Saturated and mono-unsaturated long-chain hydrocarbon profiles from Citrus unshiu juice sacs

Six cultivars of satsuma mandarin—Kawano Wase, Owari, Silverhill, Foley, Sugiyama and Nobilis—were examined for content of saturated and mono-unsaturated long-chain hydrocarbons in their juice sacs. Linear hydrocarbons accounted for more than 53% of the saturates and more than 87% of the monoenes. In the saturated fraction the major linear hydrocarbon was C₂₅ while in the monoene fraction C₂₅ and C₂₉ predominated. The ratios of linear/iso C₂₃ and C₂₅ saturates were greater than in other citrus previously investigated. Kawano Wase had profiles quite different from the other cultivars. Foley and Owari can be differentiated from the other cultivars by their linear monoene profiles. Long-chain hydrocarbon profiles intrinsic to the mandarin species, C. unshiu, were compared with profiles of non-mandarin species.     

Saturated and mono-unsaturated long-chain hydrocarbons from lemon juice sacs

Three varieties of lemon—Lisbon, Malta and Kusner—were examined for their content of juice sac saturated and mono-unsaturated long-chain hydrocarbons. The saturated fractions were 20 times the concentrations of the monoene fractions. The dominant linear hydrocarbon in the saturated fraction was C₂₅ while C₂₉ predominated in the monoene fraction. The saturated hydrocarbon profiles for Lisbon and Kusner were very similar to the profiles previously reported for Eureka lemon and Persian lime. The mono-unsaturated profiles were distinct for each of the three lemon varieties. In addition the lemon mono-unsaturated profiles were quite distinct from the hydrocarbon profiles previously reported for several other citrus species. In general the data support the elongation-decarboxylation mechanism for hydrocarbon synthesis proposed by Kolattukudy.     

Saturated and mono-unsaturated long-chain hydrocarbon profiles from mandarin juice sacs

The long-chain saturated and mono-unsaturated hydrocarbon content of the juice sacs of five mandarin cultivars (Mediterranean, Honey, Wilking, Kinnow, King) were examined. Normal homologues accounted for more than 47% of the saturated and more than 75% of the monoene hydrocarbons. In the saturated fraction the major hydrocarbon was n-C₂₅ but in the monoene fraction n-C₂₅ predominated in Kinnow and King while C₂₉ predominated in Mediterranean, Honey and Wilking. All five cultivars could be differentiated from each other and from other citrus species by their hydrocarbon patterns. The noticeably high normal/iso ratios of saturated C₂₃ and C₂₅ hydrocarbons previously shown to be characteristic of mandarin species, Citrus unshiu and C. reticulata, were also found in C. nobilis and C. deliciosa.     

Biosynthesis of acyclic methyl branched polyunsaturated hydrocarbons inPseudomonas maltophilia

Summary The hydrocarbon composition ofPseudomonas maltophilia was determined by gas chromatography-mass spectrometry. Mono-, di- and tri-unsaturated alkenes were identified with a predominance of polyunsaturated components. The carbon chains of the alkenes contained single methyl branches iniso andanteiso position and double methyl branches in theiso-iso andanteiso-anteiso configurations. The composition of the hydrocarbons from cells grown in synthetic media enriched with amino acids or volatile fatty acids demonstrated that the probable precursors incorporated into individual hydrocarbons were branched and normal fatty acid chains in the range from C₃ to C₁₆. The probable fatty acid precursors which were connected together to form the major triunsaturated hydrocarbon chains were two monounsaturated chains, whereas the major liunsaturated chains resulted from condensation of saturated and monounsaturated chains. The probable precursors for the major monounsaturated hydrocarbons were C₁₄ (C₁₅) and C₁₆ (C₁₅) fatty acids. The accumulation of hydrocarbons was not detected until the cells were in the late exponential phase of growth; the maximal levels were reached at the mid-stationary phase of growth.     

