Long-chain polyenoics and the essential dietary fatty acid requirement of the waxmoth, Galleria mellonella

The essential fatty acid requirement for normal pupal-adult ecdysis in Galleria mellonella was studied using non-axenic casein-based semisynthetic diets with or without various 99% pure fatty acids. The abilities of linoleic and linolenic acids to alleviate faulty adult emergence differed markedly, linolenic acid being 10-fold more potent than linoleic acid. One other ω6 polyunsaturated fatty acid, C20:2ω6, resembled its analogue, linoleic acid (18:2ω6), in efficacy at high dosage, but three others, C18:3ω6, C20: ω6 and C20:4ω6 (arachidonic acid), were without effect. Of five ω3 polyunsatures tested, C22:3ω3 and C20:3ω3 were as effective as linolenic acid (C18:3ω3), their shorter-chained analogue. Docosahexaenoic acid (C22:6ω3) was totally ineffective, but eicosapentaenoic acid (C20:5ω3), though supporting no perfect emergences, produced some active adults having wing malformations only, and was therefore considered partially active. It is suggested that a C18 polyunsaturate is physiologically required by G. mellonella and can be derived from various dietary longer-chained analogues by simple carbon chain shortening so long as there are no additional double bonds carboxylwards of an active di- or trienoic sequence. The partial activity of C20:5ω3 suggests there may additionally be a physiological requirement for this or a related long-chain polyunsaturate. The possibility of multiple essential fatty acid requirements in Lepidoptera in general is discussed.     

Essential fatty acid for the mosquito Culex pipiens: arachidonic acid.

A nutrient associated with animal-derived phospholipids has previously been found essential for newly-emerged adults of the mosquito Culex pipiens to fly and survive more than a few days. Pure arachidonic acid was completely effective in supporting the emergence of viable flying adults; in combination with synthetic dipalmitoyl lecithin, which slightly improves larval growth rate without inducing adult flight, it wholly adequately replaces animal phospholipids. Linoleic and linolenic acids, which have satisfied the needs of all insects hitherto shown to require an essential fatty acid, were ineffective for C. pipiens, with or without synthetic lecithin. An optimal effect on adult flight was obtained with 0.05 mg of arachidonic acid per 100 ml of dietary medium, a concentration much lower than the linoleic/linolenic concentrations needed by other insects with an essential fatty acid requirement. The relationship of this unique mosquito fatty acid requirement to the essential fatty acid needs of both vertebrates and insects in general is discussed.     

Interaction of larval age and dietary formaldehyde on the susceptibility of tufted apple budmoth (Lepidoptera: Tortricidae)to Bacillus thuringiensis

Laboratory tests of Bacillus thuringiensis var. kurstaki (strain HD-1) against Platynota idaeusalis reared on a semisynthetic diet showed that the LC₅₀ values for neonates and 9-day-old larvae showed no significant difference in susceptibility; however, 14-day-old larvae were significantly more susceptible than neonates or 9-day-old larvae. There was no evidence of any interaction between 14-day-old larvae reared on the semisynthetic diets with and without formaldehyde and B. thuringiensis toxicity at any assessment reading. Likewise the toxicity of B. thuringiensis to 14-day-old larvae reared on apple leaves did not differ from the B. thuringiensis toxicity of 14-day-old larvae reared on semisynthetic diets with and without formaldehyde.     

