Search for tissue-specific regulatory elements using Tol2 transposon as an example of evolutionary synthesis of genomics and developmental biology

The GFP gene controlled by a mini-promoter of the keratin-8 gene was cloned into a modified nonautonomous transposon Tol2 from the medaka genome. Such transposon cannot itself transpose, but external transposase allows it to integrate into the germ cell genome, where it remains after transposase is depleted. This gives rise to a transgenic zebrafish line stably maintained for many generations. This approach was used to obtain several tens of transgenic zebrafish lines, each of which demonstrates stably inherited pattern of GFP expression. This pattern depends on the enhancer activity in the vicinity of the transposon integration site. These lines can be used for the analysis of DNA sequences of enhancers, in vivo studies of complex cell morphogenesis, description of organs whose development has not been described in zebrafish, and analysis of activity of genes controlled by the identified promoters during development. Current data on the transgenic lines were integrated into the dedicated ZETRAP database. At the second stage of this project, the transposon was mobilized by a short-term exposure of two transgenic lines to transposase and left the initial chromosomal location. This allowed us to isolate about 20 transgenic lines with new expression patterns. This approach can be successfully used to study the zebrafish biology and anatomy, activity of the regulatory part of the genome, and development of new promising techniques in developmental biology and, in the foreseeable future, gene therapy.