Main Menu (Mobile)- Block
Main Menu - Block
We have developed a series of yellow genetically encoded Ca indicators for optical imaging (Y-GECOs) with inverted responses to Ca and apparent dissociation constants (K') ranging from 25 to 2400 nM. To demonstrate the utility of this affinity series of Ca indicators, we expressed the four highest affinity variants (K's = 25, 63, 121, and 190 nM) in the Drosophila medulla intrinsic neuron Mi1. Hyperpolarization of Mi1 by optogenetic stimulation of the laminar monopolar neuron L1 produced a decrease in intracellular Ca in layers 8-10, and a corresponding increase in Y-GECO fluorescence. These experiments revealed that lower K' was associated with greater increases in fluorescence, but longer delays to reach the maximum signal change due to slower off-rate kinetics.