Digestion of phosphatidylcholines, absorption, and esterification of lipolytic products by Aeshna cyanea larvae as studied in vivo and in vitro
✍ Scribed by Birgit Weiher; Hans Komnick
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 200 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0739-4462
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✦ Synopsis
Digestion and absorption of phosphatidylcholine by Aeshna cyanea larvae were studied in vivo and in vitro with the isolated digestive juice and isolated midgut. The experiments were performed with stable ether analogues (1-alkyl-2acyl-,1,2-dialkyl phosphatidylcholine, and 1-monoalkyl-lysophosphatidylcholine), with radioactive 1,2-diacylphosphatidylcholine alternatively labelled in the acyl-and choline moieties, and with several phosphatidylcholine derivatives (1-[1-14 C]acyl-and 1-[ 3 H] alkyl-lysophosphatidylcholine, [1-14 C]oleic acid, [2-14 C]glycerol, phosphoryl[methyl-14 C]choline, and [methyl-14 C]choline). Chromatographic analyses of the digestion products revealed that phosphatidylcholine was degraded via two interconnected hydrolytic pathways involving phospholipase C, phospholipase A 2 , lipase, and alkaline phosphatase. Complete hydrolysis by these pathways yielded the same four end products: free fatty acid, glycerol, choline, and P i , which were absorbed by the midgut enterocytes. Of the intermediate hydrolysates, lysophosphatidylcholine, monoacylglycerol, and possibly phosphorylcholine were also absorbed. Radiolabelled oleic acid, glycerol, lysophosphatidylcholine and monoacylglycerol (as judged from monoalkylglycerol absorption) were incorporated into phos-*Abbreviations used: AG = acylglycerols; Bet = betaine; BSA = bovine serum albumin; Chol = choline; FFA = free fatty acid; Glyc = clycerol; ME = ether analogue of MG; MG = , DG = , TG = mono-, di-and tri-acylglycerol; LPC = or lyso; PC = lysophosphatidylcholine;