食物中多不饱和脂肪酸在家蝇幼虫体内的富集与代谢及对其生长的影响

【目的】阐明家蝇 Musca domestica 幼虫对食物中各种多不饱和脂肪酸的富集能力以及代谢转化情况,并探究各种多不饱和脂肪酸对家蝇幼虫生长的影响。【方法】在基础饲料中添加不同浓度(3%, 6%和12%)的多不饱和脂肪酸(亚油酸、α-亚麻酸、花生四烯酸和二十二碳六烯酸)饲养经过脱脂传代培养的家蝇幼虫;提取家蝇幼虫的总脂肪酸,利用气相色谱仪进行检测和分析;测定统计幼虫体重,以分析多不饱和脂肪酸对家蝇幼虫生长的影响。【结果】亚油酸、α-亚麻酸和花生四烯酸在家蝇幼虫体内均能被富集,且它们的富集程度随着食物中多不饱和脂肪酸的添加浓度的升高而增加,其中亚油酸、α-亚麻酸和花生四烯酸在幼虫体内富集的最高含量(占体内总脂肪酸的比例)分别为21.93%, 16.13%和9.68%,而二十二碳六烯酸不能在家蝇幼虫体内富集,提示家蝇幼虫食物中添加的各种多不饱和脂肪酸经过代谢后并没有在其体内产生新的脂肪酸,而食物中添加的二十二碳六烯酸在家蝇幼虫体内被分解代谢后消除。饲喂α-亚麻酸及花生四烯酸后家蝇幼虫体重增长较为明显,其中6%α-亚麻酸添加组的幼虫体重显著高于对照组(取食脱脂饲料)和3%和12%α-亚麻酸添加组,3%和6%花生四烯酸添加组的幼虫体重显著高于对照组和12%花生四烯酸添加组。【结论】家蝇幼虫体内能够从食物中富集部分多不饱和脂肪酸,多不饱和脂肪酸碳链越长其富集程度越低直至不能富集,富集的多不饱和脂肪酸对家蝇幼虫生长有不同程度的影响。     

Arachidonic and other tissue fatty acids of Culex pipiens reared with various concentrations of dietary arachidonic acid

Chloroform/methanol extracts were prepared from groups of Culex pipiens reared in synthetic dietary media provided with various concentrations of arachidonic acid. Extracts were analyzed by gas-liquid chromatography to determine the fatty acid composition of whole extracts and also of phospholipid and triacylglycerol fractions separated by thin-layer chromatography from the whole extracts. The same extracts were also tested for their ability to support flight of adult C. pipiens reared in basal synthetic diet containing various concentrations of the extracts: this provided a bioassay for the presence of arachidonic acid or related polyunsaturates in the extracted lipid, since adults can fly only if provided, as larvae, with dietary arachidonic or related fatty acids. For comparison, chromatographic and bioassay data obtained from normal stock mosquitoes, reared in crude septic medium, are also presented. All extracts were shown by gas-liquid chromatography to contain some arachidonic acid and other polyunsaturated fatty acids. The proportions of arachidonic acid in extracts from mosquitoes reared in synthetic media were greater the greater the concentration of dietary arachidonic acid provided; and in the bioassay, extracts induced more flight activity in test mosquitoes the higher the dietary arachidonic acid provided for extracted mosquitoes. Extracts from stock-reared mosquitoes were more active in the bioassay than synthetic dietreared extracts, even though gas-liquid chromatography indicated lower proportions of arachidonic acid in stock-reared extract. However, stock-reared extract contained a substantial proportion of gammalinolenic acid, which is flight active for C. pipiens, as well as more linolenic acid and a large amount of linoleic acid, both of which are semi-active for flight; thus, stock-reared extract contained a higher overall proportion of flight-inducing fatty acids. Proportions of polyunsaturates in the phospholipid fractions of extracts from synthetic diet-reared mosquitoes were much greater than in the unfractionated extracts, whereas polyunsaturates were virtually absent from the triacylglycerol fractions, indicating a sequestering of polyunsaturates into phospholipids.     

Effect of varying levels of dietary essential fatty acid during early ontogeny of the sea scallop Placopecten magellanicus

