Chain Shortening Research Articles

Sex pheromone biosynthesis in the processionary moth Thaumetopoea pityocampa by delta‐13 desaturation

In vivo treatments of female sex pheromone glands of the processionary moth, Thaumetopoea pityocampa, with mass-labeled fatty acids showed that (Z)-13-hexadecen-11-ynyl acetate, the main sex pheromone component, is biosynthesized from palmitic acid by the combined action of delta-11 and delta-13 desaturases. The involvement of this unusual delta-13 has been proven by application of [16,16,16-2H3] [1,2-13C2]-hexadecanoic acid to the glands with a resultant incorporation of all labeled atoms into the pheromone and each one of the corresponding intermediates. These results seem to exclude alternative biosynthetic pathways, such as chain shortening and elongation combined with delta-11 desaturation. The delta-11 desaturase responsible for the formation of the triple bond in both the 11-hexadecynoyl and (Z)-13-hexadecen-11-ynoyl intermediates is also an unusual enzyme not previously reported in lepidopteran sex pheromone biosynthesis.

Sex pheromone biosynthesis in the Asian corn borer Ostrinia furnacalis (II): Biosynthesis of (E)‐ and (Z)‐12‐tetradecenyl acetate involves Δ14 desaturation

AbstractSex pheromone biosynthesis in the Asian corn borer Ostrinia furnacalis was studied by topical application of deuterium labelled fatty acids to the pheromone gland. The incorporation of the labelled acids into pheromone components and precursors was determined by gas chromatography with flame ionization detection and mass spectrometry in the selected ion monitoring mode. The labelling experiments suggest that the pheromone components (E)‐ and (Z)‐12‐tetradecenyl acetates are biosynthesized from palmitic acid by δ14 desaturation, followed by chain shortening (β‐oxidation), reduction, and acetylation. This is the first confirmation of a Δ14 desaturase in an eukaryotic system.

Biodegradation of oxidized regenerated cellulose

The in vitro solubilization and degradation of regenerated cellulose was studied under conditions which approximate those found in vivo, when the material is used as an adhesion barrier to assist normal wound repair. Factors affecting solubilization which were examined included the effects of serum or plasma, and the presence of hydrolytic enzymes. Products of the solubilization and degradation processes were examined by high performance liquid chromatography coupled with pulsed amperometric detection. The oxidized polymer readily undergoes chain shortening to give oligomers which, in the presence of plasma or serum, are further hydrolyzed to smaller fragments, including glucuronic acid and glucose. Proposed mechanisms of degradation are discussed.

Fatty acid chain shortening in humans

Fatty acid chain shortening in humans

Carnitine: vitamin for an insect, vital for man.

Carnitine (L-3-hydroxy-4-N-trimethylaminobutyric a id), discovered in 1905, is widely distributed in nature. Interest in the physiology and metabolism of carnitine arose when a dietary factor named vitamin BT, which was found essential for the growth of the mealworm Tenebrio molitor, was identified as carnitine (Carter et al., Arch. Biochem. Biophys., 38, 405-416, 1952). Since 1973, clinical interest in it has intensified as deficiencies of carnitine and of carnitine palmitoyltransferase (CPT) have been implicated in metabolic disorders. It is now known that in a number of life-threatening situations an insufficiency of carnitine occurs and its therapeutic provision has proven beneficial in many such situations. Healthy adults on balanced diets are able to synthesize enough carnitine for their needs, but in certain situations carnitine acquires the status of a conditionally essential nutrient. Many functions have been ascribed to carnitine. These include a role as an essential cofactor in the energy-yielding oxidation of fatty acids in mitochondria, in the chain shortening of long-chain fatty acids in peroxisomes, in the oxidation of branched chain amino acids, in providing an immediate reservoir of activated acetyl groups as acetylcarnitine, in the maintenance of the CoA/acyl-CoA ratio, and in the detoxification of those acyl groups that arise intramitochondrially as acyl-CoA esters but, not being readily oxidizable, result in the tieing up of free CoA. The latter happens in various acyl-CoA dehydrogenase and carboxylase deficiency diseases associated with organic acidurias; the extra demand placed on body carnitine in these cases leads to a deficiency of carnitine. In this group fall some of the patients of Reye-like and of sudden-infant-death syndromes. Some of the highest concentrations of carnitine are found in epididymis and in mature spermatozoa, and a role of carnitine in male reproduction is suspected (hence man in the commentary title). Implicated but less well understood are roles in ammonia detoxification, as an anti-arrhythmic agent for heart, as a hypolipidemic agent in patients with type IV hyperlipoproteinemia, and in the form of acetylcarnitine, as a memory and alertness enhancing agent in the Alzheimer's disease (Kendler, Prev. Med., 15, 373-390, 1986). Evidence so far indicates that the ability of carnitine to facilitate the membrane and (or) transmitochondrial transport of acyl groups as acylcarnitines is central to the various functions of carnitine. Studies of many, including ours, have helped elucidate this process as described below. In the 195bgs, the observations that fatty acylcarnitines appeared as intermediates when fatty acid oxidation by intact mitochondria was stimulated by a component in muscle extracts led to the recognition of the component as

