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Nova and GlyRα2 mRNAs, its nuclear alternative splicing RNA target, colocalize outside the nucleus within dendrites. Fluorescence labeling for Nova immunoreactivity (in green; A,B,C) and ISH signal (in red) for GlyRα1 (A1) or GlyRα2 mRNAs (B1,C1). (A) Within the somatic and dendritic cytoplasm of ventral horn neurons, GlyRα1/2 (A1,B1) mRNAs and Nova (A,B) labeling co-localizes (in yellow; A1,B1). The labeling pattern of Nova mirrors that of GlyRα1/2 mRNAs. Both are also unevenly distributed within the dendritic cytoplasm and sometimes accumulate at the dendritic periphery (A,B; arrowheads) and branch points (B; arrows). Note that the signal corresponding to Nova protein or GlyRα1/2 mRNAs are separated in some areas. (C) in neurons of the dorsal horn, where GlyRα2 mRNA (C1) is restricted to the somatic cytoplasm, Nova immunoreactivity is detected in nuclei (N) and to a lesser extent in somatic cytoplasm (C) resulting in a less accentuated co-localization (C2). (D–G) Ultrastructural simultaneous detection of Nova immunoreactivity and GlyRα2 mRNAs. Nova (HRP immunolabeling) and GlyRα2 mRNA ISH signal (gold particles) colocalize within the dendritic cytoplasm (arrows) and in front of synaptic boutons (arrowheads, b). Note in (E,G) the association of Nova and mRNA signals with small cisternae. Scale bar: 15μm (A–C); 0.2μm (D–F); 0.35μm (G).