Total lipid and fatty acid compositions of <Emphasis Type="Italic">Lertha sheppardi</Emphasis> (Neuroptera: Nemopteridae) during its main life stages

Total lipid and the fatty acid compositions of phospholipid and triacylglycerol fractions, prepared from eggs, 3^rd instars of larvae, pupae, male and female adults of Lertha sheppardi, were analyzed by gas chromatography and gas chromatography-mass spectrometry. The effect of diet (adults’ nutrition) on fatty acid composition of L. sheppardi adults was also investigated. Total lipid of L. sheppardi considerably increased in adults compared with immature stages. There was a significant decrease in total lipid level in larval stage in contrast with egg stage. Qualitative analysis revealed the presence of 14 fatty acids during all stages. The major components were C16 and C18 saturated and unsaturated components which are ubiquitous to most animal species. In addition to these components, one odd-chain (C17:0) and prostaglandin precursor fatty acids were found. The fatty acid profiles of phospholipids and triacylglycerols were substantially different. In phospholipid fraction, monounsaturated fatty acids were the major proportion of fatty acids in both sex of adults and pupae, whereas polyunsaturated fatty acids were the most dominant fatty acids in eggs and 3^rd instars. Results of triacylglycerol fraction revealed that fatty acid composition of eggs had higher level of C16:1, C18:0 and C18:3n-3 content than that of 3^rd instars and pupae, which suggests accumulation of energetic and structural reserve materials during embryonic development. At more advanced developmental stages, mainly in adult females, the amount of C16:1 increased once again, which may be related to the need for accumulation of sufficient energy and of carbon reservoir in the developing new vitellum. Percentages of C18:1 were significantly high in adult stages compared to other stages. These findings indicate that the accumulation and consumption of fatty acids fluctuate through different development stages. Diet did not effect the fatty acid composition of L. sheppardi adults.     

Changes in triacylglycerol, diacylglycerol and free fatty acids after fertilization in developing toad embryos

The content and fatty-acid composition of triacylglycerols, diacylglycerols and free fatty acids were analyzed from the unfertilized oocyte stage to the gastrula stage in the toad Bufo arenarum Hensel. Fertilization triggered a 30% and a 40% decrease in triacylglycerol and diacylglycerol, respectively. In contrast, free fatty acid increased continuously from oocyte to gastrula stage with an accumulation of palmitate predominating. However, the observed increase in free fatty acid was too small to account for the decreases in both neutral glycerides. The decrease in triacylglycerol might be a reflection of the activation of lipolytic enzymes and the subsequent oxidation of fatty acids to meet the increased metabolic energy requirements brought on by fertilization. The diminished diacylglycerol content due to fertilization may be accounted for, at least in part, by the utilization of diacylglycerol in the synthesis of membrane phospholipids, inasmuch as their decrease occurred simultaneously with an increase in phosphatidic acid. When cell-free homogenates taken from the three stages of development (unfertilized, fertilized and gastrula) were incubated in Tris-Ringer buffer for 90 min, free fatty acid accumulated. Triacylglycerol and diacylglycerol did not change substantially during this incubation period. This fact indicates that the free fatty acid released during incubation was not derived from neutral glycerides, but probably from membrane phospholipids. The release of free fatty acid was significantly greater in samples from the fertilized oocyte stage. The results described in this paper suggest that the synthesis of membrane phospholipids, including an enhanced turnover of the acyl moiety, plays a significant role in the metabolic events activated by fertilization.     

Enzyme activities involved in lipid metabolism during embryonic development of Macrobrachium borellii

The activities of the enzymatic systems involved in the activation and degradation of fatty acids, and in the synthesis of triacylglycerols and phospholipids were studied in vitro using total cellular homogenate and subcellular fractions of eggs of the shrimp Macrobrachium borellii at different developing stages. Egg development was divided into seven stages based on morphological features of the embryo. Palmitoyl-CoA ligase activity increased as the embryo developed and showed its maximum at stage V. An increase in the synthesis of triacylglycerols and diacylglycerols was also observed at this stage. Diacylglycerylethers were synthesized more actively during the first stages of development. The higher specific activity observed in total homogenate than in microsomal fraction suggested that their synthesis was not exclusively microsomal. Phospholipid synthesis was very active all along development, reflecting active membrane biosynthesis. The highest activity of the cytosolic triacylglycerol lipase was observed at stage V. Fatty acid degradation, measured as mitochondrial beta-oxidation activity, did not vary significantly during development. We conclude that both the anabolic and catabolic processes concerning lipid metabolism are very active, with values similar to those described for adult hepatopancreas, revealing the major role of lipids during shrimp embryogenesis energetics, and that the highest activities of lipid synthesis-hydrolysis take place at stage V when embryos are under active organogenesis. J. Exp. Zool. 286:231-237, 2000.     

