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Dmca1A Encodes Voltage-Gated Calcium Channels in Drosophila Mushroom Body Kenyon
Cells
Monica Lavian
Mentor: Diane O’Dowd
Voltage-gated calcium channels are multimeric proteins containing pore forming -subunits that
regulate the entry of calcium into excitable cells. There are three -subunit genes in Drosophila:
Dmca1D, Dmca1A, and -1. Previous studies have demonstrated that Dmca1D forms functional
calcium channel proteins in Drosophila muscle cells. Dmca1A proteins are expressed in the
presynaptic terminals of motor neurons in the fly. Since it has not been possible to record from these
cells, it is not yet known whether they form functional voltage-gated calcium channels. In this study,
we used a genetic approach to determine whether the Dmca1A gene encodes functional calcium
channels in Kenyon cells, neurons that play a critical role in learning and memory in the fly. We
generated a line of flies in which Kenyon cells were tagged with green fluorescent protein (GFP),
allowing the identification of these neurons when grown in dissociated cell culture. A calcium
indicator dye, Fura-2 AM, was used to monitor the levels of intracellular calcium in individual
neurons at 2-4 days in culture. To assess the influx of calcium through voltage-gated channels,
cultures were depolarized by exposure to high potassium in the presence of drugs that block sodium
channels and synaptic transmission. There was a significant reduction in the depolarization-induced
increase in intracellular calcium levels in the Kenyon cells of Dmca1A mutants compared to wildtype.
These data support the hypothesis that the Dmca1A gene encodes a functional voltage-gated calcium
channel -subunit in Drosophila mushroom body Kenyon cells.