Phosphates as Crystal Poisons of Calcification

Abstract

Summary1. A theory has been proposed by Neuman that some metabolites which contain phosphate groups can act in the body as crystal poisons and so influence the deposition of calcium salts in skeletal structures. This theory is explained and the evidence for it reviewed.2. A crystal poison is a compound which settles on the surface of a crystal and interferes with the continued formation of the crystal lattice. Thus crystal growth stops and the mother liquor may become supersaturated.3. The evidence in favour of the theory is considered, both for phosphatic skeletons such as bone and calcareous skeletons such as those found in many invertebrates.4. Many of the phosphate groups in metabolites can produce the inhibitory effect and it has been suggested that a phosphatase enzyme acts in destroying these crystal poisons by hydrolysing them at the site of mineralization.5. Pyrophosphates are effective crystal poisons at very great dilutions, and yet they have been shown to be present in ossifying bones and in the plasma and urine of mammals.6. Alkaline phosphatase is present during the formation of calcareous skeletons, but the explanation of the removal of a crystal poison by hydrolysis is complicated by the fact that orthophosphates also inhibit calcification.7. These data are discussed in relation to the physiology of calcification in animals with phosphatic and with calcareous skeletons and some of the implications of the theory are evaluated.

Nutritional status and metabolism of the coral Stylophora subseriata along a eutrophication gradient in Spermonde Archipelago (Indonesia)

“…At the same time, elevated inorganic nutrient input and sedimentation in near-shore reefs hamper G L , explaining the overall low increase in G L with respect to P g . Reasons for decreased G L under high nutrient levels are found in a decoupling of symbiont and host (Dubinsky et al 1990;Ferrier-Pagès et al 2000;Allemand et al 2004) or a direct inhibition of carbonate crystallization by inorganic nutrients (Simkiss 1964;Gattuso et al 1999). A support of G (light and dark) by either R or elevated nutritional status of the coral host (Houlbrèque et al 2003;Houlbrèque and Ferrier-Pagès 2008) was not evident in this study, except possibly at KAY, where highest R, tissue protein and biomass occurred together with highest G.…”

Cell Biology of Cnidarian-Dinoflagellate Symbiosis

“…However, none of these observations confirm a direct link between the presence of symbionts and the enhancement of calcification, and all attempts to mimic the effects of symbionts on the LEC have failed (but see reference 57). It has also been hypothesized that symbiotic dinoflagellates may absorb inhibitors of calcification, such as phosphates (329), but this hypothesis has not been confirmed.…”

Calcium Composition and Microstructure of Coral <i>Stylophora pistillata</i> under Phosphate Pollution Stress in the Gulf of Aqaba

“…Phosphate enrichment in seawater is known as inhibitor of calcification in corals and coralline algae as well [36] [37]. Phosphate is reported to causes a 36% inhibition of calcification in Stylophora pistillata at relatively low phosphate concentrations in seawater, and stops it completely (99%) at high concentrations [38].…”