Are there activated chemical defenses in sponges of the genus Aplysina from the Caribbean?

Abstract

The Mediterranean sponge Aplysina aerophoba has been proposed to rely on damageinduced activation of chemical defenses against pathogens and fish predators. High molecular weight brominated tyrosine derivatives have been suggested to undergo rapid, enzyme-mediated transformations into the metabolites aeroplysinin-1 and dibromocyclohexadienone following tissue damage, a process also called 'biotransformation'. These putative end-products were found to exhibit greater defensive activity compared to their precursors. Because sponges of the genus Aplysina possess similar chemical components worldwide, it has been suggested that the activation of chemical defenses is a common feature in this group. Herein, we report in situ and laboratory experiments conducted with living specimens of 2 species from the Caribbean, Aplysina insularis and A. archeri. Changes in sponge tissue secondary metabolites during time-course experiments were determined using diode-array high performance liquid chromatography coupled with mass spectrometry (LC-MS) analyses of extracts of flash frozen samples. We obtained no evidence of chemical transformation after tissue damage. In short (150 s) and long (30 and 120 min) time-course experiments, conversion of the major high molecular weight brominated constituents into the low molecular weight aeroplysinin-1 or dibromocyclohexadienone was not apparent: there was neither a reduction in the concentration of putative precursor metabolites, nor an increase in end products. Past observations of transformation may be the result of differential tissue extraction efficiency, hydrolysis from insoluble precursors or the heterogeneous distribution of metabolites in sponge tissue.

Exploring the Links between Natural Products and Bacterial Assemblages in the SpongeAplysina aerophoba

“…Thoms et al (71) also found significant differences in the concentrations of secondary metabolites between specimens of A. aerophoba collected in Croatia and France, supporting the idea that chemical variation seems to be common within species of the genus Aplysina (55). Similarly, several bacteria differed between A. aerophoba, Geodia barretti, and Cymbastela concentrica (35,41,66).…”

“…Similarly, the alkaloid content remained unchanged after cultivation of Aplysina specimens in starvation conditions and antibiotics exposure in aquaria (35). Nevertheless, other studies with emphasis on natural products quantification show considerable variability in the concentration of secondary metabolites within Aplysina species (55) and between specimens of the same Aplysina species (62). The relative composition of the main brominated compounds under ex situ and in situ cultivation of A. aerophoba remained stable, although the total alkaloid content increased twice as much ex situ than in situ (43).…”

Chemical defenses and resource trade-offs structure sponge communities on Caribbean coral reefs

“…4). For tissue samples of A. cauliformis from the Florida Keys and Bahamas Islands, fistularin 3 occurred at 2.4 mg/mL of sponge volume (SD = 1.1, n = 59) and, unlike other Aplysina species, had very low levels of other related metabolites in its tissues (24,25). Other Aplysina species, including Aplysina fulva, which ranked sixth most abundant across all sites, also had fistularin 3 as a dominant chemical defense (24).…”

Evidence of a resource trade-off between growth and chemical defenses among Caribbean coral reef sponges

“…Of the sponge species tested for the present study, Callyspongia armigera, Iotrochota birotulata and Niphates erecta lacked chemical defenses (Pawlik et al 1995), while Amphimedon compressa produces a pyridinium alkaloid that is highly deterrent to predators (Albrizio et al 1995), Aplysina spp. contain unpalatable brominated tyrosine derivatives (Puyana et al 2003, Nuñez et al 2008 and Ptilocaulis walpersi contains deterrent bromopyrroles and oroidin-class metabolites similar to members of the genus Agelas (Wright et al 1991, Assmann et al 2000. The biosynthetic pathways for sponge secondary metabolites are poorly understood, but the process is likely to be costly, as may also be the storage of metabolites and the prevention of autotoxicity (Van Alstyne et al 2001).…”

“…Some of the secondary metabolites responsible for deterrent activity in defended sponges have been isolated and identified (e.g. Albrizio et al 1995, Puyana et al 2003, Nuñez et al 2008. Assuming these complex compounds require metabolic energy to synthesize, store and deploy, a trade-off between chemical defenses and growth in sponges would be expected.…”