Further evidence for an elongation-decarboxylation mechanism in the biosynthesis of paraffins in leaves

In isolated tobacco leaves l-valine-U-¹⁴C gave rise to labeled even-numbered isobranched fatty acids containing 16 to 26 carbon atoms and iso C₂₉, iso C₃₁, and iso C₃₃ paraffins. l-Isoleucine-U-¹⁴C on the other hand produced labeled odd-numbered anteiso C₁₇ to C₂₇ fatty acids and anteiso C₃₀ and C₃₂ paraffins. Trichloroacetic acid inhibited the incorporation of isobutyrate into C₂₀ and higher fatty acids and paraffins without affecting the synthesis of the C₁₆ and C₁₈ fatty acids. Thus the very long branched fatty acids are biosynthetically related to the paraffins. In Senecio odoris leaves acetate-1-¹⁴C was incorporated into the paraffins (mainly n-C₃₁) only in the epidermis although acetate was readily incorporated into fatty acids in the mesophyll tissue. Similarly only the epidermal tissue incorporated acetate into fatty acids longer than C₁₈ suggesting that the epidermis is the site of synthesis of both paraffins and the very long fatty acids. In broccoli leaves n-C₁₂ acid labeled with ¹⁴C in the carboxyl carbon and ³H in the methylene carbons was incorporated into C₂₉ paraffin without the loss of ¹⁴C relative to ³H. Since n-C₁₈ acid is known to be incorporated into the paraffin without loss of carboxyl carbon these results suggest that the condensation of C₁₂ acid with C₁₈ acid is not responsible for n-C₂₉ paraffin synthesis in this tissue. Thus all the experimental evidence thus far obtained strongly suggests that elongation of fatty acids followed by decarboxylation is the most likely pathway for paraffin biosynthesis in leaves.     

Structural Characterization of Lipopeptide Methyl Esters Produced by Bacillus licheniformis HSN 221

Lipopeptides and their analogues are of increasing interest due to their amphiphilic structures and potential applications in various fields. Three purified lipopeptides analogues were obtained at the same time after two‐step column‐chromatographic purification from cell‐free broth cultivated by Bacillus licheniformis HSN 221. Analysis by ESI‐MS, GC/MS, HPLC, and Q‐TOF MS/MS revealed their primary structures as anteiso‐C₁₅‐ and iso‐C₁₅‐β‐hydroxy fatty acid‐Gln‐Leu‐Leu‐Val‐MeAsp‐Leu‐Ile, anteiso‐C₁₅‐ and iso‐C₁₅‐β‐hydroxy fatty acid‐MeGlu‐Leu‐Leu‐Val‐Asp‐Leu‐Ile and iso‐C₁₆‐β‐hydroxy fatty acid‐Glu‐Leu‐Leu‐Val‐MeAsp‐Leu‐Ile, respectively. The production of two surfactin monomethyl esters and one lichenysin monomethyl ester directly from microorganisms is helpful to understand the variants of metabolites.     

Fatty acid desaturase 2 (FADS2) but not FADS1 desaturates branched chain and odd chain saturated fatty acids

Branched chain fatty acids (BCFA) and linear chain/normal odd chain fatty acids (n-OCFA) are major fatty acids in human skin lipids, especially sebaceous gland (SG) wax esters. Skin lipids contain variable amounts of monounsaturated BCFA and n-OCFA, in some reports exceeding over 20% of total fatty acids. Fatty acid desaturase 2 (FADS2) codes for a multifunctional enzyme that catalyzes Δ4-, Δ6- and Δ8-desaturation towards ten unsaturated fatty acids but only one saturate, palmitic acid, converting it to 16:1n-10; FADS2 is not active towards 14:0 or 18:0. Here we test the hypothesis that FADS2 also operates on BCFA and n-OCFA. MCF-7 cancer cells stably expressing FADS1 or FADS2 along with empty vector control cells were incubated with anteiso-15:0, iso-16:0, iso-17:0, anteiso-17:0, iso-18:0, or n-17:0. BCFA were Δ6-desaturated by FADS2 as follows: iso-16:0 → iso-6Z-16:1, iso-17:0 → iso-6Z-17:1, anteiso-17:0 → anteiso-6Z-17:1 and iso-18:0 → iso-6Z-18:1. anteiso-15:0 was not desaturated in either FADS1 or FADS2 cells. n-17:0 was converted to both n-6Z-17:1 by FADS2 Δ6-desaturation and n-9Z-17:1 by SCD Δ9-desaturation. We thus establish novel FADS2-coded enzymatic activity towards BCFA and n-OCFA, expanding the number of known FADS2 saturated fatty acid substrates from one to six. Because of the importance of FADS2 in human skin, our results imply that dysfunction in activity of sebaceous FADS2 may play a role in skin abnormalities associated with skin lipids.     

