Distribution Pattern Of Fatty Acids Research Articles

The effects of diet, salinity and temperature on HUFA accumulation in Artemia

Artemia nauplii is an important live food item for marine fish and crustaceans. However, the HUFA content of Artemia from different origins varies greatly and is generally low. Compared with other species or strains, Artemia cysts in Tibet salt lakes have very high HUFA content, which may be related to their unique living conditions. This study determined the effects of dietary HUFA (P. tricornutum and C. zofingiensis), salinity (4%, 8%, and 12%), and temperature (14 °C, 19 °C, and 24 °C) on the HUFA accumulation of Lagkor Co Artemia tibetiana after 14-day culture, in comparison with Great Salt Lake Artemia franciscana. The results showed that the HUFA profile of Artemia was closely related to the dietary HUFA level, and the low temperature and low salinity could significantly increase the ARA, EPA, and DHA content. PCA results showed that the fatty acid distribution patterns of the two Artemia species were mostly affected by dietary fatty acids, which were greater than those of temperature, salinity, and Artemia species. RNA-seq analysis and qRT-PCR verification revealed that low temperature and low salinity could promote the gene expression of fatty acid binding protein gene, long chain fatty acid elongase, and desaturase, suggesting these genes may be involved in the process of HUFA accumulation in A. franciscana. In conclusion, diet is a key factor affecting HUFA accumulation in Artemia, while low temperature and low salinity led to higher HUFA retention. The findings of this study provide a reference for revealing the mechanism of HUFA synthesis and metabolism of Artemia, and to develop the Artemia products with high HUFA content through manipulation of culture conditions.

Effect of salinity on the preservation of plant-derived n-alkyl compounds in the terrestrial-aquatic interface

In sediments, plant biomolecules (n-alkanes and fatty acids) serve as robust proxies in paleoenvironmental studies. Although the factors controlling preservation and isotopic composition of plant biomolecules are understood in soil systems, the effect of changes in depositional environments in land-sea interfaces, especially in hypersaline environments, is not so well constrained. In this study, we observed that in bed sediments, the plant biomolecules are preserved with carbon preference index (CPI) values > 1 in high molecular weight (HMW) n-alkanes in the hypersaline, metahaline, and euhaline regions of the Pulicat lagoon, India. However, in sub-surface sediments (up to 70 cm depth), the CPI values are consistently < 1 in the hypersaline region, but > 1 in the euhaline and metahaline regions. In the hypersaline region, the alteration of plant biomolecules possibly results from halophilic bacterial degradation and fatty acid to n-alkane reduction in anaerobic conditions (pristane/phytane values < 1), during the weaker northeast monsoon (44–60 cm sub-surface). Prolonged hypersaline conditions and associated anoxia resulted in a higher isotopic difference between fatty acids and n-alkanes (δ13CFA-ALK value) in the hypersaline region (3.1 ± 1.5‰) compared to metahaline (2.2 ± 1.0‰) and euhaline (1.5 ± 1.0‰) regions. Although in the hypersaline region the HMW fatty acids have CPI values > 1, the higher δ13CFA-ALK value also suggests the alteration of fatty acids. This study suggests that if plant-derived n-alkanes are altered, the δ13C values and distribution patterns of plant-derived fatty acids should be critically evaluated before using it as an alternative proxy in coastal environments.

Soil Perturbation in Mediterranean Ecosystems Reflected by Differences in Free-Lipid Biomarker Assemblages.

Environmental information provided by free lipids in soil samples collected from control and disturbed plots (Madrid, Spain) was assessed by comparing molecular assemblages of terpenoids and distribution patterns of alkanes and fatty acids (FAs) analyzed by gas chromatography-mass spectrometry (GC-MS). Wildfires in pine forests led to increased proportions of retene, dehydroabietin, and simonellite. Friedo-oleananes were characteristic in soils under angiosperms, and norambreinolide-type diterpenes were characteristic in soils encroached by Cistus bushes. Steroids were major compounds in pastured sites. Enhanced Shannon's lipid biodiversity index in disturbed soils compared with in control soils suggested patterns of recent lipids overlapping a preserved original lipid signature. The extent of the environmental impacts was illustrated as Euclidean distances between paired control and disturbed sites calculated using the compounds in alkyl homologous series as descriptors. As expected, reforestation, bush encroachment, wildfires, and cultivation were reflected by changes in the molecular record of lipids in soils.

