Snail tissues

The selenium distribution in thin sections of biological tissues has been quantitatively determined by LA-ICP-MS.103 The photograph of a cross section of the snail and the selenium LA-ICP-MS image are illustrated in Figure 9.26. Higher concentrations of selenium were found in the skin and gut compared to other parts of the snail. The natural selenium concentration in a 100 pm thin section of snail tissue was observed to be up to 25pgg 1.103... 

Figure 9.26 Quantitative Se distribution in cross section of snail tissues measured by LA-ICP-SFMS on the left-hand side, photographs of the investigated sections of snail tissue are shown. (). S. Becker et al. j. Anal. At. Spectrom. 22, 736 (2007). Reproduced by permission of the Royal Society of Chemistry.)...

Fig. 15.3 Chemicals released from partly digested snail tissues attract hermit crabs (a, b) gastropod predation sites function as markets where shells may be acquired by aggression or negotiation between hermit crabs (c) the other attendants may benefit occupying shells left vacant (d). Drawn by G. Mazza...

Fig. 3.19. Imaging of essential and toxic metals in snail tissue measured by LA-ICP-MS (Agilent 7500 ce and NewWave) compared to photograph of slice left top).

Derivatives are often used in lipid chemistry to prepare fatty acid methyl esters needed to determine the fatty acid composition of lipids. Fried et al. (1992) published a technique on the transesterification of 500-mg samples of snail tissue. Because the technique is applicable to other biological tissues and fluids, it is presented herein. Lipids were extracted from snail bodies with 10 ml of chloroform-methanol (2 1) the extracts were filtered through a plug of glass wool contained in a Pasteur pipet, and nonlipid contaminants were removed by extraction with 8 ml of Folch wash (0.88% aqueous KCl). The lipid-containing lower phase was separated and evaporated just to dryness under a stream of nitrogen at room temperature. The total lipid sample was dissolved in about 30 ml of methanol, and 0.5-1.0 ml of concentrated sulfuric acid was added. The mixture was refluxed for 1 h the formed fatty acid methyl esters were extracted with 30-40 ml of petroleum ether and the extract dried over anhydrous sodium sulfate. The fatty acid methyl esters were concentrated on a Rotoevaporator at 40°C and the volume reduced to 1 ml. The fatty acid methyl esters can be separated by TLC on silica gel impregnated with silver nitrate (Christie, 1982). 

B. Experiment 2. Occurrence of Carotenoids and Xanthophyils in Snail Tissue... 

Snail tissue from N. obsoletus (Hoskin and Cheng, 1975) will show yellow-orange spots at Ry values of approximately 0.17 (xanthophylls) and 0.71 (carotenes). Other pigment spots may also appear. The Ry values of the P-carotene standard will be approximately 0.71, and the crade xanthophyll standard will have an approximate Ry value of 0.17. 

Two-dimensional systems are often used to separate complex phospholipid mixtures in plant and animal tissues. See reviews in Mangold (98) and Rouser et al. (99) for details. The first development is typically in chloroform-methanol-water (65 25 4), and development in the second direction is often in either n-butanol-acetic acid-water (60 20 20) or chloroform-acetone-methanol-acetic acid-water (5 2.1 1 0.5). Although 2-D procedures may increase the resolution of some spots, it often results in large spots with tails. Figure 6 shows a 2-D separation of phospholipids from snail tissue, and Fig. 7 shows a 2-D separation of serum lipids. Table 7 lists frequently used 2-D solvent systems for complex lipid mixtures. 

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