Comparative study of the dufour gland secretions of workers of four species of Myrmica ants

The Dufour gland secretions of myrmica rubra, M. ruginodis, M. sabuleti and M. scabrinodis have been studied. The most volatile portions of the secretion of workers of all four species were found to be similar, containing C₂C₄ oxygenated compounds. The less volatile portion consists of a mixture of hydrocarbons. In M. ruginodis this is chiefly a mixture of linear saturated and mono-unsaturated hydrocarbons, similar in composition to that of M. rubra, while in M. sabuleti it consists of (Z,E)-α-farnesene and its homologues, homofarnesene, bishomofarnesene and trishomofarnesene, similar in composition to that of M. scabrinodis. Workers of each species studied were attracted to the Dufour gland volatiles of all four species, these substances chiefly causing an increase in running speed, with the workers not distinguishing between conspecific and allospecific secretions, though small quantitative differences could be demonstrated between the speed and orientation reaction of workers of each species. The less volatile fraction of the Dufour gland secretion is used for territorial marking by foraging workers. This marking is specific for each species except between M. rubra and M. ruginodis.     

Very-Long-Chain Wax Constituents from Primula veris and P. acaulis: Does the Paradigm of Non-Branched vs. Branched Chain Dominance Universally Hold in all Plant Taxa?

Herein n-, iso- and anteiso-series of very-long-chained (VLC) alkanes (C₂₁–C₃₅), fatty acid benzyl esters (FABEs; C₂₀–C₃₂), and 2-alkanones (C₂₃–C₃₅) were identified in the wax of Primula veris L. and P. acaulis (L.) L. (Primulaceae). For the very first time in a sample of natural origin, the presence of iso- and anteiso-VLC FABEs and 2-alkanones was unequivocally confirmed by synthetic work, derivatization, and NMR. It should be noted that the studied species produced unusually high amounts of branched wax constituents (e. g., >50 % of 2-alkanones were branched isomers). The domination of iso-isomers, probably biosynthesized from leucine-derived starters, is a unique feature in the Plant Kingdom. The plant organ distribution of these VLC compounds in P. acaulis samples (different habitats and phenological phases) pointed to their possible ecological value. This was supported by a eutectic behavior of binary blends of FABEs and alkanes, as well as by high UV-C absorption by FABEs.     

Specificity effects in the biosynthesis of fatty acids in Bacillus acidocaldarius

Addition to Bacillus acidocaldarius of acids which can act as primers for fatty acid synthesis promote the synthesis of corresponding fatty acids competitively. The effective acids are n?C₅ to -?₇ (not C₄ or C₈), iso- and anteiso-C, and ?C, (not C4), and a range of cyclic acids from cyclobutylacetic and cyclopentanecarboxylic to cycloheptylacetic. New non-natural ω-cyclobutyl-, ω-cyclopentyl-, and ω-cycloheptyl-fatty acids are obtainable. The range of acceptable primers and the range of fatty acids produced therefrom indicate, respectively, the substrate specificities of the transacylase which introduces acyl species into fatty acids synthesis and the one which removes them. The specificity of the primer transacylase may be similar to that in some rumen anaerobes.     