Intestinal absorption and lymphatic transport of fish oil (MaxEPA) in the rat

Adult male, chow-fed Sprague-Dawley rats were given intradoudenally a bolus of emulsion of 0.5 ml of fish oil (MaxEPA) or olive oil plus 0.5 ml of 20 mM sodium taurochoate. Intestinal lymph was collected from a cannula in the main intestinal lymph trunk for varioustimes after oil administration. There was no difference in the absorption of either type of oil over 6 and 24 h, over which times about 40 and 70% of the administered dose was taken up. For MaxEPA, the flux triacylglycerols remained at a basal level of 0.07 μmol./min for 30 min, after which it rose rapidly to a maximum of 0.87 μmol/min between 90 and 120 min. The flux was 0.4 μmol/min for the subsequent 4 h. After 30 min, the composition of the lymph triacylglycerols began to change to show that presence of large proportions of fatty acyl chains that were characteristic of fish oil, especially eicosapentaenoate (20:5( n − 3)) and docosahexaenoate (22:6( n − 3)). The composition of the lymph remained fairly similar to that of the fish oil for up to 6 h, the last time point at which detailed analysis was done. The docosahexaenoate in the triacylglycerols of the fish oil was primarily in the sn-2 position of glycerol, whereas a more random distribution of eicosapentaenoate over all glycerol positions was found. The positional distribution of the acids in the lymph triacylglycerols was similar to that in the fish oil. There was no evidence of substantial chain elongation or shortening during absorptipn. The results indicate that fish oil is effectively absorbed from the rat intestine without substantial alteration in the acyl chains of the triacylglycerols.

Thermal melting of arachidic acid monolayers in ultrathin multilayers: A high-resolution x-ray diffraction study.

The thermal evolution of the profile structures of one, three, and ten bilayers of arachidic acid nested between two bilayers of a disubstituted diacetylene polymer in Langmuir-Blodgett multilayer films was studied by high-resolution meridional x-ray diffraction over the temperature range of 30--80 \ifmmode^\circ\else\textdegree\fi{}C. A direct correlation was found between the average, in-plane molecular chain density in an individual monolayer within an arachidic acid bilayer and the mean tilt angle for straight (all trans) chains from the monolayer normal at lower temperatures. The chains of the lower-density monolayers had a greater mean tilt angle (and a broader distribution about the mean) than the higher-density monolayers. The addition of thermal energy resulted in a two-stage process consisting of a slowly evolving, ``continuous'' untilting of the initially tilted straight (all trans) chains, extending the profile thickness of the monolayer prior to a slowly evolving, ``continuous'' decrease in the profile thickness due to chain melting via the formation of kinks and jogs. The two phenomena, the straight chain untilting and the chain shortening by formation of kinks and jogs, compete with increasing temperature over a broad range; the initially tilted, straight chains do not fully untilt before the kinks and jogs shorten the chain. Initially untilted, straight chains in the higher-density monolayers melt in a single-stage process more abruptly or ``discontinuously'' over a much narrower temperature range (via the formation of kinks and jogs). The magnitude of these thermally induced structural changes in an individual monolayer depending on the in-plane molecular chain density varies strongly with the number of melting bilayers (or dimensionality), being much greater for one bilayer versus three and ten bilayers, over the accessible temperature range for these nested multilayer samples.

