Distribution of unusual fatty acids in the triacylglycerols of sea buckthorn mesocarp oil

The structure of unusual fatty acid (FA) components of triacylglycerols (TAGs) of mature sea buckthorn (Hippophae rhamnoides L.) mesocarp oil was determined by GLC and MS, and the positional-species composition (PSC) of these TAGs was estimated using the methods of TAG chemical deacylation, TLC, GLC, and computer calculation. It was shown that the unusual FAs comprised n-cis-Δ9-hexadecenoic, n-cis-Δ9,12-hexadecadienoic (palmitolinoleic), and n-cis-Δ11-octadecenoic (cis-vaccenic) acids. The hexadecenoic acid predominated in the oil, and in its distribution in TAGs, it was similar to the total FAs differing from them only in some prevalence in the triunsaturated TAGs and in the TAGs with a shorter acyl chain, as well as in the sn-2 position of TAGs. Palmitolinoleic (16:2) acid comprised only 5% of total FAs, and it was exclusively concentrated in the sn-2 position of TAGs. As regards its distribution between various positional types and forms of TAGs, the 16:2 acid was similar to oleate and total FAs. As compared to the total TAGs, the TAGs with 16:2 acid were characterized by a lower FA chain length as well as by a highest unsaturation. The TAGs with vaccenic acid (V-TAGs) considerably exceeded O-TAGs, i.e., the TAGs containing oleic acid, another 18:1 positional isomer, both in their content in the total TAGs and in their unsaturation. In the composition of positional types and fractions of various unsaturation, O-TAGs were similar to the total TAGs, while V-TAGs were characterized by a very unusual structure, viz., a very high triunsaturated TAG level and an extremely low concentration of 1,3-disaturated-2-monounsaturated TAGs. In addition, oleic acid, like most other unsaturated FAs, was incorporated predominantly in the sn-2 position of TAGs, while vaccenic acid, being also unsaturated, was nevertheless by 90% concentrated in the sn-1,3 positions of V-TAGs. Unusual FAs were related to each other in the mechanism of their biosynthesis. In fact, hexadecenoic acid biosynthesis produced by palmitic acid desaturation, was, on the one hand, further desaturated forming palmitolinoleic acid, and, on the other hand, converted to vaccenic acid via C₂ elongation.     

Regioisomer separation and identification of triacylglycerols containing vaccenic and oleic acids,and α- and γ-linolenic acids,in thermophilic cyanobacteria Mastigocladus laminosus and Tolypothrix sp.

Reversed phase liquid chromatography–atmospheric pressure chemical ionization mass spectrometry (RP-HPLC/APCI-MS) was used for direct analysis of triacylglycerols (TAGs) from different strains of the cyanobacteria Mastigocladus laminosus, Tolypothrix cf. tenuis and Tolypothrix distorta. This technique enabled us to identify and quantify the specific molecular species of TAGs directly from lipid extracts of the cyanobacteria. The regioisomeric series of TAGs having α-linolenic and γ-linolenic and also oleic and cis-vaccenic acids were separated by RP-HPLC and identified by APCI-MS. M. laminosus produced only a few molecular species of TAGs, including both isomers of octadecenoic (oleic and vaccenic) acid, while T. distorta contained tens of molecular species of TAGs having FAs with up to four double bonds (stearidonic acid and including also its positional isomer, i.e. 3,6,9,12-octadecatetraenoic acid) and both positional isomers (α and γ) of linolenic acids. Individual strains of both cyanobacteria exhibited different contents of polyunsaturated fatty acids (Tolypothrix sp.) and different distribution of positional isomers of monoenoic fatty acids in TAGs (M. laminosus).     

Interaction between C18 fatty acids and DOPE PEG2000 in Langmuir monolayers: effect of degree of unsaturation

In this study, we address the effect of the cis-double bond in 1,2-dioleoyl-sn-glycero-3-phosphoethanolamide-N-[methoxy(polyethylene glycol)-2000, DOPE PEG2000 (DP), on the Langmuir monolayer of C18 fatty acids—namely, stearic acid (SA), oleic acid (L1), linoleic acid (L2), and linolenic acid (L3)—with the same head group but different degrees of saturation on their hydrocarbon chains. Negative values of Gibbs free energy of mixing (ΔG _mix) were obtained throughout the investigated ranges of the unsaturated C18 fatty-acid (L1, L2 and L3) mixed systems, indicating that very strong attractions occurred between molecules in the monolayers. The bend and kink effects from the cis-double bond(s) in the hydrocarbon chain affected the membrane fluidity and molecular packing in the monolayers, which resulted in a greater interaction between unsaturated C18 fatty acids and DP. The most thermodynamically stable mole composition of unsaturated C18 fatty acids to DP was observed at 50:1; this ratio is suggested to be the best mole ratio and will be subsequently used to prepare DP–C18 fatty-acid nanoliposomes. The presence of cis-double bonds in both hydrocarbon chains of DOPE in DP also created an imperfection in the membrane structure of lipid-drug delivery systems, which is expected to enhance lipid-based systems for antibody conjugation and drug encapsulation.     

