An EGFP-positive Purkinje cell whose soma was located at a distance more than one soma away from the Purkinje cell layer, defined by the rest of the EGFP-negative Purkinje cells, was counted as ‘mislocalized’. Statistical significance was defined by the χ2 test. For the statistical analysis of electrophysiological results, the Mann–Whitney U-test NVP-BKM120 datasheet was applied. Previous studies demonstrated that mouse Purkinje cells arise from the ventricular zone facing the fourth ventricle around E10–E13 (Miale & Sidman, 1961; Wang & Zoghbi, 2001; Hashimoto & Mikoshiba, 2003). Thus, to develop an IUE method for Purkinje cells, a plasmid

encoding EGFP under the control of the CAG promoter (CAG-EGFP) was injected selleck kinase inhibitor into the fourth ventricle of E10.5, E11.5 or E12.5 mice. To transfect Purkinje cell precursors, the electrodes were placed diagonally across the fourth ventricle with the anode above the cerebellar primordium at an angle of 90° or more to the targeted side of the upper rhombic lip (Fig. 1A

and Supporting Information, Fig. S1), and 33-V electrical pulses were applied five times (Fig. 1A). We observed bright EGFP signals through the skin and the skull in newborn mice that had undergone IUE at E10.5, E11.5 or E12.5. The EGFP signals were observed on the electroporated side of the cerebellum (Fig. 1B, left and middle panels), but when a series of pulses was sequentially applied in two diagonal directions, both sides of the cerebellum were transfected (Fig. 1B, right panel). More EGFP-positive cells were observed in mice that underwent IUE at E11.5 than at isothipendyl E10.5 or E12.5 (Fig. 1B). EGFP was expressed in almost the entire half of the cerebellum that underwent

IUE at E11.5 (Fig. 1B). In contrast, EGFP expression was not observed in the middle of the vermis and the edge of the hemisphere of the cerebellum that underwent IUE at E10.5; EGFP signals were restricted in the middle of the vermis and the edge of the hemisphere when IUE was performed at E12.5 (Fig. 1B). Similarly, adenovirus vectors injected into the fourth ventricle at E10.5, E11.5 and E12.5 infect only the subpopulation of Purkinje cell progenitors that were born on the day of each injection (Hashimoto & Mikoshiba, 2003). Thus, it is likely that only cells that were located at the surface of the fourth ventricle at the time of IUE were transfected. To determine the cellular specificity of transfection, we fixed the cerebella at P14 and later and immunostained them for calbindin, a Purkinje cell marker. Again, more EGFP-positive cells were observed in the cerebellar sections taken from mice that underwent IUE at E11.5 than at E10.5 or E12.5 (Fig. 1C). The vast majority of EGFP-positive cells were immunopositive for calbindin in the cerebellum (Fig. 1C).