Metals transport role

Patrone, L., Paladn, S., CharHer, J., Armand, F., Bourgoin, J.P., Tang, H. and Gauthier, S. (2003) Evidence of ffie Key Role of Metal-Molecule Bonding in Metal-Molecule-Metal Transport Experiments. Physical Review Letters, 91, 096802. 

Uptake of small organic metal complexes over transport systems of organic metabolites may be possible, for example, of small organic acids like citrate or amino acids. However, only few examples of such processes have been studied so far. Increased uptake of cadmium by an alga has been observed in the presence of citrate and has been attributed to accidental transport of the metal-citrate complex over a citrate transporter [212]. Transport systems of inorganic anions may also play a role in metal transport. Silver uptake by algae was enhanced in the presence of thiosulfate. In this case, the silver thiosulfate complex was transported over a sulfate uptake system [213]. It remains to be demonstrated how widespread these processes may be for metal uptake in the aquatic environment [12]. 

Ross, J. M. and Sherrell, R. M. (1999). The role of colloids in trace metal transport and adsorption behaviour in New Jersey Pinelands streams, Limnol. Oceanogr., 44, 1019-1034. 

In ordinary plants the evidence is for the involvement of anionic complexes of Cu and Ni for uptake and transport. This is generally taken as resulting from citrate rather than amino add complexation [as neutral bis(amino acidato)metal(II) complexes]. However, this conclusion ignores the presence of aspartic add, which is often found in exudates in relatively large amounts and would form bis-anionic spedes. A metal binding role for aspartic acid in xylem sap was proposed in some earlier work.37... 

These findings clearly demonstrate the role of colloid mineralogical composition on their ability to induce and mediate the transport of heavy metals in subsurface soil environments. In all treatments, the magnitude of colloid-mediated metal transport decreased according to the sequence montmorillonitic > illitic > kaolinitic. In spite of considerable differences between the two soils in terms of physical and... 

Describe the origin and characteristics of humic and fulvic acids and discuss their role in metal transport in soils. 

Membrane transport of toxic heavy metals not only controls their access to intracellular target sites but also helps to determine their uptake, distribution, and excretion from the body. The critical role of membranes in the toxicology of metals has attracted the attention of many investigators, and extensive information has been collected on the mechanisms of metal transfer across membranes. Characteristics of metal transport in different cells (see also Part II, Chapter 4), or even on opposite sides of the same cell, or under different physiological conditions, are not identical, and no unitary hypothesis has been formulated until now to explain this process in all cells (Foulkes 2000). 

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