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		The effects of lithium chloride induction in Medaka embryos A previous experiment conducted by Peter Burgess of Franklin & Marshall college explored the effects of lithium exposure in Medaka embryos to determine whether or not Medaka experienced teratogen-induced deficiencies in anterior-posterior development like zebrafish. In his experiment Medaka embryos were exposed to 0.15M, 0.30 M, 0.75 M of LiCl, which resulted in normal developmental patterning. The formation of a functional circulatory system, a ventrally-developing structure, was seen in all embryos. This suggests that Medaka does not experience the disturtion of dorsal-ventral specification characteristic of LiCl-treated zebrafish embryos (Stachel et. al, 1993). Burgess suggests several explanations for the differences in Zebrafish and Medaka development, including the possibility that Medaka may have different dorsal-ventral patterning than zebrafish, or perhaps a different signaling pathway. Secondly, the Medaka chorion may be less permeable than that of zebrafish. Although Burgess used a longer incubation time of 30 minutes in exposing Medaka to LiCl as opposed to 10 minutes used in the zebrafish experiment, this time period may nor have been long enough to allow the uptake of lithium chloride (Stachel et. al., 1993). This evidence suggests that the effects of lithium-induced teratogenesis vary not only among different concentrations of LiCl, but that the time of exposure may also affect the ability of the teratogen to affect development. Additionally, different species of fish experience distinct developmental effects when exposed to lithium. Where zebrafish experience vast deficits in the proper formation of anterior structures, Medakas are not noticeably affected by LiCl treatment.
		Fig. 1 Footage of a lithium-exposed medaka embryo from the Peter Burgess experiment.   J. N. White 5/13/04