Fig. 1.

Verification of antibodies to CtBP2 and Shank1a. A and B: serial 14-µm cryosections were obtained from a postnatal day 71 (P71) mouse utricle, and maximum-intensity projections are shown. Hair cell (hc) and support cell (sc) nuclei are illuminated by the DAPI stain (blue). Numerous closely associated CtBP2-and Shank1a-positive puncta can be observed in the positive immunostained section represented in A (block arrowheads). The CtBP2-positive puncta highlighted by the flared arrowhead in A may represent an undocked synaptic ribbon. No primary antibodies were included in the processing represented in the micrograph in B. The scale bar in B represents 5 µm and also applies to A. C and D: maximum-intensity projection micrographs from right and left whole mount utricles from a P65 mouse. Importantly, fixative administration into the temporal bones yielding the specimens represented in C and D was delayed 7 min to replicate the conditions associated with specimens derived from the microgravity and control specimens. The positive-immunostained specimen of the pair is shown in C, where numerous closely associated CtBP2-positive and Shank1a-positive puncta can be observed. Though faint, CtBP2-immunostained nuclei are highlighted by the flared arrowheads. The micrograph in D illustrates the results of withholding primary antibodies from the processing. Immunolabeled puncta are not observed. The scale bar in D represents 5 µm and also applies to C.