Fatty-acid-induced release of manganes from chloroplasts

The effect of both endogenous and exogenous unsaturated free fatty acids on manganese release from chloroplasts of chill-resistant (spinach) and chill-sensitive (tomato, bean) plants was studied. The level of endogenous free fatty acids increased 2–3-fold during cold and dark storage of leaves of chill-sensitive plants and was accompanied by depletion of about 60% of total chloroplast manganese content. Similar effects were observed when accumulation of free fatty acids in chloroplasts was achieved by storage of growing tomato plants for a few days in the dark at room temperature. In contrast, the cold and dark treatment of leaves of chill-resistant plant (spinach) affected neither free fatty acid, manganese levels nor Hill-reaction activity in chloroplasts. Incubation of chloroplasts of both chill-sensitive and chill-resistant plants with bean leaf galactolipase resulted in an accumulation of free fatty acids and a release of approx. 60% of total manganese content. The same amount of total manganese content was released following 3 h incubation of chloroplasts with linolenic acid at fatty acid/chlorophyll ratio (w/w, 2:1–10:1). The efficiency of C₁₈ unsaturated fatty acids/linolenic, linoleic, oleic on manganese release from chloroplasts was established in decreasing order C_18:3 > C_18:2 > C_18:1. The results indicate that the inhibitory effect of both endogenous and exogenous fatty acids on Hill reaction depends on the release from chloroplasts of functionally active, loosely bound manganese. Thus, similarly to both Tris and hydroxylamine treatments of chloroplasts, the incubation of chloroplast preparations with unsaturated fatty acids may be a useful tool for manganese depletion of chloroplasts.     

Lipids of chill-sensitive and -resistant Passiflora species: Fatty acid composition and temperature dependence of spin label motion

Polar lipids were extracted from the leaves of Passiflora species which varied in their resistance to chilling injury. The fatty acid compositions of the 8 major polar lipid classes from P. caerulea (chill-resistant) were generally similar to those of the corresponding lipids from P. flavicarpa (chill-sensitive). Using ESR spectroscopy, the motion of spin-labelled molecules was measured in phospholipids isolated from a range of Passiflora species. The temperature dependence of the motion of the spin labels showed a change at 1° for lipids of the most chill-resistant species and at 9° for the lipids of the most chill-sensitive species. Lipids from other species showed changes at intermediate temperatures, and the greater the chilling sensitivity of the species, the higher was the temperature of the change. It is concluded that pronounced differences in chilling sensitivity of the Passiflora species are correlated with physical differences in their membrane lipids; however, the degree of unsaturation of the lipids is not a reliable guide to chilling sensitivity.     

Alteration of the respiratory function in chill-sensitive callus due to low temperature stress: Involvement of the alternate pathway

The diversion of electron flow to the alternate pathway in mitochondriaof chillsensitive callus of Cornus stolonifera was studied withreference to the immediate response of the cells to chilling.Temperatures below 15?C diverted the bulk of respiration tothe alternate path, proportionally as the temperature decreasedto 0?C. The alternate path, however, existed in cells in a suppressedform at temperatures above 15?C. In chill-resistant callus ofSambucus Sieboldiana, no alteration was noted in electron apportionmentbetween the cytochrome path and the alternate path. Thus, thereseems to be a marked difference in the mode of respiration betweensensitive and resistant plant cells at low temperatures. Therespiratory control ratio also markedly declined at temperaturesbelow 15?C in chill-sensitive callus, but a higher respiratorycontrol ratio was observed below 10?C in chill-resistant callus.From these results, an alteration in the regulatory system forelectron apportionment between the two paths is probably themost immediate response of chill-sensitive cells to low temperatures. ¹Contribution No. 2154 from the Institute of Low TemperatureScience. (Received June 6, 1979; )     

Comparison of galactolipase activity and free fatty acid levels in chloroplasts of chill-sensitive and chill-resistant plants