This study investigated the biological effects of various dietary essential fatty acids levels to sea scallop larvae, Placopecten magellanicus. Scallop larvae were fed three diets from D-veliger to settlement. Diet A consisted of Isochrysis sp. and Pavlova lutheri, diet B was a mix of Isochrysis sp. and Chaetoceros muelleri and diet C consisted of the same two species, but C. muelleri was grown under silicate deprivation to alter the fatty acid composition. Pediveligers (28 days old) were sampled prior to settlement for fatty acid analysis, growth measurement and survival assessment. Survival and settlement success were measured at the end of the experiment (day 40). Our results show that feeding regime greatly influenced larval size, settlement and fatty acid composition. Diet A was severely deficient in arachidonic acid (20:4n-6, AA), leading to the poorest larval growth, survival and lipid content. Nevertheless, larvae fed diet A selectively accumulate AA by a factor three compared to the dietary amount. Shell size of 28-day-old larvae was positively correlated with AA content and negatively correlated with eicosapentaenoic acid (20:5n-3, EPA)-AA ratio, thus suggesting that these two variables are of major interest for the optimisation of larval growth in sea scallops. Finally, larvae fed diet C displayed 20% higher shell size at day 28 than larvae fed diet A and B, likely in relation to the dietary amount of saturated fatty acid (SFA). However, the moderate survival and settlement success of these groups of larvae might be associated with a relative deficiency in docosahexaenoic acid (22:6n-3, DHA). This study underlines that the overall balance between polyunsaturated fatty acid (PUFA) needs to be considered to adequately fed sea scallop larvae.     

Activities of hormone metabolizing enzymes in house flies treated with some substituted urea growth regulators.

The insect growth regulators (IGR) TH 6038 and TH 6040 affect larvae of various species by interfering with cuticle development. In a biochemical study of their effects, larvae of the house fly, $\text{Musca domestica}$ L. were reared for 2 days on diets containing 1.7 to 166.7 ppm of these compounds, then assayed for activities of the microsomal oxidases and the enzyme(s) which metabolize β-ecdysone. The activities of these enzymes were compared with the percentage of treated larvae completing pupal-adult ecdysis. The two compounds reduced the activity of the β-ecdysone metabolizing enzyme(s) by as much as 57%, reduced pupal-adult ecdysis by 43% to 100%, and stimulated microsomal oxidase activity 4- to 12-fold. Supplementation of the diet of the treated insects with the Cecropia juvenile hormone, JH I, partially restored pupal-adult ecdysis but supplementation with β-ecdysone had no effect. The mode of action indicated by these results is that the IGRs cause an accumulation of β-ecdysone in the treated larvae. This stimulates the enzyme, chitinase, which degrades chitin in preparation for formation of the new cuticle. The hormone may also cause a JH deficiency and the stimulation of DOPA decarboxylase and phenol oxidase which would further disrupt the normal molting process.     

Effect of storage on the fatty acid content of foods for post-larvae of the crustacean decapod Hippolyte inermis

Decapods are important in aquaculture practice and as models for marine biology research, due to peculiar endocrine and physiologic adaptations to various environments. For these reasons, decapods are cultivated. To promote their correct development and sexual maturation, the preparation of balanced diets is crucial. Several diets, both experimental and for aquaculture purposes, have been established, but the set of essential fatty acids is still unknown for most species. Furthermore, fatty acids contained in formulated feeds are differentially sensitive to decay over the storage time. Here we compare growth, maturation and mortality of post-larvae fed on a formulated diet containing Artemia sp., Spirulina sp. and a fatty acid integrator, as administered immediately after its production and after 12 months of storage. The same foods were analysed for their fatty acid contents using gas chromatography. The sets of fatty acids present in differently aged foods corresponded to differences in the growth rates and survival of the model organism Hippolyte inermis cultured in the laboratory. The differences were mainly due to seven fatty acids, whose abundance decreased during the storage, the most important of which were arachidonic and linolenic acid, that are known to be essential for other species of decapods.     

Fatty acid profile of the cabbage looper, Trichoplusia ni, and the effect of diet and rearing conditions

