TISSUE-SPECIFIC GENE-EXPRESSION IN THE SMALLMOUTH SALAMANDER, AMBYSTOMA-TEXANUM (CAUDATA, AMBYSTOMATIDAE)

Relative staining activity, heteropolymer assembly, and secondary isoz ymes are described for gene products of 22 loci examined for expressio n in eight tissues of Ambystoma texanum. Locus homologies based on tis sue specificity and staining patterns in mitochondria-enriched liver f ractions are proposed. Quaternary structure was inferred from polymorp hisms resolved at seven loci. Gene expression was undetectable in 17 o f the 176 tissue/locus comparisons. The phylogenetic pattern of change s in gene number and the extensive variation in tissue-specific expres sion among tetrapods suggest that these attributes will be useful as p hylogenetic characters in groups less inclusive than tetrapods.