Regulatory steps in sex pheromone biosynthesis inMamestra brassicae L. (Lepidoptera: Noctuidae)

Summary The de novo biosynthesis of (Z)-11-hexadecenyl acetate, the most abundant pheromone component inM. brassicae, starting from acetate via palmitic acid, requires the presence of a pheromone-biosynthesis-activating neurohormone. Moreover, the conversion of palmitic acid to (Z)-11-hexadecenyl acetate is strongly dependent on the presence of the neurohormone. However, no significant dependence was found for the conversion of (Z)-11-hexadecenoic acid to (Z)-11-hexadecenyl acetate. This indicates that the neurohormonal control of pheromone biosynthesis inM. brassicae occurs at the level of palmitic acid.     

Occurrence and biosynthesis of 11 (R)-hydroxy-eicosatetraenoic acid (11-R-HETE) in the Caribbean soft coralPlexaurella dichotoma

Gorgonian soft corals from the Caribbean Sea are known to contain prostaglandin-like compounds as well as other products of arachidonic acid lipoxygenation, and the formation of the latter has been suggested to represent the first step in prostaglandin biosynthesis. Here we present evidence for the presence of 11-R-hydroxy-5Z, 8Z, 12E, 14Z-eicosatetraenoic acid (11-R-HETE), as well as of the enzyme responsible for its biosynthesis, in the Caribbean gorgonianPlexaurella dichotoma. Lipid extracts fromP. dichotoma were purified by conventional SiO₂ column chromatography followed by reversed phase high-pressure liquid chromatography (HPLC). These yielded a component having chromatographic and spectroscopic properties identical to synthetic 11-HETE. Electron impact mass spectrometric analysis of the acetoxy-, methyl ester derivative of the compound confirmed its identity as 11-HETE, while chiral phase HPLC of the methyl ester derivative showed that the stereochemistry of the alcoholic carbon atom wasR. Enzymatically active homogenates fromP. dichotoma were able to convert both unlabelled and [³H] arachidonic acid into 11-HETE. In vitro biosynthesis of the latter metabolite was also observed with homogenates of the Mediterranean gorgonianParamuricea clavata, another non-prostaglandin-containing soft coral, thus suggesting that 11-R-HETE production is not necessarily accompanied by prostaglandin formation in gorgonian corals.     

Role of the δ 8 double bond of agroclavine in lysergic acid amide biosynthesis byClaviceps purpurea

Summary Agroclavine, given to actively-growing sclerotial tissue of a strain ofClaviceps purpurea which can not normally elaborate ergot alkaloids, was transformed by this tissue into lysergic acid amide with overall efficiency of approximataly 40%. By contrast, festuclavine (8, 9-dihydro-agroclavine) was not transformed, indicating specificity in the mechanism of lysergyl biosynthesis.     

A peculiar fatty acid, (Z,Z)-9,12,17-octadecatrienoic acid,identified in the phospholipids of the pea aphid,Acyrthosiphon pisum (Harris) (homoptera: aphididae)

A peculiar fatty acid previously detected in the phospholipids of the pea aphid,Acyrthosiphon pisum, is identified as (Z,Z)-9,12,17-octadecatrienoic acid. It is the first report of this compound in the literature. Comparison of fatty acid profiles of phospholipids between normal and aposymbiotic pea aphids shows that aphid symbionts are not responsible for the biosynthesis of this unusual fatty acid.     

