The cerebellar Purkinje cell monolayer is organized into heterogeneous Purkinje cell compartments that have different molecular compositions. Here we describe a transgenic mouse line, 1NM13, that shows heterogeneous transgene expression in parasagittal Purkinje cell arrays. The transgene consists of a nuclear localization signal (nls) fused to the b-galactosidase (lacZ) composite gene driven by the type 1 inositol 1,4,5-trisphosphate receptor (IP 3R1) gene promoter. IP3R1-nls-lacZ transgene expression was detected at a single Purkinje cell level over the surface of a whole-mount X-gal-stained cerebellum because of nuclear accumulation of the nls-lacZ activity. Developing cerebella of 1NM13 mice showed stripe-like X-gal staining patterns of parasagittal Purkinje cell subsets. The X-gal stripe pattern was likely determined by an intrinsic property as early as E15 and showed increasing complexity with cerebellar development. The X-gal stripe pattern was reminiscent of, but not identical to, the stripe pattern of zebrin II immunoreactivity. We designated the symmetrical X-gal-positive (transgene-positive, Tg+) Purkinje cell stripes about the midline as vermal Tg1+, Tg2(a, b)+ and Tg3(a, b)+ stripes and hemispheric Tg4(a, b)+, Tg5(a, b)+, Tg6(a, b, c) +, and Tg7(a, b)+ stripes, where a, b, and c indicate substripes. We also assigned three parafloccular substripes Tg8(a, b, c) +. The boundaries of X-gal stripes at P5 were consistent with raphes in the Purkinje cell layer through which granule cells migrate, suggesting a possible association of the X-gal stripes with raphe formation. Our results indicate that 1NM13 is a good mouse model with a reproducible and clear marker for the compartmentalization of Purkinje cell arrays.
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