The fatty acids, palmitic (16:0), palmitoleic (16:1), stearic (18:0), oleic (18:1), linoleic (18:2), and linolenic (18:3) were measured by GLC in Trichoplusia ni (Hübn.) from larvae reared on three different diets. The effect of rearing temperature and humidity on the levels of these fatty acids in pupae and pharate adults was determined. T. ni tended to accumulate 18:3 somewhat in proportion to its level in the diet. The respective levels (relative percentage) of this fatty acid in the diet and in the pupae were: bean leaves, 73·6 and 56·7; the diet based on lima beans, 10·2 and 3·5; and a meridic diet containing wheatgerm oil, 5·6 and 1·8. Pupae from larvae reared on a diet marginal in 18:3 content produced adults with deformed wings when reared at 30°C and normal wings when reared at 23 or 24°C, but there was no difference in their tissue level of 18:3. The phospholipids of last instar larvae, pharate pupae, pupae, pharate adults, and emerged adults are made up mostly of 18:0, 18:2, and 18:3 while the triglycerides of these stages contain relative large quantities of 16:0, 16:1, and 18:1. Pupal rearing temperature did not appear to influence the level of 18:3 in these two fractions enough to account for the degree of deficiency expressed as adult wing deformity. Both high (95%) and low (20%) relative humidity have an adverse effect on wing development but this effect can be overcome by 18:3 supplementation of the larval diet.     

Fatty acid composition of Ruditapes decussatus spat fed on different microalgae diets

The fatty acid composition of the Ruditapes decussatus spat fed on three different microalgal diets during 4 weeks was determined. The fatty acid pattern of each diet was also analysed. The diets used were Isochrysis galbana, clone T-ISO, Tetraselmis suecica, and Phaeodactylum tricornutum. The fatty acid composition of the spat was usually well correlated with that of the diet supplied. Major differences among spat cultures were found in 14:0, 16:0, 16:1n-9, 16:1n-7, 18:1n-9, 18:2n-6, 18:3n-3, 18:4n-3, 20:5n-3, 22:5n-6 and 22:6n-3 fatty acids. These differences were correlated with the particular fatty acid content of each diet supplied. It has been shown that R. decussatus spat have a very low capacity to elongate and desaturate linolenic acid to n-3 PUFA, so when 20:5n-3 or 22:6n-3 were not present in the diet, they were also absent, at least in measurable amounts, in the clams. The absence of any of the “essential” fatty acids, 20:5n-3 in T-ISO or 22:6n-3 in Tetraselmis, did not limit spat growth, so their role as “essential” fatty acids might be a matter for discussion. Finally, the nutritive value of each diet was discussed in terms of its fatty acid composition.     

Lipids and fatty acids of the southwestern corn borer,Diatraea grandiosella

The lipids of the adults and of several immature stages of the southwestern corn borer, Diatraea grandiosella, were studied after they were fed natural corn stalks or artificial diets. Linoleic acid (18:2) was the major fatty acid of the neutral lipids in both the natural and the artificial diets, but aleic acid (18:1) was the principal neutral lipid in all insect stages. Also, linoleic acid and oleic acid were the principal acids in the insect phospholipids of all stages. The content of linoleic acid in the natural diet was also high, but that in the artificial diet appeared to be much too low for insect requirements. Phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) were the major phospholipids in all growth stages. Thus, in larvae diapausing in the field, the unsaturated fatty acid content of PC was 59·3 per cent, primarily 16:1 and 18:1, and PE was 87·4 per cent, primarily 18:1, 18:2, and 18:3, and the fatty acids in the number 1- and 2-positions of PC were 53·6 and 97·2 per cent unsaturated, respectively. The haemolymph of diapausing southwestern corn borer larvae contained primarily glycerides but also had some PC and PE. Fat body from diapausing larvae contained primarily 16:0, 16:1, and 18:1 in a ratio of 1 : 1 : 2. Thus lipids of the southwestern corn borer do not reflect dietary lipids as closely as do other insects studied.     

Long-Chain Omega-3 Polyunsaturated Fatty Acids Have Developmental Effects on the Crop Pest,the Cabbage White Butterfly Pieris rapae

Nutritional enhancement of crops using genetic engineering can potentially affect herbivorous pests. Recently, oilseed crops have been genetically engineered to produce the long-chain omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at levels similar to that found in fish oil; to provide a more sustainable source of these compounds than is currently available from wild fish capture. We examined some of the growth and development impacts of adding EPA and DHA to an artificial diet of Pieris rapae, a common pest of Brassicaceae plants. We replaced 1% canola oil with EPA: DHA (11:7 ratio) in larval diets, and examined morphological traits and growth of larvae and ensuing adults across 5 dietary treatments. Diets containing increasing amounts of EPA and DHA did not affect developmental phenology, larval or pupal weight, food consumption, nor larval mortality. However, the addition of EPA and DHA in larval diets resulted in progressively heavier adults (F _{4, 108} = 6.78; p = 0.011), with smaller wings (p < 0.05) and a higher frequency of wing deformities (R = 0.988; p = 0.001). We conclude that the presence of EPA and DHA in diets of larval P. rapae may alter adult mass and wing morphology; therefore, further research on the environmental impacts of EPA and DHA production on terrestrial biota is advisable.     

