Edward N. Lambremont

BIOSYNTHESIS OF FATTY ACIDS IN ASEPTICALLY REARED INSECTS.

Abstract 1. 1. Both aseptic and nonaseptic adult boll weevils (Anthonomus grandis (Boheman) Col., Curculionidae) synthesize long-chain fatty acids from injected C14-1-acetate. Equivalent synthesis rates and patterns of fatty acid labeling also were found when C14-2-acetate was the precursor. 2. 2. Most radioactivity was in the C16− and C18− saturated and omno-unsaturated fatty acids. This insect appears to be incapable of synthesizing the C18 dienoic fatty acid, linoleic acid.

GLC analysis ofHeliothis virescens triglycerides at various metamorphic stages

The triglycerides ofHeliothis virescens (F.), the tobacco budworm, reared on a semidefined diet, were examined at different stages of development. The distribution of triglyceride carbon numbers and the composition of triglyceride fatty acids were determined by gas-liquid chromatographic analysis of intact triglycerides and methyl esters. Triglycerides of carbon number 50 decreased in the unfed adults with age; the decrease corresponded with a decrease in palmitic acid. Linoleic acid and carbon number 50 exhibited fluctuations in concentrations that were correlated with metamorphosis. The observed changes in specific triglyceride carbon numbers with a simultaneous change in specific triglyceride fatty acids indicate a nonrandom fatty acid distribution in the triglycerides of this insect.

Lipid biosynthesis in the boll weevil (Anthonomus grandis Boheman) (coleoptera: curculionidae): Distribution of radioactivity in the principal lipid classes synthesized from C14-1-acetate

Abstract 1. 1. The boll weevil, Anthonomus grandis Boheman, synthesized fatty acids and hydrocarbons from acetate. The fatty acids were rapidly esterified with glycerol and sterol or were incorporated into the phospholipid fraction. Radioactivity was not incorporated into the sterol fraction, an indication of the absence of sterol biosynthesis from acetate. 2. 2. The feeding history and developmental state of the adult boll weevil determined the eventual location of the newly synthesized fatty acids. Newly emerged unfed adults incorporated the fatty acids principally into the phospholipids. In insects injected with radiolabeled acetate after several days of feeding, the new fatty acids were distributed to the glycerides. 3. 3. Larvae fed a diet containing labeled acetate had an entirely different labeling pattern with much higher amounts of C14 appearing in the free fatty acid fraction.

Principal lipid classes and fatty acids synthesized during growth and development of the beetle Lyctus planicollis

Abstract Southern lyctus beetle larvae, Lyctus planicollis , incorporated [U 4 C] glucose into palmitic, palmitoleic, stearic, and oleic acids. These fatty acids were incorporated mainly into triglycerides, phosphatidyl choline, and phosphatidyl ethanolamine. Qualitatively, the lipid class spectrum remained unchanged throughout development. Lipid content remained constant during embryonic development, but decreased during the hatching of larvae. Lipids increased quantitatively during larval development and were utilized during the transitions from larva to pupa and pharate adult, and from pupa and pharate adult to emergent adult. Larvae failed to develop on a low-fat diet and, since linoleic acid and sterols were not synthesized from glucose, it is concluded that these are probably essential dietary components.

Decontamination of Campylobacter jejuni on chicken drumsticks using chemicals and radiation

A trial was conducted to compare the efficacy of four disinfectants and radiation to reduce the level of C.jejuni contamination on poultry meat. Two levels of each treatment were applied to chicken drumsticks inoculated with a known concentration of a strain of Campylobacterjejuni, biotype 1, isolated from a human patient with diarrhea.Radiation using a cobalt-60 source at a level of 0.5 KGy effected a 99% surface reduction in C.jejuni. With a mean initial surface contamination level of 1.1 × 103 Colony Forming Units/cm2, 1 KGy completely eliminated C.jejuni. Glutaraldehyde at 0.5% concentration for 30 minutes had an efficacy similar to the lower dose of radiation. Chlorine showed a negligible effect on C.jejuni. Succinic acid and Poly (hexamethylenebiguanide hydrochloride) were statistically similar in their effectiveness, ranking between glutaraldehyde and chlorine.These results strongly indicate that, of the alternatives tested, low-dose radiation is the method of choice for reducing Campylobacter contamination of poultry products.

