Matrilin-like molecules produced by circulating hemocytes of the zebra mussel (Dreissena polymorpha) upon stimulation

Since invading the Great Lakes basin, USA, in 1980s, the zebra mussel (Dreissena polymorpha) has caused significant economic and ecologic devastation. The absence of major diseases led to the belief that zebra mussel may have extraordinary host defense mechanisms. This study was undertaken in order to better understand zebra mussel hemocyte functions. A suppressive subtraction hybridization (SSH) cDNA library was constructed from naïve and stimulated hemocytes. Stimulation was performed using a mixture of lipopolysacchride (LPS), peptidoglycan (PGN), and zymosan (ZYM). In the stimulated hemocyte SHH cDNA library, 55 assembled ESTs were differentially expressed. These ESTs contained two putative immune- related molecules, namely, matrilin and agglutinin, three house-keeping genes, six cell metabolism/development genes, and 44 ESTs without putative functions. One of the putative adhesive molecules (CN-29, accession number: AM503947) was predicted to have homology with matrilins including the Von Willebrand Factor A (VWA) domain, which was identical to a matrilin molecule recently reported from the freshwater snail, Biomphalaria glabrata. Preliminary evidence suggests that the zebra mussel matrilin-like molecule is inducible upon hemocyte stimulation.