ABSTRACT
Isotope dilution ICP-MS is proposed to measure the mass fraction of Cd extracted by diluted HCl in marine sediments, using a fast and simple extraction procedure based on ultrasonic probe agitation. The 111Cd isotope was added before the extraction to achieve isotope equilibration with native Cd solubilized from the sample. The parameters affecting trueness and precision of isotope ratio measurements were evaluated carefully and subsequently corrected in order to minimize errors; they were: detector dead time, spectral interferences, mass discrimination factor and optimum sample/spike ratio. The mass fraction of Cd extracted was compared with the sum of the certified contents of the three steps of the sequential extraction procedure of the Standards, Measurements and Testing Programme (SM&T) analysing the BCR 701 sediment to validate the method. The certified and measured values agreed, giving a measured / certified mass fraction ratio of 1.05. Further, the extraction procedure itself was studied by adding the enriched isotope after the extraction step, which allowed verifying that analyte losses occurred during this process. Two additional reference sediments with certified total cadmium contents were also analysed. The method provided very good precision (0.9%, RSD) and a low detection limit, 1.8â¯ngâ¯g-1. The procedural uncertainty budget was estimated following the EURACHEM Guide by means of the 'GUM Workbench' software, obtaining a relative expanded uncertainty of 1.5%. The procedure was applied to determine the bioaccessible mass fraction of Cd in sediments from two environmentally and economically important areas of Galicia (rias of Arousa and Vigo, NW of Spain).
ABSTRACT
Seed banking has been the single most significant reaction of the research community to the alarming rates of plant genetic erosion occurring in the wild. One enduring challenge for a wiser utilization of the resources enclosed in seed banks, however, has been the estimation of their genetic potentials for agriculture's benefit. Key to detecting in landraces and/or wild relatives of modern crops any allelic variant lost during domestication and crop improvement is the use of molecular information to determine structure, evolution, and function of the genes harbouring these alleles. This paper reviews some of the theoretical and statistical issues surrounding the use of molecular population genetics tools for the detection of agronomical valuable alleles in seed banks. Emphasis is made on the technical limitations imposed by seed banking that may lessen the success of integrated and multi-disciplinary molecular approaches. The influence that population stratification and linkage disequilibrium exert on specific experimental designs for a better understanding of the evolutionary history of potential agronomic-related genes is also examined.
Subject(s)
Crops, Agricultural/genetics , Seeds/genetics , Agriculture , Alleles , Breeding , Crosses, GeneticABSTRACT
Genetic control of seed dormancy in barley (Hordeum vulgare L.) has mostly been described in terms of quantitative variation. Although some molecular markers for dormancy QTL have been identified, the corresponding genes involved in the regulation of the process have not been cloned. Induced barley mutants may constitute useful material to study the physiology and genetics of seed dormancy. The objective of this study was to identify the genetic control of this trait in a mutant (TL43) produced in the barley cv. Triumph. This mutant was selected for reduced dormancy and reduced sensitivity to abscisic acid (ABA). Two sets of F6 barley lines were selected for high and low levels of dormancy from a cross between the original dormant parent and the sodium azide-induced non-dormant TL43 mutant. Unexpectedly, given the near-isogenic nature of these two genotypes, polymorphism was detected for an SSR located in the centromeric region of chromosome 6(6H) out of a total of 92 molecular markers evenly distributed along the genome. Fortunately, upon three cycles of intensive divergent selection, every dormant and non-dormant F5 line consistently showed the genotype for this region identical to Triumph and TL43, respectively. Based on the mutagenic effect presumably attributed to sodium azide, mostly single point mutations, it cannot be clearly established if such extensive genomic variation on chromosome 6(6H) is due to the mutagenic treatment or may be an introgression from an unknown source. The means that could originate such heterogeneity are discussed; however, regardless of its origin, this genomic region shows a strong association with the expression of seed dormancy and provides an additional genetic locus for further studies of the mechanistic basis of this complex trait. In addition, since TL43 shows reduced sensitivity to ABA, the response to this hormone was determined on the F6 seed from the two sets of selected F5 lines. The results confirmed that the initial level of dormancy in the seed lot is the most important factor in determining ABA sensitivity.
Subject(s)
Abscisic Acid/metabolism , Chromosomes, Plant/genetics , Germination/genetics , Hordeum/genetics , Plant Growth Regulators/physiology , Centromere/physiology , Genetic Linkage , Genetic Markers , Genotype , Hordeum/physiology , Mutation , Polymorphism, Genetic , Seeds/genetics , Seeds/physiologyABSTRACT
Durante el año 1990 se realizaron medidas de 17 parámetros fisicoquímicos, con el objetivo fundamental de obtener información sobre el estado actual del río Grande y Castro (provincia de La Coruña, N.O. de España), en lo que respecta a la calidad de sus aguas, puesto que va a permitir controlar aquellos puntos que presentan elevadas cotas de contaminación y que constituyen un evidente peligro para el medio ambiente y que va a afectar a la colectividad humana. El estudio realizado permite deducir el buen estado general de las aguas
Subject(s)
Fresh Water/analysis , Surface Waters , Water Quality Criteria , Water Pollution/analysis , Fresh Water/chemistry , Water Quality , Water Pollution/prevention & control , SpainABSTRACT
Se ha realizado un estudio sobre el contenido de metales en aguas del río Grande y Castro, situados en la privincia de La Coruña (N.O. de España), durante 1990, determinándose la concentración de los siguientes metales: Na, K, Ca, Mg, Fe, Co, Ni, Mn, Pb, Zn, Cd y Cu, lo cual es importante por la relación entre ciertos tipos de cánceres y lesiones cardiovasculares con altos contenidos de metales. Los resultados obtenidos permiten deducir el buen estado global de las aguas
Subject(s)
Fresh Water/analysis , Water Quality Criteria , Water Quality , Cations/analysis , Fresh Water/chemistry , Specimen Handling/standards , SpainABSTRACT
Durante el año 1990 se realizaron medidas de 17 parámetros fisicoquímicos, con el objetivo fundamental de obtener información sobre el estado actual del río Grande y Castro (provincia de La Coruña, N.O. de España), en lo que respecta a la calidad de sus aguas, puesto que va a permitir controlar aquellos puntos que presentan elevadas cotas de contaminación y que constituyen un evidente peligro para el medio ambiente y que va a afectar a la colectividad humana. El estudio realizado permite deducir el buen estado general de las aguas
Subject(s)
Water Pollution/analysis , Fresh Water/analysis , Surface Waters , Water Quality Criteria , Water Pollution/prevention & control , Fresh Water/chemistry , Spain , Water QualityABSTRACT
Se ha realizado un estudio sobre el contenido de metales en aguas del río Grande y Castro, situados en la privincia de La Coruña (N.O. de España), durante 1990, determinándose la concentración de los siguientes metales: Na, K, Ca, Mg, Fe, Co, Ni, Mn, Pb, Zn, Cd y Cu, lo cual es importante por la relación entre ciertos tipos de cánceres y lesiones cardiovasculares con altos contenidos de metales. Los resultados obtenidos permiten deducir el buen estado global de las aguas