Galactolipase activity in chloroplasts of several chill-resistant plants was found to be very low [0.02-0.13 mumol free fatty acid (FFA) liberated min-1 mg protein-1] or not detected. The same phenomenon was observed for soybean and members of the Cucurbitaceae such as cucumber, pumpkin, melon and squash. Since, following cold storage of cucumber leaves, the levels of monogalactosyl-diacylglycerol and digalactosyl-diacylglycerol in chloroplasts decrease while those of FFA accumulate it seems likely that in these typical chill-sensitive plants galactolipase is present but inactivated during isolation procedure. The low galactolipase activity in chloroplasts was accompanied by a relatively low FFA content ranging from 0.05 mumol to 0.30 mumol FFA mg chlorophyll (Chl)-1. However, both pea and horse bean chloroplasts (with low galactolipase activity) exhibit about 0.45 mumol FFA mg Chl-1. Elevated galactolipase activity was observed in chloroplasts of most chill-sensitive species (ranging from 0.31 mumol to 1.32 mumol FFA liberated min-1 mg protein-1) as well as in chloroplasts from broad bean, a member of a chill-resistant species (1.26 mumol FFA liberated min-1 mg protein-1). In addition in this latter group of plants FFA level in chloroplasts often did not fit the galactolipase activity. The results suggest that there exists a tendency for chilling tolerance of plants to decrease both galactolipase activity and FFA level. However, in some plant species with elevated galactolipase activity the chloroplast FFA level does not correlate with enzyme activity.     

Changes in the Temperature Response of Hill-Reaction Activity of Chilling-Sensitive and Chilling-Resistant Plants after Hardening

The temperature response of Hill-reaction was measured in chloroplastsisolated from mung bean (very chill-sensitive), two tomato cultivars(less chill-sensitive) and pea (chill-resistant). Computer analysisof the plots of log rate against reciprocal of absolute temperatureindicated that in each case, they were composed of three straightlines, meeting at characteristic break temperatures. Neitherthe activation energies (Ea's¹), calculated from the slopesof the lines, nor the break temperatures correlated with chillingsensitivity. Treatment of the two tomato cultivars at 12 ?Cand either low humidity (effective in reducing sensitivity)or high humidity (relatively ineffective) both caused loweredEa values and increased unsaturation in the chloroplast membranephospholipids. However, this evidence does not, in general,support the idea of any relationship between chloroplast membranefluidity and chilling injury.     

甘油-3磷酸转酰酶氨基酸与植物抗冷性关系初探

甘油 - 3磷酸转酰酶 (GPAT)与植物抗冷性密切相关。南瓜 (Cucurbitamoschata)与黑子南瓜 (Cucurbitaficifolia)同属不同种 ,亲缘关系较近 ,但却存在显著的抗冷性差异。南瓜及黑子南瓜GPAT基因的克隆 ,可以使我们从二者推导的有限氨基酸的差异中对GPAT氨基酸组成及其与植物抗冷性作一定的探讨。发现在南瓜与黑子南瓜 13个不同的氨基酸残基中有 3个与抗冷性植物拟南芥菜 (Arabidopsisthaliana)、豌豆 (Pisumsativum)、红花 (Carthamustincto rius)和菠菜 (Spinaciaoleracea)等相同 ,可能与黑子南瓜比南瓜更具抗冷性的原因有关。比较南瓜、黑子南瓜、豌豆、红花、拟南芥菜和菠菜等植物中GPAT基因推导的氨基酸序列发现 ,在比较抗冷的拟南芥菜、红花、豌豆和菠菜等植物中 ,虽然它们之间的亲缘关系都比较远 ,但某些位点上的氨基酸残基却完全相同 ,而与南瓜等抗冷性较差的植物不同 ,这些位点的氨基酸残基可能也与GPAT对底物酰基的选择性有关。     

Molybdenum-induced alteration of fatty acids of thylakoid membranes contributed to low temperature tolerance in wheat

