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Stephen Shaw
Stephen Shaw
(Ph.D., St. Andrews)
(Psychology)
SRSHAW@dal.ca
I'm basically an insect physiologist-neuroanatomist working on the peripheral visual system of flies, and also interested the insect blood-brain barrier which envelops the eye and CNS. I inhabit the lab directly opposite Ian Meinertzhagen's, so we often interact and have collaborated on several projects in the past. My own current projects involve: (1) trying to explain how the electroretinogram (ERG) originates in the compound eye of higher Diptera (flies), the components of which are mistakenly thought to be well-understood already. In the fruitfly Drosophila, the integrity of the ERG is often used nowadays as a simple assay for whether the first
visual synapse is still functional or not, after some molecular-genetic intervention to study synaptic transmission. Methods used include various types of electrical recording, dye marking, some neuroanatomy and ultimately electrical modeling. (2) trying to understand the origin and significance of a particular rhythmic behavior that I've discovered in the visual system of several families of fly. Methods mainly involve electrical recording and some statistical analysis, along with trying to identify the neuromodulator(s). (3) trying to explain the origin and potency of the insect blood-brain barrier, currently in collaboration with Dr. Ami Fröhlich (MSVU). A powerful barrier surrounds the CNS in advanced insects, and I have a long-term interest in its explaining its mechanism, function, and latterly in its evolution. Currently we are looking at the eye and CNS of the primitive apterygote Petrobius, from the oldest family of wingless insects closest to the stem line along which winged insects eventually evolved from crustaceans. Methods involve light- and electron-microscopy along with quantitative microfluorometry of injected fluorescent tracers, both in vivo and in vitro.