The in vivo synthesis of acyl- and ether-bonded phospholipids in Heliothis virescens☆☆☆

Abstract Fatty acids and fatty alcohols serve as precursors in the formation of alkyl, and alk-1-enyl bonds in the phospholipids of the tobacco budworm [ Heliothis virescens (F)]. The insects are capable of interconverting the two precursors. Fatty acids of 16 or 18 carbons are preferred in acyl-bond formation, and fatty alcohols of 18 carbons are preferred in ether-bond synthesis. Alk-1-enyl glyceryl ethers appear to be derived from the saturated alkyl glyceryl ethers by dehydrogenation. The ether-bonded components are associated principally with the ethanolamine phosphoglycerids. Very little or no ether synthesis occurs in the choline, serine, or inositol phosphoglycerides.

Lipid metabolism of insects: Interconversion of fatty acids and fatty alcohols

Abstract Fatty acids and fatty alcohols are interconverted in vivo in the tobacco budworm. The oxidation of injected or dietary [1-14C] hexadecanol and [1-14C] octadecanol to hexadecanoic and octadecanoic acid respectively takes place rapidly. Forty-eight hours after injection 84 per cent of the alcohol was oxidized to fatty acid, and when given in the larval diet the oxidation of alcohol was virtually complete. The reverse reaction, reduction of fatty acids to alcohols, was demonstrated with highly purified [1-14C] hexadecanoic acid and took place sparingly. The reaction equilibrium for the interconversion was strongly displaced in the direction of the fatty acids.

Incorporation of acetate-1-14C into neutral lipids and phospholipids during late developmental stages of Heliothis zea☆

Abstract 1. 1. Last instar larvae, prepupae, pupae and adults of the bollworm Heliothis zea (Boddie) incorporated acetate-1-14C into neutral and phospholipids. 2. 2. Largest incorporation into neutral lipids was in late fifth- and early sixth-instar larvae. Most of the radioactivity was in triglycerides. As metamorphosis proceeded, radioactivity in the neutral lipids decreased to a low during the pupal stage. 3. 3. Phospholipids incorporated acetate-1-14C during both the larval and pupal stages. Phosphatidylcholine appeared to be the most active component during the metamorphic transition, but radioactivity also was found in phosphatidylethanolamine and sphingomyelin.

Synthesis and metabolism of long-chain fatty acids during late developmental stages of Heliothis zea (Lepidoptera: Noctuidae)

Abstract Fatty acids 10–20 carbons in chain-length were found by GLC analysis of 6th instar larvae, pharate pupae, pupae, and moths a day after emergence of the bollworm, Heliothis zea . The two largest acids in all stages examined were 16:0 and 18:1. Saturated and mono-unsaturated acids incorporated radioactivity in insects injected with 14 C-1-acetate. The principal acids that were synthesized had 16- and 18-carbon chains. Preparative GLC and analysis of various hydrogenated mixtures of fatty acids showed conclusively that poly-unsaturated 18-carbon acids are not synthesized by this insect. Radioactivity associated with 18:2 comes from tailing of 18:1, whereas that found with 18:3 comes from the synthesis of 20:0 which co-chromatographs with 18:3. Data reported in this paper and by other investigators suggest that Heliothis adults selectively utilize 16:0 fatty acid and conserve 18:1 and polyunsaturated acids. The data are evaluated, discussed, and compared with other observations.

Wax synthesis by an enzyme system from the honey bee

Abstract 1. 1. A cell-free system prepared from the worker honey bee, containing enzymes from active wax glands, is described which readily incorporated a long-chain fatty alcohol, [1- 3 H]tetracosanol (24:0), into wax esters. About 16% of the label is recovered in the wax ester fraction after 1 hr of incubation at 37°C. 2. 2. ATP, CoA, Mg 2+ , and a pH of 7.1 are required for maximum activity. The fatty acid component of the wax ester is derived from the endogenous lipids of the enzyme preparation. The wax-synthesizing enzyme is not highly specific for the longer chain fatty alcohols, since hexadecanol (16:0) was also incorporated into wax by the system. The system is highly sensitive to detergents. 3. 3. The findings indicate the monoester wax component of beeswax is biosynthesized by the reaction of a long-chain alcohol, such as tetracosanol, with a fatty acyl-CoA.