Influence of extraction methods on the distribution pattern and concentration of fatty acids and hydroxy fatty acids in soil samples: Acid digestion versus saponification

Influence of extraction methods on the distribution pattern and concentration of fatty acids and hydroxy fatty acids in soil samples: Acid digestion versus saponification

Compositional studies and biological activities of some mash bean (Vigna mungo (L.) Hepper) cultivars commonly consumed in Pakistan.

BackgroundIn recent years, the desire to adopt a healthy diet has drawn attention to legume seeds and food products derived from them. Mash bean is an important legume crop used in Pakistan however a systematic mapping of the chemical composition of mash bean seeds is lacking. Therefore seeds of four mash bean (Vigna mungo (L.) Hepper, family Leguminoseae) cultivars (NARC-Mash-1, NARC-Mash-2, NARC-Mash-3, NARC-Mash-97) commonly consumed in Pakistan have been analyzed for their chemical composition, antioxidant potential and biological activities like inhibition of formation of advanced glycation end products (AGE) activity and tyrosinase inhibition activity.ResultsThe investigated cultivars varied in terms of biochemical composition to various extents. Mineral composition indicated potassium and zinc in highest and lowest amounts respectively, in all cultivars. The amino acid profile in protein of these cultivars suggested cysteine is present in lowest quantity in all cultivars while fatty acid distribution pattern indicated unsaturated fatty acids as major fatty acids in all cultivars. All cultivars were found to be rich source of tocopherols and sterols. Fourier transform infrared spectroscopy (FTIR) fingerprints of seed flour and extracts indicated major functional groups such as polysaccharides, lipids, amides, amines and amino acids. Results indicated that all investigated cultivars possessed appreciable antioxidant potential.ConclusionsAll cultivars are rich source of protein and possess sufficient content of dietary fiber, a balanced amino acid profile, low saturated fatty acids and antioxidant capacity that rationalizes many traditional uses of seeds of this crop besides its nutritional importance. The collected data will be useful for academic and corporate researchers, nutritionists and clinical dieticians as well as consumers. If proper attention is paid, it may become an important export commodity and may fetch considerable foreign exchange for Pakistan.

Lipid evaluation of farmed and wild meagre (Argyrosomus regius)

Proximate, lipid, and fatty acid composition of farmed and wild meagre (Argyrosomus regius) muscle, head, skin, and liver, were comparatively studied. Distinct differences were evident in the lipid and fatty acid composition among different tissues of farmed and wild meagre. Total lipid content of the farmed fish parts was significantly higher than that of the wild fish. Neutral lipids, mainly triglycerides, predominated in muscle, head, and skin for both fish. The fact that muscle fat was found significantly lower in triglycerides (TG) concentration than head and skin indicates that muscle consumption after head and skin removal may contribute to a healthy diet. Wild fish muscle, head, and skin fat was found to have significant contribution to the phosphatidylcholine daily intake in the human diet. A. regius liver was also found to be an excellent source of glycerophospholipids. Fatty acid patterns of muscle, head and skin of farmed fish were found to be affected by the feed. MUFA/saturated fatty acid (SFA), PUFA/SFA, and DHA/eicosapentaenoic acid (EPA) ratios were found significantly higher in muscle, head, and skin TL of wild fish compared to the farmed one. Farmed fish muscle could provide similar amount of EPA + DHA and significantly higher amount of ω‐3 PUFA compared to wild fish muscle.Practical applications: Argyrosomus regius is considered a promising fish species for aquaculture due to its tasty meat and great market acceptance in the Mediterranean countries. Hence it is important to determine its lipid and fatty acid content of both farmed and wild fish edible parts (muscle, head, and skin) for nutritional purposes. Remaining parts (such as liver) could still be interesting to analyze for possible use in other food or nutraceutical applications. Here we compare the distribution pattern of lipids and fatty acids of muscles, heads, skin, and liver in wild and farmed A. regius, fed a commercial diet. Furthermore, the present study is a novel comparison between cultured and wild fish species A. regius in terms of their proximate and fatty acid composition.

