Brachiopod Metabolism and Enzymes

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Abstract
Brachiopods consume oxygen at relatively low rates, and sometimes consume none at all for hours. Specimens of Terebratulina septentrionalis survived total anoxia for 3.5 days at 3°C. Isolated tissues converted 14Cμglucose into eight carboxylic acids at an average rate of 1.5 × 10−10 mole/SOL;hr per g tissue. Carbon from labelled glucose flowed steadily into citric acid and into an unknown acid for 2 hours under both aerobic and anaerobic conditions. In the first hour, more label was found in malic acid after aerobic incubation, and more label in succinic acid after anaerobic incubation, while the fraction in lactic acid was the same. Terebratulina carried on a mixed fermentation both in the presence and in the absence of oxygen. The inarticulate Glottidia pyramidata has a succinate dehydrogenase with kinetic properties favoring succinate oxidation, while the Terebratulina enzyme is more likely to operate in the reverse direction. Lactate metabolism is relatively unimportant in both species. Information on nitrogen-compound metabolism is limited to the inarticulate Lingula reevii, which is ammonotelic. Arginase and urease activities exceeded those of bivalve mollusks, while aspartate and alanine aminotransferase rates were both much lower. Some unique features of DNA, RNA and hemerythrin from Lingula have been discovered in the last few years.
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