Revista Brasileira de Farmacognosia 25 (2015) 592–599 www .sbfgnosia.org.br/revista Original Article Metabolite variability in Caribbean sponges of the genus Aplysina a,∗ b c d Monica Puyana , Joseph Pawlik , James Blum , William Fenical a Departmento de Ciencias Biologicas y Ambientales, Universidad de Bogota Jorge Tadeo Lozano, Bogota, Colombia b Department of Biology and Marine Biology and Center for Marine Science, University of North Carolina Wilmington, NC, USA c Department of Mathematics and Statistics, University of North Carolina Wilmington, NC, USA d Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA a b s t r a c t a r t i c l e i n f o Article history: Sponges of the genus Aplysina are among the most common benthic animals on reefs of the Caribbean, and Received 14 April 2015 display a wide diversity of morphologies and colors. Tissues of these sponges lack mineralized skeletal Accepted 9 August 2015 elements, but contain a dense spongin skeleton and an elaborate series of tyrosine-derived brominated Available online 8 September 2015 alkaloid metabolites that function as chemical defenses against predatory fishes, but do not deter some molluscs. Among the earliest marine natural products to be isolated and identified, these metabolites Keywords: remain the subject of intense interest for commercial applications because of their activities in vari- Chemical ecology ous bioassays. In this study, crude organic extracts from 253 sponges from ten morphotypes among Coral reef the species Aplysina archeri, Aplysina bathyphila, Aplysina cauliformis, Aplysina fistularis, Aplysina fulva, A. Biotransformation insularis, and Aplysina lacunosa were analyzed by liquid chromatography–mass spectrometry (LC–MS) to Marine natural products Chemical defense characterize the pattern of intra- and interspecific variabilities of the twelve major secondary metabolites Induced defense present therein. Patterns across Aplysina species ranged from the presence of mostly a single compound, fistularin-3, in A. cauliformis, to a mixture of metabolites present in the other species. These patterns did not support the biotransformation hypothesis for conversion of large molecular weight molecules to smaller ones for the purpose of enhanced defense. Discriminant analyses of the metabolite data revealed strong taxonomic patterns that support a close relationship between A. fistularis, A. fulva and A. insu- laris, while two morphotypes of A. cauliformis (lilac creeping vs. brown erect) were very distinct. Two morphotypes of A. lacunosa, one with hard tissue consistency, the other soft and thought to belong to a separate genus (Suberea), had very similar chemical profiles. Of the twelve metabolites found among samples, variation in fistularin-3, dideoxyfistularin-3 and hydroxyaerothionin provided the most pre- dictive influence in decreasing order. Except for one morphotype, weak relationships were found from within-morphotype analyses of metabolite concentrations as a function of geographic location (Florida, N Bahamas, S Bahamas) and depth (<10 m, 10–20 m, >20 m). Our data suggest that metabolite profiles are strongly influenced by sponge phenotype rather than by the diverse microbiome which many Aplysina species share. © 2015 Sociedade Brasileira de Farmacognosia. Published by Elsevier Editora Ltda. All rights reserved. Introduction they appear to be capable of absorbing dissolved organic carbon as a food source (de Goeij et al., 2013), and their bodies provide Sponges now dominate the benthic community of most shelter for large numbers of invertebrates and fishes (Westinga Caribbean coral reefs, particularly when one considers overall and Hoetjes, 1981; Henkel and Pawlik, 2005). Sponges are aggres- biomass and biodiversity; integrates it across the reef commu- sive competitors for space (Aerts, 1998) and are primary agents of nity to deep water, and considers the communities within the reef carbonate bioerosion on coral reefs (Zundelevich et al., 2007). framework (Diaz and Rützler, 2001; Pawlik, 2011; Villamizar et al., Of all invertebrates, sponges have yielded the largest number 2013). Sponges are important to the overall ecology of coral reefs of secondary metabolites that have been isolated and described by for many reasons: they are very efficient filter feeders, providing an marine natural products chemists (Blunt et al., 2013 and previous important link in benthic-pelagic coupling (Southwell et al., 2008), reviews). Many of these compounds have potent pharmacological activities, including anti-tumor, anti-fungal, anti-viral, and anti- bacterial effects (Laport et al., 2009; Newman and Cragg, 2014). ∗ Because these compounds are often structurally complex or are Corresponding author. present at