Composition Of Cuticular Lipids Research Articles

Unusual Fatty Acid Composition of Cuticular Lipids From Leaves of Oenothera

Composition of cuticular lipids washed out with hexane from the surface of fresh leaves of evening primrose ( Oenothera ) was examined. 25 different lipid classes were distinguished in the extract afterwards divided into the neutral (63 %) and acidic lipids (37 %). The main components of the neutral lipid fraction were hydrocarbons and fatty acid esters of sterols or fatty alcohols. Unsaponif iable lipids constituted about 77 % of neutral lipids, however, α-linolenic acid was the principal component (90 %) of the acidic lipid fraction. The occurrence on the leaf's surface of high concentration of α-linolenic acid and only trace amounts of trienoic acids with conjugated double bonds, originated from it by oxidative rearrangement, is very unusual. The mechanism of protection of α-linolenic acid against oxidative degradation remains to be explained.

Monoterpene emissions and cuticular lipids of loblolly and slash pines: potential bases for oviposition preference of the Nantucket pine tip moth

Monoterpene emissions from intact 5- to 29-month-old loblolly and slash pine seedlings contained α-pinene, camphene, β-pinene, myrcene, sabinene, β-phellandrene, and limonene. α-Pinene made up > 50% of the volatiles from both species. β-Pinene was significantly more abundant in slash (35.6%) than in loblolly pine (15.3%), while myrcene was significantly more abundant in loblolly (10.9%) than in slash pine (3.4%). Cuticular lipids represented 0.11 and 0.06% of the dry weight biomass of shoots from loblolly and slash pines, respectively. Species differences in cuticular lipid composition were primarily in relative proportions of a group of unidentified compounds that appear to be saturated and unsaturated diols and (or) hydroxy alcohols with chain lengths of about 18 carbons. 10-Nonacosanol made up 16.2 and 14.1% of the total lipids recovered from loblolly and slash pines, respectively. The Nantucket pine tip moth, Rhyacionia frustrana (Comstock), may use these chemical differences to distinguish the susceptible loblolly pines from the resistant slash pines. Key words: Pinus taeda, Pinus elliottii, monoterpene emissions, cuticular lipids, Rhyacionia frustrana.

Chemical and ultrastructural analysis of corn cuticular lipids and their effect on feeding by fall armyworm larvae

The cuticular lipid composition of lower and upper leaves of five genotypes of field-grown corn,Zea mays L., was determined by combined gas chromatography-mass spectrometry. Surface lipids of the upper leaves had a higher proportion ofn-alkanes (45-52%) than the lower leaves, while the lower leaves had higher percentages of fatty alcohols (12-18%) than the upper leaves. Scanning electron microscopy showed that the upper leaves of two corn genotypes, MpSWCB-4 and Cacahuacintle X's, had a smooth amorphous appearance, while the lower leaves had a dense array of wax crystals.Spodoptera frugiperda (J.E. Smith) larvae weighed more and developed more rapidly when they were reared on diet containing corn foliage from which the cuticular lipids had been removed than when they were fed untreated foliage. However, growth was not inhibited when larvae were fed diet containing the cuticular lipid extracts or individual cuticular lipid components.

Epi‐ and intracuticular lipids and cuticular transpiration rates of primary leaves of eight barley (Hordeum vulgare) cultivars

The major constituents of the epi‐ and intracuticular lipids of primary leaves of 8 cultivars of barley (Hordeum vulgare L.) have been studied together with cuticular transpiration rates. The total amount of analysed cuticular lipids ranged from 9.6 to 13.4 μg cm−2 and was dominated by the epicuticular fraction, which made up 73–84% of the total. There were variations in the percentages of the analysed lipid classes, alkanes, esters, aldehydes, β‐diketones and alcohols, between epi‐ and intracuticular lipids among individual cultivars, but no clear tendency in these variations, except for the aldehydes, was found. The epicuticular lipids were richer in aldehydes than the intracuticular lipids. The cuticular transpiration rates were poorly correlated with the levels or composition of epi‐, intra‐ or total cuticular lipids. The cuticular transpiration rates were considerably altered as a response to a water stress treatment, but these changes could not be correlated with any changes in amount or composition of the cuticular lipids. From these results it is concluded that some property other than amount or composition of cuticular lipids is the most important in regulation of water diffusion through the cuticle.

Changes in lipoprotein composition during larval-pupal metamorphosis of an insect, Manduca sexta.

During the transition from the last feeding larval stage to the pupal stage of the tobacco hornworm, Manduca sexta, significant changes occur in the properties of lipophorin, the major hemolymph lipoprotein. Within the first 24 h after cessation of feeding, the larval lipophorin (HDLp-L) is first converted to a higher density form (HDLp-W2) and then HDLp-W2 is converted to a lower density form (HDLp-W1). HDLp-W1 remains in the hemolymph until pupation, when another form, HDLp-P, with a density between HDLp-W1 and HDLp-L, is present. Although all the lipophorins contain identical apoproteins, they differ in lipid content and composition; the differences in density being primarily related to diacylglycerol content. The conversion of HDLp-L to HDLp-W1 is accompanied by a loss of hydrocarbon and uptake of carotenes. These latter changes in lipophorin composition reflect alterations in cuticular lipid composition. HDLp-L was radiolabeled in the apoproteins by injecting animals with 3H-amino acids early in the last larval stage. Subsequently HDLp-L was isolated at the end of the larval stage, HDLp-W2 and HDLp-W1 were isolated during the wandering stage, and HDLp-P was isolated after pupation. The specific activity of the apoproteins in the four lipophorins was not significantly different, suggesting that the observed alterations in lipophorin properties do not require synthesis of new apoproteins but result from retailoring the lipid composition of preexisting molecules. Examination of the hemolymph of individual animals during these transitions showed that only one species of lipoprotein was present, never a mixture of two or more species. These observations suggest that the lipoprotein conversions are precisely timed and that lipoprotein metabolism during larval development and pupation cannot be considered a static process. The unique finding of these studies was that synthesis of lipophorin apoproteins proceeds actively during the first part of the fifth instar but then ceases and does not recommence during the wandering or early pupal stages.

