scholarly journals Nod genes and Nod signals and the evolution of the Rhizobium legume symbiosis.

2001 ◽  
Vol 48 (2) ◽  
pp. 359-365 ◽  
Author(s):  
F Debellé ◽  
L Moulin ◽  
B Mangin ◽  
J Dénarié ◽  
C Boivin
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Acyl Chain ◽  
Nod Factors ◽  
Nod Genes ◽  
Low Concentrations ◽  
Rhizobial Species ◽  
Legume Symbiosis ◽  
Alpha Beta

The establishment of the nitrogen-fixing symbiosis between rhizobia and legumes requires an exchange of signals between the two partners. In response to flavonoids excreted by the host plant, rhizobia synthesize Nod factors (NFs) which elicit, at very low concentrations and in a specific manner, various symbiotic responses on the roots of the legume hosts. NFs from several rhizobial species have been characterized. They all are lipo-chitooligosaccharides, consisting of a backbone of generally four or five glucosamine residues N-acylated at the non-reducing end, and carrying various O-substituents. The N-acyl chain and the other substituents are important determinants of the rhizobial host specificity. A number of nodulation genes which specify the synthesis of NFs have been identified. All rhizobia, in spite of their diversity, possess conserved nodABC genes responsible for the synthesis of the N-acylated oligosaccharide core of NFs, which suggests that these genes are of a monophyletic origin. Other genes, the host specific nod genes, specify the substitutions of NFs. The central role of NFs and nod genes in the Rhizobium-legume symbiosis suggests that these factors could be used as molecular markers to study the evolution of this symbiosis. We have studied a number of NFs which are N-acylated by alpha,beta-unsaturated fatty acids. We found that the ability to synthesize such NFs does not correlate with taxonomic position of the rhizobia. However, all rhizobia that produce NFs such nodulate plants belonging to related tribes of legumes, the Trifolieae, Vicieae, and Galegeae, all of them being members of the so-called galegoid group. This suggests that the ability to recognize the NFs with alpha-beta-unsaturated fatty acids is limited to this group of legumes, and thus might have appeared only once in the course of legume evolution, in the galegoid phylum.

scholarly journals Unusual Methyl-Branched α,β-Unsaturated Acyl Chain Substitutions in the Nod Factors of an Arctic Rhizobium,Mesorhizobium sp. Strain N33 (Oxytropis arctobia)

2001 ◽  
Vol 183 (12) ◽  
pp. 3721-3728 ◽  
Author(s):  
Véréna Poinsot ◽  
Elaine Bélanger ◽  
Serge Laberge ◽  
Guo-Ping Yang ◽  
Hani Antoun ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Acyl Chain ◽  
Resonance Spectroscopy ◽  
Rhizobial Strain ◽  
Nod Factors ◽  
Unsaturated Acyl ◽  
Acyl Chains ◽  
Methyl Branched Fatty Acids ◽  
Signaling Process

ABSTRACT Mesorhizobium sp. strain N33 (Oxytropis arctobia), a rhizobial strain isolated in arctic Canada, is able to fix nitrogen at very low temperatures in association with a few arctic legume species belonging to the genera Astragalus, Onobrychis, and Oxytropis. Using mass spectrometry and nuclear magnetic resonance spectroscopy, we have determined the structure of N33 Nod factors, which are major determinants of nodulation. They are pentameric lipochito-oligosaccharides 6-O sulfated at the reducing end and exhibit other original substitutions: 6-O acetylation of the glucosamine residue next to the nonreducing terminal glucosamine and N acylation of the nonreducing terminal glucosamine by methyl-branched acyl chains of the iso series, some of which are α,β unsaturated. These unusual substitutions may contribute to the peculiar host range of N33. Analysis of N33 whole-cell fatty acids indicated that synthesis of the methyl-branched fatty acids depended on the induction of bacteria by plant flavonoids, suggesting a specific role for these fatty acids in the signaling process between the plant and the bacteria. Synthesis of the methyl-branched α,β-unsaturated fatty acids required a functional nodE gene.

Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism

1981 ◽  
Vol 46 (02) ◽  
pp. 538-542 ◽  
Author(s):  
R Pilo ◽  
D Aharony ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Unsaturated Fatty Acids ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Low Concentrations ◽  
Induced Aggregation

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.

scholarly journals Glutathione Protects Lactobacillus sanfranciscensis against Freeze-Thawing, Freeze-Drying, and Cold Treatment

2010 ◽  
Vol 76 (9) ◽  
pp. 2989-2996 ◽  
Author(s):  
Juan Zhang ◽  
Guo-Cheng Du ◽  
Yanping Zhang ◽  
Xian-Yan Liao ◽  
Miao Wang ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Stress Responses ◽  
Freeze Drying ◽  
Unsaturated Fatty Acids ◽  
Cold Treatment ◽  
Protective Role ◽  
Intracellular Accumulation ◽  
Lactobacillus Sanfranciscensis

ABSTRACT Lactobacillus sanfranciscensis DSM20451 cells containing glutathione (GSH) displayed significantly higher resistance against cold stress induced by freeze-drying, freeze-thawing, and 4°C cold treatment than those without GSH. Cells containing GSH were capable of maintaining their membrane structure intact when exposed to freeze-thawing. In addition, cells containing GSH showed a higher proportion of unsaturated fatty acids in cell membranes upon long-term cold treatment. Subsequent studies revealed that the protective role of GSH against cryodamage of the cell membrane is partly due to preventing peroxidation of membrane fatty acids and protecting Na+,K+-ATPase. Intracellular accumulation of GSH enhanced the survival and the biotechnological performance of L. sanfranciscensis, suggesting that the robustness of starters for sourdough fermentation can be improved by selecting GSH-accumulating strains. Moreover, the results of this study may represent a further example of mechanisms for stress responses in lactic acid bacteria.

