LACTATE AND SUCCINATE OXIDOREDUCTASES IN MARINE INVERTEBRATES

Nineteen species of littoral marine invertebrates, representing Porifera, Cnidaria, Ctenophora, Brachiopoda, Mollusca, and Arthropoda, were studied with respect to the ability of tissue extracts to catalyze the lactate and succinate dehydrogenase reactions in both directions. Pyruvate reductase (PR) activity varied tremendously with species, from 0.014 μmole/min/g of tissue in the etenophore Mnemiopsis leidyi to 145 μ-moles/min in leg muscle of the horseshoe crab Limulus polyphemus, a 10,000-fold range. Lactate dehydrogenase (LD) activity varied from 0.010 in the ctenophore to 2.91 in the squid Loligo pealei, a 300-fold range. The ratio PR/LD, indicating the probability of lactic acid production, was 1,968 in muscle of the flounder, the only vertebrate studied. It was very much lower in all invertebrates; in a brachiopod, Terebratulina septentrionalis, the ratio was only 0.68. Fumarate reductase (FR) and succinate dehydrogenase (SD) activities varied less widely. The extremes of the ratio FR/SD, indicating the probability of succinic acid production, were 0.24 in the clam Mercenaria mercenaria, and 7.6 in the oyster Crassostrea virginica. PR/LD appears related to the capacity for vigorous muscular activity, sustaining rapid movement of larger animals, and FR/SD appears related to tolerance of temporary anaerobiosis, such as found in sessile animals that close their valves tightly on exposure to air during low tide. © 1969 Springer-Verlag.