Saturated mono-unsaturated long-chain hydrocarbon profiles of sweet oranges

Three varieties of midseason oranges, viz. Jaffa, Homosassa and Queen, were examined for their saturated and mono-unsaturated hydrocarbon composition in juice sacs. Hydrocarbons were isolated by lipid extraction of the juice sac powders followed by column, thin-layer and AgNO₃-TLC. After hydrogenation, the mono-unsaturated fraction and the saturated fraction were analyzed by GC. In the saturated fraction, the dominant linear hydrocarbon was C₂₃ while C₂₅ predominated in the monoene fraction. iso- And anteiso-branched hydrocarbons comprised between 53 and 63 % of the saturated fraction and only 20–26 % of the monoene fraction. Queen differed from Homosassa and Jaffa in the accumulation of higher percentages of saturated iso- and anteiso-branched hydrocarbons and conversely, showed lower percentages for these branched structures in the monoene fraction. Based on the total relative percentages of the three isomeric hydrocarbons, Homosassa could not be differentiated from Jaffa. The overall profiles for these two oranges, however. showed noticeable differences.     

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 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.     

Importance of Different Volatile Petroleum Hydrocarbon Fractions in Human Health Risk Assessment

Soil vapor data for benzene and four aliphatic and aromatic hydrocarbon fractions from five volatile petroleum hydrocarbon (VPH)-contaminated sites in western Canada were used together with the Canadian Council of Ministers of the Environment (CCME) Canada-Wide Standard for petroleum hydrocarbons to investigate the relative importance of benzene and the different fractions in human health risk assessment. VPH concentrations in soil vapor samples ranged from 4.0 to 4200?mg/m³, of which 0 to 4.6% was BTEX and 90 to 95% was hydrocarbons of the C_5–8 aliphatic fraction. VPH inhalation exposure by an adult receptor in a hypothetical, commercial building was modelled deterministically assuming 16- and 70 year occupational tenures. The magnitude of hazard quotients varied widely between sites, but their hydrocarbon fraction signatures were consistent, and characterized by higher hazard quotients in the C_5–8 and C_9–10 aliphatic and C_9–10 aromatic fractions relative to benzene and the TEX aromatic fraction. This work has shown that the C_5– and C_9–10 aliphatic fractions yield greater relative risk than the commonlyregulated TEX compounds, and that benzene becomes the primary chemical of potential concern only when an occupational tenure approaching 70 years is assumed.     

Fatty acid composition of sterol esters from Citrus sinensis,C. paradisi,C. limon aurantifolia and C. limettioides sacs

The fatty acid compositions of sterol esters from 4 citrus species, viz, orange. grapefruit, lemon and lime, were determined by GLC. Each species possessed its own intrinsic fatty acid pattern which could be used to differentiate it from the other species. In most cases varieties within a species had fatty acid patterns which could be used for varietal differentiation. In all citrus tested except Columbia lime, the major acid was linoleic acid; this acid varied from 10 to 56% of the total acid content. The ratios of 16/16:1 were distinct for each citrus species. The C₂₂-C₂₉ fatty acids were prevalent in citrus sterol esters ranging from 6·5% for some orange and grapefruit varieties to over 41% for two lime varieties. In all varieties C₂₄ was the most prominent of these longer chain fatty acids. Argentation TLC indicated that these longer chain fatty acids primarily were esterified to dimethyl sterols. ft*|One of the laboratories of the Southern Region, Agricultural Research Service, U.S. Department of Agriculture.     

