Localization of Two Brominated Metabolites, Aerothionin and Homoaerothionin, in Spherulous Cells of the Marine Sponge Aplysina fistularis (=Verongia thiona)

Abstract

Thompson, J . E., Barrow, K . D . , Faulkner, D.J. 1983. Localization of two brominated metabolites, aerothionin and homoaerothionin, in spherulous cells of the marine sponge Aplysina fistularis (=Verongia thiona). (Scripps .) -Acta zool. (Stockh.) 64, 199-210.Energy dispersive X-ray microanalysis was used to localize the two brominated natural products (aerothinonin and homoaerothionin) in the tissues of a marine demosponge, Aplysinafistularis. Virtually all of these compounds were localized within the spherules of the spherulous cells in the rnesohyl. This is the first localization of any secondary metabolite at the cellular or sub-cellular level in any marine invertebrate. In Aplysina fistularis, as in other species of the same genus studied by Vacelet. the spherulous cells are concentrated just beneath the exopinacoderrn and just beneath the endopinacoderm of the excurrent canals. Moreover, there is electron microscopic evidence for degeneration of some spherulous cells throughout the mesohyl. Presumably, this degeneration can release some aerothionin and hornoaerothionin, which are known to have antibiotic properties. After release from the spherulous cells, these brominated natural products could function (1) within the mesohyl to exclude some types of bacteria or to aggregate ingested bacteria and/or (2) within the boundary layer of the surrounding seawater for defense or offense. as considered in the discussion section.

Chemical mediation of interactions among marine organisms

“…2 ' 5 ' 26 First, we would be remiss if we did not mention the important early work by Faulkner and coworkers on this topic, which were some of the first ecologically sound studies of sponge chemical defenses. 10 " 13 Forty different sponges from San Diego, CA, were collected, and extracts were tested for suppression of bacterial and fungal growth. Many of the extracts and some pure compounds were tested for inhibition of settlement and metamorphosis of marine invertebrate larvae, behavioral modifications of adult invertebrates (a hydroid, a bryozoan, a sea star, and keyhole limpet), and feeding deterrence toward several fishes.…”

“…Faulkner, Thompson and coworkers conducted some of the first ecologically sound studies of sponge chemical defenses looking at the natural products chemistry and ecology of marine sponges in Southern California. 10 " 13 Faulkner's interest in sponge chemical ecology was long-standing resulting in recent work concerning the potential origin of sponge metabolites from cyanobacteria and symbiotic microorganisms. [14][15][16] Late in his career, John Faulkner established another collabor-ation with Margo Haygood to investigate symbiotic bacteria in macroorganisms as sources of bioactive metabolites.…”

“…17 ' 243 " 244 This question of secondary metabolite localization in sponge cells was first addressed for Aplysina fistularis. 10 Using dispersive X-ray microanalysis, Thompson and colleagues 10 demonstrated that two brominated compounds, aerothionin 53 and homoaerothionin 54, are localized in the spherulous cells of the sponge. These results suggest that the sponge rather than symbionts produces these compounds.…”

Chemical Mediation of Interactions Among Marine Organisms

“…10 " 13 Faulkner's interest in sponge chemical ecology was long-standing resulting in recent work concerning the potential origin of sponge metabolites from cyanobacteria and symbiotic microorganisms.…”

“…183 First, we would be remiss if we did not mention the important early work by Faulkner and coworkers on this topic, which were some of the first ecologically sound studies of sponge chemical defenses. 10 " 13 Forty different sponges from San Diego, CA, were collected, and extracts were tested for suppression of bacterial and fungal growth. Many of the extracts and some pure compounds were tested for inhibition of settlement and metamorphosis of marine invertebrate larvae, behavioral modifications of adult invertebrates (a hydroid, a bryozoan, a sea star, and keyhole limpet), and feeding deterrence toward several fishes.…”