Fig. 5

Co-injection of AAV9/M1-Cre & AAV9/hSyn-DIO-mcherry in WT dCA2 leads to the optimal expression accuracy comparing to the co-injections of hSyn-Cre&EF1α-DIO-EGFP in the WT dCA2, the single injections of AAV9/CMV-EGFP in the WT dCA2 and the single injections of AAV9/DIO-EGFP in the Amigo2-Cre dCA2. A image of whole brain coronal section with the co-injection of AAV9/hSyn-Cre & AAV9/EF1α-DIO-EGFP (green) in dCA2. B Confocal fluorescence images showing the expression of EGFP induced by hSyn-Cre in hippocampus. There were 4 forms: 1. it leaked in the sixth layer of cortex; 2. although there was fluorescence at the CA2 position, there was no representative soma of pyramidal cell; 3. there were also projections of contralateral CA3; 4. infection of hSyn-EGFP in CA1 showed the hSyn-Cre could not specifically and accurately label CA2. C Magnified image showing hSyn-EGFP infection in DG. D Image of whole brain coronal section with the infection of CMV-EGFP in dCA2. E–G Serial sections of WT dCA2 injected with AAV9/CMV-EGFP (n = 5 mice) showing CMV-EGFP was also expressed in CA1 and CA3 in addition to CA2. G Upper right corner showing CMV-EGFP expressed in the sixth cortex. H Whole brain fluorescence images of Amigo2-Cre transgenic mice injected with AAV9/EF1α-DIO-EGFP (n = 8 mice). I–K Serial sections of Amigo2-cre dCA2 expressing EGFP (green) and RGS14 (red). Amigo2-EGFP nonspecific leakage on (H) left corner of image and (I) right corner, however the Amigo2-cre transgenic mice had the accuracy and specificity of CA2 pyramidal neurons. L Coronal section fluorescence image of WT mice stereotaxically injected with CMV-EGFP (green). M Coronal section fluorescence image of WT mice stereotaxically injected with AAV9/M1-Cre & AAV9/hSyn-DIO-mcherry (red) (n = 6 mice). Scale bars: 100 μm (C), 200 μm (B, E–G, I-K), 1 mm (A, D, H), 500 μm (L, M)