Fatty acid profiles and their distribution patterns in microalgae: a comprehensive analysis of more than 2000 strains from the SAG culture collection

BackgroundAmong the various biochemical markers, fatty acids or lipid profiles represent a chemically relatively inert class of compounds that is easy to isolate from biological material. Fatty acid (FA) profiles are considered as chemotaxonomic markers to define groups of various taxonomic ranks in flowering plants, trees and other embryophytes.ResultsThe fatty acid profiles of 2076 microalgal strains from the culture collection of algae of Göttingen University (SAG) were determined in the stationary phase. Overall 76 different fatty acids and 10 other lipophilic substances were identified and quantified. The obtained FA profiles were added into a database providing information about fatty acid composition. Using this database we tested whether FA profiles are suitable as chemotaxonomic markers. FA distribution patterns were found to reflect phylogenetic relationships at the level of phyla and classes. In contrast, at lower taxonomic levels, e.g. between closely related species and even among multiple isolates of the same species, FA contents may be rather variable.ConclusionFA distribution patterns are suitable chemotaxonomic markers to define taxa of higher rank in algae. However, due to their extensive variation at the species level it is difficult to make predictions about the FA profile in a novel isolate.

Source determination of lipids in bulk soil and soil density fractions after four years of wheat cropping

Preservation of soil organic matter (SOM) is strongly affected by occlusion within aggregates and by association of SOM with minerals. Protection of organic carbon (C) due to adsorption to mineral surfaces can be assessed by investigation of SOM in soil density fractions. Apart from the physical properties the preservation of SOM is affected by its chemical composition. While for bulk organic C this was demonstrated for numerous soils, SOM density fractions have been scarcely studied regarding their molecular composition. Lipids as a compound class that can derive from plants, microorganisms and contamination by products from incomplete combustion or fossil carbon were not investigated in density fractions so far. We hypothesized that molecular proxies deriving from lipid composition yield a large potential to elucidate the sources of organic matter entering soil, and in combination with density fractions they enable the identification of incorporation and preservation pathways of SOM. We determined distribution patterns of aliphatic hydrocarbons and fatty acids as two representative groups for total lipids in soil density fractions. The fatty acids showed a predominant input of plant-derived poly unsaturated short chain and saturated long chain fatty acids in free particulate organic matter (fPOM). The microorganism-derived compounds such as unsaturated short chain fatty acids were largely abundant in fPOM and especially in occluded particulate organic matter (oPOM 1.6). The proportion of plant-derived components like long chain fatty acids increased with increasing density of the fractions, whereas the abundance of short chain fatty acids decreased in the same direction as indicated by the ratio of long chain vs. short chain fatty acids. The main portion of soil lipids (60% of total lipids) was recovered in the mineral (Min) fraction, which denotes the strongest protection of lipids adsorbed to mineral surfaces. For the aliphatic hydrocarbons the contribution of plant- and microorganism-derived components was the largest in fPOM. Short chain alkanes as part of the aliphatic hydrocarbons showed contamination of soil by an incompletely burned plant biomass or fossil carbon. These contaminants were the most abundant in fPOM and subsequently attributed to particles with a low density, which derived probably from soot. However, a large contribution of fossil C was found in the Min fraction as well, which is thought to be attributed to degraded soot particles being adsorbed to minerals. We demonstrated at the molecular level that the incorporation of individual C sources varies with the density fractions. It was found that microorganism-derived compounds were most abundant in fPOM and oPOM 1.6 fractions, whereas plant-derived long chain biopolymers were enriched in mineral dominated fractions (oPOM 2.0 and especially Min). Thus, preservation of plant-derived lipids in soil is strongly attributed to the association with minerals. Based on lipid composition in density fractions we evaluated several molecular proxies, which help to elucidate the sources of SOM.