Metabolism of propionic acid to a novel acyl-coenzyme A thioester by mammalian cell lines and platelets

Metabolism of propionate involves the activated acyl-thioester propionyl-CoA intermediate. We employed LC-MS/MS, LC-selected reaction monitoring/MS, and LC-high-resolution MS to investigate metabolism of propionate to acyl-CoA intermediates. We discovered that propionyl-CoA can serve as a precursor to the direct formation of a new six-carbon mono-unsaturated acyl-CoA. Time course and dose-response studies in human hepatocellular carcinoma HepG2 cells demonstrated that the six-carbon mono-unsaturated acyl-CoA was propionate-dependent and underwent further metabolism over time. Studies utilizing [¹³C₁]propionate and [¹³C₃]propionate suggested a mechanism of fatty acid synthesis, which maintained all six-carbon atoms from two propionate molecules. Metabolism of 2,2-[²H₂]propionate to the new six-carbon mono-unsaturated acyl-CoA resulted in the complete loss of two deuterium atoms, indicating modification at C2 of the propionyl moiety. Coelution experiments and isotopic tracer studies confirmed that the new acyl-CoA was trans-2-methyl-2-pentenoyl-CoA. Acyl-CoA profiles following treatment of HepG2 cells with mono-unsaturated six-carbon fatty acids also supported this conclusion. Similar results were obtained with human platelets, mouse hepatocellular carcinoma Hepa1c1c7 cells, human bronchoalveolar carcinoma H358 cells, and human colon adenocarcinoma LoVo cells. Interestingly, trans-2-methyl-2-pentenoyl-CoA corresponds to a previously described acylcarnitine tentatively described in patients with propionic and methylmalonic acidemia. We have proposed a mechanism for this metabolic route consistent with all of the above findings.     

长三角典型水稻土有机碳组分构成及其主控因子

准确把握水稻土有机碳组分构成特征及其主控因子,对定量化评价土壤有机碳质量和未来演变趋势具有重要意义。通过室内土壤呼吸培养实验结合有机碳三库一级动力学方程,模拟得到长三角地区典型水稻土剖面(0—100 cm)各土层有机碳组分含量及其分布特征;并利用主成分分析获取主控因子,建立有机碳组分回归预测模型。结果表明:水稻土活性碳、慢性碳和惰性碳含量随剖面深度增加而降低,上层土壤(0—40 cm)有机碳组分含量下降速度明显快于下层土壤(40—100 cm);水稻土活性碳构成比例不超过5.3%,惰性碳构成比例大于活性碳与慢性碳比例之和,达到60%以上,水稻土有机碳总量变异主要取决于慢性碳和惰性碳组分变异。因此,水稻土固碳重点在于慢性和惰性组分。同时,研究还发现水稻土类型和剖面深度主要在表层对有机碳组分含量和比例构成产生显著影响,土壤有机碳量、全氮和pH是影响水稻土有机碳组分含量分异的主控因子,利用主控因子可较好预测水稻土有机碳组分含量。     

Esters of trehalose from Corynebacterium diphtheriae: A modified purification procedure and studies on the structure of their constituent hydroxylated fatty acids

The purification procedure of 6,6′-diesters of trehalose from Corynebacterium diphtheriae was modified and the isolated substance was analysed by mass spectrometry as its permethylated derivative. The fatty acid moiety released from the glycolipid after alkaline hydrolysis was studied by mass spectral analysis of the O-methylated and O-acetylated methyl ester derivatives. By argentation thin-layer chromatography, three species of O-acetylated methyl esters were recognized, corresponding to saturated, mono-unsaturated and di-unsaturated α-branched-β-hydroxylated fatty acids. The double bond was located by ozonolysis of the O-acetylated methyl ester derivatives, by gas chromatography of the reaction product and mass spectrometry of the effluent from the gas chromatograph. The main components of each species of α-branched-β-hydroxylated fatty acids found in the gly colipid fraction of C. diphtheriae were 2-tetradecyl-3-hydroxyoctadecanoic acid (C₃₂H₆₄O₃, corynomycolic acid), 2-tetradecyl-3-hydroxy-11-octadecenoic acid (C₃₂H₆₂O₃, corynomycolenic acid), 2-tetradec-7′-enyl-3-hydroxy octadecanoic acid (C₃₂H₆₂O₃) and 2-tetradec-7′-enyl-3-hydroxy-11-octadecenoic acid (C₃₂H₆₀O₃, corynomycoldienic acid). The glycolipid fraction from C. diphtheriae is obviously a complex mixture of 6,6′-diesters of trehalose.     