The composition of fatty acids in the endosperm and embryo lipids of <Emphasis Type="Italic">Pinus sibirica</Emphasis> and <Emphasis Type="Italic">P. sylvestris</Emphasis> seeds

The fatty acid (FA) composition of storage lipids in the seed endosperms and embryos of two pine species, Pinus sibirica and P. sylvestris, and possible biosynthetic pathways of these acids were studied by the GLC method. Linoleic acid predominated in the embryo and endosperm lipids of both P. sibirica (43.5 and 42.6%) and P. sylvestris (44.8 and 46.8%); this was evidently determined by a high expression of the gene encoding stearoyl-Δ9 acyl-lipid desaturase and the fad2 gene encoding microsomal ω6 acyl-lipid desaturase. P. sibirica lipids of the embryo and endosperm contained more oleic acid (22.0 and 24.0%, respectively) than corresponding P. sylvestris lipids (18.7 and 14%). Storage lipids of conifer seeds contain Δ5-unsaturated FAs: taxoleic (18:2Δ5,9), ephedrenic (18:2Δ5,11), pinoleenic (18:3Δ5,9,12), skiadonic (18:3Δ5,11, 14), and coniferonic (18:4Δ5,9,12,15). In the endosperm and embryos of P. sylvestris, the content of pinolenic acid was higher (22.1 and 19.6%) than in P. sibirica seeds (19.1 and 18.6%).     

Lipid,phenol and carotenoid changes in ‘Bianca’ grapevine leaves after mechanical wounding: a case study

Metabolic changes can occur in plants in response to abiotic stress. Extensive use of leaf discs (mechanical wounding) in studies regarding the effect on the biochemical response of the grapevine to different types of biotic stress makes it necessary to understand metabolic perturbation after injury. In this study, we investigate how mechanical wounding can affect the metabolism of grapevine leaf tissue using Bianca variety as case study. Two sizes of leaf discs (1.1 and 2.8 cm in diameter) were excised from leaves, and phenol, lipid and carotenoid perturbation were investigated 0, 6, 12, 24, 48, 96 and 120 h post cutting. In our study, we found an accumulation of molecules belonging to stilbenoid and stilbene classes such as trans-resveratrol, trans-piceide, Z-miyabenol C, E-cis-miyabenol C and ampelopsin D + quadrangularin A after abiotic stress. The increase in fatty acids such as linoleic acid, linolenic acid and oleic + cis-vaccenic acid during the first 12 h after injury, followed by a return to basal level, allowed us to surmise their role in response to abiotic stress, in particular to mechanical wounding in grapevine leaves. Different-sized discs caused a different response to the tissue, with a higher accumulation in 1.1-cm-diameter discs, especially of phenol compounds. The results of this work can be used to better understand metabolic changes due to biotic stress, having previous knowledge about the perturbation caused by abiotic stress.     

The role of free fatty acids in mitochondrial energetic metabolism in winter wheat seedlings

The effect of fatty acids (FAs) (C12–C24) on the functioning of winter wheat (Triticum aestivum L.) mitochondria was studied. Such fatty acids as C12:0, C16:0, and C18:0 and unsaturated FAs, such as C18:1 (n-9 cis), C18:1 (n-12 cis), C18:2 (n-9, 12), (18:3, n-3), and C22:1 (n-9 cis) caused efficient uncoupling of oxidative phosphorylation in mitochondria, i.e., an increase in the nonphosphorylating respiration rate and a decrease in the respiratory control value. It was established that C16:0 had the strongest uncoupling effect among all saturated FAs, and C18:3, among unsaturated FAs. The uncoupling effect of saturated FAs is provided by the ADP/ATP-antiporter, while plant uncoupling proteins play an important role in the uncoupling effect of unsaturated FAs. In addition, unsaturated, as well as saturated FAs might serve as oxidative substrates for mitochondria. It was concluded that the role of FAs in energetic metabolism of winter wheat seedlings consisted of uncoupling of oxidative phosphorylation and of serving as substrates for oxidation.     