Biochemistry of development in insects. Incorporation of fatty acids into different lipid classes.

1. To study the different metabolic behaviour of various stages of development of the insect Ceratitis capitata, the incorporation of labelled decanoic, lauric, myristic, palmitic, stearic, oleic, and linoleic acids into triacylglycerols by insect homogenates was investigated. The time-course of incorporation of labelled fatty acids was firstly studied by using oleic acid; it showed that after 10 min of incubation the levels of radioactivity incorporated into triacylglycerols and those remaining in the free fatty acids were practically unchanged. 2. All labelled fatty acids were efficiently incorporated by larval homogenates; however, most of the radioactivity remained as free fatty acids in the presence of pharate adult homogenates, palmitic, and stearic acids being the most scarcely incorporated by this stage of development of the insect. 3. Plots of triacylglycerol and free fatty acid radioactivites versus the stage of development defined a crossing-zone in coincidence with the larval-pupal apolysis. This metabolic difference between larval and pharate adult homogenates could not be explained through differences in the acyl-CoA synthetase activity of the insect; this enzyme activity was notably higher in pharate adult homogenates than in the larval homogenates whatever would be the nature of the fatty acid. 4. [14C]Triolein was scarcely hydrolyzed by both larval and pharate adult homogenates. 5. Double-label experiments were carried out by incorporating either [3H]oleic acid or [3H]-palmitic acid and [14C]glycerol 3-phosphate by larval and pharate adult homogenates at different incubation intervals. Diacylglycerols, triacylglycerols, and phosphoglycerides were isolated and the 14C/3H molar ratio calculated. Results suggest the existence of a different acyltransferase activity in the different stages of development of the insect.     

The impact of seasonal alteration in the lipid composition of broodstock diets on egg quality in the European sea bass

Groups of European sea bass Dicentrarchus labrax L., broodstock were fed two pelleted, lipid-enriched diets [maize oil, low essential fatty acid (EFA) or fish oil, high EFA]. Those fed the high EFA diet for 12 months or only during vitellogenesis (September to February) with the low EFA diet fed for the remaining 6 months, showed improved egg quality and higher hatching rates when compared to two groups fed the high EFA diet during either previtel-logenesis (February to September) or the spawning period (February to April). The higher quality eggs contained higher levels of total n-3 fatty acids, including increased levels of both docosahexaenoic acid (DHA) and eicosapaentaenoic acid (EPA). High levels of triacylglycerol (TAG) were linked with the poorer quality eggs from those groups fed the low EFA diet during the period of vitellogenesis. The present work identifies vitellogenesis as the period in the maturation during which EFA are incorporated most effectively into the developing oocytes.     

Changes in lipid class and fatty acid composition during development in white seabream (Diplodus sargus) eggs and larvae

To establish the changes which occur during embryogenesis and early larvae development, eggs, yolk-sac larvae (one day old larvae) and absorbed yolk-sac larvae (three day old larvae) of white sea bream were examined for lipid class and fatty acid composition. The development was characterized by a decrease in all lipid classes with the exception of phosphatidylserine (PS) and fatty free acids (FFA) which increased, and sphingomyelin (SM) which remained unchanged. The changes observed in lipid class content and the decrease in fatty acids in total lipid (TL) reflect the utilization and mobilization of lipids during both embryogenesis and early larvae development. Fluctuations in the relative composition of fatty acids in phosphatidylcholine (PC) during development suggest a selective bulk uptake and catabolism of fatty acids in this lipid class. Unlike PC, catabolism of triacylglycerol (TG) fatty acid appears to be non-selective. During development, the decrease in levels of polyunsaturated fatty acids (PUFA) eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) in total lipid denotes their utilization as energy substrate by Diplodus sargus larvae.     

