Biochemical investigations on the cells that localizes dysiherbaine in marine sponge Dysidea herbacea.

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We have investigated the cellular localization of the marine sponge-derived excitatory amino acid dysiherbaine (DH), and found that DH-like immunoreactivity was densely located in the large (10 μm) globular cells. On the basis of 18S rDNA sequence analysis it was shown that this cell belongs to the sponge itself, however, results from fluorescent microscopy and immunohistochemistry using anti-phycobilin antibody indicated that this cell contains phycobilin, a photosynthetic pigment of cyanobacteria. Although number of histological observations of D.herbacea are available in literature, cells with this morphological or biochemical characteristics have never been reported.A comparison of the extract of D.herbacea collected in various regions in Yap, Palau, or Guam indicated that DH is unique to the Yap specimen. Among the Yap specimens, however, concentration of DH varied significantly. Interestingly, all the Yap specimens we have examined so far contained the globular cells regardless of the DH concentration, but the cells were not observed in the sponges collected in Palau or Guam. As expected, the globular cells of the DH-free Yap specimen were unlabeled by the antibody. These findings suggested that DH was produced and stored in the "globular cells" which is a previously unidentified type of sponge cells unique to Yap specimen of D.herbacea, and biosynthesis of DH in this cell might be controlled by some unknown factors.