Allelic isozyme variants in the mexican axolotl (Ambystoma mexicanum) as potential markers for developmental experiments

Abstract

AbstractFour isozyme systems were surveyed in our laboratory‐bred colony of axolotls (Ambystoma mexicanum) to determine whether there were elecrophoretic variants that could be used as markers in developmental experiments. For malate dehydrogenase (MDH), lactate dehydrogenase (LDH), and phosphoglucomutase (PGM), the best separations were obtained by isoelectric focussing on polyacrylamide slab gels, whereas for soluble esterases (Est), conventional polyacrylamide gel electrophoresis was used. The patterns for both MDH and LDH were consistent with two‐locus models, but no variation was obtained. The results for PGM support a single‐locus model with two alleles that are expressed codominantly in heterozygotes. There is also evidence for a third, null allele. The pgm gene maps approximately 24 map units from its centromere. The majority of the animals tested produced four esterase bands. We propose that each is controlled by a separate locus. One of the bands, Est‐3, is absent in some animals. The results of various crosses support the proposition that these animals are homozygous for a null allele. The est‐3 gene is distant from its centromere.