Changes in the content of acyl-lipid desaturases gene transcripts in Arabidopsis (
Arabidopsis thaliana
Heynh. (L.), ecotype Columbia) plants subjected to low temperature hardening for 5 days at 2°C ...were investigated. In the course of the experiments with hourly dynamics of plant chilling, it was established that the genes under study by their responses to cold action can be separated into two groups. The genes of the first group represented by
ADS2
,
FAD2
, and
FAD7
are characterized by the amount of their transcripts that rapidly increase even for the first 2–4 h of cold exposition, while the same value for the genes
FAD3
,
FAD6
, and
FAD8
belonging to the second group remained unchanged under the same conditions. The experiments with the above hardening dynamics provided evidence for consecutive character of genes
ADS2
,
FAD2
, and
FAD7
transcript accumulation, where the process for
ADS2
was sharply intensified even for the first days of hardening, while that for other two genes achieved maximal intensity only on the fourth day of hardening. These results, taken together, lead to the conclusion that the agreeing in time increase in the transcript content of genes
ADS2
,
FAD2
, and
FAD7
encoding Δ9-, Δ12-, and ω3-desaturases resulted in the change of FAs composition of chloroplast lipids. Increasing portion in them of triene FAs during hardening time provided the maintenance of chloroplast membranes in a native state allowing the Arabidopsis plant to successfully adapt to hypothermia.
Chlorophyll
b
-containing cyanobacterium
Prochlorothrix hollandica
is characterized by a high content of esterified fatty acids (FA) with 14 and 16 carbon atoms in the membrane lipids. Depending on ...the conditions of cultivation, the relative amount of myristic (C
14:0
) and myristoleic (C
14:1
) acids can reach 35%, and palmitic (С
16:0
) and palmitoleic (С
16:1
) acids can reach 60% of the sum of all fatty acids in cells. Monounsaturated FAs are represented by C
14:1
, and C
16:1
with an olefinic bond presumably located in the Δ
9
position. We cloned the gene of acyl-lipid Δ9-desaturase,
desC1
, from
Prochlorothrix hollandica
and characterized its specificity to the length of the substrate using the heterologous expression in
Escherichia coli
cells adding C
14:0
or stearic (C
18:0
) acids as exogenous substrates. The results show that DesC1 Δ
9
desaturase generates olefinic bonds in the FAs with a length of 14 to 18 carbon atoms with an approximately equal efficiency. This indicates that the length of the FA chain in
P. hollandica
is determined by the activity of the FA synthase, and the chain is desaturated at the Δ
9
position nonspecifically relatively to its length.
Plankton filament cyanobacteria
Prochlorothrix hollandica
is characterized by a very high content of C
14
and C
16
fatty acids (FA) in the lipid membranes. Depending on culturing conditions of the ...cyanobacteria, total concentrations of myristic and myristoleic acids can reach 35% and those of palmitic and palmitoleic acids can reach 60% of all esterified FA cells. In
P. hollandica
, a variety of monounsaturated FA is represented by myristoleic and palmitic acids, and by hexadecenoic (C
16:1
) acid with olefin bond of
cis
-configuration, located in the Δ4 position. The process of intensive culturing for
P. hollandica
cells to yield a maximal biomass in order to isolate the pure drug of myristoleic acid derivative has been optimized. The use of a threestage purification gives 30 mg of chromatographically pure myristoleic acid methyl ester from 17 g of
P. hollandica
raw biomass (dry mass is 3 g), which is 1% of dry cell mass.
Changes in the fatty acid (FA) composition of leaf and root lipids of heat-loving tobacco (Nicotiana tabacum L., cv. Samsun) plants during low-temperature hardening (8°C for 6 days) were studied. ...Hardening could improve leaf but not root cold tolerance. As this took place, the relative content of polyunsaturated (18:2n-6 and 18:3n-3) FAs increased and the proportion of saturated and monounsaturated FAs decreased. In contrast, in the roots hardening slightly increased the concentration of saturated FAs (16:0 and 18:0) and reduced the level of unsaturated FAs (18:1n-9, 18:2n-6, and 18:3n-3). At the same time, root lipids contained much C20–24 FAs, and their content increased during hardening. It was suggested that an increased FA saturation and elevated proportion of C20–24 FAs in the root lipids resulting in the lower membrane fluidity could be a reason for incapability of heat-loving tobacco plant roots of hardening and plant death at the lowtemperature stress.
Based on the own experimental data and the literature ones, a supposed relationship between the polarities of esterified unsaturated higher fatty acids contained in the native lipids in the presence ...of silver nanoclusters and possible variations in the coordination numbers of separate silver atoms in these clusters participating in the π-complex formation is described. Some new molecular parameters for satisfactory description of the chromatographic behavior and the general physicochemical characteristics of unsaturated hydrocarbon chains as constituents of individual lipid molecules in the presence of silver compounds are proposed. Some variants of possible applications of complex organic structures including their polyatomic clusters are mentioned.
