A new component of the female sex pheromone ofBlattella germanica (L.) (Dictyoptera: Blattellidae) and interaction with other pheromone components

A fourth component, 3,11-dimethyi-2-heptacosanone, was identified as a cuticular contact sex pheromone of the female German cockroach,Blattella germanica. In behavioral assays, higher dosages of 3,11-dimethyl-2-heptacosanone were needed to elicit similar sexual responses in males to those elicited by the major pheromone component, 3,11-dimethyl-2-nonacosanone. A 15∶85 blend of the C27 and C29 methyl ketone homologs resulted in a dose-response curve intermediate between that of each of the components alone, indicating independence of activity of each component and lack of synergism. Moreover, the activity of 3,11-dimethyl-2-nonacosanone was not enhanced by female cuticular hydrocarbons. The relationship between sexual responses of males to females and to isolated female antennae, and the amount of cuticular pheromone on whole females was investigated. Cuticular sex pheromone found on females increased with the age of the female, as did the male response to whole females. However, a bimodal male response was elicited by isolated female antennae. Differences between behavioral and analytical assays of pheromone are discussed.

Structural correlation between cuticular hydrocarbons and female contact sex pheromone of German cockroachBlattella germanica (L.)

The structural relationships between the cuticular hydrocarbons and the contact sex pheromone of the female German cockroach,Blattella germanica, were investigated. Cuticular hexane extracts were separated into hydrocarbon and ketone fractions by TLC or silicic acid column chromatography. The ketone fraction (which contains the major contact sex pheromone component) was analyzed by GC-MS before and after reduction to ydrocarbon. In addition to 3,11-dimethyl-2-nonacosanone, 3,11-dimethyl-2-heptacosanone was also identified. Females have the 3,11- and 3,9-dimethyl C27 and C29 alkanes, but only the 3,11- isomer of the dimethylketones. Inddition to the hydrocarbon components previously reported, a number of new components were characterized. Although the ratios of cuticular hydrocarbons differ among nymphs, adult males, and adult females, they have qualitatively identical hydrocarbon profiles, suggesting that the production of the contact sex pheromone results from the sex-specific oxidation of 3,11-imethylalkanes to pheromone components by the female.

Identification and characterization of the pyrokinin/pheromone biosynthesis activating neuropeptide family of G protein-coupled receptors from Ostrinia nubilalis

Insects have two closely related G protein-coupled receptors belonging to the pyrokinin/pheromone biosynthesis activating neuropeptide (pyrokinin/PBAN) family, one with the ligand PBAN or pyrokinin-2 and another with diapause hormone or pyrokinin-1 as a ligand. A related receptor is activated by products of the capa gene, periviscerokinins. Here we characterized the PBAN receptor and the diapause hormone receptor from the European corn borer, Ostrinia nubilalis. We also identified a partial sequence for the periviscerokinin receptor. Quantitative PCR of mRNA for all three receptors indicated differential expression in various life stages and tissues. All three splice variants of the PBAN receptor were identified with all variants found in pheromone gland tissue. Immunohistochemistry of V5 tags of expressed receptors indicated that all three variants and the diapause hormone receptor were expressed at similar levels in Spodoptera frugiperda 9 (Sf9) cells. However, the A- and B-variants were not active in our functional assay, which confirms studies from other moths. Functional expression of the C-variant indicated that it is has a 44 nM half effective concentration for activation by PBAN. The diapause hormone receptor was activated by diapause hormone with a 150 nM half effective concentration.