high concentrations in sponge tissues, they are likely E-mail: [email protected] (M. Puyana). http://dx.doi.org/10.1016/j.bjp.2015.08.002 0102-695X/© 2015 Sociedade Brasileira de Farmacognosia. Published by Elsevier Editora Ltda. All rights reserved. M. Puyana et al. / Revista Brasileira de Farmacognosia 25 (2015) 592–599 593 Table 1 to be metabolically expensive to make and store, and to have Sites from which sponges were collected for this study. Sites were subdivided into some adaptive purpose. By far, the most commonly hypothe- three regions, Northern Bahamas, Southern Bahamas and Florida Keys. sized defensive role for these compounds is predator deterrence, Site Region GPS coordinates but antifouling, anti-overgrowth, antimicrobial and UV-protective functions have also been proposed (Pawlik, 2011). Acklins Island S Bahamas 22.186474, −74.300231 − Our understanding of the ecology of sponges on Caribbean reefs Andros Island N Bahamas 24.618540, 77.683952 Bimini Island N Bahamas 25.667746, −79.319229 has changed substantially over the past 20 years. Before the mid- Black Rock S Bahamas 22.662327, −74.023134 1990s, the conventional view of sponge ecology on Caribbean reefs Cat Island S Bahamas 24.123313, −75.513862 was that there was no top-down (predator) control of sponge Cay Lobos S Bahamas 22.381946, −77.591482 populations, because only a few fish species spread their preda- Cay Santo Domingo S Bahamas 21.719539, −75.762152 Chub Cay N Bahamas 25.393290, −77.880825 tory activities over a wide variety of sponge species (Randall and Conch Reef Florida Keys 24.946651, −80.456086 Hartman, 1968). Subsequent research on the chemical defenses of Egg Island N Bahamas 25.498649, −76.898396 sponges demonstrated the importance of predation, with sponges Eleuthera Point S Bahamas 24.606181, −76.154849 falling into three categories: preferred species that are grazed Little San Salvador-Pinnacles S Bahamas 24.588934, −75.974433 − completely from the reef and restricted to refugia inside the reef Long Cay S Bahamas 22.562957, 74.393792 North Key Largo Dry Rocks Florida Keys 25.130833, −80.292017 framework, palatable species that are common on the reef and tol- North North Key Largo Dry Rocks Florida Keys 25.136778, −80.288621 erate grazing because they heal, grow or reproduce fast enough Pickles Reef Florida Keys 24.984737, −80.413676 to persist, and defended species that are protected from preda- − Porpoise Rocks N Bahamas 25.140337, 77.135227 tion by chemical defenses (Pawlik, 2011). A conceptual model of San Salvador S Bahamas 24.062287, −74.545403 Stirrup Cay N Bahamas 25.822565, −77.932398 sponge ecology on Caribbean reefs, based on an understanding of Sweetings Cay N Bahamas 26.556550, −77.880492 sponge chemical defenses and resource trade-offs with growth or Three Sisters Reef Florida Keys 25.021933, −80.396383 reproduction, was validated in cross-Caribbean surveys of sponge communities on heavily overfished and less-fished coral reefs (Loh and Pawlik, 2014). As part of those surveys, it was established that sponges of the genus Aplysina are among the most common chem- Florida Keys, USA, in May 2000. Categorization of sponge morpho- ically defended species, with Aplysina cauliformis the single most types, and subsequent discriminant analysis, was based on the most abundant species on Caribbean coral reefs (Loh and Pawlik, 2014). up-to-date taxonomic determination found in Zea et al. (2014), Caribbean sponges of the genus Aplysina are strongly chemically which includes photographs of the variation in morphologies seen defended against sponge-eating fishes (Pawlik et al., 1995; Loh and for morphotypes based on location. Pawlik, 2014). Interestingly, these defenses do not extend to cer- Whenever possible, whole sponges were gently removed from tain nocturnal and cryptic molluscan predators, such as cowries, the bottom using latex gloves. Larger or thicker sponge individuals which leave behind grazing trails and pits on the surfaces of several were sliced at their base with a sharp knife. Sponge samples were species, including Aplysina fistularis (Pawlik and Deignan, 2015). individually placed in sealable plastic bags underwater, keeping Ecologically relevant bioassays have also been used to demonstrate track of the site, depth and location of collection. Fresh samples ◦ − that the secondary metabolites of sponges of this genus have potent were placed directly into a 20 C freezer and kept frozen until antimicrobial (Kelly et al., 2005) and allelopathic effects (Pawlik extraction. et al., 2007). The metabolites responsible for these biological activ- For extraction, frozen sponges were cut in 0.5 inch cubes and ities were among the earliest marine natural products described, placed in a graduated