activos como los de flujo dinámico y los biomonitores. Los medios de artificiales como los de filtro presentan desventajas, entre ellas de manejo, y requieren niveles analíticos extremadamente bajos. Los equipos de flujo dinámico son más eficientes, dan medidas puntuales e integradas en el tiempo, pero son muy costosos. El biomonitoreo, permite registros de largo plazo con bajo costo y la logística es más sencilla, proporciona información respecto a la distribución espacial del contaminante, e indica cambios en el ecosistema, aunque la interpretación es más dificultosa. Los líquenes son los organismos más frecuentemente usados como bioindicadores de la calidad del aire. Sin embargo, el mecanismo por el cual los líquenes retienen Hg está poco estudiado y es necesario para interpretar estudios de campo. Este trabajo propone el uso de líquenes fruticosos in situ y trasplantados para estudiar la respuesta a la presencia de Hg en la atmósfera Hg. Los contenidos de Hg en los líquenes se determinarán por Análisis por Activación Neutrónica, RA-6, Centro Atómico Bariloche. Los contenidos de Hg de la atmósfera se cuantificarán utilizando una estación de detección perteneciente al proyecto Sistema Global de Observación de Mercurio; GMOS) ubicada en la sede Salmonicultura perteneciente al INIBIOMA-CONICET-UNCOMA, San Carlos de Bariloche. Se pretende correlacionar las mediciones de los contenidos de Hg atmosféricos con la acumulación de Hg de los talos liquénicos teniendo en cuenta variables atmosféricas. Este estudio brindaría información valiosa para una mejor interpretación del ciclo del Hg en estos ambientes.Mercury (Hg) is included in the list of the ten main chemicals of greatest concern for public health, and for this reason, programs to monitor atmospheric Hg worldwide are promoted. This element is transported long distances impacting remote places like the Arctic and the Antarctic. Once deposited in the lithosphere, Hg can accumulate and transform in biota to reach toxic values. In order to protect the quality of the environment, the Hg level is monitored by different means: artificial, which can be passive filters / traps or active as dynamic flow techniques and biomonitors. Artificial media, such as filter media, have disadvantages such as requiring extremely low analytical levels. Dynamic flow equipments are more efficient; they can provide point and time integrated measurements but are very expensive. Regarding biomonitoring, it allows long-term records with low cost and easier logistics, provides accurate information regarding the spatial distribution of the pollutant, and indicates changes in the ecosystem, however the interpretation is more difficult. Lichens are longlived organisms which are the more frequently used as atmospheric biomonitors of air quality. However, the mechanism by which lichens retain Hg is poorly understood and is important for the interpretation of field studies. The aim of this work is to correlate the Hg atmospheric measurements with the Hg bioaccumulated in lichen thalli taking into account atmospheric variables. This study would provide valuable information for a better interpretation of the Hg cycle in these environments

Mercury and REE contents in fruticose lichens from volcanic areas of the south volcanic zone

Volcanic eruptions represent one of the natural sources of Hg along with evasion from the oceans. This work evaluates the influence of these sources on the Hg bioaccumulation by fruticose lichens. The sampling areas were located in nearby sites affected by recent volcanic activity in the Patagonia Andean range. Geological techniques such as the study of REE and multi-element patterns were used to identify the volcanic ash sources. The relationship among Hg and semi volatile elements with the distance to the emitting points were considered. In general, the results found in the lichens were in agreement with the provenance of glass fractions from volcanic eruptions in the influenced zone. The diagrams of lichen multi-elements concentration showed similar patterns for lichens taken from locations further south (near Hudson volcano) which were different from the lichens taken from the northern area (near Puyehue, Calbuco and Copahue volcanoes). The average values of LREE/MREE showed similar values in lichen samples taken from the north and south areas from Puyehue Cordon Caulle Volcanic Complex and the ranges of the volcanic glass particles expelled during the 2011 eruption. The results suggest that normalized patterns of the REEs in fruticose lichens might provide a proxy record of the elements released from a volcanic source. Correlations of concentration of semi volatile elements to the volcanic distances and to the Pacific Ocean showed that Hg and Sb bioaccumulation in lichens had one or both contributions.Fil: Perez Catán, Soledad. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Ingeniería Nuclear. Laboratorio de Análisis por Activación Neutrónica; ArgentinaFil: Bubach, Debora Fabiana. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Ingeniería Nuclear. Laboratorio de Análisis por Activación Neutrónica; ArgentinaFil: Messuti, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Arribére, María Angélica. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro | Universidad Nacional de Cuyo. Instituto Balseiro. Archivo Histórico del Centro Atómico Bariloche e Instituto Balseiro; ArgentinaFil: Ribeiro Guevara, Sergio. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Unidad de Actividad de Ingeniería Nuclear. Laboratorio de Análisis por Activación Neutrónica; Argentin