FATTY ACIDS AND HYDROXY FATTY ACIDS IN THREE SPECIES OF FRESHWATER EUSTIGMATOPHYTES

The monocarboxylic fatty acids and hydroxy fatty acids of three species of freshwater microalgae—Vischeria punctata Vischer, Vischeria helvetica (Vischer et Pascher) Taylor, and Eustigmatos vischeri (Hulbert) Taylor, all from the class Eustigmatophyceae— were examined. Each species displayed a very similar distribution of fatty acids, the most abundant of which were 20:5n-3, 16:0, and 16:1n-7; C₁₈ polyunsaturated fatty acids were minor components. These fatty acid distributions closely resemble those found in marine eustigmatophytes but are quite distinct from those found in most other algal classes. These microalgae also contain long-chain saturated and unsaturated monohydroxy fatty acids. Two distinct types of hydroxy fatty acids were found: a series of saturated α-hydroxy acids ranging from C₂₄ to C₃₀ with a shorter series of monounsaturated α-hydroxy acids ranging from C₂₆ to C₃₀ together with a series of saturated β-hydroxy acids ranging from C₂₆ to C₃₀. The latter have not previously been reported in either marine or freshwater microalgae, although C₃₀ to C₃₄ midchain (ω-18)-hydroxy fatty acids have been identified in hydrolyzed extracts from marine eustigmatophytes of the genus Nannochloropsis, and C₂₂ to C₂₆ saturated and monounsaturated α-hydroxy fatty acids have been found in three marine chlorophytes. These findings have provided a more complete picture of the lipid distributions within this little studied group of microalgae as well as a range of unusual compounds that might prove useful chemotaxonomic markers. The functions of the hydroxy fatty acids are not known, but a link to the formation of the lipid precursors of highly aliphatic biopolymers is suggested.     

Cell Envelope Phospholipid Composition of Burkholderia multivorans

Burkholderia multivorans causes opportunistic pulmonary infections in cystic fibrosis and immunocompromised patients. The purpose of the present study was to determine the nature of the phospholipids and their fatty acid constituents comprising the cell envelope membranes of strains isolated from three disparate sources. A conventional method for obtaining the readily extractable lipids fraction from bacteria was employed to obtain membrane lipids for thin-layer chromatographic and gas chromatography-mass spectrophotometric analyses. Major fatty acid components of the B. multivorans readily extractable lipid fractions included C_16:0 (palmitic acid), C_16:1 (palmitoleic acid), and C_18:1 (oleic acid), while C_14:0 (myristic acid), ΔC_17:0 (methylene hexadecanoic acid), C_18:0 (stearic acid), and ΔC_19:0 (methylene octadecanoic acid) were present in lesser amounts. Fatty acid composition differed quantitatively among strains with regard to C_16:0, C_16:1, ΔC_17:0, C_18:1, and ΔC_19:0 with the unsaturated:saturated fatty acid ratios being significantly less in a cystic fibrosis type strain than either environmental or chronic granulomatous disease strains. Phospholipids identified in all B. multivorans strains included lyso-phosphatidylethanolamine, phosphatidylglycerol, phosphatidylethanolamine, and diphosphatidylglycerol in similar ratios. These data support the conclusion that the cell envelope phospholipid profiles of disparate B. multivorans strains are similar, while their respective fatty acyl substituent profiles differ quantitatively under identical cultivation conditions.     

