Ontogeny of LDH-isozymes in Mexican Axolotl, Ambystoma mexicanum by thin-layer isoelectric focusing.

The ontogeny of lactate dehydrogenase (LDH) isozymes in developing Mexican axolotl, Ambystoma mexicanum was investigated by thin-layer isoelectric focusing in polyacrylamide gel. The isoelectric points (pI values) of the isozymes were determined. The minor components generally remained masked during conventional electrophoresis, but became sharp as isofocusing progressed. We identified in developing eggs and embryos five major LDH isozymes, which could also be traced in the ovarian eggs. All these isozymes, except LDH-1, consisted of one major and one minor component. Heterogeneity in axolotl LDH is reported for the first time. The separated isozymes had pI values from 5.24-6.60. Contrary to observations made by others, it was found that the anodal forms of LDH (PIs 5.24-5.80) were prominent throughout, while the remainder (pIs 6.16-6.60) gradually lost their stainability. It thus appears that isoelectric focusing is a possible method for the analysis of protein mixtures and can be successfully applied to problems of differentiation.