It is now a fundamental principle that diffusible molecules act intracellularly to translate an external signal into appropriate cellular responses. Second messengers like calcium, inositol polyphosphates and cyclic nucleotides, are such molecules. Calcium in particular can mediate cellular reactions as diverse as muscle contraction, neurotransmitter release, phototransduction and neuron excitability. One important question is how an elevation of intracellular calcium mediates so many processes. The answer lies in the versatility of the calcium signaling system. Assessing the role of calcium in biological systems involves powerful biophysical techniques such as electrophysiology and calcium sensitive dyes; other techniques involve measurement of calcium using calcium-sensitive microelectrodes. An example is shown below for Drosophila.

Set up for measurement of extracellular voltage and calcium by means of calcium-sensitive microelectrodes in the retina of Drosophila
Anoxia activates light-sensitive channels as monitored by calcium influx: extracellular voltage change (ERG, top trace) and measurement with calcium-sensitive microelectrode (ECa, bottom trace) in response to light (LM, light monitor) and anoxia (N2).

The following links provide more information about specific projects in several laboratories of the department.