Pericarp formation in early divergent species of Arecaceae (Calamoideae,Mauritiinae) and its ecological and phylogenetic importance

Lepidocaryum tenue, Mauritia flexuosa and Mauritiella armata belong to the subtribe Mauritiinae, one early divergent lineage of the Arecaceae and one of the few of Calamoideae that occur in South America. These species occur in swampy environments and have fruits that are characteristically covered with scales. The objective of this study was to describe the formation of the layers of the pericarp within this subtribe and attempt to correlate fruit structure with the environment where species typically occur. Toward this goal, flowers in pre-anthesis and anthesis and fruits throughout development were analyzed using standard methods for light microscopy. The ontogeny of the layers of the pericarp of all three species was found to be similar. The scales were formed from non-vascularized emergences composed of exocarp and mesocarp. The median mesocarp accumulates lipids only in M. flexuosa and M. armata. The inner mesocarp together with the endocarp becomes papyraceous and tenuous in all species. This internal region of pericarp showed collapsed cells due to seed growth at the end of fruit development. Fruits of Mauritiinae are baccate, and the characters of the pericarp, especially the inner mesocarp and endocarp, help to maintain moisture. On the other hand, many species close to Mauritiinae show pericarp with sclerenchyma adjacent to the seed. This variation can contribute to understand the importance of this striking character in dispersal, germination and colonization in Arecaceae.     

Function and regulation of tau conformations in the development and treatment of traumatic brain injury and neurodegeneration

One of the two common hallmark lesions of Alzheimer’s disease (AD) brains is neurofibrillary tangles (NFTs), which are composed of hyperphosphorylated tau protein (p-tau). NFTs are also a defining feature of other neurodegenerative disorders and have recently been identified in the brains of patients suffering from chronic traumatic encephalopathy (CTE). However, NFTs are not normally observed in traumatic brain injury (TBI) until months or years after injury. This raises the question of whether NFTs are a cause or a consequence of long-term neurodegeneration following TBI. Two conformations of phosphorylated tau, cis p-tau and trans p-tau, which are regulated by the peptidyl-prolyl isomerase Pin1, have been previously identified. By generating a polyclonal and monoclonal antibody (Ab) pair capable of distinguishing between cis and trans isoforms of p-tau (cis p-tau and trans p-tau, respectively), cis p-tau was identified as a precursor of tau pathology and an early driver of neurodegeneration in AD, TBI and CTE. Histological studies shows the appearance of robust cis p-tau in the early stages of human mild cognitive impairment (MCI), AD and CTE brains, as well as after sport- and military-related TBI. Notably, cis p-tau appears within hours after closed head injury and long before other known pathogenic p-tau conformations including oligomers, pre-fibrillary tangles and NFTs. Importantly, cis p-tau monoclonal antibody treatment not only eliminates cis p-tau induction and tau pathology, but also restores many neuropathological and functional outcome in TBI mouse models. Thus, cis p-tau is an early driver of tau pathology in TBI and CTE and detection of cis p-tau in human bodily fluids could potentially provide new diagnostic and prognostic tools. Furthermore, humanization of the cis p-tau antibody could ultimately be developed as a new treatment for AD, TBI and CTE.     

Use of lipids for chemotaxonomy of octocorals (Cnidaria: <Emphasis Type="Italic">Alcyonaria</Emphasis>)

The relationship between taxonomic position and the lipid composition of octocorals from coastal waters of Vietnam was investigated. The principal component analysis of the total fatty acid (FA) composition of 64 coral specimens showed that total FAs are markers at the family level. A good distinction was obtained between antipatarians, gorgonians, and alcyonarians. Azooxanthellate corals of the genus Dendronephthya formed a separate group. The alcyonarian genera Sinularia, Lobophytum, and Sarcophyton were distinguished only by the composition of polyunsaturated FAs. The taxon-specific composition of FAs in octocorals is likely to be determined by differences in the nutrition of food sources, symbiont composition, and the enzymatic activity of FA biosynthesis.     

