Tools to investigate transepithelial ammonia transports

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In my NSERC funded research program the mechanisms responsible for the epithelial transport of ammonia, a highly toxic metabolic waste product from protein metabolism, is investigated with the focus on amphibians and invertebrates including planarians, insects, crustaceans, annelids and nematodes. For a thorough study of transport processes an integrative approach is imperative. The requested tool is a highly versatile 6-channel Voltage-Current Clamp/Ussing chamber system. This system allows the determination of the electrophysiological properties of a given transport epithelium including the tissue-generated transepithelial voltage difference, the produced electrical current and the ion permeability (conductance) but can simultaneously also be used for transepithelial flux measurements of specific ions and solutes. The Ussing chamber itself allows the usage of a wide variety of different tissue holders with different apertures (ca. 1 cm2 to 1 mm2). It is therefore suitable for the investigation of epithelia of different sizes, so that e.g. the intestine of butterfly larvae or frog skin can be mounted and investigated. Since several sets of custom-made tissue holders are already at hand for this system, in this application, holders for mounting frog skin (0.9 cm2) and split crab gill lamella (1 mm2) are requested. The requested equipment fills the gap between my studies using the living animal and investigations on the molecular level by allowing the examination of transport kinetics, electric properties, and transport mechanisms and their regulation in the transporting epithelium employing a "near in-vivo" set-up. The same model as the requested equipment is an essential element in my research and involved in several current projects which are conducted by 7 HQP. However, the apparatus in place right now is on loan from the German Research Foundation (DFG) and must be returned to Germany immediately. Therefore the requested system is necessary to ensure the continuation of my research program, my competitiveness as a researcher on a national and international level and also to allow my students to finish their ongoing projects in a timely manner.