Comparative Biochemistry and Physiology Part B 137 (2004) 413–420 1096-4959/04/$ - see front matter  2004 Elsevier Inc. All rights reserved. doi:10.1016/j.cbpc.2004.01.010 Phospholipase A2 in porifera Timo J. Nevalainen *, Ron J. Quinn , John N.A. Hooper a,b, b b,c Department of Pathology, University of Turku, Kiinamyllynkatu 10, FIN-20520, Turku, Finland a Natural Product Discovery, Griffith University, Brisbane, Queensland, Australia b Queensland Museum, Brisbane, Queensland, Australia c Received 23 September 2003; received in revised form 15 December 2003; accepted 31 January 2004 Abstract Phospholipase A2 (PLA2) catalytic activity was measured in aqueous extracts of 83 freeze-dried specimens representing 55 marine sponge species collected from the east coast of Australia including the Great Barrier Reef. High levels () 500 uyl) of PLA2 activity (defined as the amount of activity that releases 1 mmol of fatty acid per min) were found in four out of 55 species (7%), moderate activities (100–499 uyl) in 6y55 (11%), low activities (1–99 uyl) in 11y55 (20%) and no PLA2 activity in 34y55 (62%). Species with high PLA2 activity levels included Cymbastela coralliophila (2118 uyl, specific activity 10 590 uyg of protein), Acanthella cavernosa (1318 uyl, specific activity 2470 uyg), Spirastrella vagabunda (1036 uyl, specific activity 1727 uyg and Theonella swinhoei (567 uyl, specific activity 354 uy g). It was postulated that poriferan PLA2 may be involved in eicosanoid metabolism and antimicrobial and toxic defence of the animal.  2004 Elsevier Inc. All rights reserved. Keywords: Antimicrobials; Eicosanoid metabolism; Innate immunity; Marine invertebrates; Marine sponges; Phospholipase A2; Porifera; Toxins 1. Introduction Phospholipase A2 (PLA2) catalyses the hydrol- ysis of the sn-2 acyl ester bond of phospholipids in a reaction resulting in the release of a free fatty acid and lysophospholipid. PLA2s are present as membrane-associated and soluble enzymes in almost all cell types and play important roles in the biosynthesis of eicosanoids, turnover of membrane phospholipids, cellular signalling and protection of membranes against peroxidation damage (van Kuijk et al., 1987; Balsinde et al., 2002). PLA2s are essential components of snake and other venoms where the various forms of the *Corresponding author. Tel.: q358-2-333-7500; fax: q358- 2-333-7459. E-mail address: timo.nevalainen@utu.fi (T.J. Nevalainen). enzyme have haemolytic, myotoxic, neurotoxic, procoagulant and anticoagulant functions (David- son and Dennis, 1990). In humans, PLA2s are associated with numerous clinical inflammatory processes (Nevalainen et al., 2000). In addition to intracellular PLA2s, 10 secreted small molecular mass (14 kDa) PLA2s have been described recent- ly in mammals (Six and Dennis, 2000). An impor- tant property of secretory PLA2s is their capability of killing bacteria in vitro (Weinrauch et al., 1996; Koduri et al., 2002) and in vivo (Laine et al., 1999). The marine environment offers a great biodiv- ersity for the isolation of pharmacologically active compounds (Quinn et al., 2002). Efficient high- throughput screening methods have been devel- oped to exploit the marine biodiversity including