My laboratory is studying the responses of single-cells to environmental toxins. Our focus is on environmental toxins that cause long-lasting impairment of neurons weeks or even months after a person has been exposed to them. We have recently built a prototype biosensor device that quickly measures such toxins, hopefully before they can harm the nervous system. The device is based on a new idea -that neurotoxins can be measured by their interference with natural color changes in animal cells. Early tests of this idea proved successful, and so we are now learning all we can about the fundamental biology of color change in animals.
Color changes in the skin of fish, amphibians and reptiles are accomplished through a mechanism that is conceptually similar to color changes taking place on a color computer monitor. In the skin, each "pixel" is in fact a single living cell called a chromatophore. The "video signal" that causes changes in the intensity of these living pixels is, in fact, the continually changing mixture of neurotransmitters and hormones that originate from a two-dimensional network of nerve endings and blood capillaries in the skin. Chromatophores change their color through enzyme-dependent movements of their colored subcellular organelles. We think that chromatophores are affected by neurotoxins because neurons use similar enzymatic machinery to carry materials over the long distance between the neuron's cell body and its distant processes.