Regulation of pheromone biosynthesis by a brain hormone in two moth species

Experiments were performed to characterize the action of a brain hormone on pheromone biosynthesis in female redbanded leafroller and cabbage looper moths. Results showed that the two species differed in their respective control mechanisms. In the cabbage looper, pheromone titer from decapitated females that received either saline or brain extract injections was not significantly different from control females, suggesting that pheromone biosynthesis was not dependent on the presence of the brain hormone. In contrast, with redbanded leafroller females, studies using radiolabeled acetate incorporation as well as incorporation of deuterium-labeled hexadecanoic acid showed that (i) the brain hormone was required for pheromone biosynthesis, (ii) the brain hormone regulated pheromone biosynthesis by activating synthesis of octadecanoyl and hexadecanoyl intermediates, and (iii) the brain hormone did not control other enzymes in the pathway. Regulation of fatty acid synthetase was unlikely since assays of the enzyme from decapitated and normal females showed no differences in the amount or distribution of the 18- and 16-carbon acyl end products. These results in conjunction with those from organ cultures of the pheromone gland suggest that the brain hormone acts by increasing the substrate supply for fatty acid synthesis.

The identification of an age- and female-specific putative PBAN membrane-receptor protein in pheromone glands of Helicoverpa armigera: possible up-regulation by Juvenile Hormone

The present study was designed to determine the age and female specificity of a membrane protein that binds to a pheromone biosynthesis activating neuropeptide (PBAN) ligand and to elucidate the effect of Juvenile Hormone (JH) on binding as well as pheromone activation. The precise age at which developing adult females of Helicoverpa armigera begin to respond to PBAN was determined. PBAN activates in vitro pheromone biosynthesis as well as its intracellular second messenger, cAMP, only in intersegments of newly emerged adult female pheromone glands (i.e. 1-day-old females). An increase in response was observed in 2-day-old females. Intersegments of female pupae and the homologous tissues of adult males do not respond to PBAN. However, in the presence of Juvenile Hormone II (JH II) PBAN induced a response in females, 1 day before emergence (pharate females), but not in younger female pupae. This phenomenon was also observed after topical applications of the JH analog fenoxycarb (FX). In addition the response to PBAN by intersegments of FX-treated emerged adults increased significantly to the level of 2-day-old females. JH II also stimulated the level of incorporation of (35)S-labelled amino acids in female pupae into membrane proteins that are typical in adult intersegments. Using a photoaffinity-biotin labelled PBAN analog we demonstrate specific binding of a membrane protein (estimated MW: 50 kD) in adult females. This binding was not detected in female pupae 3 days before emergence. However, in such female pupae specific binding of the 50 kD protein by the photoaffinity-biotin labelled PBAN analog was induced after JH II or FX treatments thereby providing evidence that JH may up-regulate this putative receptor protein.

Pyrokinin/PBAN-like peptides in the central nervous system of Drosophila melanogaster

The pyrokinin/pheromone biosynthesis activating neuropeptide (PBAN) family of peptides found in insects is characterized by a 5-amino-acid C-terminal sequence, FXPRLamide. The pentapeptide is the active core required for diverse physiological functions, including stimulation of pheromone biosynthesis in female moths, stimulation of muscle contraction, induction of embryonic diapause in Bombyx mori, and stimulation of melanization in some larval moths. Recently, this family of peptides has been implicated in accelerating the formation of the puparium in a dipteran. Using bioassay and immunocytochemical techniques, we demonstrate the presence of pyrokinin/PBAN-like peptides in the central nervous system of Drosophila melanogaster. Pheromonotropic activity was shown in the moths Helicoverpa zeaand Helicoverpa armigera by using dissected larval nervous systems and adult heads and bodies of D. melanogaster. Polyclonal antisera against the C-terminal ending of PBAN revealed the location of cell bodies and axons in the central nervous systems of larval and adult flies. Immunoreactive material was detected in at least three groups of neurons in the subesophageal ganglion of 3rd instar larvae, pupae, and adults. The ring gland of both larvae and adults contained immunoreactivity. Adult brain-subesophageal ganglion complex possessed additional neurons. The fused ventral ganglia of both larvae and adults contained three pairs of neurons that sent their axons to a neurohemal organ connected to the abdominal nervous system. These results indicate that the D. melanogasternervous system contains pyrokinin/PBAN-like peptides and that these peptides could be released into the hemolymph.

