Linkage conservation of homologous esterase loci in fish (Cyprinodontoidei: Poeciliidae).

Homologies among esterase isozymes in fish in the poeciliid genera Poeciliopsis and Xiphophorus are proposed. Esterase homologies are based on their tissue distributions and inhibition and substrate properties. The five esterases include two carboxylesterases, one eserine sulfate-sensitive esterase, and two esterases resistant to inhibition, one of which reacts only with acetate esters. Linkage studies in Poeciliopsis monacha indicate that the loci encoding the two carboxylesterases are linked to each other and to the locus for eye-specific lactate dehydrogenase. Comparisons of the linking reported here with earlier studies in Xiphophorus suggest that there is a large region of linkage homology in the genetic maps of Poeciliopsis and Xiphophorus.