Primitive actimoterigian fishes can synthesize ascorbic acid

Amphibians and reptiles evolved with the capacity to synthesize ascorbic acid. Some higher vertebrates, like bats, guinea pigs, primates, and humans have lost the microsomal enzyme gulonolactone oxidase, and in cases of ascorbic acid deficiency suffer from symptoms of scurvy. The question of whether the capacity to synthesize ascorbate is also present in lower vertebrates could throw light on the evolution of this pathway. In order to find out whether ascorbic acid synthesis took place in two primitive Actinopterigian fish, the paddlefish (Polydon spathula) and the white sturgeon (Acipenser transmontanus) were fed with a scorbutogenic diet or diet(s) supplemented with a graded level of ascorbic acid. We found no growth depression nor external symptoms of scurvy, which would be pronounced in modern bony fishes (Teleostei) under similar conditions. The tissue level of ascorbate in both these primitive species indicated that vitamin C in intestine and liver is not depleted when fed a scorbutogenic diet. Gulonolactone oxidase activity was found in the kineys of the Actinopterigian fishes. Thus, I question the accepted evolutionary pathway for ascorbic acid biosynthesis in lower vertebrates and suggest that the modern bony fishes,Teleostei, lost their ability to express the gulonolactone oxidase genes after they had separated during the Silurian from their common ancestor with the coelacanths (Latimeria) and Dipnoi.     

Biosynthesis of 1-alkenes in the defensive secretions ofTribolium confusum (Tenebrionidae); stereochemical implications

Summary The terminally unsaturated hydrocarbons of the defensive secretion ofTribolium confusum are biosynthesized from fatty acids by oxidative decarboxylation. The process involves an enantiospecific cleavage of the C–H bond of thepro-(S) C(3)–H atom and simultaneous decarboxylation of the acid into an 1-alkene and carbon dioxide via ananti-periplanar transition state geometry (anti-elimination). The stereochemistry of this biotranformation is identical in all respects with the same reaction in higher plants. The mechanism seems to be of general importance for the biosynthesis of many vinylic substructures of natural products from oxygen-containing precursors.     

Insect tissues,not microorganisms,produce linoleic acid in the house cricket and the American cockroach

Summary Biosynthesis of linoleic acid, 182(n–6), was unambiguously demonstrated to occur in the cockroach,Periplaneta americana, and the cricket,Acheta domesticus. Axenic tissue from both of these insect species was demonstrated by radio-gas-liquid chromatography (radio-GLC) and radio-high-performance liquid chromatography (radio-HPLC) to incorporate [1-¹⁴C]acetate and [1-¹⁴C]oleate into this essential fatty acid.This work was supported by the National Science Foundation under grant DCB-8914417. We would like to thank Coby Schal for his generous gift of American cockroaches and Tania Kellermeyer for her excellent technical assistance.     

Gonyauline: A novel endogenous substance shortening the period of the circadian clock of a unicellular alga

Summary The circadian clock in the unicellular algaGonyaulax polyedra is accelerated by a substance in extracts from the cells themselves. The extracts have been fractionated using the circadian rhythm of bioluminescence as bioassay. The active substance, termed gonyauline, has been isolated and characterized as a novel low molecular weight cyclopropanecarboxylic acid (S-methyl-cis-2-(methylthio) cyclopropanecarboxylic acid). Synthetic gonyauline has a similar shortening effect on the period of the circadian clock.     

Isolation of indole-3-acetic acid methyl ester,a metabolite of indole-3-acetic acid fromPseudomonas amygdali

From the culture filtrates ofPseudomonas amygdali the methyl ester of indole-3-acetic acid (IAA), a product of indole-3-acetic acid metabolism which has the same auxin activity as the free acid, has been isolated. This is the first report of its occurrence as a microbial metabolite.     

Toxic effects of boric acid on the German cockroach

Boric acid is a slow-acting, inorganic insecticide whose mode of action has not been satisfactorily elucidated. Reported here is evidence which shows that ingested boric acid destroys the cellular lining of the foregut of German cockroaches,Blattella germanica (L.). This effect appears to be sufficient to bring about the death of the insects, perhaps ultimately by starvation. This finding is important because resistance to conventional insectivides may re-establish boric acid as a prominent cockroach control chemical.     

Fungal competition and mycotoxin production on corn

Summary Aflatoxin and secalonic acid D production in corn in laboratory and field by mixed cultures ofPencillium oxalicum andAspergillus flavus orA. parasiticus was lower than production by the pure cultures. However, mixed culture of these molds withFusarium spp. did not affect mycotoxin production.     