Cell wall glycopolymers of type strains from three species of the genus <Emphasis Type="Italic">Actinoplanes</Emphasis>

The structures of cell wall glycopolymers from the type strains of three Actinoplanes species were investigated using chemical methods, NMR spectroscopy, and mass spectrometry. Actinoplanes digitatis VKM Ac-649^T contains two phosphate-containing glycopolymers: poly(diglycosyl-1-phosphate) →6)-α-D-GlcpNAc-(1-P-6)-α-D-GlcpN-(1→ and teichoic acid →1)-sn-Gro-(3-P-3)-β-[β-D-GlcpNAc-(1→2]-D-Galp-(1→. Two glycopolymers were identified in A. auranticolor VKM Ac-648^T and A. cyaneus VKM Ac-1095^T: minor polymer–unsubstituted 2,3-poly(glycerol phosphate), widely abundant in actinobacteria (Ac-648^T), and mannan with trisaccharide repeating unit →2)-α-D-Manp-(1→2)-α-D-Manp(1→6)-α-D-Manp-(1→(Ac-1095^T). In addition, both microorganisms contain a teichuronic acid of unique structure containing a pentasaccharide repeating unit with two residues of glucopyranose and three residues of diaminouronic acids in D-manno- and/or D-gluco-configuration. Each of the strains demonstrates peculiarities in the structure of teichuronic acid with respect to the ratio of diaminouronic acids and availability and location of O-methyl groups in glucopyranose residues. All investigated strains contain a unique set of glycopolymers in their cell walls with structures not described earlier for prokaryotes.     

Abscisic acid biosynthesis under water stress: anomalous behavior of the 9-<Emphasis Type="Italic">cis</Emphasis>-epoxycarotenoid dioxygenase1 (<Emphasis Type="Italic">NCED1</Emphasis>) gene in rice

The gene NCED1 encodes 9-cis-epoxycarotenoid dioxygenase, which catalyzes oxidative cleavage of 9-cis-epoxycarotenoids neoxanthin and violaxanthin to xanthoxin, a key step in the biosynthesis of abscisic acid (ABA) in higher plants. In the present study, the complete NCED1 of 1 917 bp was cloned and characterized from rice (Oryza sativa L. cv. N22) as no earlier reports were available for its characterization from the indica cultivar. The NCED1 had no intron and encoded a protein of 639 amino acids with a predicted molecular mass of 68.62 kD and pI of 6.07. The aliphatic index and grand average of hydropathicity were found to be 77.04 and -0.148, respectively. Multiple alignment analysis revealed that the sequence shared a high identity with the Oryza sativa japonica group (100 %) followed by Triticum aestivum (90 %), Hordeum vulgare (90 %), and Zea mays (89 %). The enzyme had a RPE65 domain of 476 amino acid residues. The RPE65 domain requires Fe(II) as a cofactor coordinated with 4 histidine residues and 3 glutamic acid residues. The phylogenic tree shows that NCED1 of japonica rice and NCED1 of indica rice were in the same group. They might have been evolved from a common ancestor. Analysis with a PSORT III tool shows that NCED is a chloroplastic protein. The real-time quantitative PCR and RNA-sequencing studies show that the expression of NCED1 was progressively reduced with increasing water stress, and a negative correlation between expression of OsNCED1 and severity of stress was established. Further, NCED1 expression negatively correlated with ABA accumulation under water stress whereas in some other species, its expression increased along with ABA accumulation. This might be due to feedback inhibition of the ABA biosynthesis in rice.     

Production of <Emphasis Type="Italic">cis</Emphasis>-Vaccenic Acid-oriented Unsaturated Fatty Acid in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Biodiesel is produced worldwide as an alternative energy fuel and substitute for petroleum. Biodiesel is often obtained from vegetable oil, but production of biodiesel from plants requires additional land for growing crops and can affect the global food supply. Consequently, it is necessary to develop appropriate microorganisms for the development of an alternative biodiesel feedstock. Escherichia coli is suitable for the production of biodiesel feedstocks since it can synthesize fatty acids for lipid production, grows well, and is amenable to genetic engineering. Recombinant E. coli was designed and constructed for the production of biodiesel with improved unsaturated fatty acid contents via regulation of the FAS pathway consisting of initiation, elongation, and termination steps. Here, we investigated the effects of fabA, fabB, and fabF gene expression on the production of unsaturated fatty acids and observed that the concentration of cis-vaccenic acid, a major component of unsaturated fatty acids, increased 1.77-fold compared to that of the control strain. We also introduced the genes which synthesize malonyl-ACP used during initiation step of fatty acid synthesis and the genes which produce free fatty acids during termination step to study the effect of combination of genes in elongation step and other steps. The total fatty acid content of this strain increased by 35.7% compared to that of the control strain. The amounts of unsaturated fatty acids and cis-vaccenic acid increased by 3.27 and 3.37-fold, respectively.     