The fact that molybdenum (Mo) applications can alleviate low temperature stress (LTS) in plants has been widely reported, but the underlying mechanisms are not fully understood. The effects of Mo (0 and 0.15 mg kg^?1) on photosynthetic pigments, fatty acids and the chlorophyll–protein complex of wheat seedlings in pot culture were investigated at 0, 2, 4 and 6 days of LTS. Chlorophyll a and b, total chlorophyll and carotenoid contents were significantly enhanced by Mo application. The palmitic acid (C16:0) content and total saturated fatty acids (TSFA) were drastically decreased in wheat cultivar 97003 at 2 and 4 days of LTS and in wheat cultivar 97014 at 2 days of LTS. The linolenic acid (C18:3) content and total unsaturated fatty acids (TUSFA) were significantly increased in both cultivars at 2 and 4 days of LTS. The palmitoleic acid (C16:1) content was also drastically increased in cultivar 97003 at 2 days of LTS, suggesting that Mo induced a greater production of unsaturated fatty acids or the conversion of TSFA to TUSFA. The ratio of unsaturated to saturated fatty acids and the index of unsaturated fatty acids in the thylakoid membranes were enhanced with supplemental Mo, suggesting that Mo might improve the degree of unsaturation. However, no significant differences were observed in the chlorophyll–protein complexes between the +Mo and ?Mo treatments. These results indicated that the alteration of fatty acids induced by Mo application in the thylakoid membranes of wheat contributed to LTS tolerance.     

The Effect of Temperature on the Level and Biosynthesis of Unsaturated Fatty Acids in Diacylglycerols of Brassica napus Leaves

Experiments on the effects of temperature on the levels of unsaturated fatty acids and their rates of desaturation in Brassica napus leaf lipids have shown that significant differences occur in the composition of all diacylglycerols in the leaf between plants grown at high and low temperatures. In the major thylakoid diacylglycerols, monogalactosyl-diacylglycerol and digalactosyldiacylglycerol, not only is there an increase in the level of unsaturation at low temperatures, but there is a change in the balance between molecular species of chloroplastic origin (16/18C) and cytosolic origin (18/18C). Radioactivity tracer data indicate that at low temperatures there are two distinct phases of desaturation in the fatty acids of the major diacylglycerols of these leaves. A rapid phase, which appears in plants grown at low temperatures and results in the desaturation of palmitic acid to hexadecadienoic acid and oleic acid to linoleic acid may explain the high levels of unsaturated fatty acids found in the leaf diacylglycerols from plants grown at low temperatures. The appearance of this rapid phase is controlled by the temperature at which the plant is grown and is not subject to rapid variations in environmental temperature.     

The Fatty Acid Profile Analysis of Cyperus laxus Used for Phytoremediation of Soils from Aged Oil Spill-Impacted Sites Revealed That This Is a C18:3 Plant Species

The effect of recalcitrant hydrocarbons on the fatty acid profile from leaf, basal corm, and roots of Cyperus laxus plants cultivated in greenhouse phytoremediation systems of soils from aged oil spill-impacted sites containing from 16 to 340 g/Kg total hydrocarbons (THC) was assessed to investigate if this is a C18:3 species and if the hydrocarbon removal during the phytoremediation process has a relationship with the fatty acid profile of this plant. The fatty acid profile was specific to each vegetative organ and was strongly affected by the hydrocarbons level in the impacted sites. Leaf extracts of plants from uncontaminated soil produced palmitic acid (C16), octadecanoic acid (C18:0), unsaturated oleic acids (C18:1-C18:3), and unsaturated eichosanoic (C20:2-C20:3) acids with a noticeable absence of the unsaturated hexadecatrienoic acid (C16:3); this finding demonstrates, for the first time, that C. laxus is a C18:3 plant. In plants from the phytoremediation systems, the total fatty acid contents in the leaf and the corm were negatively affected by the hydrocarbons presence; however, the effect was positive in root. Interestingly, under contaminated conditions, unusual fatty acids such as odd numbered carbons (C15, C17, C21, and C23) and uncommon unsaturated chains (C20:3n6 and C20:4) were produced together with a remarkable quantity of C22:2 and C24:0 chains in the corm and the leaf. These results demonstrate that weathered hydrocarbons may drastically affect the lipidic composition of C. laxus at the fatty acid level, suggesting that this species adjusts the cover lipid composition in its vegetative organs, mainly in roots, in response to the weathered hydrocarbon presence and uptake during the phytoremediation process.     