Isoproterenol attenuates myosin phosphorylation and contraction of tracheal muscle

The effects of isoproterenol on isometric force, unloaded shortening velocity, and myosin phosphorylation were examined in thin muscle bundles (0.1-0.2 mm diam) dissected from lamb tracheal smooth muscle. Methacholine (10(-6) M) induced rapid increases in isometric force and in phosphorylation of the 20,000-Da myosin light chain. Myosin phosphorylation remained elevated during steady-state maintenance of isometric force. The shortening velocity peaked at 15 s after stimulation with methacholine and then declined to approximately 45% of the maximal value by 3 min. Isoproterenol pretreatment inhibited methacholine-stimulated myosin light chain phosphorylation, shortening velocity, and force during the early stages of force generation. However, the inhibitory effect of isoproterenol on force and myosin phosphorylation is proportionally greater than that on shortening velocity. Isoproterenol pretreatment also caused a rightward non-parallel shift in the methacholine dose-response curves for both isometric tension and myosin light chain phosphorylation. These data demonstrate that isoproterenol attenuates the contractile properties of airway smooth muscles by affecting the rate and extent of myosin light chain phosphorylation, perhaps through a mechanism that involves the synergistic interaction of myosin light chain kinase phosphorylation and Ca2+ metabolism.

Adrenoleukodystrophy. The chain shortening of erucic acid (22:1( n−9)) and adrenic acid (22:4( n−6)) is deficient in neonatal adrenoleukodystrophy and normal in X-linked adrenoleukodistrophy skin fibroblasts

The metabolism of long chain unsaturated fatty acids was studied in cultured fibroblasts from patients with X-linked adrenoleukodystrophy (ALD) and with neonatal ALD. By using [14− 14C] erucic acid (22:1( n−9)) as substrate it was shown that the peroxisomal β-oxidation, measured as chain shortening, was impaired in cells from patients with neonatal ALD. The β-oxidation of adrenic acid (22:4( n−6)), measured as acid-soluble products, was also reduced in the neonatal ALD cells. The peroxisomal β-oxidation of [14− 14C]erucic acid (22:1( n−9)) and [2− 14C]adrenic acid (22:4( n−6)) was normal in cells from X-ALD patients. The β-oxidation, esterification and chain elongation of [1- 14C]arachidonic acid (22:4( n−6)) and [1- 14C]eicosapentaenoic acid (20: 5( n − 3)) was normal in both X-linked ALD and in neonatal ALD. Previous studies suggest that the activation of very long chain fatty acids by a lignoceryl (24:0)-CoA ligase is deficient in X-linked ALD, while the peroxisomal β-oxidation enzymes are deficient in neonatal ALD. The present results suggest that the peroxisomal very long-chain acyl-CoA ligase is not required for activation of unsaturated C 20 and C 22 fatty acids and that these fatty acids can be efficiently activated by the long chain acyl-(palmityl)-CoA ligase.

Localized vibrations around a soliton in polyacetylene

Localized vibrations and optical and acoustic phonons are calculated for finite length C nD n+2 containing a charged soliton. The molecular orbital method and normal coordinate analysis have been used in this calculation. The localized translational mode couples with the CH bending mode when the chain length is short (n ≈17). The coupling explains well the two broad peaks in the i.r. spectrum. It is also found that dopant pinning has effects similar to chain shortening; i.e. raising the frequency of the T mode and causing coupling of the T and TH modes. Approximate phonon dispersions are calculated for finite trans-polyacetylene with a charged soliton. Branch modes of the previously known localized modes are discussed in connection with the corresponding optical phonons.