The influence of linoleic acid and linolenic acid on adult moth emergence of Homona coffearia from meridic diets in vitro

The fatty acids linoleic and linolenic acids have been found to be critical dietary supplements for the successful adult emergence of Homona coffearia reared in meridic diets in vitro. When the levels of these fatty acids were sub-optimal, the moths were able to emerge only partially and a few that emerged fully were deformed with naked wings. In the presence of optimal amounts of these fatty acids, the Δ⁷ sterol, ergosterol, available in the brewer's yeast provided in the diets was found to be adequate for growth and adult emergence. The availability of linoleic acid, which appeared to be the more critical requirement, was sufficient for successful adult emergence, provided that the diet was supplemented with additional amounts of ergosterol. The above two fatty acids seemed to be the only critical dietary supplements offered by whole tea leaves incorporated in a previously described oligidic diet. The provision of a dietary source of a Δ⁷ sterol was found essential as this insect was unable to utilize cholesterol.     

A search for an ‘Ouabain-like’ substance from the electric organ of Electrophorus electricus which led to arachidonic acid and related fatty acids

The electric organ of Electrophorus electricus contains substances which inhibit (Na⁺ + K⁺)-ATPase activity, the specific binding of [³H]ouabain to purified (Na⁺ + K⁺)-ATPase and ⁸⁶Rb⁺ uptake by chick cardiac cells in culture. The active organic material was extracted from microsomal membranes. Its purification was carried out by chromatography on Sep-Pak C-18 and thin-layer chromatography. Reverse-phase liquid chromatography and mass spectrometry identified the active material as a mixture of unsaturated fatty acids. Linoleic (18:2), arachidonic (20:4), linolenic (18:3) and docosahexaenoic acids (22:6) contributed to about 60% of the total activity of the active material. The other active substances could be arachidonic analogs, since they have both a lipophilic and carboxylic character. Pure unsaturated fatty acids have been shown to be active in the different biological assays used to analyze the endogenous ‘ouabain-like’ activity. Linolenic, arachidonic and docosahexaenoic acids were the most active, whereas saturated fatty acids and glyceryl esters or methyl esters of unsaturated fatty acids were inactive. It is possible that in pathological situations in which the level of unsaturated fatty acids increases, these molecules may then act as physiological inhibitors of the sodium pump.     

Lipid and fatty acid composition during embryo and larval development of puye Galaxias maculatus Jenyns, 1842, obtained from estuarine, freshwater and cultured populations

Galaxias maculatus eggs and larvae obtained from broodfish captured either in an estuarine or a freshwater environment, as well as from cultured broodstock were analysed to compare their lipid and fatty acid profiles. Results showed a lower lipid content in embryos and larvae from estuarine populations than those from fresh water, denoting the influence of environmental conditions. The n-3:n-6 ratio was higher in eggs from estuarine and cultured populations, being in the range of marine fishes, whereas for eggs from freshwater fish was lower and typical of freshwater fishes. The polyunsaturated fatty acids (PUFA), particularly docosahexaenoic acid (22:6n-3) and eicosapentaenoic acid (20:5n-3), were higher in eggs and larvae of broodstock coming from culture or estuarine environments than in those from fresh water. Moreover, these fatty acids markedly increased after hatching in larvae coming from estuarine populations, suggesting the effect of the environment on fatty acid profiles to physiologically prepare the larvae to adapt to higher salinity conditions. Linoleic acid (18:2n-6) content was higher in fresh water fish and its reduction during embryo and larval development was accompanied by a significant increase of arachidonic acid (20:4n-6), which was not observed in embryos or larvae from broodstock fish from estuary or aquaculture origin. Both environment and diet of broodstock fish affected lipid and fatty acid composition of G. maculatus embryo and larvae as well as their changes during development.     