Sex pheromone levels in pheromone glands and identification of the pheromone and hydrocarbons in the hemolymph of the moth Scoliopteryx libatrix L. (Lepidoptera: Noctuidae)

The hydrocarbon sex pheromone (13-methyl-Z6-heneicosene) of Scoliopteryx libatrix L. (Lepidoptera: Noctuidae) was found to reach its highest levels on pheromone glands of 3-day-old females. Pheromone levels were not different between the time of maximum calling (end of scotophase) and at the middle of photophase. Overwintering females collected in October had sex pheromone present. Decapitation did not lower the amount of pheromone present, indicating that a head factor is not involved in maintaining pheromone titers. Hemolymph also contained the pheromone, indicating that it is made by oenocytes and transported to the sex pheromone gland. Longer chain length hydrocarbons were also identified from the hemolymph and on the cuticular surface. Quantitative differences in hydrocarbon profiles were found with more methyl-branched hydrocarbons found in the hemolymph than on the cuticular surface. Arch.

Prostaglandin biosynthesis by fat body from true armyworms, Pseudaletia unipuncta

We describe prostaglandin (PG) biosynthesis by microsomal-enriched fractions of fat body prepared from true armyworms, Pseudaletia unipuncta. PG biosynthesis was sensitive to experimental conditions, including incubation time, temperature, pH, substrate and protein concentration. Optimal PG biosynthesis conditions included 1 mg of microsomal-enriched protein, incubated at 28 degrees C for 7.5 min at pH 8. These preparations yielded four major PGs: PGA(2), PGE(2), PGD(2) and PGF(2alpha). PGA(2) and PGE(2) were the predominant eicosanoids produced under these conditions. Two non-steroidal anti-inflammatory drugs, indomethacin and naproxen, effectively inhibited PG biosynthesis. Unlike other invertebrate PG biosynthetic systems studied so far, the true armyworm system appeared to be independent of the usual exogenous co-factors required by mammalian and other invertebrate systems. These findings are discussed with respect to PG biosynthesis in other invertebrate and vertebrate systems.

Identification of cuticular hydrocarbons and the alkene precursor to the pheromone in hemolymph of the female gypsy moth, Lymantria dispar

Hydrocarbons were extracted from the surface of the cuticle and from the hemolymph of adult female gypsy moths. GC and GC/MS analysis indicated that the cuticular hydrocarbons with chain lengths >21 carbons were the same as those found in the hemolymph. These consisted of mostly saturated straight chain hydrocarbons with heptacosane the major component. Methyl branched hydrocarbons were also identified including a series of tetramethylalkanes with chain lengths of 30, 32, and 34 carbons. In addition to those found on the cuticle surface, the hemolymph contained the alkene pheromone precursor, 2-methyl-Z7-octadecene and two saturated analogues, 2-methyl-octadecane and 2-methyl-hexadecane. No evidence was obtained for the presence of the pheromone 2-methyl-7, 8-epoxy-octadecane in the hemolymph. Pheromone gland extracts indicated that small amounts (<1 ng) of the alkene precursor were also present in the gland. Relatively larger amounts of the alkene precursor were found in the hemolymph at the time when pheromone titers were higher on the gland. The presence of the hydrocarbon pheromone precursor in the hemolymph is discussed in relation to possible biosynthetic pathways for producing the gypsy moth pheromone.