Peroxisomes of the midgut epithelium, malpighian tubules and fat body of larvae of the dragonfly, Aeshna cyanea

The enterocytes of the midgut epithelium of Aeshna cyanea larvae are rich in peroxisomes while the nidal regenerative and endocrine cells contain only a few. Most of the enterocytic peroxisomes are microperoxisomes lacking a crystalloid nucleoid, but peroxisomes with well developed nucleoid are also present. The peroxisomes are usually concentrated in the basal region of the cells but may also spread into the apical region and closely intermingle with absorptive lipid droplets. They significantly increase in number, when the larvae are regularly fed lipid-rich natural food or long-chain monounsaturated fatty acids that are unusual dietary components of these animals. This observation seems to indicate that the enterocytic peroxisomes are involved in chain shortening and degradation of fatty acids absorbed from the gut lumen. Numerous microperoxisomes are also present in the lipid-storing cells of the Malpighian tubules and fat body.

Compliance in a randomized clinical trial of dietary fat reduction in patients with breast dysplasia

Chain shortening of palmitic acid was examined in vivo by comparing oxidation rates of [1-13C]palmitate vs [16-13C]palmitate fed to four male subjects consuming a high-fat diet. For 9 d subjects were fed a diet of normal foods providing an energy intake equal to their estimated requirements. The diet provided (as energy) approximately 14% protein, 46% carbohydrate, and 40% fat at a P:S ratio of 0.25. Analysis of breath 13CO2 enrichment on day 3 permitted analysis of background 13C contribution from the test diet alone. On days 4 and 7 either [1-13C]palmitic acid or [16-13C]palmitic acid (9-13.5 mg/kg body wt) was fed with the breakfast meal. The whole-body rate of oxidation of [1-13C]palmitic acid was significantly greater than that observed for [16-13C]palmitic acid. These results suggest that up to 34% of dietary palmitic acid consumed may be subjected to extramitochondrial chain shortening.

Fatty acid chain-shortening activity in the pulmonary type II cell

Type II cells obtained from fetal rabbit lung tissue in culture were incubated with [ 14C]palmitic and [ 14C]stearic acids labeled at either the carboxyl or the terminal methyl groups. Significant chain shortening of [18- 14C]stearic acid to radiolabeled palmitic acid was observed, with little chain shortening of palmitic acid to myristic acid. Incorporation of 14C into palmitic acid by β-oxidation followed by de novo fatty acid biosynthesis was not detectable under the same experimental conditions. The palmitic acid supplied by chain shortening was preferentially incorporated into phosphatidylcholine instead of other lipids. Fatty acid chain-shortening activity in the type II cell appears to be capable of increasing the amount and relative proportion of palmitic acid available for phosphatidylcholine biosynthesis.

Calculation of Localized Vibrational Modes and Infrared Spectra around a Soliton in Polyacetylene

Frequencies of the localized modes around a soliton are calculated for finite length C n H n +2 + , C n H n +2 - , C n D n +2 + and C n D n +2 - ( n odd). The molecular orbital method and three dimensional normal coordinate analysis are used. The frequency of the C–C stretching translational mode (T) is significantly affected by the chain length for both isotopes. For C n D n +2 + , this mode couples with the C–D bending translational mode (TH). This coupling is seen clearly in the displacement vectors. The coupling explains well the two broad peaks in the i.r. spectrum if the chain lengths have a distribution around n ≃13∼21. It is also found that dopant pinning has similar effects to chain shortening; namely, reducing the soliton width, raising the frequency of the T mode, and causing coupling of the T and TH modes. The effective mass of a soliton is found to have the same value in C n H n +2 + , C n H n +2 - , C n D n +2 + and C n D n +2 - .

Sex pheromone biosynthesis of (E,E)-8,10-dodecadienol in codling mothCydia pomonella involvesE9 desaturation

