Calcification in the Green AlgaHalimeda

Publisher Website
Google Scholar
Abstract
The effects of a number of metabolic inhibitors on calcification and photosynthesis in Halimeda tuna, H. discoidea, and H. macroloba are described. The inhibitors used are CCCP, DNP, DCMU, azide, cyanide, chloramphenicol, cycloheximide, and Diamox. The effects of these inhibitors, although complex, are consistent with our model of calcification in Halimeda. Inhibition of photosynthetic CO2 uptake inhibits calcification as does stimulation of respiratory CO2 evolution (i.e. uncoupling). There is also indirect evidence for the presence of a possible light stimulated H+ efflux which inhibits calcification. The observed calcification rate is therefore the result of a number of factors which affect the concentration of CO⅔−and the pH in the intercellular space of the Halimeda thallus. The results obtained with the carbonic anhydrase inhibitor Diamox provide further evidence for the effective separation of the intercellular space from the external medium by the appressed peripheral utricles.