Isolation and Characterization of a Cysteine Protease from the Latex of <i>Araujia hortorum</i> Fruits

A new protease (araujiain h l) was purified to mass spectroscopy homogeneity from the latex of Araujia hortorum Fourn. (Asclepiadaceae) fruits by ultracentrifugation and ion exchange chromatography. The enzyme has a molecular mass of 24,031 (mass spectrometry) and an isoelectric point higher than 9.3. The optimum pH range for casein hydrolysis was 8.0–9.5. The enzyme showed remarkable caseinolytic activity at high temperatures, although its thermal stability decayed rapidly. The proteinase was activated by thiol compounds and inhibited by common thiol-blocking reagents, particularly E-64 and HgCl₂, suggesting the enzyme belongs to the cysteine protease family. The concentration of active sites as determined by titration with E-64 was 3.3 μM. When assayed on N-α-CBZ-amino acid-p-nitrophenyl esters, the enzyme showed higher preference for the glutamine derivative, followed by those of alanine, asparagine, glycine, and leucine, in decreasing order. Partial homology (36–48%) with other plant cysteine proteinases was observed in an internal fragment obtained by Protease V8 treatment.Centro de Investigación de Proteínas Vegetale

Morrenain b I, a Papain-like Endopeptidase from the Latex of <i>Morrenia brachystephana</i> Griseb. (<i>Asclepiadaceae</i>)

A new cysteine endopeptidase (morrenain b I) has been purified and characterized from the latex of stems and petiols of Morrenia brachystephana Griseb. (Asclepiadaceae). Morrenain b I was the minor proteolytic component in the latex but showed higher specific activity than morrenain b II, which was the main active fraction. Both enzymes showed similar pH profiles and molecular masses, but kinetic parameters and N-terminal sequences were quite distinct, demonstrating that they are different enzymes instead of different forms of the same enzyme.Centro de Investigación de Proteínas Vegetale

Inorganic mercury (Hg2+) uptake by different plankton fractions of Andean Patagonian lakes (Argentina)

The species composition and the size structure of natural planktonic food webs may provide essential information to understand the fate of mercury and, in particular, the bioaccumulation pattern of Hg2+ in the water column of lake ecosystems. Heterotrophic and autotrophic picoplankton and phytoplankton are the most important entry points for Hg in aquatic ecosystems since they concentrate Hg2+ and MeHg from ambient water, making them available to planktonic consumers at higher trophic levels of lake food webs. In this investigation we studied theuptake of 197Hg2+ in natural plankton assemblages from four Andean lakes (Nahuel Huapi National Park, Patagonia, Argentina), comprised in the size fractions 0.2-2.7 µm (picoplankton), 0.2-20 µm (pico and nanoplankton) and 20-50 µm microplankton) through experiments using Hg2+ labeled with 197Hg2+. The experimental results showed that the uptake of Hg2+ was highest in the smallest plankton fractions (0.2-2.7 µm and 0.2-20 µm) compared to the larger fraction comprising microplankton (20-50 um). This pattern was consistent in all lakes, reinforcing the idea that among pelagic organisms, heterotrophic and autotrophic bacteria with the contribution of nanoflagellates and dinoflagellates constitute the main entry point of Hg2+ to the pelagic food web. Moreover, a significant direct relationship was found between the Hg2+ uptake and surface index of the planktonic fractions (SIf). Thus, the smaller planktonic fractions which bore the higher SI were the major contributors to the Hg2+ passing from the abiotic to the biotic pelagic compartments of these Andean lakes.Fil: Dieguez, Maria del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; ArgentinaFil: Soto Cárdenas, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; ArgentinaFil: Ribeiro Guevara, Sergio. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear. Unidad de Actividad de Ingenieria Nuclear. Laboratorio de Analisis Por Activacion Neutronica; ArgentinaFil: Dipasquale, Mark Marvin. United States Geological Survey; Estados UnidosFil: Gerea, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; ArgentinaFil: Arribére, María. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear. Unidad de Actividad de Ingenieria Nuclear. Laboratorio de Analisis Por Activacion Neutronica; ArgentinaFil: Queimaliños, Claudia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentin

Purification and Biochemical Characterization of Asclepain c I from the Latex of <i>Asclepias curassavica</i> L.

In this work we report the isolation, purification and characterization of a new protease from latex of Asclepias curassavica L. Crude extract (CE) was obtained by gathering latex on 0.1M citric-phosphate buffer with EDTA and cysteine with subsequent ultracentrifugation. Proteolytic assays were made on casein or azocasein as substrates. Caseinolytic activity was completely inhibited by E-64. Stability at different temperatures, optimum pH and ionic strength were evaluated by measuring the residual caseinolytic activity at different times after the incubation. CE showed the highest caseinolytic activity at pH 8.5 in the presence of 12 mM cysteine. CE was purified by cation exchange chromatography (FPLC). Two active fractions, homogeneous by SDS-PAGE, were isolated. The major purified protease (asclepain cI) showed a molecular mass of 23.2 kDa by mass spectrometry and a pI higher than 9.3. The N-terminal sequence showed a high similarity with those of other plant cysteine proteinases. When assayed on N-α-CBZ-aminoacid-p-nitrophenyl esters, the enzyme showed higher preference for the glutamine derivative. Determinations of kinetic parameter (km and Kcat) were performed with PFLNA.Centro de Investigación de Proteínas Vegetale

Two new cysteine endopeptidases obtained from the latex of Araujia hortorum fruits

Two new endopeptidases were purified to homogeneity from the latex of Araujia hortorum fruits by a simple purification procedure involving ultracentrifugation and ion exchange chromatography. Molecular weights of araujiain h II and araujiain h III were 23,718 and 23546 (mass spectrometry), respectively. The isoelectric point of araujiain h II was 8.9, whereas araujiain h III had a pI higher than 9.3. Maximum proteolytic activity on caseine was reached at pH 8.0-9.0 for both endopeptidases, which were irreversibly inhibited by iodoacetate and E-64, suggesting they belong to the cysteine protease family. Esterolytic activity was determined on N-alpha-CBZ-amino acid-p-nitrophenyl esters, and the highest kcat/Km values for the both enzymes were obtained with the glutamine derivative. The N-terminal sequences of araujiain h II and araujiain h III showed a high degree of homology with other plant cysteine endopeptidases.Centro de Investigación de Proteínas Vegetale

Comparison of Two Cysteine Endopeptidases from Latices of Morrenia brachystephana Griseb. and Morrenia odorata (Hook et Arn.) Lindley (Asclepiadaceae)

The properties of morrenain b II, a proteinase isolated from the latex of Morrenia brachystephana, were compared with those of morrenain o II, a proteinase obtained from the latex of Morrenia odorata. Both peptidases were purified to homogeneity by acetone precipitation followed by cation exchange chromatography. The enzymes have pi values higher than 9.3 and similar molecular masses (close to 26 kDa) as determined by SDS-PAGE. They display maximum proteolytic activity within an alkaline pH range, and also exhibit esterolytic activity. The N-terminal sequences of morrenain o II and morrenain b II show a high degree of homology between each other and to other cysteine plant proteinases.Centro de Investigación de Proteínas Vegetale

Purification and Biochemical Characterization of Asclepain c I from the Latex of <i>Asclepias curassavica</i> L.