Regulatory <Emphasis Type="Italic">cis</Emphasis>-elements on citrus peel-specific expressed gene, <Emphasis Type="Italic">CuCRTISO-like</Emphasis>, promoter respond to hormones and abiotic stresses in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

We identified a peel-specific expressed gene in Citrus unshiu fruits by differentially expressed gene (DEG) analysis, which showed a homology with carotenoid isomerase-like genes identified from other plants and, therefore, designated as CuCRTISO-like. Here we determined the promoter sequence of CuCRTISO-like and analyzed histochemical GUS activity using transgenic Arabidopsis plants harboring CuCRTISO-like promoter-GUS gene constructs (pCRTL-Prom1~pCRTL-Prom5 lines). The promoter activity of CuCRTISO-like was detected in the cotyledon at 5 and 10 days after germination (DAG), young leaf, and anther, but not in the cotyledon at 15 DAG and mature leaf. Several cis-acting elements involved in hormones and abiotic stresses are located on the CuCRTISO-like promoter. Salicylic acid and ethylene treatments induced the GUS activity in the pCRTL-prom1 and pCRTL-Prom4 line, respectively. Treatment of drought and wounding stress induced the GUS activity in the pCRTL-Prom4 and pCRTL-Prom3 line, respectively. Heat stress treatment induced GUS activity more strongly as the promoter length decreased except for no GUS activity in the pCRTL-Prom5 line. The CuCRTISO-like expression during fruit maturation of C. unshiu showed a peel-specific expression pattern. Our results suggest that CuCRTISO-like promoter activity is regulated in a developmental and organ-specific manner, and responds to hormones and abiotic stresses.     

Changes in the fatty acid composition of symbiotic dinoflagellates from the hermatypic coral <Emphasis Type="Italic">Echinopora lamellosa</Emphasis> during adaptation to the irradiance level

The composition of fatty acids (FAs) of symbiotic dinoflagellates isolated from the hermatypic coral Echinoporal lamellosa adapted to the irradiance of 95, 30, 8, and 2% PAR was studied. Polar lipids and triacylglycerols (TAG) differed between them in FA composition. Polar lipids were enriched in unsaturated FAs, whereas TAG, in saturated FAs. Light exerted a substantial influence on the FA composition in both polar lipids and TAG. The elevation of irradiance resulted in the accumulation of 16:0 acid in both lipid groups and 16:1(n-7) acid in TAG. It seems likely that de novo synthesis of 16:0 acid occurred actively in the cells of symbiotic dinoflagellates in high light. Since these processes are energy-consuming ones, they utilize excessive energy. When light intensity declined, 18:4(n-3) and 20:5(n-3) acids accumulated in polar lipids, which was accompanied by the increase in the content of chlorophyll a in the cells of zooxanthellae, whereas the levels of 22:6(n-3) and 20:4(n-6) acids reduced. Although the relative content of particular FAs varied substantially in dependence of irradiance, the balance between the sum of saturated and unsaturated FAs changed insignificantly. We concluded that the role of photoadaptation could not be limited only to changes in the degree of lipid unsaturation and membrane fluidity. It is supposed that light-induced changes in the FA composition reflect the interrelation between photosynthesis and FA biosynthesis.     

Revision of the shield-bug genera <Emphasis Type="Italic">Holcostethus</Emphasis> Fieber and <Emphasis Type="Italic">Peribalus</Emphasis> Mulsant et Rey (Heteroptera,Pentatomidae) of the Palaearctic Region

A complex of the heteropteran genera centering around Peribalus Mulsant et Rey and Holcostethus Fieber is considered. The genus Dryadocoris Kirkaldy reveals no relationship with the above genera and is believed to represent a separate clade of the family Pentatomidae. The genera Peribalus and Holcostethus are revised. The former includes three subgenera: Peribalus s. str. with two species, Asioperibalus subgen. n. (type species Cimex inclusus Dohrn) with six species, and Tianocoris subgen. n. (type species Holcostethus manifestus Kiritshenko) with two species. Holcostethus embraces two subgenera: Holcostethus s. str. and the monotypic Enigmocoris subgen. n. (type species H. fissiceps Horváth). Two new species are described: Peribalus tianshanicus sp. n. from the Tien Shan Mts. and P. przewalskii sp. n. from the northern part of China (Huan He River). P. capitatus Jakovlev and P. vernalis (Wolff) are downgraded to subspecies of P. strictus (F.). P. ovatus Jakovlev is synonymized with P. inclusus (Dohrn). Two new monotypic genera related to the revised complex of genera are established, Paraholcostethus gen. n. (type species Peribalus breviceps Horváth) and Himalayastethus gen. n. (type species H. pilosus sp. n. from Kashmir). A key to, and morphometric characters for all the taxa considered are provided. The key characters, including both male and female genitalia, are illustrated, and distributional maps are given.     