Composition of soluble cuticular lipids and water permeability of cuticular membranes from Citrus leaves

Water permeability and composition of soluble cuticular lipids of isolated cuticular membranes from leaves of Citrus aurantium L. were investigated for 3 successive years. The average water permeability coefficient determined using 169 cuticular membranes was 1.09·10(-7) cm s(-1) with a standard deviation of 0.78·10(-7) cm s(-1). There were no significant differences in water permeability between years. Cuticular membranes are characterized by a great variability in water permeability both within and between years. Both water permeability of individual membranes and variability between membranes are shown to be determined by soluble cuticular lipids contained within the cuticular membranes. The soluble cuticular lipids of Citrus leaves are composed of fatty acids, primary alcohols, esters, and hydrocarbons. They occur in amounts of 9.84 μg cm(-2), which represents approx. 3% of the total mass of isolated cuticular membranes. The specific weight of cuticular membranes (365.4 μg cm(-1)) and total amount of soluble cuticular lipids did not vary significantly between years. Significant differences were observed for the amounts and composition of the constituent classes of lipids. Six homologues comprise 86% of the fatty acids (C16; C18; C19; C21; C24; C26), 83% of the primary alcohols (C24; C26; C28; C30; C32; C34) and 88% of the esters (C36; C38; C40; C41; C42; C44). Eleven major homologues amount only to 62% of the total hydrocarbons (C16; C17; C18; C20; C26; C27; C29; C30; C31; C32; C33). Variability in the composition of soluble cuticular lipids between years was much smaller than variability of water permeability and, therefore, no relation between composition of soluble cuticular lipids and water permeability could be found. It is suggested that this may be due to the fact that the lipid composition observed represents the averages of 20 to 30 membranes analyzed so that differences between individual membranes may have been leveled out.

The Chemical Composition of Cuticular Lipids from Dragonflies (Odonata)

The cuticular lipids of 4 species (Aeschna grandis, A. mixta, Sympetrum sanguineum, S. danae) of the insect order Odonata (dragonflies) have been analysed. Alkanes, triglycerides, and free fatty acids predominate and minor amounts of monoester waxes have been detected. Among the hy­drocarbons unbranched odd-numbered (56 - 66%) predominate, followed by monometnyl-alkanes with the branch in the middle of molecule (11 - 19%), 3-methylalkanes (7 - 15%), and 2-me­thyl-alkanes (1 - 13%). Moreover, alkanes (1 - 12%) were detected. The composition of triglyceri­des and free fatty acids were very similar with 14 : 0, 16 : 0, 18 : 0, 16 : 1. 18 : 1 and 18 : 2 being main constituents. Ester waxes were composed of unbranched and predominantly even-numbered fatty acids and alcohols with chain lengths C14- C30. The results are discussed from a chemotaxonomic viewpoint. Similarities of the integumental lipjids from Odonata and Plecoptera were found.

Effect of anomalous cuticular phospholipids on penetration of insecticides in susceptible and resistant house flies

The cuticular lipid composition of resistant and susceptible strains of house flies ( Musca domestica L.) was altered by incorporation of dl-carnitine and 2-dimethylaminoethanol into the artificial diet under axenic conditions. β-Methyl-choline or 2-dimethylaminoethanol partially replaced the naturally occurring phospholipids (phosphatidyl choline and phosphatidyl ethanolamine) in the cuticular lipids of the adult of all strains. Effects of altered cuticular lipid composition on absorption of DDT, dieldrin, diazinon, parathion, and carbaryl in susceptible and resistant strains of house flies were studied. Upon incorporation of β-methyl-choline, the absorption pattern in the susceptible strain was decreased slightly, but this qualitative change caused increased absorption of DDT, dieldrin, diazinon, and parathion in one or more resistant strains. Incorporation of 2-dimethylaminoethanol changed the absorption pattern of insecticides in both susceptible and resistant strains of house flies to a slightly greater extent than did β-methyl-choline.

Sex-dependent composition of cuticular lipids from the beetle Rhagonycha fulva.

Sex-dependent composition of cuticular lipids from the beetle Rhagonycha fulva.

Critical temperature and changes in cuticular lipids in the rabbit tick, Haemaphysalis leporispalustris

The epicuticle in the rabbit tick, Haemaphysalis leporispalustris, appeared to be continuously changing, with deposition and removal of lipids during and after engorgement. These changes were accompanied by corresponding changes in critical temperature. The correlation between changes in critical temperature and composition of cuticular lipids (i.e. changes in the number, types, and relative concentration of lipid classes) suggested that changes in lipid composition could be responsible for changes in critical temperature. A hypothesis, alternative to those of Beament and Locke, is proposed to explain the phenomenon of critical temperature. At critical temperature, certain lipids probably change phase from crystal to liquid crystal, with hydrocarbon chains in a highly mobile condition. The hypothesis is not based on the presence of a water-proofing monolayer, and is supported by transition phenomena known in many lipids.

Cuticular lipids of insects

AbstractCuticular lipids cover nearly all parts of insect and are the chief agent for restricting water loss. The structure of insect epicuticles is reviewed, with emphasis on the role of cuticular lipids and the metabolism of cuticular lipids. The chemical composition of insect cuticular lipids are discussed with particular emphasis on the types in which hydrocarbons, was esters and fatty alcohols predominate. What little evidence is available on the biosynthesis of insect cuticular lipids is discussed.