Influence of finishing systems and sampling site on fatty acid composition and retail shelf-life of lamb

Thirty 7-month-old crossbred lambs (Poll Dorset × Border Leicester × Merino) finished over 5 weeks on either low quality pasture or grain-with-hay on a farm in southern Victoria were assessed for carcass parameters, muscle fat composition and retail colour stability. Lambs on the grain diet had a mix of barley grain (80%) and lentils (20%) at 800 g/head.day (air-dry basis ~ad libitum) with cape weed (Arctotheca calendula) hay available at all times. Lambs under grazing had predominantly rye grass (Lolium perenne) and barley grass (Hordeum leporinum) available ad libitum. Carcass weight tended to be higher (P = 0.14) in grain-fed lambs than in grass-fed lambs, but fatness indicated by GR (total muscle + fat tissue thickness at 11 cm from midline) did not differ between feeding systems. Fatty acid composition was determined in the loin from the forequarter (M. longissimus thoracis) and lumbar (M. longissimus lumborum) regions and from the leg region (M. semimembranosus). This showed that grain-finished lamb had higher muscle fat (P &lt; 0.001) and omega-6 fatty acid (P &lt; 0.001) content. Alpha-linolenic acid, eicosapentaenoic acid (EPA) or total omega-3 fat did not differ (P &gt; 0.05) between feeding groups. Saturated fatty acids were greater (P &lt; 0.01) in both loin sampling sites than the leg. The levels of EPA, docosahexaenoic acid and docosapentaenoic acid were lower (P &lt; 0.01) in the forequarter (9%) or lumbar (11%) sites than the leg sampling site. The distribution pattern of fatty acids across the three sampling sites did not differ between feed types. Retail colour stability determined over 4 days of display (only performed in muscle from the lumbar site), evaluated by the redness (HunterLab a*-value) and metmyoglobin formation (reflectance ratio at 630 : 580-nm wavelengths) was superior for grass-fed lamb compared with short-term grain-finished lamb. The results demonstrate that the health claimable omega-3 fat mainly EPA or total omega-3 fat content in lamb was not altered by short-term grain finishing compared with lamb finished under pasture grazing conditions.

Recombinant Factor C (rFC) Assay and Gas Chromatography/Mass Spectrometry (GC/MS) Analysis of Endotoxin Variability in Four Agricultural Dusts

Endotoxin exposure is a significant concern in agricultural environments due to relatively high exposure levels. The goals of this study were to determine patterns of 3-hydroxy fatty acid (3-OHFA) distribution in dusts from four types of agricultural environments (dairy, cattle feedlot, grain elevator, and corn farm) and to evaluate correlations between the results of gas chromatography/mass spectrometry (GC/MS) analysis (total endotoxin) and biological recombinant factor C (rFC) assay (free bioactive endotoxin). An existing GC/MS-MS method (for house dust) was modified to reduce sample handling and optimized for small amount (<1 mg) of agricultural dusts using GC/EI-MS. A total of 134 breathing zone samples using Institute of Occupational Medicine (IOM) inhalable samplers were collected from agricultural workers in Colorado and Nebraska. Livestock dusts contained approximately two times higher concentrations of 3-OHFAs than grain dusts. Patterns of 3-OHFA distribution and proportion of each individual 3-OHFA varied by dust type. The rank order of Pearson correlations between the biological rFC assay and the modified GC/EI-MS results was feedlot (0.72) > dairy (0.53) > corn farm (0.33) > grain elevator (0.11). In livestock environments, both odd- and even-numbered carbon chain length 3-OHFAs correlated with rFC assay response. The GC/EI-MS method should be especially useful for identification of specific 3-OHFAs for endotoxins from various agricultural environments and may provide useful information for evaluating the relationship between bacterial exposure and respiratory disease among agricultural workers.

