title: Immunolocalization of the Toxin Latrunculin B within the Red Sea Sponge Negombata magnifica (Demospongiae, Latrunculiidae).
abstract: The location of latrunculin B, the major toxin of the Red Sea sponge Negombata magnifica, was revealed using specific antibodies. Antibodies from rabbits immunized with a conjugate of latrunculin B with keyhole limpet hemocyanin (KLH) were purified over a latrunculin B-Sepharose affinity column. Analysis of immunohistochemical and immunogold-stained sponge sections, using light and transmission electron microscopy, revealed latrunculin B labeling mostly beneath the sponge cortex at the border between the external (ectosome) and internal (endosome) layers (ectosome-endosome border). The endosome was less labeled than the border. Immunogold localization revealed latrunculin B in the sponge cells but not in its prokaryotic symbionts. Archeocytes and choanocytes were significantly more labeled than other cells. The antibodies primarily labeled membrane-limited vacuoles within archeocytes and choanocytes that are perhaps latrunculin B secretory or storage vesicles. Peripheral latrunculin B may have a role in defense against external epibionts, predators, and competitors.
authors.affiliation: Department of Zoology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel, IL.
authors.forename: O
authors.initials: O
authors.lastname: Gillor
authors.forename: S
authors.initials: S
authors.lastname: Carmeli
authors.forename: Y
authors.initials: Y
authors.lastname: Rahamim
authors.forename: Z
authors.initials: Z
authors.lastname: Fishelson
authors.forename: M
authors.initials: M
authors.lastname: Ilan