Metabolism of n-3 polyunsaturated fatty acids and modification of phospholipids in cultured rabbit aortic smooth muscle cells

The metabolism of the linolenic acid family (n-3) of fatty acids, e.g., linolenic, eicosapentaenoic, and docosahexaenoic acids, in cultured smooth muscle cells from rabbit aorta was compared to the metabolism of linoleic and arachidonic acids. There was a time-dependent uptake of these fatty acids into cells for 16 hr (arachidonic greater than docosahexaenoic, linoleic, eicosapentaenoic greater than linolenic), and the acids were incorporated mainly into phospholipids and triglycerides. Eicosapentaenoic and arachidonic acids were incorporated more into phosphatidylethanolamine and phosphatidylinositol plus phosphatidylserine and less into phosphatidylcholine than linolenic and linoleic acids. Docosahexaenoic acid was incorporated into phosphatidylethanolamine more than linolenic and linoleic acids and into phosphatidylinositol plus phosphatidylserine less than eicosapentaenoic and arachidonic acids. Added linolenic acid accumulated mainly in phosphatidylcholine and did not decrease the arachidonic acid content of any phospholipid subfraction. Elongation-desaturation metabolites of linoleic acid did not accumulate. Cells treated with eicosapentaenoic acid accumulated both eicosapentaenoic and docosapentaenoic acids mainly in phosphatidylethanolamine and the arachidonic acid content was decreased. Added docosahexaenoic acid accumulated mainly in phosphatidylethanolamine and decreased the content of both arachidonic and oleic acids. The following conclusions are drawn from these results. The three n-3 fatty acids are utilized differently in phospholipids. The arachidonic acid content of phospholipids is reduced by eicosapentaenoic and docosahexaenoic acids, but not by linolenic acid. Smooth muscle cells have little or no desaturase activity, but have significant elongation activity for polyunsaturated fatty acids.     

UTILIZATION OF POLYUNSATURATED FATTY ACID SUPPLEMENTS BY CULTURED NEUROBLASTOMA CELLS1

Abstract— Brain phosphoglycerides are known to contain large amounts of polyunsaturated fatty acids (PUFA). However, neuroblastoma cells contain very low amounts of PUFA. Since the serum used for cell culture has been shown to be deficient in PUFA, a supplementation of this serum with various PUFA was undertaken. Linoleic, arachidonic and docosahexaenoic acids were incorporated in cell phosphoglycerides, mainly at the expense of oieic acid, while linolenic acid was only poorly incorporated. Linoleic. linolenic and arachidonic acids were transformed to their elongation and desaturation products; but the last step of transformation, which involves the action of a Δ 4 desaturase, was never observed. The levels of incorporation and transformation of exogenous PUFA could vary strikingly in different lines of neuroblastoma cells. The simultaneous addition of two PUFA (linoleic and linolenic acids) was followed by a reduction in the amount of their respective derivatives in cell phosphoglycerides. compared to that obtained when only one PUFA was given to the cells, suggesting a competitive inhibition of the desaturation of each PUFA. Such alterations in membrane lipids may provide a useful model for the study of membrane structure-function relationships.     

Growth and fatty acid composition of freshwater prawn, Macrobrachium rosenbergii, larvae fed diets containing various ratios of cod liver oil–corn oil mixture