Structural characterization of the lipid A region of Aeromonas salmonicida subsp. salmonicida lipopolysaccharide

The lipid A components of Aeromonas salmonicida subsp. salmonicida from strains A449, 80204-1 and an in vivo rough isolate were isolated by mild acid hydrolysis of the lipopolysaccharide. Structural studies carried out by a combination of fatty acid, electrospray ionization-mass spectrometry and nuclear magnetic resonance analyses confirmed that the structure of lipid A was conserved among different isolates of A. salmonicida subsp. salmonicida. All analyzed strains contained three major lipid A molecules differing in acylation patterns corresponding to tetra-, penta- and hexaacylated lipid A species and comprising 4′-monophosphorylated β-2-amino-2-deoxy- d-glucopyranose-(1→6)-2-amino-2-deoxy- d-glucopyranose disaccharide, where the reducing end 2-amino-2-deoxy- d-glucose was present primarily in the α-pyranose form. Electrospray ionization-tandem mass spectrometry fragment pattern analysis, including investigation of the inner-ring fragmentation, allowed the localization of fatty acyl residues on the disaccharide backbone of lipid A. The tetraacylated lipid A structure containing 3-(dodecanoyloxy)tetradecanoic acid at N-2′,3-hydroxytetradecanoic acid at N-2 and 3-hydroxytetradecanoic acid at O-3, respectively, was found. The pentaacyl lipid A molecule had a similar fatty acid distribution pattern and, additionally, carried 3-hydroxytetradecanoic acid at O-3′. In the hexaacylated lipid A structure, 3-hydroxytetradecanoic acid at O-3′ was esterified with a secondary 9-hexadecenoic acid. Interestingly, lipid A of the in vivo rough isolate contained predominantly tetra- and pentaacylated lipid A species suggesting that the presence of the hexaacyl lipid A was associated with the smooth-form lipopolysaccharide.

Lipid characterisation and distribution in the fillet of the farmed Australian native fish, Murray cod ( Maccullochella peelii peelii)

The objective of this study was to determine the distribution pattern of lipids and fatty acids in different tissues of farmed Murray cod ( Maccullochella peelii peelii). Differences in lipid content were found amongst different portions of the fillet, being lowest in the dorsal/cranial portion (P1) and highest in the more ventral/caudal portion (P8) ( P < 0.05). The latter also recorded the highest amount of monounsaturated fatty acid (MUFA) and the lowest in polyunsaturated fatty acids (PUFA), arachidonic acid, 20:4 n − 6 (ArA), docosahexaenoic acid, 22:6 n − 3, (DHA) and the n3/ n6 ratio. In general, lipid content in the different fillet portions was inversely correlated to PUFA and directly to MUFA. Contents of saturated fatty acids (SFA) and eicosapentaenoic acid, 20:5 n − 3 (EPA) did not show any discernible trends in the different fillet portions, while significant differences in contents of DHA and ArA were observed. This study shows that lipid deposition in Murray cod varies markedly and that different fatty acids are deposited differently throughout the fillet.

13C nuclear magnetic resonance spectroscopy to check 1,3‐random, 2‐random pattern of fatty acid distribution in olive oil triacylglycerols

The fatty acid distribution between the 1,3‐ and 2‐positions of triglycerides was determined in the olive oil set sampled in the Marche region, by using the 13C NMR method which applies the DEPT pulse sequence. The results confirmed that the oleic and linoleic acids were not randomly distributed at the 2‐position of triacylglycerols but were lower for oleic acid and higher for linoleic acid compared to the theoretical values expected for a random distribution. Moreover, the unsaturated acids deviated from the 2‐random distribution at different extents according to the acid concentration of triglyceride.The 13C NMR results, they were obtained for three olive oil samples characterized by high, medium and low oleic acid at 2‐position (Ofound) corresponding to a low, medium, high deviation rate from the 2‐random pattern, were compared to those calculated by the computer program based on the 1,3‐random‐2‐random distribution of fatty acids in the triglycerides.The molar concentrations of the triglyceride species LLL and OLL were calculated from the molar concentrations of oleic and linoleic acids at the 2‐ and 1,3‐positions obtained by using 13C NMR and the computer method. The LLL and OLL triglycerides determined by the computer method were found to be markedly higher in the “high Ofound” oil as compared to NMR. No differences were detected between the two methods for both triglyceride species in the “low Ofound” oil.

