Developmental Effects of Lithium and Zinc in Planaria

Abstract

An investigation was carried out of the stage-specific effects of lithium and zinc on planaria embryologic development. These two reagents had dramatically different effects on the morphological development of planaria: Zinc induced the formation of bifurcations or trifurcations of the head region. In contrast, lithium induced the formation of round masses of cells. The earliest embryological stages (S1 and S2, cryptic larva formation) exhibited extreme sensitivity to lithium, since the lethal dose was at least one order of magnitude lower than for subsequent stages 3-5, suggesting that beta-catenin 1 expression is tightly regulated during the initial embryologic stages and that even slightly increased activity is lethal.