A feeding trial was conducted to determine the effect of replacing costly cod liver oil with corn oil as a source of dietary lipid on the growth and fatty acid composition of the larval freshwater prawn, Macrobrachium rosenbergii de Man. Prawn larvae were weaned to artificial diets containing cod liver oil and corn oil either singly or in various combinations (2 : 1, 1 : 1, 1 : 2, w/w). Weaning to artificial diets from Artemia nauplii commenced at larval stage III with complete substitution by stage X. The reference group was reared solely on Artemia nauplii during the entire experiment. Incorporation of corn oil at 33–67% of dietary supplemental oil did not have significant effects on the post‐larval production. However, larvae fed with corn oil alone revealed a significantly lower post‐larval production compared to other experimental diets as well as to the reference group. No significant differences (P > 0.05) were observed in dry weight, protein and lipid concentration among larvae fed on various dietary treatments. Palmitic (16 : 0) and oleic/vaccenic (18 : 1) acids were the dominant saturated and monounsaturated fatty acids in larval tissues, respectively, whereas the polyunsaturated fraction was dominated by eicosapentaenoic (20 : 5n‐3) acid. The polyunsaturated fatty acid composition was dominated by n‐3 acids rather than n‐6 fatty acids. The fatty acid composition of the prawn in general reflected that of the diet. Larvae on diets containing higher concentrations of corn oil rich in linoleic (18 : 2n‐6) acid showed a higher concentration of this acid in their tissues. No evidence of de novo synthesis of linoleic (18 : 2n‐6) acid was found. Higher levels of stearic (18 : 0), arachidonic (20 : 4n‐6) and eicosapentaenoic (20 : 5n‐3) acids found in larvae as compared with those fed Artemia and artificial diets strongly indicated the larval ability in chain elongation and desaturation of palmitic (16 : 0), linoleic (18 : 2n‐6) or linolenic (18 : 3n‐3) acids, respectively. Despite a large variation of n‐3 to n‐6 ratios of the live and artificial diets, larval n‐3 to n‐6 ratios were relatively stable among different dietary treatments, possibly indicative of the importance of such a ratio in the larval fatty acid metabolism.     

Dynamics of follicle development and lipid storage in the tsetse fly Glossina palpalis palpalis fed on serum albumin deficient diets

Females of Glossina p. palpalis were fed on a mixture of bovine erythrocytes and a serum substitute which had been lyophilized, for a period of 30 days. The rate of ovarian development and lipid incorporation and the fatty acid composition of whole flies were examined at five-day intervals. Results showed that in flies fed serum albumin-deficient diets, ovarian development was seriously impaired and ovulation did not take place. Flies which were fed on a serum albumin-containing diet ovulated and produced larvae, though at a lower rate than control flies. Compared with controls, lipid incorporation was reduced in experimental flies, but more in the albumin-deficient group than in the albumin-containing group. The diet composition had no marked influence on the relative composition of fatty acids in any one group. It is concluded that, though an essential nutritional element for cow blood fed G. p. palpalis, serum albumin was not the only missing essential factor in the diets that were used in this study.     

The effects of unsaturated fatty acids on hepatic microsomal drug metabolism and cytochrome P-450

1. The effects of unsaturated fatty acids on drug-metabolizing enzymes in vitro were measured by using rat and rabbit hepatic 9000g supernatant fractions. 2. Unsaturated fatty acids inhibited the hepatic microsomal metabolism of ;type I' drugs with inhibition increasing with unsaturation: arachidonic acid>linolenic acid>linoleic acid>oleic acid. Inhibition was independent of lipid peroxidation. Linoleic acid competitively inhibited the microsomal O-demethylation of p-nitroanisole and the N-demethylation of (+)-benzphetamine. 3. The hepatic microsomal metabolism of ;type II' substrates, aniline and (-)-amphetamine, was not affected by unsaturated fatty acids. 4. The rate of reduction of p-nitrobenzoic acid and Neoprontosil was accelerated by unsaturated fatty acids. 5. Linoleic acid up to 3.5mm did not decelerate the generation of NADPH by rat liver soluble fraction, nor the activity of NADPH-cytochrome c reductase of rat liver microsomes. Hepatic microsomal NADPH oxidase activity was slightly enhanced by added linoleic acid. 6. No measurable disappearance of exogenously added linoleic acid occurred when this fatty acid was incubated with rat liver microsomes and an NADPH source. 7. The unsaturated fatty acids used in this study produced type I spectra when added to rat liver microsomes, and affected several microsomal enzyme activities in a manner characteristic of type I ligands.