EFFECTS OF CROWDING ON THE NEUTRAL AND POLAR LIPIDS OF BIOMPHALARIA GLABRATA AS DETERMINED BY HIGH-PERFORMANCE THIN-LAYER CHROMATOGRAPHY-DENSITOMETRY AND OBSERVATIONS ON SNAIL SURVIVAL AND FECUNDITY

Abstract

High performance thin-layer chromatography-densitometry was used to characterize and quantify neutral and polar lipid classes present in Biomphalaria glabrata snails subjected to crowding. Observations on survival and fecundity were made on a noncrowded population (10 snails per culture), a moderately crowded population (20 snails per culture), and a heavily crowded population (40 snails per culture). Each culture contained 800 mL of artificial spring water, and snails were maintained at 25 ± 1°C and fed romaine lettuce ad libitum. After 4 weeks of culture, the snails were necropsied and the digestive-gland gonad complex (DGG) of each snail was extracted in chloroform-methanol for lipid analysis. Lipids were separated on 10 × 20 cm Analtech channeled HPTLC-HLF silica gel plates with a preadsorbent zone. For neutral lipids, the mobile phase petroleum ether-diethyl ether-glacial acetic acid (80:20:1) and 5% ethanolic phosphomolybdic acid detection reagent were used to analyze the DGG of each snail. Chloroform-methanol-deionized water (65:25:4) mobile phase and 10% cupric sulfate in 8% phosphoric acid detection reagent were used to determine the polar lipids in the DGG of each snail. Quantitative densitometric analysis was performed using a CAMAG TLC Scanner 3 with the tungsten light source set at 610 nm for neutral lipids and the deuterium source at 370 nm for polar lipids. No significant differences in any of the neutral and polar lipid classes were found among all three of the aforementioned snail populations (ANOVA, p < 0.017).