S. Benazettambutte et D. Allemand, WATER PERMEABILITY OF THE ORAL EPITHELIAL LAYERS OF THE SEA-ANEMONE, ANEMONIA-VIRIDIS, The Journal of experimental zoology, 279(1), 1997, pp. 1-8
Water permeability of the oral epithelial layers of the anthozoan Anem
onia viridis was studied. We determined a diffusional water permeabili
ty of 17 x 10(-5) cm s(-1) and an osmotic water permeability of 2.5 10
(-5) cm s(-1). These permeability coefficients were independent of the
state of contraction of the tentacle. Compared to other tissues, wate
r permeability in sea anemones is relatively low. This result is quite
surprising, since we determined in a previous study that the ionic pe
rmeabilities of the oral epithelial layers of A. viridis were characte
ristic of a leaky tissue (Benazet-Tambutte et al., '96a). The low wate
r permeability of the oral epithelial layers of A. viridis can be cons
idered as an adaptational mechanism for maintaining a hydrostatic skel
eton. The ratio P-o/P-d was about 14. The osmotic flow was symmetric w
hatever the direction of the gradient. Temperature did not affect diff
usional water flux. Tile Arrhenius energy of activation for osmotic fl
ux was about 5 kcal mol(-1). Osmotic water flow was insensitive to mer
cury. Our results suggest the possible existence of HgCl2-insensitive
water channels. (C) 1997 Wiley-Liss, Inc.