Lipid and fatty acid composition of muscle and liver from wild and captive mature female broodstocks of white seabream, Diplodus sargus

Total lipids (TL), lipid classes, and their associated fatty acids from muscle and liver of captive and wild mature female broodstocks were investigated in order to estimate the fatty acid requirements of white seabream ( Diplodus sargus). The results showed that the percentage of triacylglycerol was higher in liver and muscle of captive fish than in wild fish. The distribution of phospholipid classes in liver and muscle of both fish groups was similar, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol being the predominant lipid classes. The general pattern of fatty acid distribution in total lipid of liver and muscle from captive and wild fish was similar. However, the relative percentage of specific fatty acids differed in captive and wild fish. The most noteworthy difference was the lower proportion of arachidonic acid (20:4n-6, AA) and the higher proportion of eicosapentaenoic acid (20:5n-3, EPA) in liver and muscle of captive fish with respect to those of wild fish. The proportion of docosahexaenoic acid (22:6n-3, DHA) did not differ between the two fish groups. The differences in EPA and AA proportions between captive and wild fish implied that captive fish presented a higher EPA/AA ratio and a lower DHA/EPA ratio than wild fish. In general terms, in both liver and muscle, the differences in fatty acid composition observed for TL were extended to all lipid classes. The results suggest that the different AA, EPA and DHA proportions in liver and muscle between captive and wild broodstocks are attributed to different levels of these fatty acids in broodstock diets.

The Fatty Acid Composition of Glycolipids of Marine Macrophytes

Specific patterns of fatty acid distribution in individual glycolipids were found for marine macrophytes from different phyla: Palmaria stenogona (Rhodophyta), Undaria pinnatifida (Phaeophyta), Ulva fenestrata (Chlorophyta), and Zostera marina (Magnoliophyta). In P. stenogona and U. fenestrata, polyunsaturated fatty acids with maximum unsaturation were concentrated in monogalactosyldiacylglyceride, whereas in U. pinnatifida and Z. marina they were also localized in digalactosyldiacylglyceride. For all species investigated, the highest concentration of saturated and monounsaturated fatty acids was found in sulfoquinovosyldiacylglyceride; however, this lipid from Z. marina also had high contents of 18 : 2n-6 and 18 : 3n-3 acids.

Membrane fatty acid unsaturation, protection against oxidative stress, and maximum life span: a homeoviscous-longevity adaptation?

Aging is a progressive and universal process originating endogenously that manifests during postmaturational life. Available comparative evidence supporting the mitochondrial free radical theory of aging consistently indicates that two basic molecular traits are associated with the rate of aging and thus with the maximum life span: the presence of low rates of mitochondrial oxygen radical production and low degrees of fatty acid unsaturation of cellular membranes in postmitotic tissues of long-lived homeothermic vertebrates in relation to those of short-lived ones. Recent research shows that steady-state levels of free radical-derived damage to mitochondrial DNA (mtDNA) and, in some cases, to proteins are lower in long- than in short-lived animals. Thus, nonenzymatic oxidative modification of tissue macromolecules is related to the rate of aging. The low degree of fatty acid unsaturation in biomembranes of long-lived animals may confer advantage by decreasing their sensitivity to lipid peroxidation. Furthermore, this may prevent lipoxidation-derived damage to other macromolecules. Taking into account the fatty acid distribution pattern, the origin of the low degree of membrane unsaturation in long-lived species seems to be the presence of species-specific desaturation pathways that determine membrane composition while an appropriate environment for membrane function is maintained. Mechanisms that prevent or decrease the generation of endogenous damage during the evolution of long-lived animals seem to be more important than trying to intercept those damaging agents or repairing the damage already inflicted. Here, the physiological meaning of these findings and the effects of experimental manipulations such as dietary stress, caloric restriction, and endocrine control in relation to aging and longevity are discussed.