Chilling-Induced Ethylene Production in Relation to Chill-Sensitivity in Phaseolus spp.

Guye, M. G, Vigh, L. and Wilson, J. M. 1987. Chilling-inducedethylene production in relation to chill-sensitivity in Phaseolusspp.—J. exp. Bot. 38: 680–690. Ethylene production from the primary leaves of six bean (Phaseolusspp.) cultivars known to differ in chill-sensitivity, was monitoredat 23 ?C following chilling of whole plants at 5 ?C for 24 h.The more chill-tolerant cultivars produced greater amounts ofchilling-induced ethylene than the chill-sensitive cultivars.The onset of maximum ethylene production rates and the followingdecline in rates was more rapid in chill-tolerant cultivars.This pattern of ethylene production was also similar when chill-tolerancewas chemically enhanced by choline treatment. The low levelsof ethylene production in chill-sensitive genotypes was alsoreflected by their poor ability to convert the exogenously appliedethylene precursor, 1-aminocyclopropane-l-carboxylic acid (ACC),to ethylene. Moderate levels of leaf water deficit induced by chilling chill-tolerantcultivars and choline treated plants appeared to stimulate chilling-inducedethylene production. High levels of leaf wilt, shown by morechill-sensitive cultivars, reduced this stimulatory effect.Ethylene production was slightly greater when warming was carriedout in the light rather than in the dark. Key words: Ethylene, ACC, choline, chill-sensitivity, Phaseolus     

Total fatty acid content of the plasma membrane of Saccharomyces cerevisiae is more responsible for ethanol tolerance than the degree of unsaturation

The effect of change in unsaturated fatty acid composition on ethanol tolerance in Saccharomyces cerevisiae overexpressing ScOLE1 (?9 fatty acid desaturase gene of S. cerevisiae), CaFAD2 (?12 fatty acid desaturase gene of Candida albicans), or CaFAD3 (ω3 fatty acid desaturase gene of C. albicans) was examined. ScOLE1 over-expression increased the total unsaturated fatty acid content and enhanced ethanol tolerance, compared with a control strain. In contrast, overexpression of CaFAD2 and CaFAD3, which led to production of linoleic acid (18:2) and α-linolenic acid (18:3), respectively, neither changed total unsaturated fatty acids nor enhanced ethanol tolerance. The total unsaturated fatty acid content rather than the degree of unsaturation is thus an important factor for ethanol tolerance.     

Does an increase in membrane unsaturated fatty acids account for Tween 80 stimulation of glucosyltransferase secretion by Streptococcus salivarius?

When Streptococcus salivarius was grown in batch culture in the presence of various Tween detergents, the fatty acid moiety of the detergent was incorporated into the lipids of its membrane. Tween 80 (containing primarily oleic acid) markedly stimulated the production of extracellular glucosyltransferase and also increased the degree of unsaturation of the membrane lipid fatty acids. The possibility that an increase in membrane unsaturated fatty acids promoted extracellular glucosyltransferase production was examined by growing cells at different temperatures in the presence or absence of Tween 80. The membrane lipids of cells grown at 30 degrees C, 37 degrees C and 40 degrees C without Tween 80 exhibited unsaturated/saturated fatty acid ratios of 2.06, 1.01 and 0.87 respectively. A significant increase in the production of extracellular glucosyltransferase was observed at 30 degrees C compared to cells grown at 40 degrees C. However, cells produced much more exoenzyme at all temperatures when grown with Tween 80. The results indicated that an increase in the unsaturated fatty acid content of the membrane lipids was not by itself sufficient to account for the stimulation of extracellular glucosyltransferase production by Tween 80, but that the surfactant also had to be present.     

