Novel free ceramides as components of the soldier defense gland of the Formosan subterranean termite (Coptotermes formosanus)

Abstract

Of the lipid extracts of the defense secretion from the Formosan subterranean termite, Coptotermes formosanus Shiraki, on high-performance thin-layer chromatography analysis, no glycolipids or phospholipids were detected, but free fatty acids and three novel ceramides were found (termed TL-1, TL-2, and TL-3). Free fatty acids were confirmed to be lignoceric acid (C24:0) and hexacosanoic acid (C26:0), as described previously [Chen, J., G. Henderson, and R. A. Laine. 1999. Lignoceric acid and hexacosanoic acid: major components of soldier frontal gland secretions of the Formosan subterranean termite (Coptotermes formosanus). J. Chem. Ecol. 25: 817-824]. TL-1, TL-2, and TL-3 were characterized as ceramides differing in hydrophobicity based on results of matrix-assisted laser desorption-ionization timeof-flight mass spectrometry analysis, mild alkaline treatment, GC-MS analysis of fatty acid methylesters, and GC-MS analysis of sphingoid long-chain bases (LCBs) as trimethylsilyl derivatives. Fatty acids in TL-1 and TL-2 were C18:0, C20:0, and C22:0, and those in TL-3 were 2-hydroxy C18:0, C20:0, and C22:0. The most predominant LCB in TL-2 was a novel trihydroxy C 14 -sphingosine, 1,3,9-trihydroxy-2-amino-6-tetradecene. TL-3 contained C 18 -sphinganine and two kinds of novel sphingadienines, 1,3-dihydroxy-2-amino-7,10-hexadecadiene and 1,3-dihydroxy-2-amino-11,14-eicosadiene. Although examination of the biological activities of these novel ceramides was beyond the scope of these studies, because of the minuscule quantities available from termite secretions, it will be interesting in the future to synthesize these molecules for biological testing. Many termite species, including the Formosan subterranean termite, Coptotermes formosanus Shiraki, have a soldier caste that is morphologically and physiologically specialized for defense (1). The physiological defense strategies are used by mechanically and chemically armed soldier termites. Weapons of the soldiers include mandibles modified for crushing and, most interesting, a defense secretion sprayed from its frontal gland, ejected from a foramen at the front of the head (2). The secretion has several properties, including immobilization, acting like a glue, and as an irritant against predators such as ants. The secretion apparently contains an unidentified alarm pheromone that repels workers and attracts soldiers (3). Furthermore, chemical signals in the secretion may stimulate workers exposed to the fluid to morph into soldiers during their next two molts (4). Chemical analyses of the defense gland secretions from the families Rhinotermitidae and Termitidae have revealed an impressive diversity of chemical components: monoterpenes, diterpenes, sesquiterpenes, quinones, macrocyclic lactones, alkanes, alkenes, nitroalkenes, vinyl ketones, and aldehydes (5, 6).In Coptotermitinae, chemical analyses of the frontal gland components have been performed in only a few species. A heterogeneous suspension of n-alkanes and mucopolysaccharides was reported in Coptotermes l...

Communication and Social Regulation in Termites

“…In Coptotermes, secretions are composed of various compounds such as simple hydrocarbons, aromatic compounds, ketones, alcohols, and ceramides that may act as fumigants (Chen et al 1998(Chen et al , 1999Zhang et al 2006;Ohta et al 2007), and the presence of Coptotermes formosanus soldiers has been shown to inhibit the formation of additional soldiers Raina 2003, 2005). This primer effect produced by the soldiers requires direct contact between the soldiers and the undifferentiated individuals (Dong et al 2009).…”

Systematic analyses of free ceramide species and ceramide species comprising neutral glycosphingolipids by MALDI-TOF MS with high-energy CID

“…Liquid chromatography-electrospray ionization mass spectrometry (LC/ESI-MS) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) have been well utilized to characterize sphingolipids with high throughput [5,6,[12][13][14][15][16][17][18][19][20][21], but these reports did not fully characterize ceramide species including hydroxyl FAs (HFAs) and/or trihydroxy-LCBs (tLCBs) of both free ceramides and the constituent ceramides in GSLs. Namely, in the analyses of GSLs these investigations focused on sugar sequences by releasing sugars from the lipid portions [22,23]; therefore, detailed information regarding the constituent ceramide species in GSLs is limited [20].…”

Social Recognition in Invertebrates

“…In Coptotermes, secretions are composed of various compounds such as simple hydrocarbons, aromatic compounds, ketones, alcohols, and ceramides that may act as fumigants (Chen et al 1998(Chen et al , 1999Ohta et al 2007), and the presence of Coptotermes formosanus soldiers has been shown to inhibit the formation of additional soldiers Raina 2003, 2005). This primer effect produced by the soldiers requires direct contact between the soldiers and the undifferentiated individuals (Dong et al 2009).…”