Sex pheromone biosynthesis in the codling mothCydia pomonella (Lepidoptera; Tortricidae) was studied by topical application of deuterated fatty acids in DMSO to pheromone glands. The incorporation of deuterium label into fatty acids and alcohols in the pheromone gland was monitored by gas chromatography with flame ionization detection and mass spectrometry in the selected ion monitoring mode. Dodecanol, (E)-9-dodecenol, (E,E)-8,10-dodecadienol, tetradecanol, and hexadecanol were found in gland extracts. The application of [12,12,12-(2)H3]dodecanoic acid resulted in labeled dodecanol, (E)-9-dodecenol, and (E,E)-8,10-dodecadienol, as well as the corresponding labeled acids. No label was incorporated into tetradecanol or hexadecanol or any acid with more than 12 carbon atoms. The application of labeled tetradecanoic or hexadecanoic acid introduced label not only into the 12-carbon alcohols, but also into tetradecanol, or tetradecanol and hexadecanol, respectively. The application of (E)-[11, 11,12,12,12,-(2)H5]9-dodecen-oic acid, whose facile synthesis is described, resulted in labeled (E)-9-do-decenol and (E,E)-8,10-dodecadienol. The (E,E)-8,10-dodecadienol so produced was characterized by an ion atm/z 186, equivalent to [M](+) of a dienol labeled with four deuterons. Thus, one deuterium label is lost when the labeled (E)-9-monoene is converted to the (E,E)-8,10-diene. We conclude that (E,E)-8,10-dodecadienol is synthesized by chain shortening (β-oxidation) of palmitic acid to dodecanoic acid, followed by an unusualE9 desaturation and subsequent conversion of this intermediate into the conjugated precursor, which is finally reduced to the pheromone alcohol. The evolutionary significance ofE9 desaturation being responsible for pheromone production in an Olethreutinae species is discussed.

Reinvestigation confirms action of ?11-desaturases in spruce budworm moth sex pheromone biosynthesis

The biosynthesis of a large number of sex pheromone components of various moth species has been shown to start with common fatty acids and involve chain shortening by two carbons and introduction of a double bond at the 11-12 position. A recent report indicates that one of these common components, (E)-11-tetradecenyl acetate, is present in the eastern spruce budworm,Choristoneurafumiferana, but is not made by this pathway. Reinvestigation of this insect using in vivo and in vitro techniques indicates that the acetate indeed is made by a sequence of reactions similar to that used in other leafroller moths. In fact, evidence was found for the presence of several Δ11-desaturase systems in spruce budworm. One produced a large quantity of (Z)-11-hexadecanoic acid, and another produced (E)-11-tetradecanoic acid. It is not known if the small amount of (Z)-11-tetradecanoic acid is produced by either of those two systems or by a third system. A comparison with other species showed that cabbage looper moths have only the first system, redbanded leafroller moths use the last two systems, and European corn borer moths have all three.

Sex pheromone precursors in Spodoptera littoralis (Lepidoptera: Noctuidae)

Female pheromone gland extracts of Spodoptera littoralis were analyzed for pheromone precursors. Large amounts of fatty methyl esters were found and a positive relationship between the methyl esters and the pheromonal components was observed. The esters were identified on the basis of capillary gas chromatography, coupled gas chromatography with mass spectroscopy and dimethyl disulfide derivatization, and subsequent gas chromatography with mass spectrometry. The characteristic fatty esters of S. littoralis are methyl ( Z)-9-tetradecenoate, ( E)- and ( Z)-11-tetradecenoate, ( Z, E)-9,12-tetradecadienoate, ( Z, E)-9,11-tetradecadienoate, and ( Z)-11-hexadecenoate. The biosynthesis of the monosaturated acids involves probably the common E11 and Z11 desaturases and chain shortening. For the biosynthesis of the novel diene acids, we propose a second, specific desaturation of ( Z)-9-tetradecenoate by an E11 desaturase to produce ( Z, E)-9,11-tetradecadienoate or by an E12 desaturase to produce ( Z, E)-9,12-tetradecadienoate.

Influence of chain shortening on the inhibitor properties of hirudin and eglin c.

To find out minimal sizes of the proteinase inhibitor proteins hirudin and eglin necessary for their biological activity the inhibitors were incubated with exopeptidases. From the incubation mixtures shortened derivatives were isolated and characterized. Eglin c can be N-terminally shortened by up to 6 amino-acid residues without any loss of affinity towards chymotrypsin. The complex of thrombin with hirudin lacking 3 C-terminal amino-acid residues showed a 15-20-fold increased Ki value as found previously for desulfato-hirudin and desulfato-hirudin shortened by 2 amino-acid residues. Obviously, the C-terminal part of the hirudin molecule has a positive influence on its affinity to thrombin.

