Abstract
Methods: :
To detect Myo3A in mouse retina we raised an antibody against a region of the protein encoded by exon 30. Myo3B in the mouse retina was detected using an antibody against the tail domain of the protein. Myo3A and Myo3B were localized in adult retinas by immunocytochemistry (ICC) on paraformaldehyde-fixed frozen sections. Myo3B sections were boiled in sodium citrate for epitope unmasking. Other antibodies used were directed against melanopsin, rhodopsin, and tyrosine hydroxylase.
Results: :
Both Myo3A and Myo3B are present in the IS of photoreceptors; however their distribution differs. Myo3B is present throughout the IS whereas Myo3A is present only in the outer portion of the IS. Also, while Myo3B is present in the OS of blue cones, no Myo3A immunoreactivity was detected in OS. In the ACL Myo3B was present in a subpopulation of tyrosine hydroxylase (TH)-immunoreactive (ir) amacrine cells and some Myo3B-positive cells were not TH-ir. Similarly, in the GCL Myo3B was present in a subpopuplation of melanopsin-positive cells, and some Myo3B-ir cells were melanopsin-negative. Cells brightly labeled with the melanopsin antibody did not show Myo3B immunoreactivity.
Conclusions: :
Here we report for the first time the presence both Myo3A and Myo3B in the IS of photoreceptors. This supports the hypothesis that Myo3B compensates for Myo3A defects and thus preserves normal retinal function in individuals with progressive hearing loss. In the inner retina Myo3B immunoreactivity may define a new biochemical subclass of neurons and perhaps labels a particular type of melanopsin-ir cell.
Keywords: photoreceptors • ganglion cells • amacrine cells