Insect pheromones--an overview of biosynthesis and endocrine regulation

This overview describes, compares, and attempts to unify major themes related to the biosynthetic pathways and endocrine regulation of insect pheromone production. Rather than developing and dedicating an entirely unique set of enzymes for pheromone biosynthesis, insects appear to have evolved to add one or a few tissue-specific auxiliary or modified enzymes that transform the products of "normal" metabolism to pheromone compounds of high stereochemical and quantitative specificity. This general understanding is derived from research on model species from one exopterygote insect order (Blattodea) and three endopterygote insect orders (Coleoptera, Diptera, and Lepidoptera). For instance, the ketone hydrocarbon contact sex pheromone of the female German cockroach, Blattella germanica, derives its origins from fatty acid biosynthesis, arising from elongation of a methyl-branched fatty acyl-CoA moiety followed by decarboxylation, hydroxylation, and oxidation. Coleopteran sex and aggregation pheromones also arise from modifications of fatty acid biosynthesis or other biosynthetic pathways, such as the isoprenoid pathway (e.g. Cucujidae, Curculionidae, and Scolytidae), or from simple transformations of amino acids or other highly elaborated host precursors (e.g. Scarabaeidae and Scolytidae). Like the sex pheromone of B. germanica, female-produced dipteran (e.g. Drosophilidae and Muscidae) sex pheromone components originate from elongation of fatty acyl-CoA moieties followed by loss of the carbonyl carbon and the formation of the corresponding hydrocarbon. Female-produced lepidopteran sex pheromones are also derived from fatty acids, but many moths utilize a species-specific combination of desaturation and chain-shortening reactions followed by reductive modification of the carbonyl carbon. Carbon skeletons derived from amino acids can also be used as chain initiating units and elongated to lepidopteran pheromones by this pathway (e.g. Arctiidae and Noctuidae). Insects utilize at least three hormonal messengers to regulate pheromone biosynthesis. Blattodean and coleopteran pheromone production is induced by juvenile hormone III (JH III). In the female common house fly, Musca domestica, and possibly other species of Diptera, it appears that during hydrocarbon sex pheromone biosynthesis, ovarian-produced ecdysteroids regulate synthesis by affecting the activities of one or more fatty acyl-CoA elongation enzyme(s) (elongases). Lepidopteran sex pheromone biosynthesis is often mediated by a 33 or 34 amino acid pheromone biosynthesis activating neuropeptide (PBAN) through alteration of enzyme activities at one or more steps prior to or during fatty acid synthesis or during modification of the carbonyl group. Although a molecular level understanding of the regulation of insect pheromone biosynthesis is in its infancy, in the male California fivespined ips, Ips paraconfusus (Coleoptera: Scolytidae), JH III acts at the transcriptional level by increasing the abundance of mRNA for 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in de novo isoprenoid aggregation pheromone biosynthesis.

Prostaglandin production in response to a bacterial infection in true armyworm larvae

Prostaglandin levels were determined by fluorometric HPLC analysis of hemolymph collected from larvae of the true armyworm, Pseudaletia unipuncta, that had been injected with bacteria. Prostaglandins were extracted and derivatized with the fluorogenic compound 9-anthryldiazomethane and detected by fluorescence-HPLC. One of the prostaglandins produced was identified as prostaglandin F(2alpha) based on HPLC retention time. The chemical identity of prostaglandin F(2alpha) was confirmed by isolation and derivatization followed by gas chromatography mass spectrometry analysis. Larvae injected with heat-killed bacteria, Serratia marcescens, produced about 4 times as much prostaglandin F(2alpha) as larvae injected with saline. In a separate experiment, larvae injected with bacteria and the prostaglandin precursor arachidonic acid produced still higher levels of prostaglandin F(2alpha). The production of prostaglandin was inhibited with phenidone, a dual cyclooxygenase and lipoxygenase inhibitor. These data indicate that bacterial injections stimulate increased eicosanoid biosynthesis in true armyworms, particularly biosynthesis of prostaglandin F(2alpha). Our findings add considerable support to the hypothesis that eicosanoids mediate insect cellular immune reactions to bacterial infections. Arch. Copyright 1999 Wiley-Liss, Inc.

Identification of soluble binding proteins for an insect neuropeptide

A photoaffinity analog of Helicoverpa zea pheromone biosynthesis activating neuropeptide (Hez-PBAN) was used to identify PBAN binding proteins in various tissues of the corn earworm moth, H. zea. Synthetic Hez-PBAN was derivatized on Lys-27 with p-benzoyldihydrocinnamoyl-N-hydroxysuccinimide ester (BZDC-NHS ester). The resulting BZDC-PBAN stimulated pheromone production in H. zea isolated abdomens at levels comparable to those of the unmodified peptide. Photoaffinity labeling experiments using [3H]BZDC-PBAN with female moth tissues revealed soluble 100 and 115 kDa proteins in the brain-subesophageal ganglia complex, ventral nerve cord, and thoracic muscle that were specifically labeled with the PBAN analog.

