The Tol2 transposable element of the medaka fish: an active DNA-based element naturally occurring in a vertebrate genome

Several DNA-based transposable elements are known to be present in vertebra te genomes, but few of them have been demonstrated to be active. The Tol2 e lement of the medaka fish is one such element and, therefore, is potentiall y useful for developing a gene tagging system and other molecular biologica l tools applicable to vertebrates. Towards this goal, analyses of the eleme nt at the molecular, cellular and population levels are in progress. Result s so far obtained are described here.