Permeability of the oral epithelial layers in cnidarians

Bénazet-Tambutté, Sylvie; Allemand, Denis; Jaubert, Jean

doi:10.1007/bf00571376

Cited by 48 publications

(29 citation statements)

References 46 publications

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“…Small separated polyps were incubated for 2·h in jars containing 200·ml filtered SW (0.25·mm) that were partially submerged in shallow, flow-through aquaria in full sunlight (PPFD 800-1900·mmol·photons·s -1 ·m -1 ; 23-25°C). Polyps destined for secondary ion mass spectrometry (SIMS) analysis were incubated in vials containing 10·ml of artificial seawater (ASW) (Benazet-Tambutté et al, 1996) in which 44 CaHCO 3 replaced 40 CaHCO 3 . Incubation was carried out under the same conditions of light and temperature for 1·min or 8·min.…”

Section: Methodsmentioning

confidence: 99%

Electron and ion microprobe analysis of calcium distribution and transport in coral tissues

Marshall

Clode

Russell

et al. 2007

Journal of Experimental Biology

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Section: Methodsmentioning

confidence: 99%

Electron and ion microprobe analysis of calcium distribution and transport in coral tissues

Marshall

Clode

Russell

et al. 2007

Journal of Experimental Biology

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“…2). Since the mouth of the polyp opens the coelenteron to the seawater and given that the oral epithelial layers can be assumed to be permeable to ions via a paracellular pathway (Benazet-Tambutte et al, 1996), we define an advective flux that exchanges all state variables between the coelenteron and the seawater at a constant exchange rate. The seawater compartment is connected to an overlying atmosphere via the air-sea gas-exchange of CO 2 (Wanninkhof, 1992).…”

Section: Model Descriptionmentioning

confidence: 99%

Modelling coral polyp calcification in relation to ocean acidification

Hohn

Merico

2012

Biogeosciences

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Abstract. Rising atmospheric CO 2 concentrations due to anthropogenic emissions induce changes in the carbonate chemistry of the oceans and, ultimately, a drop in ocean pH. This acidification process can harm calcifying organisms like coccolithophores, molluscs, echinoderms, and corals. It is expected that ocean acidification in combination with other anthropogenic stressors will cause a severe decline in coral abundance by the end of this century, with associated disastrous effects on reef ecosystems. Despite the growing importance of the topic, little progress has been made with respect to modelling the impact of acidification on coral calcification. Here we present a model for a coral polyp that simulates the carbonate system in four different compartments: the seawater, the polyp tissue, the coelenteron, and the calcifying fluid. Precipitation of calcium carbonate takes place in the metabolically controlled calcifying fluid beneath the polyp tissue. The model is adjusted to a state of activity as observed by direct microsensor measurements in the calcifying fluid. We find that a transport mechanism for bicarbonate is required to supplement carbon into the calcifying fluid because CO 2 diffusion alone is not sufficient to sustain the observed calcification rates. Simulated CO 2 perturbation experiments reveal decreasing calcification rates under elevated pCO 2 despite the strong metabolic control of the calcifying fluid. Diffusion of CO 2 through the tissue into the calcifying fluid increases with increasing seawater pCO 2 , leading to decreased aragonite saturation in the calcifying fluid. Our modelling study provides important insights into the complexity of the calcification process at the organism level and helps to quantify the effect of ocean acidification on corals.

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“…The sea anemone, A. viridis, was also used since this anthozoan possesses long tentacles from which oral tissues are easy to obtain. Briefly, one piece of tentacle was cut longitudinally and placed between the two Ussing half-chambers as described previously by Bénazet-Tambutté et al [31]. Resistance was then calculated from the values of intensity and voltage (for details see electronic supplementary material, material and methods).…”

Section: (B) Calcein Experimentsmentioning

confidence: 99%

Calcein labelling and electrophysiology: insights on coral tissue permeability and calcification

et al. 2011

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The mechanisms behind the transfer of molecules from the surrounding sea water to the site of coral calcification are not well understood, but are critical for understanding how coral reefs are formed. We conducted experiments with the fluorescent dye calcein, which binds to calcium and is incorporated into growing calcium carbonate crystals, to determine the permeability properties of coral cells and tissues to this molecule, and to determine how it is incorporated into the coral skeleton. We also compared rates of calcein incorporation with rates of calcification measured by the alkalinity anomaly technique. Finally, by an electrophysiological approach, we investigated the electrical resistance of coral tissues in order to better understand the role of tissues in ionic permeability. Our results show that (i) calcein passes through coral tissues by a paracellular pathway, (ii) intercellular junctions control and restrict the diffusion of molecules, (iii) intercellular junctions should have pores of a size higher than 13 Å and lower than 20 nm, and (iv) the resistance of the tissues owing to paracellular junctions has a value of 477 + 21 Ohm cm 2 . We discuss the implication of our results for the transport of calcium involved in the calcification process.

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Permeability of the oral epithelial layers in cnidarians

Cited by 48 publications

References 46 publications

Electron and ion microprobe analysis of calcium distribution and transport in coral tissues

Electron and ion microprobe analysis of calcium distribution and transport in coral tissues

Modelling coral polyp calcification in relation to ocean acidification

Calcein labelling and electrophysiology: insights on coral tissue permeability and calcification

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