Biosynthetic pathway for producing the sex pheromone component (Z,E)-9,12-tetradecadienyl acetate in moths involves a delta 12 desaturase

Sex pheromones are used by insects as a form of chemical communication for the purpose of attracting conspecific mates. Female moths Cadra cautella and Spodoptera exigua use the diene (Z,E)-9,12-tetradecadienyl acetate as the major pheromone component. Biosynthesis of this pheromone component was demonstrated to occur through delta 11 desaturation of hexadecanoic acid (palmitate) to produce (Z)-11-hexadecenoic acid which is then chain-shortened to (Z)-9-tetradecenoic acid. A unique delta 12 desaturase uses the (Z)-9-tetradecenoic acid to produce (Z,E)-9,12-tetradecenoic acid which is reduced and acetylated to form the acetate ester pheromone component. Both moths also use a pheromonotropic peptide to stimulate pheromone biosynthesis.

Biosynthetic enzymes regulating ratios of sex pheromone components in female redbanded leafroller moths

Changes in key enzymes in the biosynthetic pathways of sex pheromone components can produce differences in component ratios and structures. The sex pheromone communication system is critical to reproduction and the maintenance of a species and so changes in this system can play a major role in the speciation process. Artificial selection of female redbanded leafroller moths that produced either higher or lower ratios of 14-/12-carbon pheromone components was used to study how the biosynthetic pathways were affected in the high and low populations. The results showed that the chain shortening enzymes were selective for the (E) isomer and so left the 14-carbon acyl intermediates enriched in the (Z) isomer. Thus, the high population, which has a higher amount of 12-carbon components, also has a lower ratio of E11-/Z11-14:OAc pheromone components. The data also suggested that chain shortening occurred prior to reduction and acetylation of the 14-carbon components. These changes are not sufficient to isolate the redbanded leafroller populations, but we discuss some cases where significant changes in pheromone component ratios are affected by the chain-shortening enzymes.

Action of PBAN and related peptides on pheromone biosynthesis in isolated pheromone glands of the redbanded leafroller moth, Argyrotaenia velutinana

Isolated pheromone glands from the redbanded leafroller moth, Argyrotaenia velutinana, were utilized to demonstrate the action of pheromone biosynthesis activating neuropeptide (PBAN) and bursa pheromonotropic peptide plus several other related peptides on pheromone biosynthesis. All peptides belonging to the PBAN family and the bursa peptide stimulated pheromone biosynthesis as measured by pheromone titer and incorporation of radiolabeled acetate. These peptides required the presence of extracellular Ca2+ for expression of full activity and several inorganic Ca2+ channel blockers inhibited the stimulation of pheromone biosynthesis. The Ca2+ ionophore A23187 alone stimulated pheromone biosynthesis as did a cAMP analogue. Stimulation by the cAMP analogue in the absence of extracellular Ca2+ was observed. Maximum pheromone titers were observed in 16 hr gland incubations; however, 2-6 hr incubations were required if pheromone biosynthesis was measured by incorporation of radiolabeled acetate. Radiolabeled glucose incorporation was not increased in the presence of PBAN. These results are discussed in the context of how the pheromone biosynthetic pathway is stimulated by these peptides.

Stimulation of pheromone biosynthesis in the moth Helicoverpa zea: action of a brain hormone on pheromone glands involves Ca2+ and cAMP as second messengers