Regulation Of The Fatty Acid Composition Of Platelet Phospholipids

1981 ◽  
Author(s):  
M L McKean ◽  
J B Smith ◽  
M J Silver
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Unsaturated Fatty Acids ◽  
De Novo ◽  
Membrane Phospholipids ◽  
De Novo Biosynthesis ◽  
Coa Transferase

The fatty acid composition of cell membrane phospholipids does not remain constant after de novo biosynthesis, but undergoes continual remodelling. One of the major routes for remodelling probably includes the deacylation-reacylation steps of the Lands Pathway. This has been shown to be important for the incorporation of long chain, polyunsaturated fatty acids into phospholipids by liver and brain. An understanding of the mechanisms involved in these processes in platelets is especially important in light of the large stores of arachidonic acid (AA) in platelet phospholipids and the role of AA in hemostasis and thrombosis. Previous results from this laboratory have shown that the turnover of radioactive AA, 8,11,14-eicosatrienoic and 5,8,11,14,17-eicosapentaenoic acids in the phospholipids of resting platelets is more rapid than the turnover of radioactive C16 and C18 saturated and unsaturated fatty acids. However, little is known about how fatty acids, especially AA and its homologues, are incorporated into platelet phospholipids during de novo biosynthesis or how they are exchanged during remodelling.At least three enzymes are involved in the deacylation- reacylation of phospholipids: phospholipase A2; acyl CoA synthetase; and acyl CoA transferase. We have studied acyl CoA transferase and have found considerable activity in human platelet membranes. Experiments are in progress to determine the substrate specificity and other properties of this enzyme.

The Effect of Fatty Acids upon Tumor Cell Respiration and Transplantability

1963 ◽  
Vol 9 (5) ◽  
pp. 530-543 ◽  
Author(s):  
Bernard J Katchman ◽  
Robert E Zipf ◽  
James P F Murphy
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Tumor Cells ◽  
Chemical Structure ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Leukemic Cells ◽  
Endogenous Respiration ◽  
Low Concentrations

Abstract The kinetic effect of palmitate, stearate, oleate, linoleate, and linolenate upon in vitro endogenous respiration of rat chloromyeloid leukemic cells has been investigated. Inhibition of respiration has been correlated with the ability of fatty acids to cause decreased cell viability and cell count; in the bioassay of fatty acid-treated tumor inocula, the increase in animal life span is correlated to the degree of dilution of the inocula due to cell lysis. The degree of lysis is dependent upon the chemical structure of the fatty acid, concentration, and duration of contact; unsaturated fatty acids are more effective than saturated fatty acids. Tumor cells, when incubated at low concentrations of fatty acids, show stimulation of O2 uptake; however, in the bioassay these fatty acid-treated inocula showed no loss in tumor activity. The nature of the physiochemical interaction between fatty acids and tumor cells is discussed.

scholarly journals Comparing the Effects of Different Unsaturated Fatty Acids on Fermentation Performance of Saccharomyces cerevisiae and Aroma Compounds during Red Wine Fermentation

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 538 ◽  
Author(s):  
Pei-Tong Liu ◽  
Chang-Qing Duan ◽  
Guo-Liang Yan
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Decanoic Acid ◽  
Isoamyl Acetate ◽  
Aroma Compounds ◽  
Ethyl Esters ◽  
Yeast Fermentation ◽  
Ethyl Hexanoate ◽  
Low Concentrations ◽  
The Individual

To understand the individual enological function of different unsaturated fatty acids (UFAs), the separated effects of three different UFAs, linoleic acid (LA), oleic acid (OA), and α-linolenic acid (ALA), on yeast fermentation and aroma compounds were investigated in the alcoholic fermentation of Cabernet Sauvignon wine. The results showed that, besides concentration, UFAs types could also influence fermentation process and volatiles in final wine. Low concentrations of UFAs (12 and 60 mg/L), especially LA and OA, significantly promoted fermentation activity and most volatiles when compared to the control, however, the effect became the inhibition with increasing concentrations of UFAs (120 and 240 mg/L). It was interesting to find that OA addition (12 and 60 mg/L) could generate more acetate esters (especially isoamyl acetate) in wine, while 12 mg/L LA facilitated more fatty acids formation (octanoic acid and decanoic acid). In comparison, 120 and 240 mg/L ALA produced more amount of C6 alcohols (1-hexanol) and higher alcohols (isobutyl alcohol and 2,3-butanediol). UFAs additions were unfavorable for ethyl esters formation, except for an increment of ethyl hexanoate in 12 mg/L OA wine. As a result, different aromatic profiles of wines were generated by variations of UFAs types and levels, as shown by PCA. The transcriptional data revealed that the expressions of aroma-related genes, such as BAT1, BAT2, PDC1, PDC5, PDC6, ACC1, FAS1, ATF1, EEB1, and EHT1 were correlated with aroma compounds productions in different treatments. Our data suggested that the three UFAs have different enological functions and they could generate different aromatic profiles. Thus, besides concentrations, it is essential to consider the types of UFAs when applying the strategy to adjust UFAs contents to modulate the aromatic quality of wines.

Sign in / Sign up

Export Citation Format

Share Document