The Effect of Tobacco Plant Transformation with a Gene for Acyl-Lipid Δ9-Desaturase from <Emphasis Type="Italic">Synechococcus vulcanus</Emphasis> on Plant Chilling Tolerance

Tobacco plants with the introduced desC gene for acyl-lipid Δ9-desaturase from the thermophilic cyanobacterium Synechococcus vulcanus were cultivated on agar-solidified Murashige and Skoog nutrient medium supplemented with ferulic acid and antibiotics at 22°C and a 16-h photoperiod. Control plants were transformed with an empty pGA482 vector. The analysis of fatty acids (FAs) showed that, in transgenic plants, the level of 16:0 and 18:0 FAs decreased substantially, whereas the levels of di- and trienoic FAs increased. Transformed plants were more cold-tolerant. The tolerance to chilling was evaluated from electrolyte leakage from tissues damaged by cold treatments and from the accumulation of a product of lipid peroxidation, malondialdehyde. It was concluded that acyl-lipid Δ9-desaturase was actively expressed in transgenic tobacco plants and converted stearic acid into oleic acid, thus producing a substrate for further synthesis of di- and trienoic FAs. An increased proportion of polyunsaturated FAs in membrane lipids resulted in improved tobacco plant tolerance to chilling.     

Antarctic red macroalgae: a source of polyunsaturated fatty acids

The n-3 and n-6 series of polyunsaturated fatty acids (PUFAs) are important for numerous metabolic functions that reduce the risk of inflammation, cancer, and heart diseases. These fatty acids (FAs) have been detected in high concentrations in some species of algae. The amount of the n-3 and n-6 PUFAs is closely associated with abiotic factors, such as solar radiation intensity, salinity, and temperature variation. However, abiotic influence on PUFA levels, along with the physiological function of these molecules in algae, remains inconclusive. In the present study, the quantities of the n-3 and n-6 in Antarctic red algae species Iridaea cordata, Palmaria decipiens, Plocamium cartilagineum, and Pyropia endiviifolia were determined. The lipids were extracted from the macroalgae according to the method followed by Bligh and Dyer (1959) and converted to methyl esters for further analysis using gas chromatography. The main n-6 PUFA identified and quantified in this study of Antarctic red algae were linoleic acid (18:2n-6), dihomo-γ-linolenic acid (20:3n-6), and arachidonic acid (20:4n-6). The eicosapentaenoic acid was detected at high concentrations in all species, with approximately 62.8% of total FA in P. endiviifolia, 75.4% in P. decipiens, 50.4% in I. cordata, and 20.1% in P. cartilagineum. The results corroborate those of the literature and show that PUFAs increased in red algae environments, with increased production of n-3 and n-6 PUFAs.     

Changes in Triacylglycerol Composition in Maturing Sea Buckthorn (Hippophaë rhamnoides) Seeds

Sea buckthorn (Hippophaë rhamnoides L.) seeds on the 29th, 53rd, 80th, and 107th day after pollination were used for determining, by lipase hydrolysis, the qualitative and quantitative composition of the triacylglycerol (TAG) positional types, groups, and positional species, as well as the factor of selectivity of incorporation of unsaturated fatty acids, octadecenoic, linoleic, and linolenic, into the sn-2-position of TAGs. Until the 80th day after pollination, there was a predominant formation of triunsaturated TAGs, which included linolenic and linoleic acid residues. After the 80th day, the absolute content of these major components of total TAGs markedly decreased, and an increase in total TAG content was mainly accounted for by the rise in the level of those TAG species, which included saturated fatty acids, palmitic and stearic (monosaturated–diunsaturated and disaturated–monounsaturated), as well as in the level of sn-2-octadecenoyl species belonging to the triunsaturated and palmito–diunsaturated types of TAGs. At each maturation stage, the quantitative dynamics of separate TAG species was determined by the content of fatty acid species available for TAG formation and the factor of selectivity of these species. The decrease in the content of a certain group of triunsaturated TAGs found here seems to be caused by their metabolization during seed maturation.