Isolated abdomen and pheromone gland bioassays were utilized to determine the physiological action of the pheromone-biosynthesis-activating neuropeptide (PBAN) in the corn earworm moth Helicoverpa (= Heliothis) zea. An isolated pheromone gland bioassay showed that synthetic PBAN was active at 0.02 pmol, with maximal activity occurring at 0.5 pmol and 60 min of incubation. Second-messenger studies demonstrated that extracellular Ca2+ is necessary for PBAN activity on isolated pheromone glands. The Ca2+ ionophore A23187 stimulated pheromone biosynthesis alone, whereas the Ca2+ channel blockers La3+ and Mn2+ inhibited PBAN activity. However, the organic Ca2+ channel blockers verapamil and nifedipine did not inhibit PBAN activity. Both forskolin and two cAMP analogues stimulated pheromone biosynthesis in the absence of extracellular Ca2+, indicating that Ca2+ may activate an adenylate cyclase. The biogenic amine octopamine did not elicit pheromone production in isolated gland or abdomen bioassays or when injected into intact female moths. Removal of the ventral nerve chord, including the terminal abdominal ganglia in isolated abdomens, did not affect PBAN stimulation of pheromone production. Similar levels of stimulation were found when isolated abdomens were treated with PBAN in scotophase or photophase.

In vitro inhibition of prostaglandin H synthase by compounds from the exocrine secretions of lace bugs

1. Selected lace bug-derived and related compounds were shown to be in vitro inhibitors of mammalian and insect derived prostaglandin H synthase. 2. Two compounds, 2,6-dihydroxyacetophenone and 2,4,6-trihydroxyacetophenone, were significantly better inhibitors of prostaglandin synthesis than aspirin, whereas 2-nonyl-5,7-dihydroxychromone and 1-(2,6-dihydroxyphenyl) dodecan-1-one were equivalent to aspirin. 3. 2,4-Dihydroxyacetophenone was less effective in inhibiting the prostaglandin H synthase and 2-nonyl-5-hydroxychromanone showed no inhibition. 4. Three compounds, 2,6-dihydroxyacetophenone, 2,4,6-trihydroxyacetophenone and 1-(2,6-dihydroxyphenyl) dodecan-1-one were equal to aspirin in PSI inhibition with fat body preparations of the American cockroach Periplaneta americana L.

Tissue and chain length specificity of the fatty acyl-CoA elongation system in the American cockroach

The elongation of fatty acyl-CoAs, reactions involved in hydrocarbon biosynthesis, was examined in the cockroach, Periplaneta americana. Products were analyzed by radio-HPLC and radio-GLC. The majority of the elongation activity was observed in microsomes prepared from abdominal epidermal tissue. Linoleoyl-CoA (18:2-CoA) was elongated most efficiently followed by stearoyl-CoA (18:0-CoA), linolenoyl-CoA (18:3-CoA; n-3) and oleoyl-CoA (18:1-CoA). The products of 18:2-CoA elongation included all even numbered acyl groups up to 28 carbons, and the products of 18:0-CoA included all even numbered acyl groups to 26 carbons. The 18:3-CoA was elongated only to 20 and 22 carbons. Radioactivity from both 18:2-CoA (5.4%) and 18:0-CoA (1.2%) was recovered in the hydrocarbon fraction. Analysis of this hydrocarbon fraction showed that the radio-activity from 18:2-CoA was present in (Z,Z)-6,9-heptacosadiene and that the radioactivity from 18:0-CoA was present in n-pentacosane. These data demonstrate for the first time in an in vitro insect system that the fatty acid elongation reactions are coupled with the conversion of the elongated product to hydrocarbon. Thus, each of the expected intermediates in the conversion of 18:0 and 18:2 to 25 and 27 carbon hydrocarbons, respectively, was observed, and the results demonstrate high tissue, substrate, and product specificity.

De novo biosynthesis of arachidonic acid and 5,11,14-eicosatrienoic acid in the cricket Teleogryllus commodus