Positional distribution of constituent fatty acids in phosphatidylethanolamine during early development in Rana nigromaculata

Qualitative and quantitative changes in phosphatidylethanolamine (PE) were analyzed in the eggs, embryos and tadpoles of the Japanese pond frog, Rana nigromaculata, at various stages of development. The weight percentage of PE to total phospholipid and to total lipid was about 15-18% and about 3-4%, respectively, during embryonic life. At all stages from the unfertilized egg to the feeding tadpole, the major fatty acids at the 1-position of PE were palmitic, stearic and oleic acids. At the 2-position, arachidonic, oleic, palmitic, stearic and linoleic acids were present during embryonic life. The most abundant fatty acid at the 2-position was arachidonic acid at the unfertilized egg and hatching embryo stages. However, palmitic acid was the most prevalent 2-fatty acid at the posthatching tadpole and the feeding tadpole stages. Thus, there were marked changes in the positional distribution of the constituent fatty acids in PE during development.     

Lipid and protein composition at different developmental stages of Pediculus capitis (Arthropoda, Phthiraptera).

Protein and lipid compositions were studied at different developmental stages of Pediculus capitis De Geer 1778. Phosphatidylcholine was found to be the predominant lipid at all stages and in both sexes. Palmitic and oleic acids were the main fatty acids throughout the 3 stages studied. A marked decline was observed in the total lipid content and triacylglyceride concentration during development, suggesting that their consumption is an energy source. The electrophoretic mobility revealed the predominance of a 320-kDa protein in eggs and adult females, whereas 2 major proteins of 514 and 439 kDa were found in nymphs, as well as in male and female adults. Two very high density lipoprotein fractions were isolated by ultracentrifugation of egg cytosol in a density gradient of NaBr. Both reserve lipoproteins contained phospholipids and triacylglycerols as the predominant lipids and a protein band of around 320 kDa. The structure of this band is likely to be similar to that found in females in a vitellogenic state.     

Characterization of the constituent fatty acids in phosphatidylinositol during early development in Rana nigromaculata

1. Qualitative and quantitative changes in phosphatidylinositol (PI) were analyzed in the eggs, embryos and tadpoles of the Japanese pond frog, Rana nigromaculata, at various stages of development. 2. The weight percentage of PI to total phospholipid and lipid was about 8.4-15.2% and 1.4-2.6%, respectively, during embryonic life. 3. At the early stages of the unfertilized egg and the two-cell embryo, the predominant fatty acids are palmitic, stearic, oleic and linoleic acid. From the dorsal lip, early gastrula stage and beyond, the percentage of linoleic acid declines and there is an increase in palmitoleic acid. A relatively large amount of arachidonic acid was noted at the unfertilized egg stage at the 1-position. 4. A large amount of arachidonic acid was also observed at the 2-position of PI in the unfertilized egg, hatching embryo and post-hatching tadpole stages, relative to palmitic and stearic acid. 5. Palmitic and stearic acid were increased at the 2-position of PI in the other embryo and the feeding tadpole stages, relative to arachidonic acid, indicating a shift in these molecular species. 6. Thus, there were marked changes in the positional distribution of the constituent fatty acids in PI during early development of R. nigromaculata.     

Egg yolk triglycerides during development of the domestic chicken

The triglycerides isolated from egg yolk lipids of eggs at various stages of incubation were fractionated according to the degree of unsaturation by argentation chromatography, and individual fractions were analyzed for their fatty acids by gas liquid chromatography. The proportions of the various fractions were constant during development. Fatty acid composition of the fractions were constant also. Fractions with one saturated fatty acid and two monoenoic fatty acids (SM₂) constituted over 40% of the total triglyceride. Palmitic acid constituted over 30%, and oleic acid over 45% of the fatty acid of total triglycerides. It is suggested that during development of thick embryo there is no selective utilization of the egg yolk triglycerides.     

Effect of acute streptozotocin diabetes on fatty acid content and composition in different lipid fractions of rat skeletal muscle.

The aim of the present study was to examine the effect of acute streptozotocin diabetes on long chain fatty acid content and composition in different lipid classes of particular muscle types in the rat. Two days after streptozotocin administration, rats were anesthetised, and the white and red sections of the gastrocnemius, the soleus and the blood were taken. Lipids were extracted with chloroform/methanol and separated into different fractions (phospholipids, free fatty acids, di- and triacylglycerols) by means of thin layer chromatography. Fatty acids of each fraction were identified and quantified by means of gas-liquid chromatography. The diabetes resulted in elevation of the concentration of blood glucose (over four-fold) and the plasma free fatty acid (over two-fold). Total free fatty acid content in the muscles of diabetic rats increased by 26% in the white, 24% in the red gastrocnemius and 21% in the soleus. There were also changes in the composition of that fraction in each muscle. Diacylglycerol fatty acid content was elevated in both parts of the gastrocnemius (the white part by 15%, the red part by 44%) and remained stable in the soleus of the diabetic rats. The content of triacylglycerol fatty acids was elevated only in the red gastrocnemius in the diabetic group (by 112%), but changes in fatty acid composition in this fraction occurred in each muscle. The content of phospholipid fatty acids was elevated in the white gastrocnemius (by 13%) and remained stable in other muscles. There were only minor changes in phospholipid fatty acid composition in the diabetic rats. We concluded that acute insulin deficiency changes fatty acid content and composition in skeletal muscle lipids. The changes depend both on lipid fraction and muscle type.     

