Phosphoglucose isomerase gene duplication in the bony fishes: An evolutionary history

Abstract

Electrophoretic patterns of phosphoglucose isomerase (PGI) in bony fishes provide strong evidence for a model of genetic control by two independent structural gene loci, most likely resulting from a gene duplication. This model is confirmed by a comparison of certain kinetic and molecular properties of the PGI homodimers (PGI-1 and PGI-2) isolated from extracts of the teleost A s t y a n a x mexicanus. In addition, in most higher teleosts examined, the PGI enzymes show a regular pattern of tissue distribution, with PGI-2 predominant in muscle, the heterodimer often strongest in the heart, and PGI-1 predominant in liver and other organs. An examination of 53 species of bony fishes belonging to 38 families indicates a widespread occurrence of duplicate PGI loci and an early origin of the gene duplication, perhaps in the Leptolepiformes. The apparent presence of three PGI loci in trout and goldfish exemplifies how new loci can be incorporated into the genome through polyploidization.

BIOCHEMICAL GENETICS OF SUNFISH. I. GEOGRAPHIC VARIATION AND SUBSPECIFIC INTERGRADATION IN THE BLUEGILL,LEPOMIS MACROCHIRUS

“…Notwithstanding a general flexibility in buffer requirements for some enzymes, we have found certain buffers particularly useful in a wide variety of fishes (see Avise and Selander, 1972;Avise and Kitto, 1973). Thus, we list the proteins examined in the bluegill with a generally appropriate buffer as follows: (1) esterases and general proteins-lithium hydroxide; (2) malate dehydrogenases, lactate dehydrogenases, glutamate oxalate transaminases, and isocitrate dehydrogenasescontinuous tris-citrate II; (3) phosphoglucose isomerases, phosphoglucomutases, lactate dehydrogenases, and indophenol oxidases-discontinuous tris-citrate (Poulik) (indophenol oxidase appears on gel slices stained for phosphoglucomutase when exposed to light); (4) isocitrate dehydrogenases and 6-phosphogluconate dehydrogenases-tris-malate.…”

EVOLUTIONARY GENETICS OF DIPLOID—TETRAPLOID SPECIES OF TREEFROGS OF THE GENUS HYLA

“…And it is this factor that holds greater interest in relation to the evolutionary significance of genic variation in natural populations. The pattern of occurrence of unique alleles over loci in H. versicolor is as follows: Six of the nine alleles occur at loci that are polymorphic in both eastern and' western populations of H. chrysoscelis It has been suggested that, following gene duplication, one locus of the pair is free to accumulate new mutations and regulatory modifications because the other member maintains its original function and thus reduces the selective constraints normally imposed on a single gene-enzyme locus (Ohno, 1970;Avise and Kitto, 1973;Markert et al, 1975). This hypothesis predicts that, in the early stages of this process, duplicated loci will be more variable than unduplicated ones because new and initially deleterious mutations are shielded from the effects of selection.…”

Evidence for the duplication of PGI genes in Dipcadi serotinum L. (Liliaceae)

“…Examples of such gene duplications have been documented in animals and plants (Ingran, 1961;Markert et a!., 1975;Avise and Kitto, 1973; Gottlieb, 1977;Pichersky and Gottlieb, 1983;Ellstrand eta!., 1983;Warwick and Gottlieb, 1985). The two loci coding for the cytosolic isozymes of PGI in D. serotinum have diverged structurally and must differ significantly in their sequences, because none of the electrophoretic variants at either locus overlap the mobility of any variant at the other.…”