Synthesis of β-hydroxy fatty acids and β-amino fatty acids by the strains of Bacillus subtilis producing iturinic antibiotics

The iturinic antibiotics, which contain long chain β-amino acids, are produced by Bacillus subtilis. Screening these strains for the presence of a possible precursor of the iturinic antibiotics, we isolated a lipopeptide containing β-hydroxy fatty acids. The structure of this compound was studied and it appears to be identical or structurally very similar to surfactin. The carbon chain of its β-hydroxy fatty acids was n C₁₆, iso C₁₆, iso C₁₅ or anteiso C₁₅. The percentages of each β-hydroxy fatty acids varied according to the strain producing iturinic antibiotics and were influenced by addition of branched-chain α-amino acids to the culture medium. These results demonstrate for the first time that iso C₁₄ β-hydroxy fatty acid is a constituent present in such a surfactin like lipopeptide. Besides, the presence of radioactive β-hydroxy fatty acids in the phospholipids when the strains were grown in the presence of sodium [¹⁴C]acetate seems also characterize the different strains producing iturinic antibiotics.     

The dufour gland substances of the workers of Formica fusca and Formica lemani (hymenoptera: formicidae)

• 1.1. The Dufour gland secretions of Formica fusca consist mainly of saturated straight and branched chain hydrocarbons (C₉–C₁₉), one unsaturated hydrocarbon (C₁₃) and two sesquiterpenoids, farnesene and homofarnesene.
• 2.2. In F. lemani, the Dufour gland contains branched, saturated and unsaturated hydrocarbons (C₉–C₁₉) and two farnesenes.
• 3.3. The two species were distinguished chiefly by the presence of a relatively large proportion of farnesene in F. fusca, with very little homofarnesene and by contrast, little farnesene but much more homofarnesene in F. lemani.
• 4.4. The contents of the Dufour gland can be used as a chemotaxonomic clue to distinguish between the species.

     

Effects of phospholipid acyl chain structure on thermotropic phase properties. 3. Phosphatidylcholines with (−), and (±)-anteiso acyl chains

We have synthesized a number of anteiso-branched fatty acids, both as racemates and as pure (?)-stereoisomers, as well as the corresponding di-anteiso-acyl phosphatidylcholines (PCs). The phase transition temperatures (_c of the hydrated PCs have been determined by differential thermal analysis (DTA). Consideration of the observed effects of acyl chain length and terminal see-butyl group configuration on anteiso acid melting points and di-anteiso-acyl PC transition temperatures leads us to the conclusion that the terminal branched portions of anteiso acyl chains interact only weakly with adjacent acyl chains in the hydrated phosphatidylcholine bilayer and probably in the anhydrous fatty acid crystal as well. In agreement with this conclusion, we observe that the DTA heating transition endotherms for hydrated di-anteiso-acyl PCs appear to be considerably less strongly endothermic, and occur at much lower temperatures, than do the major transition endotherms for the di-n-acyl PCs of like carbon number. Our findings generally support the proposal that anteiso acyl lipids tend to fluidize membranes, although they do so less effectively than do cis-unsaturated acyl lipids.     

Aliphatic Hydrocarbons of Cladosporium resinae Cultured on Glucose,Glutamic Acid,and Hydrocarbons

The carbon source markedly influenced the qualitative and quantitative composition of cellular hydrocarbons in Cladosporium resinae. Total lipid and hydrocarbon content was greater in cells grown on n-alkanes than in cells grown on glucose or glutamic acid. Glucose-grown cells contained a spectrum of aliphatic hydrocarbons from C₇ to C₃₆; pristane and n-hexadecane comprised 98% of the total. Cells grown on glutamic acid contained C₇ to C₂₃ hydrocarbons; n-tridecane, n-tetradecane, n-hexadecane, and pristane made up 74% of the total. n-Decane-grown cells yielded C₈ to C₃₂ compounds, and n-hexadecane (96%) was the major hydrocarbon. Cells grown on individual n-alkanes from C₁₁ to C₁₅ all contained C₁₁ to C₂₈ hydrocarbons, and cells grown on n-hexadecane contained C₁₁ to C₃₂ hydrocarbons. In n-undecane-grown cells, n-hexadecane and pristane made up 92% of the total, but in cells grown on C₁₂ to C₁₆ n-alkanes the major cellular hydrocarbon was the one on which the cells were grown. This suggests that cells cultured on n-alkanes of C₁₂ or longer accumulate n-alkanes prior to oxidizing them.     

