enetic dissection of adult zebrafish brain by Tol2 transposon mediated Gal4-UAS system and gene trap and enhancer trap method

Pradeep Lal1,2,Koichi Kawakami2,3


The understanding of relationship between anatomy and function of adult zebrafish brain has been limited by the inability to visualize and manipulate different brain regions. To explore this, we have developed the Gal4-UAS system and gene trap and enhancer trap methods in zebrafish using the Tol2 transposon system. We isolated transgenic fish lines that expressed Gal4 transactivator in specific tissues. By crossing these Gal4 lines with the UAS-GFP line, it is possible to visualize the Gal4-expressing cells. To identify transgenic lines showing Gal4 expression in a subset of neurons in adult zebrafish brain, we observed 466 adult Gal4/GFP fish lines and selected 142 lines showing strong GFP fluorescence in the brain. These selected lines were further analyzed by sectioning into 100μ coronal slices of the brain. The observed GFP fluorescence patterns show unique patterns varying from ubiquitous brain to very restricted expression, such as only in medial/lateral telencephalon, habenula or sub-region in hypothalamus etc. For most of these regions, anatomical description or marker genes have not been reported. So, these lines are useful for describing new regions in the brain and discovering new marker genes. I will discuss how the expression patterns in embryos, those in the adult brain and the trapped genes are relevant. To deduce the role of these Gal4 labeled neurons in adult zebrafish behavior, these lines can be crossed with the UAS-tetanus toxin line, which will selectively block the activity of Gal4 labeled neurons and then, look for any resulting change in behavior.