Lipid absorption by isolated intestinal preparations

Weintraub, Hana; Tietz, Alisa

doi:10.1016/0020-1790(78)90036-7

Cited by 26 publications

(2 citation statements)

References 13 publications

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“…In insects, the process of dietary fat absorption requires the hydrolysis of triacylglycerols, which occurs in the lumen of the midgut ; Weintraub & Tietz, 1973,1978Tsuchida & Wells, 1988). The FFA are absorbed and incorporated by the midgut cells into triacylglycerols, diacylglycerols (DG),1 and phospholipids (PL).…”

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Hydration and Localization of Diacylglycerol in the Insect Lipoprotein Lipophorin. A 13C-NMR Study

Rivera²,

Fa³

et al. 1994

Biochemistry

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In order to probe the organization of diacylglycerol (DG) in lipophorin, 13C-enriched lipophorin was prepared for NMR investigations. We obtained 13C-enriched lipophorin labeled exclusively in DG by feeding insects tobacco leaves coated with [1-13C]palmitic acid or [1-13C]oleic acid. Lipophorins enriched up to 5% with a [13C]fatty acid were obtained by this procedure. NMR studies of the isolated lipophorin DG showed that palmitic acid accumulates almost entirely (> 90%) in the sn-1 position. Oleic acid was found equally distributed between the sn-1 and sn-2 positions, yielding a DG enriched equally at both positions. The 13C-NMR spectra of both [13C]palmitate- and [13C]oleate-enriched lipophorins showed that DG had one narrow carbonyl resonance indicative of rapid motion. A comparative analysis of the 13C carbonyl chemical shift data for DG in organic solvents, aqueous solutions, and dispersions with the DG carbonyl chemical shift of native lipophorin enriched in [13C]palmitate or [13C]oleate shows a high degree of water exclusion from the DG carbonyls in lipophorin. This result is consistent with the existence of a lipophorin lipid core containing most of the lipophorin DG. This study represents the first attempt to elucidate the organization of DG in lipophorin. The possibility of obtaining [13C]DG-enriched lipophorins, selectively enriched in one or both acyl chains of DG, should provide a powerful tool for further analysis of the organization and the dynamic properties of DG in native lipoproteins.

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“…The FFA are absorbed and incorporated by the midgut cells into triacylglycerols, diacylglycerols (DG),1 and phospholipids (PL). Most of the fatty acids are released from the midgut as DG, which are transported through the hemolymph by the major insect lipoprotein lipophorin (Weintraub & Tietz, 1978;Tsuchida & Wells, 1988;Bauerfeind & Komnick, 1992).…”

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confidence: 99%

Hydration and Localization of Diacylglycerol in the Insect Lipoprotein Lipophorin. A 13C-NMR Study

Rivera²,

Fa³

et al. 1994

Biochemistry

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Digestion of phosphatidylcholines, absorption, and esterification of lipolytic products byAeshna cyanea larvae as studied in vivo and in vitro

Weiher¹,

Komnick²

1997

Arch. Insect Biochem. Physiol.

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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‐2‐acyl‐,1,2‐dialkyl phosphatidylcholine, and 1‐monoalkyl‐lysophosphati‐dylcholine), with radioactive 1,2‐diacylphosphatidylcholine alternatively labelled in the acyl‐ and choline moieties, and with several phosphatidylcholine derivatives (1‐[1‐14C]acyl‐ and 1‐[3H] alkyl‐lysophosphatidylcholine, [1‐14C]oleic acid, [2‐14C]glycerol, phosphoryl[methyl‐14C]choline, and [methyl‐14C]choline). Chromatographic analyses of the digestion products revealed that phosphatidylcholine was degraded via two interconnected hydrolytic pathways involving phospholipase C, phospholipase A2, lipase, and alkaline phosphatase. Complete hydrolysis by these pathways yielded the same four end products: free fatty acid, glycerol, choline, and Pi, 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 phospholipids and acylglycerols of the midgut enterocytes and were released into the haemolymph primarily in the form of diacylglycerols. In the case of glycerol ingestion, a small fraction of haemolymph radioactivity was associated with free glycerol and glycerolphosphate. After absorption by the enterocytes, radiolabelled choline was partly oxidized to betaine, partly phosphorylated, and partly incorporated into lyso‐ and phosphatidylcholine. It was recovered from the haemolymph predominantly as free choline, phosphorylcholine, and betaine. Arch. Insect Biochem. Physiol. 36:273–293, 1997. © 1997 Wiley‐Liss, Inc.

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Lipophorin lipase from the yolk of Manduca sexta eggs: Identification and partial characterization

Antwerpen

Law

1992

Arch Insect Biochem Physiol

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In the hawkmoth Manduca sexta high density lipophorin from adult insects (HDLp-A) delivers lipids to developing oocytes. During this lipid delivery HDLp-A is taken up by the oocyte and converted to a very high density lipophorin (VHDLp), which is stored in protein storage granules (yolk bodies). A membrane-free lysate of isolated M. sexta yolk bodies was demonstrated to contain lipoprotein lipase activity that hydrolyses the diacylglycerol of HDLp-A. With HDLp-A as a substrate yolk body lipophorin lipase (YBLpL) activity was shown to be maximal between pH 9 and pH 9.5. NaCl concentration was optimal between 0.7 M and 1 M. YBLpL activity required neither bovine serum albumin nor calcium ions but appeared to be stimulated by 5 mM EDTA. Diisopropyl fluorophosphate effectively inhibited YBLpL activity, indicating the presence of a serine in the active site of the enzyme. The identified lipase activity co-eluted with lipophorins and vitellins from the yolk in the void volume of a Sephadex G-75 gel filtration column. This observation suggests that the lipase has a Mr of more than 80,000, or that the enzyme is associated with the lipoproteins. Incubation of HDLp-A with yolk body lysate converted HDLp-A to two classes of higher density lipophorins. The highest density lipophorins produced during this incubation approached the density of VHDLp as it is isolated from mature eggs. The possible role of YBLpL activity in the delivery of lipids to developing oocytes is discussed.

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Lipid absorption by isolated intestinal preparations

Cited by 26 publications

References 13 publications

Hydration and Localization of Diacylglycerol in the Insect Lipoprotein Lipophorin. A 13C-NMR Study

Hydration and Localization of Diacylglycerol in the Insect Lipoprotein Lipophorin. A 13C-NMR Study

Digestion of phosphatidylcholines, absorption, and esterification of lipolytic products byAeshna cyanea larvae as studied in vivo and in vitro

Lipophorin lipase from the yolk of Manduca sexta eggs: Identification and partial characterization

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