Biosynthesis of triacylglycerols by rat intestinal mucosa in vivo.

The structure of mucosal triacylglycerols was studied in rat intestinal mucosa in vivo during the absorption of a low molecular weight fraction of butter oil and of the corresponding free fatty acids of medium and long chain length. The mucosal lipids were isolated by solvent extraction and the acylglycerol structures were determined by combined AgNO3- thin-layer chromatography and gas-liquid chromatography techniques and stereospecific analysis. Evidence was obtained for a rapid biosynthesis of triacylglycerols from diacylglycerols arising from the operation of both the monoacylglycerol and the phosphatidic acid biosynthetic pathways. Both sn-1,2- and sn-2,3-diacylglycerols appeared to be converted to triacylglycerols at significant rates, but a preferential utilization of sn-1,2-diacylglycerols could not be excluded. Endogenous dilution varied from a miniumum of 5% during triacylglycerol biosynthesis from monoacylglycerols to 15% during their synthesis from free fatty acids, and was characterized by a preferential placement of the endogenous acids in the sn-3 and 2 positions of the triacylglycerol molecules. Exogenous myristic acid was preferentially associated with the sn-3 position, and stearic acid became preferentially bound to the sn-1 position. The complexity of the triacylglycerol end products prevented an exact estimate of the contribution of the phosphatidic acid pathway, but the acylglycerol structures were compatible with a minimum of 20% of total triacylglycerol yield at all times.     

Triacylglycerol biosynthesis in everted sacs of rat intestinal mucosa.

The molecular specificity of the biosynthesis of triacylglycerols by rat intestinal mucosa was examined by means of radioactive and mass tracers, and thin-layer chromatography with silver nitrate and gas-liquid chromatography with radioactivity monitoring. Bile salt micelles of alternately labeled monoacylglycerols and free fatty acids were incubated with everted sacs of intestinal mucosa for various periods of time and the triacylglycerols isolated by solvent extraction and thin-layer chromatography. Analyses of the molecular species of the triacylglycerols labeled from monoacylglycerols showed that the 2-monoacylglycerol pathway was responsible for the biosynthesis of a maximum of 90% and the X-1-monoacylglycerol pathway for about 10% of the total radioactive triacylglycerols. Detailed analyses of the molecular species of triacylglycerols labeled fro free fatty acids showed that the phosphatidic acid pathway contributed a minimum of 20-30% of the total labeled triacylglycerol formed. There was a preferential utilization in triacylglycerol biosynthesis of the more unsaturated diacylglycerols arising from the monoacylglycerol pathway and of the more saturated diacylglycerols originating from the phosphatidic acid pathway. The above experiments do not allow a demonstration of the utilization of the sn-2,3-diacylglycerols in triacylglycerol biosynthesis but are not inconsistent with it.     

Substrate specificities of lipases from corn and other seeds

Lipases from several seed species were shown to be relatively specific on triacylglycerols containing the major fatty acid components of the storage triacylglycerols in the same species. In a direct comparison using individual triacylglycerol as well as mixed triacylglycerol preparations, highest activities were observed in corn lipase on trilinolein and triolein, castor bean lipase on triricinolein, rapeseed lipase on trierucin, and elm seed lipase on tricaprin. This pattern of fatty acyl specificity was also observed on diacylglycerols, monoacylglycerols, and fatty acyl 4-methylumbelliferone, although the pattern became less distinct. The seed lipases were inactive on lecithins. Corn lipase was more active on tri- than di- or monolinolein, and released linoleic acids from both primary and secondary positions. As judged from the kinetics of hydrolysis of rac-glyceryl-2,3-stearate-1-oleate and rac-glyceryl-1,3-stearate-2-oleate, and of trilinolein and dilinoleins, corn lipase exerted some degree of preference in releasing fatty acid from the primary than the secondary position of a triacylglycerol. At the primary position, corn lipase was more active on oleyl ester than stearyl ester.     

