A zebrafish SKIV2L2-enhancer trap line provides a useful tool for the study of peripheral sensory circuit development

The zebrafish is an ideal model for elucidating the cellular and molecular mechanisms that underlie development of the peripheral nervous system. A transgenic line that selectively labels all the sensory circuits would be a valuable tool for such investigations. In this study, we describe such a line: the enhancer trap zebrafish line Tg(SKIV2L2:gfp) ^j1775 which expresses green fluorescent protein (gfp) in the peripheral sensory ganglia. We show that this transgene marks all peripheral ganglia and sensory nerves, beginning at the time when the neurons are first extending their processes, but does not label the efferent nerves. The trapped reporter is inserted just upstream of a previously poorly described gene: lhfpl4 on LG6. The expression pattern of this gene by in situ hybridization reveals a different, but overlapping, pattern of expression compared to that of the transgene. This pattern also does not mimic that of the gene (skiv2l2), which provided the promoter element in the construct. These findings indicate that reporter expression is not dictated by an endogenous enhancer element, but instead arises through an unknown mechanism. Regardless, this reporter line should prove to be a valuable tool in the investigation of peripheral nervous system formation in the zebrafish.