Biosynthesis of a monoene and a conjugated diene sex pheromone component of the lightbrown apple moth by Δ11 desaturation

Summary Fatty acyl moieties present in the female sex pheromone gland of the lightbrown apple moth,Epiphyas postvittana, include the analogues of the two sex pheromone components, (E)-11-tetradecenyl acetate and (E,E)-9,11-tetradecadienyl acetate. Application of deuterium-labelled fatty acids followed by analysis by gas chromatographymass spectrometry showed that biosynthesis of the two pheromone components involved initial 11-desaturation of myristic and palmitic acids respectively.     

Hepatic acid hydrolases of albino rats,Mastomys natalensis and albino mice duringPlasmodium berghei infection

Summary Changes in liver acid hydrolase activities during the infection of albino rats,Mastomys or mice withPlasmodium berghei are described. B-Glucosidase, B-galactosidase and N-acetyl-B-D-glucosaminidase exhibited widely different responses with acid phosphatase and cathepsin-B the least responsive and are likely to be causally related to immunity of animals.     

New tamjamine class alkaloids from the marine ascidianAtapozoa sp. and its nudibranch predators. Origin of the tambjamines inAtapozoa

Summary Two new tambjamine class alkaloids, possessing ichthyodeterrent properties, have been isolated from the organic extracts of the marine ascidianAtapozoa sp. and its nudibranch predators. The structure of the new metabolites were elucidated through interpretation of their physical and spectral data and by comparison with spectral data for related compounds. Microscopic examination ofAtapozoa considering the yellow color of the tambjamines suggested thatAtapozoa is capable of the de novo biosynthesis of these metabolites.     

Über einen möglichen Weg der Biosynthese der Carotinoide beiMucor hiemalis

Summary Our experiments up to now lead us to the hypothesis, that the biosynthesis of carotenoids may be started on acetyl-coenzyme A. The condensation of two molecules of acetyl-coenzyme A leads to acetoacetyl-coenzyme A which can be regarded as the precursor of-methylcrotonic acid. For a long time the latter compound was postulated as the precursor of the natural isoprene derivatives. The participation of the citric acid cycle in the biosynthesis of carotenoids is discussed.     

Eicosapentaenoic acid in tissue lipids ofPieris brassicae

Summary Larvae of the cabbage white butterfly,Pieris brassicae, have a dietary requirement for linolenic acid (C183n3) and were found to accumulate two other members of the n-3 family, C203n3 and C205n3 (eicosapentaenoic acid) especially in testicular phospholipids. Arachidonic acid was observed in trace amounts only. During diapause the relative titer of eicosapentaenoic acid increased in testicular phospholipids to about 4.2% of the fatty acids. Eicosapentaenoic acid is a possible precursor of prostaglandins, suggesting that prostaglandins of the 3-series predominate in this insect.     

Isolation of plant growth regulators fromPseudomonas amygdali

Summary Trans-zeatin and indole-3-acetic acid were isolated, as the main components of the cytokinin and indole mixtures respectively from culture filtrates ofPseudomonas amygdali, the causal agent of hyperplastic bacterial canker of almond.     

L-gulonolactone oxidase is present in the invertebrate,Limulus polyphemus

Summary L-Gulonolactone oxidase (EC 1.1.3.8) which catalyzes oxidation of L-gulonolactone to L-ascorbic acid was detected in tissues ofLimulus polyphemus.     

Biological activity of flucycloxuron,a novel benzoylphenylurea derivative,onTenebrio molitor: comparison with diflubenzuron and triflumuron

Flucycloxuron, a novel benzoylphenylurea (BPU) derivative, exhibited insecticidal activity when injected into newly ecdysed pupae ofTenebrio molitor. Mortality occurs because of defective adult ecdysis. Treatment caused a reduction in both cuticle thickness and incorporation of¹⁴C-labelled precursor into chitin, although it had no significant effect on the protein synthesis. The potencies of other BPU compounds as inhibitors of chitin biosynthesis have been examined and results showed that diflubenzuron was less effective than either flucycloxuron or triflumuron.