Direct demonstration of spatial water distribution in the sponge Suberitesdomuncula by in vivo NMR imaging

Until now, direct, non-invasive in vivo studies on water and metabolite dis tribution in Living sponges have not been possible. Here we apply for the f irst time the noninvasive technique of nuclear magnetic resonance (NMR] ima ging to determine the spatial distribution of water in the marine sponge Su berites domuncula. After transfer of the sponge into deuterated water (D2O) for a short incubation period of 18 min, no significant water exchange was observed, neither in S. domuncula nor in the hermit crab living in symbios is with it, suggesting D2O to be an ideal contrast enhancing agent for NMR imaging of sponges. Thus, NMR imaging provides a promising technique for th e detection land possibly quantification) of the distribution and transport of water both by diffusion and active transport in a living sponge.