Hydra and Niccolo Paganini (1782-1840) - two peas in a pod? The molecular basis of extracellular matrix structure in the invertebrate, Hydra

The body wall of Hydra is organized as an epithelial bilayer with an interv ening extracellular matrix (ECM). Molecular and biochemical analyses of Hyd ra ECM have established that it contains components similar to those seen i n more complicated vertebrates such as human. In terms of biophysical param eters, Hydra ECM is highly flexible; a property that facilitates continuous movements along the organism's longitudinal and radial axis. A more rigid ECM, as in vertebrates, would not be compatible with this degree of movemen t. The flexible nature of Hydra ECM can now be explained in part by the uni que structure of the organism's collagens. Interestingly, some aspects of t he structural features of Hydra collagens mimic what is seen in Ehlers-Danl os syndrome, an inherited condition in humans that results in an abnormally flexible ECM that can be debilitating in extreme cases. This review will f ocus on structure-function relationships of the ECM of Hydra. (C) 2001 John Wiley & Sons, Inc.