Coexpression of distinct eye‐ and liver‐specific LDH isozymes in cichlid fish

Abstract

In a recent electrophoretic survey of lactate dehydrogenase (LDH) in neotropical cichlid fishes (Perciformes, Cichlidae) we have discovered several species in which a cathodal liver-specific isozyme is expressed along with the highly-anodal eye-specific isozyme (LDH-C4) typically encountered in perciform fishes. We believe this fourth, liver-specific LDH isozyme to be real and not artifactual since homogenization of fresh liver from one of these species, the Basketmouth cichlid (Acaronia nassa), in either of two nondenaturing detergents or in the presence of the protease inhibitor phenylmethylsulfonylfluoride affects neither the presence nor mobility of this cathodal band. Moreover, it continues to be expressed in the captively bred F1 of these same wild fish. The discovery of several fish species, like the Basketmouth, in which biochemically distinct eye- and liver-specific LDH isozymes are coexpressed, is discussed in light of the currently accepted hypothesis that these two isozymes are encoded by a single locus (LDH-C) which has undergone divergent tissue expression in several other major teleost groups. Preliminary characterization of the liver-specific isozyme relative to the eye-specific LDH-C4 in the Basketmouth cichlid with respect to thermolability and NADH-induced binding to oxamate-sepharose columns suggests that the eye- and liver-specific LDH isozymes are biochemically quite distinct in this fish and that they are probably encoded by two distinct loci.

An immunochemical analysis of the novel liver‐restricted LDH activity from cichlid fishes (Cichlidae: Teleostei) confirms its non‐orthology with piscine LDH‐C

“…The immunochemical data presented here, along with previous biochemical characterization (Holt & Leibel, 1987;Leibel &Peairs, 1990) suggests that, at best, it is a highly anomalous LDH activity, only distantly related, if at all, to the family of isozymes that comprise lactate dehydrogenase (E.C. 1.1.1.27) sensu stricto.…”

“…What is clear from these data, however, is that the eye-and liver-restricted LDH isozymes of basketmouth and a variety of other cichlids (Holt & Leibel, 1987) are not alike antigenically and, thus, they most likely are encoded by distinct loci as has been previously suggested on the basis of biochemical characterization (Holt & Leibel, 1987;Leibel & Peairs, 1990). However it is equally clear that the liverrestricted isozyme of basketmouth is unlike the liver-specific LDH-C,s of the two representative Cypriniforms tested here.…”

“…Recently, several teleost species (Perciformes, Cichlidae) have been found to coexpress both a cathodal liver-restricted and an anodal eye-restricted LDH in the same organism, and evidence supporting the hypothesis that these must be the products of two distinct loci has been presented (Holt & Leibel, 1987;Leibel & Peairs, 1990). However, the relationship of these cichlid-specific isozymes to the eye-restricted and liver-restricted analogues in other teleosts remained untested.…”

Variation of Lactate Dehydrogenase Isozymes in Angelfish (Pterophyllum scalare) according to Acute Environmental Change

“…LDH C4 동위효소의 전기영동상은 눈 조직의 경우 강한 음하전을 띠어 양극 쪽에 서 eye-specific LDH C4 동위효소가 나타나고, 간 조직의 경우 강한 양하전을 나타내어 음극 쪽에서 liver-specific LDH C4 동위효소가 나타난다 [18,30,36,37,42]. 눈과 간 조직에서 LDH C4 동위효소가 동시에 나타나는 어류는 두 조직에서 모두 음 하전을 띠는 경우 [3,19], 두 조직에서 모두 양하전을 띠는 경우 [36,37] 및 두 조직에서 하전이 각기 다른 경우 [17,29] (Fig. 2).…”

Tissue-Specific Isoenzyme Variations in Tilapia Fish, <i>Oreochromis niloticus</i>

“…Several investigations have been concerned with the characterization of tissue-and organ-specific isoenzyme patterns [5][6][7][8][9][10][11][12] among which little were concerned with fishes. Few studies have concerned with the isoenzymatic profiles in the Nile tilapia [4,13].…”