Influence of nitrogen deficiency on biochemical composition of the green alga <Emphasis Type="Italic">Botryococcus</Emphasis>

A study has been carried out to investigate the influence of nitrogen deficiency on intracellular lipid composition, including total fatty acid composition of lipids, polar lipids, and triacylglycerols, of the alga Botryococcus braunii Kütz IPPAS H-252 in batch culture. Under nitrogen limitation, the alga accumulates lipids as triacylglycerols and the total fatty acid (FA) composition changes: trienoic acids decrease (from 52.8–57.2 to 19.5–24.7% of the total FAs) and the oleic acid increases (from 1.1–1.2 to 17.1–24.4%) as does the saturated acids (from 23.7–26 to 32.9–46.1%). A similar rearrangement in the FA spectrum occurs at later times in the control culture, but it is less pronounced. Under nitrogen limitation, considerable changes in the polar lipid FAs are registered at day 13: saturated acids increase (from 28.6–35.5 to 76.8%) and all polyenoic acids markedly decrease (from 56.9–64.1 to 6.8%). Changes in the triacylglycerol fatty acid spectrum are seen on day 7: the oleic acid increases (from 14.7 to 34.2%) and remains at a high level till the end of the culture. In the control, triacylglycerols with large contents of oleic acid are detected at day 13, the total lipids and triacylglycerols still remaining unchanged.     

In vitro and in vivo synthesis of long-chain fatty acids from (1-14C) acetate in the renal papillae of rats.

1. The relationship between the rate of [1-14C] acetate incorporation into the fatty acids of renal papillary lipids and the acetate concentration in the medium has been measured. 2. [1-14C] acetate was incorporated mainly into fatty acids of phospholipids and triacylglycerols. Only a few per cent of the radioactivity was found in the free fatty acid fraction. 3. The major part of the [1-14C] acetate was found to be incorporated by a chain elongation of prevalent fatty acids. The major component of the poly-unsaturated fatty acids in triacylglycerols and the major product of fatty acid synthesis from [1-14C] acetate in vitro was demonstrated by mass spectrometry to be docosa-7,10,13,16-tetraenoic acid. 4. The radioactivity of docosa-7,10,13,16-tetraenoic acid accounted for 40% of total radioactivity in triacylglycerol fatty acids (lipid droplet fraction) and 20% of total radioactivity in membrane phospholipid fatty acids.     

Subcellular Metabolite and Lipid Analysis of Xenopus laevis Eggs by LAESI Mass Spectrometry

Xenopus laevis eggs are used as a biological model system for studying fertilization and early embryonic development in vertebrates. Most methods used for their molecular analysis require elaborate sample preparation including separate protocols for the water soluble and lipid components. In this study, laser ablation electrospray ionization (LAESI), an ambient ionization technique, was used for direct mass spectrometric analysis of X. laevis eggs and early stage embryos up to five cleavage cycles. Single unfertilized and fertilized eggs, their animal and vegetal poles, and embryos through the 32-cell stage were analyzed. Fifty two small metabolite ions, including glutathione, GABA and amino acids, as well as numerous lipids including 14 fatty acids, 13 lysophosphatidylcholines, 36 phosphatidylcholines and 29 triacylglycerols were putatively identified. Additionally, some proteins, for example thymosin β4 (Xen), were also detected. On the subcellular level, the lipid profiles were found to differ between the animal and vegetal poles of the eggs. Radial profiling revealed profound compositional differences between the jelly coat vitelline/plasma membrane and egg cytoplasm. Changes in the metabolic profile of the egg following fertilization, e.g., the decline of polyamine content with the development of the embryo were observed using LAESI-MS. This approach enables the exploration of metabolic and lipid changes during the early stages of embryogenesis.     

The anomalous kinetics of coupled aspartate aminotransferase and malate dehydrogenase. Evidence for compartmentation of oxaloacetate.