Application of Two‐Way Hierarchical Cluster Analysis for the Identification of Similarities between the Individual Lipid Fractions of Lucilia sericata

The composition of the cuticular and internal lipids of larvae and pupae of Lucilia sericata was studied using chromatographic techniques. The lipids from both stages of L. sericata had similar free fatty acid (FFA) profiles and also contained alcohols and cholesterol. The range of the number of C‐atoms detected for these classes of compounds was to some extent similar in larvae and pupae, but the relative amounts of each class differed between stages. Saturated as well as unsaturated FFAs with even and odd numbered C‐atom chains were present in both cuticular and internal lipids. The alcohol fractions of L. sericata were represented by free, straight‐chain primary alcohols containing an even number of C‐atoms. The lipid composition of male and female L. sericata adults and the hydrocarbon composition of all stages of L. sericata had previously been analyzed. To have a full overview of the lipid composition and to identify similarities or dissimilarities between the individual lipid fractions in this insect species, two‐way hierarchical cluster analysis (HCA) was performed using also the data from these previous publications. The content of FFA 18 : 1 (n‐9) was noticed to be very high in the cuticular fractions of larvae and pupae as well as in all internal fractions (male, female, larvae, and pupae) and low in the cuticular fractions of male and female imago. The contents of FFAs 16 : 0 and 16 : 1 (n‐9), cholesterol, and the n‐alkanes n‐C₃₁, n‐C₂₉, n‐C₂₇, n‐C₂₅, and n‐C₂₃ varied between particular fractions, whereas the amounts of other compounds were similar in all fractions.     

Electroantennographic and field responses of the pea moth, Cydia nigricana, to sex attractants and related compounds

Electroantennographic (EAG) responses of the male pea moth, Cydia nigricana, to a range of saturated and unsaturated straight chain alcohols and acetates were examined. Responses to saturated compounds of different chain lengths (C₁₀ to c₁₆) showed that acetates are much more active than alcohols, the shorter chain compounds (particularly C₁₂ acetates) being the most active. With mono-unsaturated compounds, C₁₂ acetates with the double bond at C-8, C-9 or C-10 elicited the largest responses and (El-10-dodecenyl acetate produced a greater response than any other compound tested. By analogy with results obtained with C.pomonella, (E, E)-8,lO-dodecadienyl acetate was tested and gave an EAG response larger than that for (E)-10-dodecenyl acetate. (E)-10-dodecenyl acetate and (E, E)-8,lO-dodecadienyl acetate were found to be strong attractants for male C.nigricana in the field.     

Eubacterium cellulosolvens Alters its Membrane Protein,Lipoprotein, and Fatty Acid Composition in Response to Growth on Cellulose

The cellulolytic bacterium, Eubacterium cellulosolvens, altered its cytoplasmic membrane protein composition in response to growth on specific energy substrates. Electrophoresis profiles obtained from membrane protein fractions of cellulose-grown cells were different from that obtained from cells cultivated with other carbohydrates, such as cellobiose or glucose. In addition, [³H]palmitic acid labelling of cellulose-grown E. cellulosolvens revealed two lipoproteins that were not detected in glucose- or cellobiose-grown cultures. These lipoproteins partitioned with the membrane fraction, indicating their association with the cytoplasmic membrane. Proteinase K treatment of whole cells further suggested that these lipoproteins were exposed to the surface of the cell envelope. These membrane proteins and lipoproteins appear to be under some substrate-specific regulatory control with distinct, but as yet undetermined, roles in cellulose utilization. In addition, cellulose-grown E. cellulosolvens was found to posses a higher ratio of oleic acid (C_18:1) to palmitic acid (C_16:0) than cells cultivated on soluble carbohydrates. This change in the ratio of unsaturated to saturated fatty acids was consistent with a comparative increase of membrane fluidity. Further analysis of this shift in the fatty acid profile revealed a correlation with the appearance of protruberances on the cell surface. Such a shift of fatty acid composition may indicate that the assembly and function of proteins for cellulose utilization necessitates an increase of the membrane fluidity.     