In this work we report the isolation, purification and characterization of a new protease from latex of Asclepias curassavica L. Crude extract (CE) was obtained by gathering latex on 0.1M citric-phosphate buffer with EDTA and cysteine with subsequent ultracentrifugation. Proteolytic assays were made on casein or azocasein as substrates. Caseinolytic activity was completely inhibited by E-64. Stability at different temperatures, optimum pH and ionic strength were evaluated by measuring the residual caseinolytic activity at different times after the incubation. CE showed the highest caseinolytic activity at pH 8.5 in the presence of 12 mM cysteine. CE was purified by cation exchange chromatography (FPLC). Two active fractions, homogeneous by SDS-PAGE, were isolated. The major purified protease (asclepain cI) showed a molecular mass of 23.2 kDa by mass spectrometry and a pI higher than 9.3. The N-terminal sequence showed a high similarity with those of other plant cysteine proteinases. When assayed on N-α-CBZ-aminoacid-p-nitrophenyl esters, the enzyme showed higher preference for the glutamine derivative. Determinations of kinetic parameter (km and Kcat) were performed with PFLNA.Centro de Investigación de Proteínas Vegetale

Heavy metal concentrations in different compartments of Andean lakes of Northern Patagonia

Los elementos traza, que incluyen a los metales pesados, llegan a los ecosistemas acuáticos desde fuentes naturales y antrópicas. Los metales pesados se encuentran entre los contaminantes ambientales más importantes debido a su toxicidad, permanencia y tendencia a acumularse en los organismos acuáticos, por lo que su estudio es necesario por el riesgo ambiental que representan. El objetivo de este trabajo es presentar los resultados más relevantes en relación a los niveles de metales pesados existentes en diferentes compartimentos de lagos del noroeste de Patagonia. Los estudios realizados determinaron concentraciones de elementos traza en testigos sedimentarios, sedimentos suspendidos, agua, plancton, macroinvertebrados y músculo e hígado de peces. En términos generales, los niveles de metales pesados en los distintos compartimentos fueron similares a los valores medidos en otros ambientes de agua dulce. La excepción la constituyen el mercurio y la plata, que presentan enriquecimientos superiores a los niveles de línea de base de la zona en las últimas décadas. En el caso de la plata fueron observadas mayores concentraciones en sitios cercanos a los asentamientos humanos, y en algunos casos alcanzaron valores correspondientes a situaciones de contaminación moderada. En ningún caso, la acumulación de metales en músculo de peces superó los límites considerados para el consumo humano. Esta revisión permite identificar niveles de referencia y evaluar la tendencia del impacto antrópico, aportando información de base para futuros monitoreos de los ambientes lacustres de la región.Trace elements, including heavy metals, can reach the aquatic ecosystems from natural or anthropogenic sources. Heavy metals are amongst the most important environmental contaminants due to its toxicity, permanency and its tendency to bioaccumulate in aquatic organisms. Because of those factors it is important to study these elements to assess the environmental risk they represent to the aquatic ecosystems of the region.The objective of this work is to present the most relevant results concerning the levels of heavy metals in different compartments of lakes in Northwestern Patagonia. These results allow the analysis of trace element concentrations in sediment cores, suspended sediments, water, plankton, macroinvertebrates and fish muscle and liver. In general, heavy metal concentrations in the different compartments are similar to those found in other freshwater ecosystems. The exceptions are mercury and silver, which show enrichment in the last decades in the upper sections of the sediment cores and higher Ag concentration in sites near human settlements. In some cases, mercury concentrations in sediment and Ag and selenium in biota are similar to ecosystems affected by moderate levels of contamination.Although bioaccumulation of trace elements was observed in fish muscle, in any case the concentrations are above the limits allowed for human consumption by SENASA. This review will help to identify reference values for trace element concentrations and to discern patterns of anthropogenic impacts through time which will help future monitoring of the lacustrine environments of the region