NEUTRAL LIPIDS IN SNAIL CONDITIONED WATER FROM 2 STRAINS OF HELISOMA-TRIVOLVIS (GASTROPODA, PLANORBIDAE)

Densitometric thin-layer chromatography (TLC) was used to study neutra l lipids in snail conditioned water (SCW) from two strains of Helisoma trivolvis (Colorado and Pennsylvania strains). Snail conditioned wate r with feces (SCW-WF) and snail conditioned water without feces (SCW-W OF) were analyzed. Free sterol was the major lipid fraction released d uring the first 2 h of incubation by the Colorado (CO) and the Pennsyl vania (PA) strains. The major neutral lipid fraction in SCW-WF release d by the CO strain within 4 h postincubation was free sterol, while th e major fraction released within 4 h by the PA strain was free fatty a cid. The mean+/-SE of free sterol released within 4 h by the CO and PA strains, 0.6+/-0.1 and 3+/-2 mu g per snail per ml of water, respecti vely, was not significantly greater than that released within 2 h, 0.5 +/-0.2 and 0.1+/-0.5 mu g per snail per mi of water, respectively. The free fatty acid released within 4 h by the CO and PA strains, 0.3+/-0 .1 and 4+/-2 mu g per snail per mi of water, respectively, was signifi cantly greater than that released within 2 h, 0.04+/-0.01 and 0.10+/-0 .02 mu g per snail per ml of water, respectively. The major neutral li pid in SCW-WOF al 2 h postincubation was free sterol for both strains. The mean+/-SE of free sterol released within 4 h by the CO and PA str ains, 0.7+/-0.2 and 0.9+/-0.8 mu g per snail per ml of water, respecti vely, was not significantly greater than that released within 2 h, 0.6 +/-0.2 and 0.7+/-0.2 mu g per snail per mi of water, respectively. By 4 h postincubation, the major neutral lipid in SCW from both strains w as free fatty acid. The mean+/-SE of free fatty acids released within 4 h by the CO and PA strains was 0.7+/-0.5 and 3.1+/-0.5 mu g per snai l per mi of water, respectively. The free fatty acid fraction released within 2 h by the CO and PA strains was below the quantification leve l of the experiment, 0.12 mu g per snail per mi of water for each stra in. Snails also released a hydrocarbon fraction that was not quantifie d. The lipids in the fecal and mucous extracts of both snail strains w ere analyzed qualitatively by TLC, and the zones were similar to those seen in the analyses of SCW-WF. However, the zones were more intense in fecal than in mucous extracts. The significance of these neutral li pids as chemoattractants remains to be determined. (C) 1997 Academic P ress.