Biosynthesis of saturated very long chain fatty acids by purified membrane fractions from leek epidermal cells

Elongation of fatty acids by microsomal fractions obtained from leek epidermal cells was measured by the incorporation of [1-¹⁴C]stearate, [1-¹⁴C]stearyl CoA, and [1-¹⁴C]stearyl ACP in the presence of malonyl CoA and NADPH. Stearoyl CoA appears to be the primer of the elongase (s) rather than stearoyl ACP. There are at least two elongases, the first elongating C₁₈ to C₂₀, the second synthesizing C₂₂ to C₃₀ fatty acids from C₂₀. The main site of the elongase (s) is a subcellular fraction enriched in endoplasmic reticulum. The plasma membrane-enriched fraction, which contains large amounts of saturated very long chain fatty acids, synthesizes only minor amounts of them.     

Anti-microfouling Activity of Lipidic Metabolites from the Invasive Brown Alga Sargassum muticum (Yendo) Fensholt

The purification of the chloroform extract from the brown invasive macroalga Sargassum muticum, through a series of chromatographic separations, yielded 12 fractions that were tested against strains of bacteria, microalgae, and fungi involved in marine biofilm formation. The chemical composition of four (a, c, g, and k) out of the six fractions that exhibited anti-microfouling activity was investigated. Fraction a contained saturated and unsaturated linear hydrocarbons (C₁₂–C₂₇). Arachidonic acid was identified as the major metabolite in fraction c whereas fraction g contained mainly palmitic, linolenic, and palmitoleic acids. Fraction k was submitted to further purification yielding the fraction kAcaF1e that was composed of galactoglycerolipids, active against the growth of two of the four bacterial strains (Shewanella putrefaciens and Polaribacter irgensii) and all tested fungi. These promising results, in particular the isolation and the activity of galactoglycerolipids, attest the potential of the huge biomass of S. muticum as a source of new environmentally friendly antifouling compounds.     

Characterisation of DNA from condensed and dispersed human chromatin

Condensed and dispersed chromatin fractions were isolated from human placental nuclei. The DNA of each fraction was purified and characterised by isopycnic centrifugation, thermal fractionation on hydroxylapatite (HAP) and sequence complexity studies. The DNAs had identical buoyant densities in neutral CsCl (1.698 g/cm³) and similar melting profiles on HAP. Analytical ultracentrifugation in Ag⁺-Cs₂SO₄, however, showed that satellite DNAs were present in the condensed fraction DNA (DNA_C) but were not visible in the dispersed fraction DNA (DNA_D). In addition, DNA_C was found to be enriched in highly reiterated sequences (20% reassociated by C₀t 10^?3) which can be correlated with the presence of satellite DNAs, whereas DNA_D contained only 3% of these fast reassociating sequences. In contrast DNA_D contained 30% intermediate sequences (reassociating between C₀t 10^?3 and C₀t 100) which represent only 10% of DNA_C. The reassociated highly repeated sequences of DNA_C showed the presence of two components in both CsCl density gradients and HAP thermal elution studies. This suggests that either there are sequence relationships resulting in partial mismatching between the different highly repeated DNA sequences in this fraction, or that highly repeated sequences are associated with less repetitious DNA. The results are discussed in terms of possible differences in genetic activity between the chromatin fractions.     

The cuticular hydrocarbons of the Triatoma sordida species subcomplex (Hemiptera: Reduviidae)

