EFFECTS OF TEMPERATURE ON THE NEUTRAL LIPID CONTENT OF BIOMPHALARIA GLABRATA AS DETERMINED BY HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY-DENSITOMETRY AND OBSERVATIONS ON SNAIL FECUNDITY

Abstract

High performance thin-layer chromatography with densitometry was used to examine the effects of extreme temperature on the neutral lipid content of Biomphalaria glabrata, and observations on fecundity were made at these extreme temperatures of 32, 28, and 14°C. Fecundity results showed that egg laying at 32°C was higher than at 28 and 14°C. Free sterols, free fatty acids, and triacylglycerols were quantified at 2 and 4 weeks after the initiation of the experiment using Analtech channeled high performance silica gel plates with a preadsorbent zone. Plates were developed using the Mangold mobile phase, petroleum ether-diethyl ether-glacial acetic acid (80:20:1), and after treatment with 5% ethanolic phosphomolybdic acid spray reagent and 10 min of heating at 110°C, neutral lipids appeared as blue zones on a yellow background. Quantitative densitometric analysis was performed using a CAMAG TLC Scanner II with the tungsten light source set at 610 nm. Quantitative identification was based on correspondence of R_f values of sample and neutral lipid standard zones. At week 2 after the initiation of the experiment, there were significant differences in triacylglycerol content between all three temperatures, suggesting that at the higher temperatures snails were building reserves of depot fat.

Global climate changes have led to concerns about the spread of infectious disease, including snail born infections such as schistosomiasis. Some of these concerns relate to the ability of vector snails to adapt to climate change, making studies on lipid use of vector snails at temperature extremes crucial to a better understanding of the potential spread of snail-borne disease.

Keywords:

• Biomphalaria glabrata
• densitometry
• free fatty acids
• free sterols
• high performance thin-layer chromatography
• HPTLC
• snail fecundity
• temperature effects
• triacylglycerols

ACKNOWLEDGMENTS

We are indebted to Dr. Fred A. Lewis for supplying the adult B. glabrata snails used in this study through NIH-NIAID contract NO1-AI-55270. Jeff Bolstridge was supported by a Camille & Henry Dreyfus Foundation Senior Scientist Mentor Program award to Professor Joseph Sherma, and the Lafayette College EXCEL Scholars program.

Notes

^a Cultures maintained at this temperature had 9 snails, whereas the cultures at the other temperatures each had 10 snails.

^a There was a statistically significant difference (P < 0.017) between group A and B.

^b There were statistically significant differences (P < 0.017) between all groups.

^c Value had a standard error that was too large for inclusion.