Pseudomonas putida NCTC 10936 balances membrane fluidity in response to physical and chemical stress by changing the saturation degree and the trans/cis ratio of fatty acids

This study explored the capability of Pseudomonas putida NCTC 10936 to maintain homeoviscosity after changing the growth temperature, incubating resting cells at different temperatures or at a constant temperature in the presence of 4-chlorophenol (4-CP). After raising the growth temperature from 20 to either 30 or 35 degrees C, the degree of saturation of the organism's fatty acids increased and the ratio of trans to cis unsaturated fatty acids decreased somewhat. In contrast, after the incubation temperature of resting cells was raised (grown at 30 degrees C) from 20 to 30 or 35 degrees C the degree of saturation of the fatty acids remained nearly constant, while the ratio of trans to cis unsaturated fatty acids increased. Incubating resting cells (grown at 30 degrees C) at 20 degrees C in the presence of 4-CP again caused no major changes in the degree of saturation, but cis to trans conversion of unsaturated fatty acids was induced, with a corresponding increase in the trans/cis ratios. Increases in both the saturation degree of the fatty acids and the trans/cis ratio of the unsaturated fatty acids correlated with increases in the fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene intercalated in the bilayers of liposomes prepared from the cells of P. putida NCTC 10936. Electron transport phosphorylation (ETP) could be stabilized by adaptive adjustments in the fluidity of the cytoplasmic membrane mediated by changes in fatty acid composition such as those observed. Whether changes in the degree of saturation or in the trans/cis ratio are more effective can be decided by studying P. putida NCTC 10936.     

Seasonal Changes of Fatty Acid Compositions in Overwintering Larvae of Rice Stem Borer,Chilo suppressalis (Lepidoptera: Pyralidae)

Cold acclimation and overwintering state can affect fatty acid compositions of insects. To determine compositional change of fatty acids during nondiapause and diapause stages, an experiment was conducted to investigate fatty acid constituents from whole body of C. suppressalis larvae. Five most abundant fatty acids were found to be palmitoleic (35–58%), palmitic (18–44%), oleic (14–23%), stearic (0.5–2.5%) and linoleic acid (0.4–2%). However, linolenic, erucic, lauric and myristic acid were found at lower level. Saturated fatty acids significantly decreased and conversely unsaturated fatty acids increased from August (pre-diapause) to October (initiation of diapause). The increase in seasonal cold hardiness during cold acclimation, exposed at −15°C for 24 h, was related to degree of fatty acid unsaturation. The elevation of palmitoleic acid content at low temperature resulted in an increase in the overall degree of unsaturation in the whole body. These results indicated the importance of unsaturated fatty acids composition to prepare larvae entering diapause phase.     

Alterations of the composition and size of the free fatty acid pool of Tetrahymena responding to low-temperature stress

Cells of Tetrahymena mimbres (formerly T. pyriformis NT-1) in midlogarithmic growth under isothermal conditions (at 39 degrees C) contained a very small, compositionally discrete pool of free fatty acids, principally (60.6% of the total free fatty acid mass) palmitic and stearic acids. The composition, degree of unsaturation, and size of this free fatty acid pool were rapidly (15 min or less) altered in response to chilling. During the acclimation period following chilling to 15 degrees C, the size of the free fatty acid pool increased from a mean value of 15.5 nmol free fatty acid/mumol lipid phosphorus in 39 degrees C cells to 24.2 nmol free fatty acid/mumol lipid phosphorus. The degree of free fatty acid saturation rapidly increased over the initial hour following the onset of hypothermal conditions, but by 24 h the unsaturated free fatty acid/saturated free fatty acid ratio was 0.35 (equivalent to a 2.7-fold increase in unsaturation relative to 39 degrees C controls (unsaturated/saturated ratio = 0.13) and 4.4-fold greater than cells acclimated for 1 h (unsaturated/saturated ratio = 0.08)). By 24 h the percentage of palmitic and stearic acids had decreased to 45.6%. Similar, and in some instances more pronounced, changes were observed to occur in triacylglycerol-bound fatty acids. Modulation of steady-state free fatty acid composition could also be achieved by the addition of exogenous fatty acids to the growth medium. The ability to manipulate the level of intracellular free fatty acids should prove to be a valuable experimental tool in determining how specific fatty acids regulate various lipid-modifying enzymes.     