Winter and Spring Characterization of Particulate and Dissolved Organic Matter in the Danube–Black Sea Mixing Zone

The mixing zone between the Danube and the Black Sea was investigated at the front of the Chilia and Sulina branches of the Danube delta, in April–May 1997, during two periods corresponding to conditions at the end of winter (Chilia and Sulina branches) and the beginning of spring (Sulina branch). The distribution of the organic matter in the particulate, colloidal and truly dissolved pools along the salinity gradient was characterized at both global and molecular levels using biochemical parameters. The distribution of particulate organic carbon (POC) paralleled that of total suspended matter in winter, whereas decoupling was observed in spring, reflecting active biological mechanisms in the mixing zone off the Sulina branch during this period. This is supported by distribution patterns of polyunsaturated fatty acids (PUFA) and branched fatty acids (BrFA), which are indicators of phytoplankton and bacteria activities, respectively. The δ 13C isotopic signature of POC in the Danube–Black Sea mixing zone varied of between −29·1 and −24·6‰, which is consistent with the usual temperate range of estuarine systems. In spring, the observed shift towards lower values in the area of salinity 0–5 suggested a gradual change in the composition of POC, such as that caused by cell lysis of riverine planktonic populations induced by a salinity increase. A subsequent increase of δ 13C values towards higher salinities indicated phytoplankton growth in the estuarine/marine zone, as assessed by high concentrations of PUFA. Indirect evidence of sedimentation of terrestrial particles in the upper part of the salinity gradient in the range of 2–3 was suggested by the decrease of the content of particles and POC in fatty acids (C 24–C 32) and n-alkanes (C 25–C 35), both constituents of cuticular waxes of higher plants. A tight coupling was suggested between phytoplankton and bacteria by similar distributions of PUFA and BrFA along the salinity gradient. The distribution of dissolved organic carbon (DOC) varied according to the season. In spring, the DOC concentrations remained constant across the salinity gradient in front of the Sulina branch at about 2·7 mg l −1, whereas higher concentrations, >4 mg l −1, were observed in winter at stations located in the low salinity (2–4 and 5–8) area. A few data were obtained for δ 13C of the DOC pool, with an average of −26·9‰ in the Danube River end-member and values close to those of POC off the various branches. The low molecular weight (LMW) fraction of DOC isolated from water by sequential cross-filtration was evaluated by summing the pool of the combined and free amino acids and that of the combined and free carbohydrates. The distribution of LMW DOC along the salinity gradient was similar in the three investigated areas. Off the Sulina branch, proportions of LMW DOC fluctuated between 17 and 37‰ in winter and between 23 and 35‰ in spring. Two zones of high LMW DOC were located in two ranges of salinity—between 2 and 4 and between 5 and 8—probably originating from the release of decaying diatoms, assessed by high molecular proportions of serine in the combined amino acids. LMW DOC indicated a high potential for microbal activity, as shown by concomitant distributions of branched fatty acids.

Dietary conjugated linoleic acids affect tissue lipid composition but not de novo lipogenesis in finishing pigs