The optimum cofactor requirements for triacylglycerol biosynthesis in rat adipose-tissue homogenates containing mitochondrial, microsomal and cytosolic fractions were investigated. In general the optimum concentrations of cofactors for triacylglycerol biosynthesis were found to differ from those for total fatty acid esterification. The results provided further evidence for the key role of phosphatidate phosphohydrolase in the regulation of triacylglycerol biosynthesis. Albumin was included in the incubation medium to permit the use of concentrations of added fatty acids that would swamp the effects of endogenous fatty acids. The addition of albumin had little effect on the incorporation of palmitic acid and stearic acid into lipids including triacylglycerols. By contrast, a critical concentration of albumin (about 60 muM) was required before incorporation of oleic acid or linoleic acid into triacylglycerols occurred. The system was used to study the incorporation of different 1-14C-labelled fatty acids from a mixture of unesterified fatty acids [palmitic acid 30%; stearic acid 10%; oleic acid 40%; linoleic acid 20% (molar percentages)] separately into the positions 1,2 and 3 of triacyl-sn-glycerols. In general the stereo-specific distribution of the labelled fatty acids incorporated into triacylglycerols paralleled the normal distribution of fatty acids within rat adipose-tissue triacylglycerols, suggesting that the specificities of the relevant acyltrasferases have the major role in determining the positional distribution of fatty acids within triacylglycerols.     

Fatty acid composition and lipid synthesis in developing safflower seeds

Linoleic acid predominated in every lipid class during the whole period of seed development of safflower, while linolenic acid decreased with increasing maturation and it was not detected in mature seeds. Just before the initiation of triacylglycerol accumulation, the fatty acid composition of triacylglycerols changed more rapidly than those of phospholipids and glycolipids. Saturated fatty acids tended to accumulate at the 1- and 3-positions of the glycerol molecule and the more highly unsaturated acids at the 2-position. The fatty acid compositions at the 1- and 3-positions were similar in all cases investigated, but in none of the triacylglycerols was the distribution completely symmetrical. The positional distribution of linolenic acid in triacylglycerols prepared from the immature seeds 2 days after flowering and from the leaves was unusual; in spite of its highest degree of unsaturation, it was preferentially esterified at the 1- and 3-positions. When triacylglycerol was most rapidly accumulated (14–18 days after flowering), the incorporation of acetate-[U- ¹⁴C] into total lipids was also maximum and dienoic fatty acids were the principal acids labelled. Diacylglycerols and compound lipids reached the highest rate of synthesis 15 days after flowering, and then a maximum incorporation into triacylglycerol occurred 18 days after flowering. Incubation temperature affected the synthesis of individual lipid classes. Triacylglycerol was more rapidly synthesized at 32° than at 10°, while diacylglycerols and compound lipids were accumulated under the low-temperature condition. A rise of incubation temperature caused a depression in dienoic acid synthesis.     

Characterization of triacylglycerols from overwintering prepupae of the alfalfa pollinator Megachile rotundata (Hymenoptera: Megachilidae)

Alfalfa leafcutting bees, Megachile rotundata (F.), overwinter as prepupae. The internal lipids were extracted from prepupae that had been wintered at 4 degrees C for 7 months. Megachile rotundata prepupae possessed copious quantities of internal lipids (20% of the fresh weight) that were extracted with CHCl3/methanol (2:1). Transmission electron microscopy revealed that lipids were stored within very large intracellular vacuoles. Separation by silica chromatography revealed that 88% of the internal lipids were triacylglycerols. Ester derivatives of fatty acids from triacylglycerol components were analyzed by gas chromatography-mass spectrometry and 15 fatty acid constituents were identified. The majority (76%) of the triacylglycerol fatty acids were unsaturated fatty acids. The major triacylglycerol fatty acid constituent (30%) was the C16 monounsaturated fatty acid, palmitoleic acid (16:1, hexadec-9-enoic acid), with substantial amounts of linolenic acid (18:3, octadec-9,12,15-trienoic acid, 15%), palmitic acid (16:0, hexadecanoic acid, 14%) and oleic acid (18:1, octadec-9-enoic acid, 13%). Palmitoleic acid as the major fatty acid of an insect is an unusual occurrence as well as the presence of the 16-carbon polyunsaturated fatty acids, 16:2 and 16:3. The major intact triacylglycerol components were separated and identified by high performance liquid chromatography-mass spectrometry. A complex mixture of approximately 40 triacylglycerol components were identified and major components included palmitoyl palmitoleoyl oleoyl glycerol, palmitoyl palmitoleoyl palmitoleoyl glycerol, myristoyl palmitoleoyl palmitoleoyl glycerol, myristoleoyl palmitoyl palmitoleoyl glycerol, and palmitoyl palmitoleoyl linolenoyl glycerol. The function of these internal lipids and their relevance to winter survival and post-wintering development of M. rotundata is discussed.