At three stages of fruit ripening of three euonymus species (Euonymus sp.), growth parameters, the development of morphologo-anatomical structure, and the accumulation of neutral acylglycerols (NAG) ...of fatty acids were studied. It was established that, in all species studied, in the cells of endosperm and cotyledons, as well as in arillus cells, small oleosomes of similar size were formed, whereas in Euonymus europaeus and E. maximowiczianus large oleosomes differing in their sizes also appeared. Independently of fruit age, dry weight of seeds exceeded that of arils by several times. At the determination of separate NAG classes: TAG (1,2,3-triacyl-sn-glycerols) and acDAG (3-acetyl-1,2-diacyl-sn-glycerols), it was shown that the absolute content of acDAG in seeds was 1.5 orders of magnitude higher than that of TAG; in contrast, in arils TAG were much more abundant than acDAG. Euonymus species differed markedly in the growth pattern and NAG accumulation in seeds and arils.
Transgenic (DesA-LicBM3) potato (Solanum tuberosum L., cv. Desnitsa) plants expressing gene encoding Δ12 acyl-lipid desaturase from Synechosystis sp. PCC 6803 were obtained. A significant increase in ...the relative content of polyunsaturated (linoleic and linolenic) fatty acids in transformants as compared with original genotype was demonstrated. The improved resistance of transgenic plants to late blight causal agent (Phytophthora infestans) as compared with original cultivar was observed.
Qualitative and quantitative compositions of esterified fatty acids (FAs) in the total lipids from the leaves, shoots, and roots of halophile plants, such as suaeda (Suaeda altissima), samphire ...(Salicornia europaea), and wormwood (Artemisia lerchiana), collected in their natural environments were estimated by GLC techniques. It was shown that the vegetative organs of these halophytes contained 24 FA species, and 16 of them were tentatively identified as the very-long-chain FAs (VLCFAs). There were four VLCFA groups, viz. C₂₀, C₂₁, C₂₂, and C₂₃, each including saturated, mono-, and diunsaturated components; C₂₄ and C₂₅ FAs were also present. The concentration of VLCFAs in the total FAs comprised 4-64%. In vegetative organs of higher plants not subjected to genetic transformation, such a high VLCFA content was found for the first time. Saturated and even-numbered components predominated among the VLCFAs, and the roots exceeded severalfold the above-ground organs in the total VLCFA content. Possible pathways of VLCFA biosynthesis in plants, VLCFA content in the vegetative tissues, and the physiological role of membrane lipid FA composition in the plant salt metabolism are discussed.
The pattern of distribution of X-FAs among individual positional species of the X-triacylglycerols (X-TAGs) in the sea buckthorn (Hippophaë rhamnoides L.) mesocarp oil by the 80th, 90th, and 105th ...day after pollination (DAP) was investigated. The X-FAs comprised oleic acid (O) as well as unusual FAs, viz. hexadecenoic (H), palmitolinoleic (Pl), and cis-vaccenic acid (V). During mesocarp growth, the number of X-TAG species decreased dramatically as a result of their metabolism, but their proportion in the total TAGs remained constant. H-TAGs predominating in the oil were similar to total TAGs in their composition and the pattern of their dynamics during maturation. As regards minor Pl-TAGs, there was a tendency for an increase in the level of species including palmitolinoleic acid in the middle (sn-2) position of their molecules. Throughout the entire process of fruit maturation, oleic acid was by 98.0-98.8% concentrated in the sn-2 position of O-TAGs. At the same time, cis-vaccenic acid, a Δ11-positional isomer of oleic acid, was predominantly incorporated in the side positions of V-TAGs, and its 98.1% concentration in these positions was achieved only by the 105th DAP. A virtually absolute selectivity of the distribution of oleic and cis-vaccenic acids in TAGs was found here for the first time. Discussed are the possible physicochemical and biochemical factors of a highly selective incorporation of these FAs in the sea buckthorn TAGs, the pathways of enzymatic biosynthesis of O- and V-TAGs, the metabolic role of discrimination of incorporation of some FA species in the glycerol residue of glycerolipids, and the causes for the disappearance of some TAG species during maturation.
The paper presents the design of a fiber-optic microwave signal transmission line. The use of the developed design of a fiber-optic microwave transmission line allows the radar operating frequency ...range to be at least doubled. In addition, the number of functional blocks is reduced to ensure the operation of the radar in this frequency range. The results of experimental studies are presented.
PDF