Other Publications (1)
Articles by Ahmed M. Hamam in JoVE
Measuring Fluxes of Mineral Nutrients and Toxicants in Plants with Radioactive Tracers Devrim Coskun1, Dev T. Britto1, Ahmed M. Hamam1, Herbert J. Kronzucker1 1Department of Biological Sciences, University of Toronto In planta measurement of nutrient and toxicant fluxes is essential to the study of plant nutrition and toxicity. Here, we cover radiotracer protocols for influx and efflux determination in intact plant roots, using potassium (K+) and ammonia/ammonium (NH3/NH4+) fluxes as examples. Advantages and limitations of such techniques are discussed.
Other articles by Ahmed M. Hamam on PubMed
42K Analysis of Sodium-induced Potassium Efflux in Barley: Mechanism and Relevance to Salt Tolerance The New Phytologist. Apr, 2010 | Pubmed ID: 20122133 *Stimulation of potassium (K(+)) efflux by sodium (Na(+)) has been the subject of much recent attention, and its mechanism has been attributed to the activities of specific classes of ion channels. *The short-lived radiotracer (42)K(+) was used to test this attribution, via unidirectional K(+)-flux analysis at the root plasma membrane of intact barley (Hordeum vulgare), in response to NaCl, KCl, NH(4)Cl and mannitol, and to channel inhibitors. *Unidirectional K(+) efflux was strongly stimulated by NaCl, and K(+) influx strongly suppressed. Both effects were ameliorated by elevated calcium (Ca(2+)). As well, K(+) efflux was strongly stimulated by KCl, NH(4)Cl and mannitol , and NaCl also stimulated (13)NH(4)(+) efflux. The Na(+)-stimulated K(+) efflux was insensitive to cesium (Cs(+)) and pH 4.2, weakly sensitive to the K(+)-channel blocker tetraethylammonium (TEA(+)) and quinine, and moderately sensitive to zinc (Zn(2+)) and lanthanum (La(3+)). *We conclude that the stimulated efflux is: specific neither to Na(+) as effector nor K(+) as target; composed of fluxes from both cytosol and vacuole; mediated neither by outwardly-rectifying K(+) channels nor nonselective cation channels; attributable, alternatively, to membrane disintegration brought about by ionic and osmotic components; of limited long-term significance, unlike the suppression of K(+) influx by Na(+), which is a greater threat to K(+) homeostasis under salt stress.