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  • Author or Editor: Joseph Sherma x
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This review examines the use of thin-layer chromatography (TLC) for the analysis of neutral lipids and phospholipids in medically and economically important gastropod molluscs (snails). It discusses methods for isolating lipids from snails, and the use of layers, mobile phases, and detection reagents for the TLC analysis of snail neutral lipids and phospholipids. Quantitative densitometric studies are reviewed, with particular emphasis on class separations of neutral lipids and phospholipids. The review considers significant findings on the effects of diet and larval trematode parasitism on lipids in snails as determined by TLC.

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The purpose of this study was to identify and quantify various neutral and polar lipids in certain organs of mice using high-performance thin-layer chromatography (HPTLC). Four mice infected with Schistosoma mansoni and three control mice were used for this study. At 6 weeks postinfection, the mice were necropsied, and the liver, spleen, and small intestine were removed and prepared for lipid analysis. Lipids were separated on laned, preadsorbant Analtech HPTLC-HLF 20 × 10-cm silica gel plates. Neutral lipids were separated using petroleum ether-diethyl ether-glacial acetic acid (80:20:1) mobile phase and were detected by spraying with 5% ethanolic phosphomolybdic acid detection reagent. Polar lipids were separated with chloroform-methanol-deionized water (65:25:4) mobile phase and detected using 10% cupric sulfate in 8% phosphoric acid reagent. The analyzed neutral lipids were free sterols, free fatty acids, and triacylglycerols. Using HPTLC, no significant differences were found in these lipids between the infected and uninfected mice organs. The polar lipids analyzed were phosphatidylcholine (PC) and phospatidylethanolamine (PE). There was a significantly higher PC content in the liver and small intestine of the uninfected mice compared with that of infected mice.

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High-performance thin-layer chromatography was used to examine the phospholipid profiles in the urine of Echinostoma caproni infected mice, uninfected mice, and humans. Phospholipids were extracted from urine with chloroform-methanol, 2:1, and determined on silica gel plates with 19 lanes and a concentration zone that were developed with chloroform-methanol-water, 65:25:4. Separated zones were detected by charring with aqueous cupric sulfate reagent and quantified by visible mode slit-scanning densitometry at 370 nm. Ninhydrin spray reagent was used to confirm the presence of phosphatidylethanolamine and spiking analyses were used to confirm the identity of phosphatidylcholine in human urine. Lysophosphatidylcholine was found in human but not mouse urine. Comparison of chromatograms from the urine of infected and uninfected mice showed no qualitative or quantitative differences in the phospholipid profiles, suggesting that urinary phospholipids may not serve as biological markers for trematode infection in mice. Marked differences between the overall polar lipid profiles of mouse and human urine suggest that mice may not be useful models for humans in analyses of the effects of metabolic and infectious diseases on polar lipids.

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Diapause in insects typically results in metabolic adjustments that may include the levels of feeding and activity, metabolic rate, and the accumulation and utilization of reserves. The objective of this study was to characterize and quantify the various neutral lipid classes in the pitcher-plant mosquito (Wyeomyia smithii) that are associated with photoperiod-induced diapause. We used high-performance thin-layer chromatography (HPTLC) with 10 cm × 20 cm silica gel plates, petroleum ether-diethyl ether-glacial acetic acid 80:20:1 as the mobile phase, and 5% ethanolic phosphomolybdic acid solution as detection reagent to determine the percentage of replicate larvae samples (consisting of 16–31 larvae) that contained free sterols (FS), free fatty acids (FFA), triacylglycerols (TG), methyl esters (ME), and steryl esters (SE). Irrespective of the growth treatment (shortdays or long-days), the greatest concentrations of neutral lipids in all samples examined were TG. The effects of day length were such that during long-day (diapause terminating) conditions larvae contained less TG, more FS, and more FFA than larvae exposed to short-day (diapause inducing) conditions. Furthermore, the effects of body mass affected our results such that larger larvae contained more TG when in diapause, but less TG when not in diapause. Both ME and SE were only found in trace amounts in the short-day mosquitoes and not at all in long-day group. Our results are consistent with previous research that suggests TGs are important storage lipids during insect diapause.

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This paper reviews the use of thin-layer chromatography (TLC) for the analysis of neutral lipids and phospholipids in medically and economically important snails (gastropod molluscs). It updates and fills in unintentionally neglected papers from earlier reviews on this topic published in 1990 and 2006 in this journal, and extends coverage to lipophilic pigments for the first time. The review discusses all steps of the TLC procedure, including sample preparation, sample and standard application, layers and mobile phases, detection of zones, and quantification. Significant findings on the effects of temperature, larval parasitism, diet, and environmental changes on the lipid and lipophilic pigment content in the snails as determined by TLC as well as the results of other miscellaneous studies and advantages and future prospects are presented.

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