The cuticular hydrocarbons of the Triatoma sordida subcomplex (Hemiptera: Reduviidae: Triatominae) were ana-lysed by gas chromatography and their structures identified by mass spectrometry. They comprised mostly n-alkanes and methyl-branched alkanes with one-four methyl substitutions. n-alkanes consisted of a homologous series from C21-C33 and represented 33-45% of the hydrocarbon fraction; n-C29 was the major component. Methyl-branched alkanes showed alkyl chains from C24-C43. High molecular weight dimethyl and trimethylalkanes (from C35-C39) represented most of the methyl-branched fraction. A few tetramethylalkanes were also detected, comprising mostly even-numbered chains. Several components such as odd-numbered 3-methylalkanes, dimethylalkanes and trimethylalkanes of C37 and C39 showed patterns of variation that allowed the differentiation of the species and populations studied. Triatoma guasayana and Triatoma patagonica showed the most distinct hydrocarbon patterns within the subcomplex. The T. sordida populations from Brazil and Argentina showed significantly different hydrocarbon profiles that posed concerns regarding the homogeneity of the species. Triatoma garciabesi had a more complex hydrocarbon pattern, but it shared some similarity with T. sordida. The quantitative and qualitative variations in the cuticular hydrocarbons may help to elucidate the relationships between species and populations of this insect group.     

Significant year-to-year variation of the response to radiation-induced stress shown by gill fatty acid metabolism in eels (Anguilla anguilla captured from the wild

• 1.1. In eels captured in Roskilde Fjord in 1972 and 1975, a specifically enhanced synthesis was found from ¹⁴C-acetate of ¹⁴C-labelled mono-unsaturated fatty acids (C_16:1 and C_18:1) relative to saturated fatty acids (C_16:0 and C_18:0) in sea water 4 days after irradiation (10 Gy, ⁶⁰Co).
• 2.2. Corresponding experiments in 1976 and 1982 showed rather the opposite: irradiation resulted in more ¹⁴C-labelled saturated fatty acids relative to unsaturated fatty acids, both in fresh and sea water.
• 3.3. The latter effect was less marked than that in 1972 and 1975, but still statistically clearly significant.

     

Comparative sensitivity of 'Prior Lisbon' lemon and 'Valencia' orange trees to foliar sodium and chloride concentrations

Abstract While citrus rootstocks differ in capacity for sodium and chloride ion exclusion, citrus scion species also vary in foliar sensitivity to NaCl salinisation. Of two common scions, ‘Lisbon’ lemon appears more sensitive, whereas ‘Valencia’ orange in less sensitive to leaf salt. In an attempt to explain this difference. ‘Valencia’ orange (Citrus sinensis [L.] Osbeck) and ‘Prior Lisbon’ lemon (Citrus limon [L.] Burm. F.) were budded to rootstocks known to differ in their ability to exclude sodium ions viz, the strong excluder Trifoliata (Poncirus trifoliata [L.] Raf.), and the weaker excluder Troyer citrange (C. sinensis×P. trifoliata); neither rootstock shows strong exclusion of chloride ions. Budded trees were held under a photosynthetic photon flux density of 450 μmol m ² S ¹ and watered with nutrient solution containing either 0 or 50 mol m ³ NaCl. Growth and photosynthetic responses were measured over 58 d following onset of salinization: salinity effects on leaf gas exchange were studied in relation to changes in leaf water status, compatible solutes and foliar content of sodium and chloride ions, over that same period. Once root-zone salinization began to influence leaf solutes (day 30 onwards), lemon showed a steeper increase in leaf chloride than occurred for orange. Although rootstock differences were without effect on this ingress of chloride ions for either scion, sodium ions were excluded from both scions to a larger extent by Trifoliata than by Troyer citrange. Carbon dioxide assimilation of scion foliage was reduced earlier and to a much larger extent by rootzone salinization in lemon than in orange. Furthermore, comparisons of CO₂ assimilation in relation to leaf tissue solutes between scions (on either rootstock) showed stronger responses for both sodium and chloride ions in lemon than in orange. Faster ingress of chloride into lemon leaves was identified as the crucial factor which predisposed towards expression of that contrast between scions. Although contrasts between scions in photosynthetic responses to salinization matched a faster ingress of chloride into lemon than into orange leaves, the sharper photosynthetic response of ‘Prior Lisbon’ lemon to salinity was not solely attributable to higher concentrations of chloride ions (cell sap basis). A difference between species in subcellular compartmentation of the chloride ion under saline conditions was invoked.