Ref ID : 4908
Akio Miyake, Federico Buonanno, Piero Saltalamacchia, Miyuki Eiraku Masaki, and Hideo Lio; Chemical defence by means of extrusive cortical granules in the heterotrich ciliate Climacostomum virens. Europ.J.Protistol. 39:25-36, 2003
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The heterotrich ciliate Climacostomum virens has colourless cortical granules morphologically similar to pigmentocysts (extrusive pigment granules) in the two coloured heterotrichs, Blepharisma japonicum and Stentor coeruleus, in which toxic pigments in pigmentocysts are used for chemical defence against pedators. We examined whether cortical granules in C. virens are also defensive organelles. We showed: 1) cortical granules in C. virens are toxin-containing extrusive organelles; 2) artificially-induced cortical-granules-deficient cells in C. virens are more vulnerable than normal cells to the raptorial ciliate Dileptus margaritifer, while they are indistinguishable from intact cells in their capacity to grow; 3) cortical granules contain the colourless resorcinolic toxin climacostol, 1,3-dihydroxy-5-[(Z)-2'-nonenyl]benzene, which was recently isolated from C. virens; and 4) chemically-synthesized climacostol induces in D. margaritifer behavioural and pathological reactions which are essentially the same with those observed in the interaction with C. virens. We conclude that cortical granules of C. virens are extrusomes (extrusive organelles in protists) for chemical defence against predators and that they carry out the defence by discharging colourless toxins including climacostol. The function of chemical defence in extrusomes of heterotrich ciliates is, therefore, independent of pigmentation.