Polyunsaturated fatty acids of mosquitos reared with single dietary polyunsaturates

Stock adults of Culex pipiens and tarsalis reared in crude media had a third of their phospholipid fatty acids as polyunsaturates, mainly 18C but including prominent proportions of arachidonic (20:4 n6) and eicosapentaenoic (20:5 n3) acids. Adults reared with synthetic media devoid of polyunsaturated fatty acids and therefore unable to fly at emergence contained no more than trace amounts of any polyunsaturate. With synthetic media containing single polyunsaturates the following findings emerged. Of four polyunsaturates known to be highly effective essential fatty acids individually 20:4 n6 or 20:5 n3 appeared unchanged in tissue phospholipids in proportions reflecting dietary concentrations; dietary 22:4 n6 or 22:6 n3 (docosahexaenoic acid) appeared also as 20:4 n6 or 20:5 n3, respectively, retroconverted from the administered dietary fatty acids, which were detected only in traces. Two moderately effective dietary fatty acids, 18:3 n6 (γ-linolenic) and 20:3 n6 (homo-γ-linolenic), which support weak flight at emergence, appeared in tissue phospholipids respectively as 18:3 n6 only, or as similar proportions of 18:3 n6 and 20:3 n6, this latter indicating shortening to the 18C analogue as well as accumulation of the dietary 20C acid. Six other polyunsaturates [18:2 n6 (linoleic), 18:3 n3 (linolenic) and their 20C and 22C analogues], all considered slightly effective as essential fatty acids although unable to support proper flight, appeared in tissue phospholipid in dose-related proportions as the 18C basal n6 or n3 family analogues, with only traces of the higher analogues when these were the dietary fatty acids provided, indicating sequential chain shortening within each series, n6 or n3, no interconversion of n6 and n3 members (also shown by all other data), and efficient accumulation of the resultant 18C polyunsaturates. These findings show no capability for de novo synthesis of polyunsaturated fatty acids, afford an insight into the metabolic interrelations of diet-derived polyunsaturates and indicate a primary importance for endogenous arachidonic and eicosapentaenoic acids in mosquito essential fatty acid physiology.

Beta-Oxidation of polyunsaturated fatty acids by rat liver peroxisomes. A role for 2,4-dienoyl-coenzyme A reductase in peroxisomal beta-oxidation.

beta-Oxidation of unsaturated fatty acids was studied with isolated solubilized or nonsolubilized peroxisomes or with perfused liver isolated from rats treated with clofibrate. gamma-Linolenic acid gave the higher rate of beta-oxidation, while arachidonic acid gave the slower rate of beta-oxidation. Other polyunsaturated fatty acids (including docosahexaenoic acid) were oxidized at rates which were similar to, or higher than, that observed with oleic acid. Experiments with 1-14C-labeled polyunsaturated fatty acids demonstrated that these are chain-shortened when incubated with nonsolubilized peroxisomes. Spectrophotometric investigation of solubilized peroxisomal incubations showed that 2,4-dienoyl-CoA esters accumulated during peroxisomal beta-oxidation of fatty acids possessing double bond(s) at even-numbered carbon atoms. beta-Oxidation of [1-14C]docosahexaenoic acid by isolated peroxisomes was markedly stimulated by added NADPH or isocitrate. This fatty acid also failed to cause acyl-CoA-dependent NADH generation with conditions of assay which facilitate this using other acyl-CoA esters. These findings suggest that 2,4-dienoyl-CoA reductase participation is essential during peroxisomal beta-oxidation if chain shortening is to proceed beyond a delta 4 double bond. Evidence obtained using arachidionoyl-CoA, [1-14C]arachidonic acid, and [5,6,8,9,11,12,14,15-3H]arachidonic acid suggests that peroxisomal beta-oxidation also can proceed beyond a double bond positioned at an odd-numbered carbon atom. Experiments with isolated perfused livers showed that polyunsaturated fatty acids also in the intact liver are substrates for peroxisomal beta-oxidation, as judged by increased levels of the catalase-H2O2 complex on infusion of polyunsaturated fatty acids.