Branched-chain amino acid metabolism controls membrane phospholipid structure in Staphylococcus aureus

Branched-chain amino acids (primarily isoleucine) are important regulators of virulence and are converted to precursor molecules used to initiate fatty acid synthesis in Staphylococcus aureus. Defining how bacteria control their membrane phospholipid composition is key to understanding their adaptation to different environments. Here, we used mass tracing experiments to show that extracellular isoleucine is preferentially metabolized by the branched-chain ketoacid dehydrogenase complex, in contrast to valine, which is not efficiently converted to isobutyryl-CoA. This selectivity creates a ratio of anteiso:iso C₅-CoAs that matches the anteiso:iso ratio in membrane phospholipids, indicating indiscriminate utilization of these precursors by the initiation condensing enzyme FabH. Lipidomics analysis showed that removal of isoleucine and leucine from the medium led to the replacement of phospholipid molecular species containing anteiso/iso 17- and 19-carbon fatty acids with 18- and 20-carbon straight-chain fatty acids. This compositional change is driven by an increase in the acetyl-CoA:C₅-CoA ratio, enhancing the utilization of acetyl-CoA by FabH. The acyl carrier protein (ACP) pool normally consists of odd carbon acyl-ACP intermediates, but when branched-chain amino acids are absent from the environment, there was a large increase in even carbon acyl-ACP pathway intermediates. The high substrate selectivity of PlsC ensures that, in the presence or the absence of extracellular Ile/Leu, the 2-position is occupied by a branched-chain 15-carbon fatty acid. These metabolomic measurements show how the metabolism of isoleucine and leucine, rather than the selectivity of FabH, control the structure of membrane phospholipids.     

Cellular Fatty Acid Composition of Nine Pathovars of Xanthomonas campestris

Cellular fatty acids of 80 strains of Xanthomonas campestris, representing 9 different pathovars, were analyzed by gas-liquid chromatography and mass spectrometry. A total of 48 fatty acids were identified, the most important being the 16:0 (averaging at least 4.5 % of the total), the cis- and trans- 9 16 : 1 (over 14.4 %), and the iso and anteiso 15 : 0 (over 30 %). Other major fatty acids (averaging over 1 % of total) were the saturated 14 : 0 and 15 : 0, the hydroxy-substituted iso 3-OH 11 : 0, 3-OH 12 : 0 and iso 3-OH 13 : 0, and the branch-chained iso 11 : 0, iso 16 : 0, iso 17 : 1, iso 17 : 0 and anteiso 17 : 0. Of 33 minor fatty acids detected and identified, only 7 have been previously reported in the xanthomonads. Significant differences in mean percentages of 5 major fatty acids and 4 (chemical) class totals were detected among pathovars, which statistically segregated into three groups by rank analysis. X. campestris pv. dieffenbachiae was in a group by itself; pvs. campestris, citri (pathotypes A and B), manihotis, phaseoli, pruni and vesicatoria were in a seond group, and pvs. glycines, begonia and citri (pathotype E) were in a third.     

Hydrocarbons and fatty acids of Lycopodium

The analysis of fatty acids and hydrocarbons in the sporophytes of three Lycopodium species has revealed a characteristic distribution of C₁₆ and C₁₈ acids. The hydrocarbon fraction of the lipids contain a homologous series of monounsaturated alkenes in the C₁₇C₃₀ range with an even to odd preference. Maxima at both C₁₇ and C₂₇ among the n-alkanes reveals similarities both to the distribution of hydrocarbons in other plant groups. The production of spores and their inclusion with one sporophyte does not alter the fatty acid pattern but does decrease the alkene concentration and modifies the alkane distribution, shifting both maxima. The presence of pristane and phytane in all specimens, the dual maxima of alkanes and slight odd to even preference of alkanes is noteworthy in that these characteristics are possessed by geological deposits derived from Lycopodium ancestors.     

