title: Metal ion-responsive transgenic Xenopus laevis as an environmental monitoring animal.
abstract: We generated germ line-transgenic Xenopus laevis that monitors environmental heavy metal ions. Sperm nuclei were transduced with cDNA of enhanced green fluorescent protein (EGFP) driven by murine metallothionein-1 gene promoters and were microinjected into unfertilized eggs. The eggs developed to sexually matured adults. The transgenic tadpoles at the premetamorphic stage were reared in water containing Zn(2+) and Cd(2+) separately at the concentrations of 0.38-1.52 and 0.09-0.44 μM, respectively. These animals responded to Zn(2+) at as low as 0.38 μM and Cd(2+) at as low as 0.44 μM. The level of EGFP fluorescence emitted by tadpoles increased as the concentration increased up to 1.52 μM and the exposure time prolonged up to 120 h. The fluorescent response was much more sensitive to Cd(2+) than to Zn(2+). We concluded that these transgenic tadpoles are useful as an animal indicator of environmental heavy metal ions.
authors.affiliation: Tissue Regeneration Project, Hiroshima Prefecture Collaboration of Regional Entities for the Advancement of Technological Excellence, Japan Science and Technology Corporation, Hiroshima Prefecture Institute of Industrial Science and Technology, Higashihiroshima, Hiroshima 739-0046, Japan; Laboratory of Developmental Biology, Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526, Japan; ProPhoenix Company Ltd., Higashihiroshima, Hiroshima 739-0046, Japan; Towa-Kagaku Corporation Ltd., Hiroshima, Hiroshima 730-0841, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Oofusa
authors.forename: Osamu
authors.initials: O
authors.lastname: Tooi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kashiwagi
authors.forename: Keiko
authors.initials: K
authors.lastname: Kashiwagi
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kondo
authors.forename: Masanobu
authors.initials: M
authors.lastname: Obara
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Yoshizato