These transgenic mice express green fluorescent calcium indicator GCaMP6f in subsets of excitatory neurons in the brain and possibly other cell types and tissues. The transgene contains a mouse Thy1 promoter, GCaMP6f, woodchuck hepatitis virus posttranscriptional regulatory element (WPRE), and bovine growth hormone (bGH) polyadenylation sequence. The GCaMP6f indicator is an ultrasensitive detector of single neuronal action potentials and has fast response kinetics (PMID 23868258 and PMID 25250714). The mice can be used for imaging-based monitoring of neuronal activity in individual neurons in the brain and elsewhere.
Functional imaging experiments require 50-100mW average laser power (940 nm) as compared to alternative 10-25 mW in GCaMP viral transduction protocols. Stable expression levels of the GP5.12 line is reported to be moderate in the piriform area, S1, hippocampus, thalamus, and V1. Weak signal is reported in the olfactory bulb, M1, amygdala, hypothalamus, cerebellum, pons and medulla. No signal is reported in the midbrain.
The GP5.12 mice are generally healthy, but when animals are several months of age, a small percentage of cells in the visual cortex may exhibit signs of GCaMP toxicity: the GCaMP is no longer excluded from the nucleus in those cells, and the calcium transients are much longer. The GCaMP toxicity is thought to result from over-expression.
These mice were made by the Genetically-Encoded Neuronal Indicator and Effector (GENIE) Project at the HHMI's Janelia Farm Research Campus.