Changes in content and fatty acid profiles of total lipids and sulfolipids in the halophyte Crithmum maritimum under salt stress

In the halophyte Crithmum maritimum, the sulfolipid content increased considerably in the presence of NaCl. There were no significant changes in the total fatty acid composition of sulfolipids during salt treatment, except for linoleic and linolenic acids. In comparison to the control plants, sulfolipids in NaCl-treated plants showed a decrease in the percentage of unsaturated fatty acid (C18:3), and a corresponding increase in the percentage of unsaturated fatty acids (C18:2). As a whole, the data reported in this work suggest that sulfolipds may be one important aspect of strategies involved in salt tolerance of this halophyte.     

Unsaturated fatty acid synthesis in sunflower (Helianthus annuus L.) seeds in response to night temperature

The incorporation of ¹⁴CO₂ into unsaturated fatty acids during seed development was measured in sunflowers grown in controlled environments with day temperatures of 28°C and night temperatures of 15°C or 22°C. While the average temperatures to which the plants were exposed did not differ greatly, the ratio of linoleic acid to oleic acid synthesized was much greater at a night temperature of 15°C than at 22°C. These results support the proposal (Harris et al. 1978) that the mean minimum temperature experienced during seed development is the major environmental factor influencing the unsaturated fatty acid composition of sunflower seed oil.     

Effects of chill stress on prompt and delayed chlorophyll fluorescence from leaves

This paper describes the utilization of a portable solid state device for the simultaneous measurement of prompt and delayed fluorescence transients in leaves from a variety of species subjected to temperature lowering. The induction transients of the two phenomena were not identical as the peak in prompt fluorescence yield always preceded that of delayed fluorescence. Temperature lowering delayed the occurrence of peak fluorescence, increased prompt fluorescence yield, decreased delayed fluorescence yield, and caused the occurrence of a new, more rapid delayed fluorescence transient. Leaves from all species had qualitatively the same type of induction curves although the response to temperature differed between species. The delayed fluorescence yield of chill-sensitive species was reduced to a greater extent than that of chill-insensitive species. Cold hardening leaf material did not greatly change the fluorescence response to temperature lowering. Arrhenius plots showed a linear relationship between delayed fluorescence yield and temperature. There were no breaks that would suggest membrane lipid phase changes. The data indicate that thylakoid membranes of chill-sensitive species are less capable of maintaining a light-induced high energy state at low temperatures than are thylakoid membranes of chill-resistant species.     

Alteration in the contents of unsaturated fatty acids in dnaA mutants of Escherichia coli

DnaA protein, the initiator of chromosomal DNA replication in Escherichia coli , has a high affinity for acidic phospholipids containing unsaturated fatty acids. We have examined here the fatty acid composition of phospholipids in dnaA mutants. A temperature-sensitive dnaA46 mutant showed a lower level of unsaturation of fatty acids (ratio of unsaturated to saturated fatty acids) at 42°C (non-permissive temperature) and at 37°C (semi-permissive temperature), but not at 28°C (permissive temperature), compared with the wild-type strain. Plasmid complementation analysis revealed that the dnaA46 mutation is responsible for the phenotype. Other temperature-sensitive dnaA mutants showed similar results. On the other hand, a cold-sensitive dnaAcos mutant, in which overinitiation of DNA replication occurs at low temperature (28°C), showed a higher level of unsaturation of fatty acids at 28°C. Based on these observations, we discuss the role of phospholipids in the regulation of the activity of DnaA protein.     

Mechanism of the apparent regulation of Escherichia coli unsaturated fatty acid synthesis by exogenous oleic acid.

Starvation of strains of Escherichia coli which are glycerol auxotrophs and are also defective in beta oxidation results in the accumulation of large amounts of free fatty acid (Cronan, J. E., Jr., Weisberg, L. W., and Allen, R. G. (1975) J. Biol. Chem. 250, 5835-5840). We now report that addition of exogenous oleic acid to these cultures results in no decrease in the synthesis of the unsaturated acids of the free fatty acid fraction although a 40 to 60% decrease of [14C]acetate incorporation into phospholipid unsaturated acyl moieties occurs under these conditions. This result indicates that the decreased synthesis of phospholipid unsaturated acyl moieties observed by others during oleic acid supplementation can be attributed to competition between exogenous and endogenously synthesized unsaturated fatty acids rather than a curtailment of unsaturated fatty acid synthesis per se.