The Role of Iron-Deficiency Stress Responses in Stimulating Heavy-Metal Transport in Plants1

Plant accumulation of Fe and other metals can be enhanced under Fe deficiency. We investigated the influence of Fe status on heavy-metal and divalent-cation uptake in roots of pea (Pisum sativum L. cv Sparkle) seedlings using Cd2+ uptake as a model system. Radiotracer techniques were used to quantify unidirectional 109Cd influx into roots of Fe-deficient and Fe-sufficient pea seedlings. The concentration-dependent kinetics for 109Cd influx were graphically complex and nonsaturating but could be resolved into a linear component and a saturable component exhibiting Michaelis-Menten kinetics. We demonstrated that the linear component was apoplastically bound Cd2+ remaining in the root cell wall after desorption, whereas the saturable component was transporter-mediated Cd2+ influx across the root-cell plasma membrane. The Cd2+ transport system in roots of both Fe-deficient and Fe-sufficient seedlings exhibited similar Michaelis constant values, 1.5 and 0.6 μm, respectively, for saturable Cd2+ influx, whereas the maximum initial velocity for Cd2+ uptake in Fe-deficient seedlings was nearly 7-fold higher than that in Fe-grown seedlings. Investigations into the mechanistic basis for this response demonstrated that Fe-deficiency-induced stimulation of the plasma membrane H+-ATPase did not play a role in the enhanced Cd2+ uptake. Expression studies with the Fe2+ transporter cloned from Arabidopsis, IRT1, indicated that Fe deficiency induced the expression of this transporter, which might facilitate the transport of heavy-metal divalent cations such as Cd2+ and Zn2+, in addition to Fe2+.

El Heavy Metal en España, 1978-1985: fases de formación, cristalización y crecimiento

El heavy metal es uno de los movimientos socioculturales más extendidos de la cultura occidental. Musicalmente es, además, uno de los géneros más ricos de cuantos conforman el crisol de la música popular urbana, habiendo despertado el interés de sociólogos y musicólogos, fundamentalmente europeos y norteamericanos, que lo han introducido en el currículo académico. Una normalización que contrasta, sin embargo, con su apreciación en España, donde apenas se ha considerado como objeto de estudio, y mantiene un estatus de marginalidad. Esta tesis doctoral se plantea como punto de partida de una nueva línea de investigación, analizando las etapas evolutivas del heavy metal español; y con la intención de alcanzar la normalización que unifique criterios con las corrientes musicológicas anglosajonas. Trata de demostrar que existió una escena significativa de heavy metal en España, con unas características propias que la diferenciaron del resto, y que tuvo una presencia importante en el panorama musical y cultural español de principios de los años ochenta. A partir de esta hipótesis, presenta los siguientes objetivos principales: -­‐ Establecer una historia detallada de la evolución del heavy metal en España en sus fases de formación, cristalización y crecimiento, dentro de un contexto histórico, social y cultural. -­‐ Detallar las características musicales del heavy metal español en sus fases de formación, cristalización y crecimiento. -­‐ Esclarecer las principales influencias, los precedentes y la dimensión verbal del heavy metal español. -­‐ Evidenciar la trascendencia del heavy metal sobre la cultura y la música popular española. -­‐ Asentar el heavy metal como objeto de estudio en la musicología española. Debido a su doble enfoque histórico musical y analítico, la investigación está dividida en dos partes diferenciadas: una primera que trata el género desde su vertiente histórica, teniendo en cuenta su evolución dentro de un contexto político, social y cultural determinado; y una segunda, técnica, que atiende a su condición de estilo musical...

Heavy metal contents in Fe-Mn nodules and crusts from R/V Vityaz polygons and stations in the East Indian Ocean

Regional variations in abundance, morphology, and chemical composition of Fe-Mn nodules have a zonal character. Due to circumcontinental zonality of terrigenous sedimentation the main mass of the nodules occurs in the pelagic part of the ocean, in areas of minimal sedimentation rates. In spatial variations in morphology and chemical composition of the nodules the latitudinal zonality is very clear and associated with latitudinal changes in facial conditions of sedimentation. Elevated contents of Mn, Ni, and Cu and of Mn/Fe ratio occur in nodules from the radiolarian belt. Changes of chemical composition of the nodules with depth (vertical zonality of mineralization) are confirmed. Local variations in abundance, morphology and chemical composition of the nodules are caused by ruggedness of relief and depth variations, variations in sedimentation rate, age of ore formation, intensity of diagenetic redistribution of metals.

Neutron production by medium-energy protons on heavy metal targets /

Photocopy. [Oak Ridge, Tenn. : U.S. Dept. of Energy, Technical Information Center, 1979]

Organochlorine and heavy metal concentrations in blubber and liver tissue collected from Queensland (Australia) dugong (Dugong dugon)

Tissue samples of liver and blubber were salvaged from fifty-three dugong (Dugong dugon) carcasses stranded along the Queensland coast between 1996 and 2000. Liver tissue was analysed for a range of heavy metals and blubber samples were analysed for organochlorine compounds. Metal concentrations were similar in male and female animals and were generally highest in mature animals. Liver concentrations of arsenic, chromium, iron, lead, manganese, mercury and nickel in a number of individual animals were elevated in comparison to concentrations previously reported in Australian dugong. Dieldrin, DDT (and its breakdown products) and/or heptachlor epoxide were detected in 59% of dugong blubber samples. In general, concentrations of organochlorines were similar to those reported in dugong 20 years earlier, and were low in comparison to concentrations recorded from marine mammal tissue collected elsewhere in the world. With the exception of lead, the extent of carcass decomposition, the presence of disease or evidence of animal starvation prior to death did not significantly affect dugong tissue concentrations of metals or organochlorines. The results of the study suggest that bioaccumulation of metals and organochlorine compounds (other than dioxins) does not represent a significant risk to Great Barrier Reef dugong populations, particularly in the context of other pressures associated with coastal development and other anthropogenic activities. (c) 2004 Elsevier Ltd. All rights reserved.