Abstract
We have monitored the incorporation of 3H-glycine into, and the excretion of, soluble tissue and extrapallial fluid proteins in the hardshell clam Mercenaria mercenaria in an attempt to follow some of the metabolic events that occur antecedent to shell deposition. After incubating at 20°C for 48 h, clams were killed and the distribution of incorporated and unincorporated tritium in seawater, mantle fluid, hemocoelic-tissue fluid, extrapallial fluid and tissue was determined. Most of the incorporated tritium was in the insoluble tissue proteins. Much more incorporated tritium was found in the hemocoelic-tissue fluid fraction than in the extrapallial fluid. We assume that most of the radioactivity we followed was due to free or incorporated radioactive glycine. The ratio of 3H-protein to 3H-glycine was greater in the extrapallial fluid than in the hemocoelic-tissue fluid, suggesting either protein secretion into or glycine removal from the extrapallium. We also observed that both 3H-protein and 3H-glycine concentrations were higher in the mantle fluid than in the external sea water, although the ratios of 3H-glycine to 3H-protein in these two fluids were not different.
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Communicated by J.S. Pearse, Santa Cruz
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Young, S.D., Crenshaw, M.A. & King, D.B. Mantle protein excretion and calcification in the hardshell clam Mercenaria mercenaria. I. Protein excretion in the intact clam. Mar. Biol. 41, 253–257 (1977). https://doi.org/10.1007/BF00394911
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DOI: https://doi.org/10.1007/BF00394911