TISSUE-SPECIFICITY AND ONTOGENY OF LACTATE-DEHYDROGENASE IN SNOW CRAB, CHIONOECETES-OPILIO (BRACHYURA, MAJIDAE)

In the snow crab, Chionoecetes opilio (Brachyura: Majidae), LDH is present in five isozymic forms, as revealed by the five coloration zones in zymograms. This is characteristic of a tetrameric LDH enzyme formed by the random association between two distinct sub-units. Isozymes of C. opilio LDH show tissue specificity. No LDH activity is detected in the hepatopancreas. The LDH-B* locus is expressed in all other tissues examined, except the eye, in which LDH-A* is the only locus detected. Both loci are expressed in nervous, midgut and leg muscle tissues, the last showing individual variability. At least among males, the LDH-B* locus is expressed in leg muscle tissue at every developmental stage, while LDH-A* locus expression is initiated only in the VIIth post-larval stage, just before the onset of gametogenesis. Results suggest that LDH sub-units in C. opilio have distinct physiological roles. This is very well known in vertebrates, but is virtually undocumented in invertebrates.