Biosynthetic and environmental effects on the stable carbon isotopic compositions of anteiso- (3-methyl) and iso- (2-methyl) alkanes in tobacco leaves

Nicotiana tabacum is the only plant known to synthesise large quantities of anteiso- (3-methyl) alkanes and iso- (2-methyl) alkanes. We investigated the carbon isotope ratios of individual long-chain n-alkanes, anteiso- and iso-alkanes (in the C₂₉-C₃₃ carbon number range) extracted from tobacco grown in chambers under controlled conditions to confirm the pathway used by the tobacco plant to synthesise these particular lipids and to examine whether environmental data are recorded in these compounds. Tobacco was grown under differing temperatures, water availabilities and light intensities in order to control its stable carbon isotope ratios and evaluate isotopic fractionations associated with the synthesis of these particular lipids. The anteiso-alkanes were found to have a predominant even-carbon number distribution (maximising at C₃₂), whereas the iso-alkanes exhibit an odd-carbon number distribution (maximising at C₃₁). Iso-alkanes were relatively more abundant than the anteiso-alkanes and only two anteiso-alkanes (C₃₀ and C₃₂) were observed.The anteiso-alkanes and iso-alkanes were found to be enriched in ¹³C by 2.8-4.3‰ and 0-1.8‰ compared to the n-alkanes, respectively, consistent with different biosynthetic precursors. The assumed precursor for the odd-carbon-numbered iso-alkanes is iso-butyryl-CoA (a C₄ unit derived from valine) followed by subsequent elongation of C₂ units and then decarboxylation. The assumed precursor for even-carbon-numbered anteiso-alkanes is α-methylbutyryl-CoA (a C₅ unit derived from isoleucine) and subsequent elongation by C₂ units followed by decarboxylation. The ratio of carbon atoms derived from α-methylbutyryl-CoA and subsequent C₂ units (from malonyl-CoA) is 1:5 for the biosynthesis of a C₃₀anteiso-alkane. The ratio of carbon atoms derived from iso-butyryl-CoA and subsequent C₂ units (from malonyl-CoA) is 4:25 for the synthesis of a C₂₉iso-alkane. An order of ¹³C depletion n-alkanes > iso-alkanes > anteiso-alkanes is evident from compound specific isotope data. This trend can probably be attributed to the ratio of the two different sources of carbon atoms in the final wax components.Higher water availability generally results in more depleted stable carbon isotope ratios due to maximised discrimination during carboxylation, associated with less diffusional limitation. This was confirmed in the present study by compound specific isotope analyses of iso-alkanes, anteiso-alkanes and n-alkane lipids extracted from the tobacco leaves. Likewise, light intensity has been shown to influence plant bulk δ¹³C in previous studies. The carbon isotope ratios of n-alkanes in tobacco grown under low-light conditions were about 2‰ more depleted in ¹³C than those of lipids extracted from tobacco grown under elevated light conditions. A similar order of difference is observed for the iso-alkanes and anteiso-alkanes (1.8‰ and 1.9‰, respectively). A negligible depletion in carbon isotope ratios was observed for the iso-alkanes and anteiso-alkanes extracted from tobacco grown under elevated temperatures. These results are consistent with the work of Farquhar [Farquhar, G.D., 1980. Carbon isotope discrimination by plants: effects of carbon dioxide concentration and temperature via the ratio of intercellular and atmospheric CO₂ concentrations. In: Pearman, G.I. (Ed.), Carbon Dioxide and Climate: Australian Research. Springer, Berlin, pp. 105-110] where temperature appears to have only a minor effect on plant bulk δ¹³C.     

Comparative alkane chemistry of Parthenium argentatum (guayule) and some F1 hybrids

The leaf alkanes of Parthenium argentatum (guayule), P. tomentosum var. stramonium, P. fruticosum var. trilobatum, and the first filial (F₁) generations obtained from crosses with guayule were investigated by GC and mass spectrometry and shown to be useful in chemotaxonomic studies. The identified n-alkanes ranged from C₁₉ to C₄₀ with either n-C₂₉ or n-C₃₁ as the main component. The alkane chemistry of guayule with n-C₃₁ being the main component predominated in most of the F₁ hybrids. The presence of iso-branched alkanes (C₂₇, C₂₉, C₃₁) in P. tomentosum and its hybrids could be detected by GC/MS. These preliminary investigations indicate that epicuticular wax alkanes can be useful in inheritance studies of guayule and its hybrids.