Dietary conjugated linoleic acids (CLA) have been reported to profoundly affect lipid metabolism and to act as repartitioning agents. Currently, little is known about their effect on the fatty acid profile of tissue lipids in pigs. In the present study we determined the lipid composition of the backfat inner (BFI) and outer layer (BFO), omental fat (OF) and intramuscular fat (IMF) of the longissimus dorsi muscle in 24 Swiss Large White pigs fed diets supplemented either with 2% CLA- enriched oil (containing 58.9 g CLA isomers.100 g -1 of total fatty acids), linoleic acid-enriched oil (SO), or lard (LA). Animals were individually penned at 70 kg live weight and fed 2.8 kg .d -1 of the respective diet to slaughter at 105 kg. Growth performance, carcass characteristics and muscle mea- surements were not significantly affected by the dietary fats, although average daily weight gain and feed conversion ratio tended to be numerically improved 5-7% in the CLA-fed pigs compared to pigs of the other two treatments. Independent of the tissue, pigs fed the CLA diet exhibited higher levels of saturated fatty acids ( P < 0.05) and lower levels of monounsaturated fatty acids ( P < 0.05). By contrast, there was no difference in the distribution pattern of the saturated fatty acids between the LA and SO groups, but pigs fed the SO diet had lower monounsaturated and higher polyunsaturated fatty acid levels compared to those fed the LA diet. The CLA content of the BFO, BFI and OF was similar and did not indicate a preferential incorporation in one of the tissues. Compared to the adipose tissue, approximately 67% lower total CLA concentrations were found in the IMF. The in vitro activity of lipogenic enzymes was not altered by the dietary fat suggesting that lipogenesis was not affected by CLA. The distinct shift towards higher deposition of saturated fatty acids and lower deposition of monounsaturated fatty acids indicated a potential down-regulation of Δ9-desaturase activ- ity by dietary CLA.

Molecular organic geochemical evidence for paleoenvironmental changes at 11.87–12.28 m in GS-1 sedimentary core, Gucheng Lake, East China

Organic lipids with different occurrence modes in a sedimentary core in a subtropical freshwater lake, Gucheng Lake, were sequentially extracted, separated and analyzed. The down-core variations of OEP index of alkanes, C18:2/C18:0 ratios of fatty acids, ratios of bound, fatty acids to free fatty acids, thermo-maturity indices of hopanoid hydrocarbons and rerative concentrations of sedimentary minerals revealed an evident increasing in allochthonous input from rock detritus below 12.28 m in the sedimentary profile. The distribution pattern of tightlybound β-hydroxy fatty acids indicated a difference in bacterial communities above and below the boundary, as well as the gammacerane index may assign a significant change in lake water salinity. The evidence, in general, suggested that a significant paleoenvironmental change had taken place in ca. 9.6 kaBP on the regional basis.

Lipid class and fatty acid distributions in particulate and dissolved fractions in the north Adriatic sea

Lipid classes (Iatroscan TLC/FID method) and fatty acids (GC/MS) of settling particles and dissolved fraction were investigated in the north Adriatic sea in June 1995. The differences in composition and concentrations were examined according to distance from Isonzo river Estuary, depth and fraction (particulate versus dissolved). Total particulate lipids showed large variations, from 32.6 to 139.5 μg/l. The highest concentration was observed as for POC and total individual fatty acids in surface waters close to the river mouth. The ratio particulate lipids/POC ranged from 0.14 to 0.40 (average 0.27), which expressed different biosynthetic pathways by planktonic communities, as previously shown when nitrogen limitation can favor a switch from protein to lipid metabolism. The highest value was found in surface waters in the central part of the Gulf of Trieste, suggesting the existence of different stress conditions such as nutrient limitation, from those existing near the Isonzo river mouth. Total dissolved lipids did not show large variations (49–88 μg/l). The ratio dissolved lipids/DOC also varied in a narrow range (0.03–0.04), but with much lower values than those found in the particulate fraction. The comparison between particulate and dissolved lipid classes and fatty acids indicated a decoupling between the two reservoirs. Inputs from living organisms and freshly synthesized organic matter were clearly revealed in the dissolved fraction by phospholipids and polyunsaturated fatty acids. Degradation indicators such as free fatty acids and monoacylglycerols were significantly more represented in the particulate fraction than in the dissolved one near the river mouth, whereas the contrary was observed in the central part of the Gulf. Complementary informations were obtained from fatty acid distribution patterns such as for terrestrial originating inputs using the long-chain series. The importance of bacteria was observed using branched fatty acids and 18:1 ω7. The two bacterial signatures were found in both fractions, with highest imprints near the river mouth. Some enrichment of the branched fatty acids in the dissolved fraction in the central part of the Gulf could be related with the high contribution of polar lipids, suggesting a marked contribution of bacteria to the polar lipid fraction.