Regulation of lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH) synthesis in liver nuclei, following their transfer into oocytes.

The regulatory effect of oocyte cytoplasm on the synthetic activity of transferred somatic cell nuclei was studied using an interspecific hybrid combination of Ambystoma texanum and Ambystoma mexicanum (axolotl). The enzymes lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH) were used as markers of gene activity. In both species of salamanders, LDH is synthesized in the liver and oocytes, while ADH is tissue-specific being synthesized in the liver but not oocytes. Both LDH and ADH show species-specific patterns on starch gels which permit detection of enzymes synthesized by texanum liver nuclei following their transfer into axolotl oocytes. Analysis of recipient oocytes after 1-3 weeks in culture reveals the presence of newly synthesized texanum LDH but not ADH. These results indicate that the transferred texanum liver cell nuclei continue to synthesize a product (LDH) found in both liver cells and oocytes, but fail to synthesize the liver-specific product (ADH) which is normally absent in oocytes. Thus, in the case of ADH and LDH the oocyte cytoplasm appears to be able to regulate the synthetic activity of the transferred somatic cell nuclei so as to conform to the oocytes' normal synthetic output.