Purchase this article with an account.
F. P. Gaillard, S. Kuny, Y. Sauve; Disabled-1 (dab1) Immunoreactivity in the Retina of the Diurnal Rodent, Arvicanthis Niloticus. Invest. Ophthalmol. Vis. Sci. 2010;51(13):1850.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Dab1 is a cytoplasmic adaptor protein that mediates reelin signaling during development of layered brain structures in mammals. In the retina, Dab1 is mainly expressed by AII amacrine cells. We relied on this feature to examine whether the cone-rich retina of the Nile rat contains previously undetected AII amacrines.
Dab1 expression was determined using Western blots, serial frozen sections (20 µm thick; 3 separate animals) and whole mounted preparations (n = 5). Immunoreactions were performed with an affinity-purified antibody (Dab1-B3; B. Howell, Upstate, NY), alone or in combination with antibodies specific to inner retina neurons. Results were examined by confocal microscopy and quantified with ImageJ.
Western blotting of protein extracts from fresh retinas clearly showed Dab1 expression in Nile rat retinas (a major doublet at ≈ 80 kDa and minor products at 47 and 36 kDa as in control mouse). In cryosections, immunoreactivity was observed in horizontal cells as well as in neurons located at the INL/IPL border. In both cell types, Dab1 staining was present in the soma cytoplasm and the dendrites. Dab1-positive neurons in the INL did not stain for parvalbumin, calbindin, PKC (a marker for rare A12 amacrines), ChAT, GAD67 and TH. Conversely, they expressed calretinin and the glycine transporter GlyT1 indicating they are glycinergic. These cells have small ovoid cell bodies (dia. = 7.1±1.05 µm; n = 58), a main dendrite spanning through the IPL, and bistratified terminal plexii in sublaminas 1 and 5. Preliminary quantitation yielded a mean density > 2200 cells/sq.mm and a rather regular distribution across the retinal surface (nearest neighbour distances ≈ 15 µm; Voronoi domains ≈ 411.4 sq.µm; and regularity indexes ≈ 4.33). Similar values were reported for Dab1-positive AII amacrines in cat, guinea pig, human, rabbit and rat regardless of the retinal sector.
Dab1 is expressed in two cell populations in the adult Nile rat retina: the horizontal cells and a subpopulation of amacrine cells that are likely of the AII type. To date, such dual cell patterning has only been found in humans.
This PDF is available to Subscribers Only