Differential expression of PKCα and -β in the zebrafish retina
The retina is a complex neural circuit in which visual information is transmitted and processed from light perceiving photoreceptors to projecting retinal ganglion cells. Much of the computational power of the retina rests on signal integrating interneurons, such as bipolar cells in the outer retina. While mammals possess about 10 different bipolar cell types, zebrafish (Danio rerio) has at least six ON-type, seven OFF-type, and four mixed-input bipolar cells. Commercially available antibodies against bovine and human conventional protein kinase C (PKC) and -{beta} are frequently used as markers for retinal ON-bipolar cells in different species, despite the fact that it is not known which bipolar cell subtype(s) they actually label.\n\nMoreover, the expression pattern of the five prkc genes (coding for PKC proteins) has not been systematically determined. While prkcg is not expressed in retinal tissue, the other four prkc (prkcaa, prkcab, prkcba, prkcbb) transcripts were found in different parts of the inner nuclear layer and some as well in the retinal ganglion cell layer.\n\nImmunohistochemical analysis in adult zebrafish retina using PKC and PKC{beta} antibodies showed an overlapping immunolabeling of ON-bipolar cells that are most likely of the BON s6L or RRod type and of the BON s6 type. However, comparison of transcript expression with immunolabling, implies that these antibodies are not specific for one single zebrafish conventional PKC, but rather detect a combination of PKC - and -{beta} variants.