The de novo biosynthesis of 5,11,14-eicosatrienoic acid (5,11,14-20:3), arachidonic acid (20:4(n - 6] and eicosadienoic acid (20:2(n - 6] and the elongation/desaturation of linoleic acid (18:2(n - 6] to 20:4(n - 6) and alpha-linolenic acid (18:3(n - 3] to eicosapentaenoic acid (20:5(n - 3] were demonstrated in adult males of the field cricket Teleogryllus commodus. Sodium [1-14C]acetate, [1-14C]18:2(n - 6) and [1-14C]18:3(n - 3) were injected into adult male crickets and after an incubation period, the testes and remaining tissues were extracted and the methyl esters obtained from the phospholipid and triacylglycerol fractions were analyzed. After 5 days of daily injections of [1-14C]acetate, the methyl esters of the triene and tetraene fatty acids from the testicular phospholipid fraction were purified by AgNO3-TLC and HPLC and analyzed by GLC, radio-HPLC, and radio-GLC of ozonolysis products. The results demonstrate the de novo biosynthesis of 20:2(n - 6), 20:4(n - 6) and an isomer of 20:3(n - 6) with double bonds in the 5,11,14 positions. the elongation/desaturation of 18:2(n - 6) to 20:4(n - 6) and 18:3(n - 3) to 20:5(n - 3) was demonstrated by analysis of the methyl esters derived from the testicular phospholipid fraction by radio-HPLC after injecting crickets with radiolabeled substrates.

De novo biosynthesis of polyunsaturated fatty acids in the cockroach Periplaneta americana

The de novo biosynthesis of 6,9,12-linolenic acid, 11,14-eicosadienoic acid, 5,11,14-eicosatrienoic acid, and arachidonic acid was demonstrated in adult female cockroaches, Periplaneta americana. These four polyunsaturated fatty acids (PUFA) were present primarily in the phospholipid (PL) fraction of both males and females. They were purified by AgNO3 thin-layer chromatography and high pressure liquid chromatography. The double bond positions of the major isomer of eicosatrienoic acid were shown to be at the delta 5,11,14 positions by gas chromatography-mass spectrometry (GC-MS) of both methoxy and epoxide derivatives and gas-liquid chromatography (GLC) and GC-MS of ozonolysis products. The other PUFAs cochromatographed with standards on both packed and capillary GLC columns. The in vivo incorporation of [1-14C]acetate into 5,11,14-eicosatrienoic acid, 11,14-eicosadienoic acid, 6,9,12-linolenic acid, and arachidonic acid was demonstrated by radio-GLC and radio-HPLC and for 5,11,14-eicosatrienoic acid by radio-GLC of ozonolysis products. The latter technique clearly demonstrated that the entire eicosatrienoic acid molecule was labeled. Thoracic tissue contained the highest amount of radiolabeled 5,11,14-eicosatrienoic acid (1.6% of total radioactivity incorporated into PL) while radiolabeled 11,14-eicosadienoic acid was found primarily in abdominal epidermal tissue (2% of total radioactivity incorporated into PL). Radiolabeled arachidonic and 6,9,12-linolenic acids comprised 0.1 and 0.02%, respectively, of the total radioactivity in the PL fraction. These data document the de novo biosynthesis of di-, tri-, and tetraunsaturated fatty acids in the American cockroach, and indicate that this animal can desaturate on both sides of the delta 9 double bond of oleic acid.

De novo biosynthesis of prostaglandins by the Australian field cricket, Teleogryllus commodus

The accumulation and metabolism of certain polyunsaturated fatty acids by testes from the Australian field cricket, Teleogryllus commodus, are described. Testes accumulated a substantial proportion (about 16%) of label from radioactive C20:3n6 that was injected into the haemocoel. Fifty percent of the label accumulated by testes was associated with the phospholipid fraction, whereas in the remainder of the body 30% was incorporated into the phospholipid fraction. Prostaglandins (PG) E1, E2 and F2 alpha were quantified in extracts of the testes of adult insects by radioimmunoassay. Label from injected radioactive C18:2n6, C20:3n6 and C20:4n6 was recovered as prostaglandins PGE and PGF. The radioactivity from C18:2n6 that was recovered as PGE1 and PGF1 alpha indicated elongation/desaturation to C20:3n6 followed by conversion to PG. Since C18:2n6 is readily formed from acetate in T. commodus, these findings indicate the de novo biosynthesis of C20 polyunsaturated fatty acids and prostaglandins by this species.