Phospholipid Profile Research Articles

Characterization of phospholipid profiles of egg yolks: Newly classified plasmalogens, distribution of polyunsaturated fatty acids, and the effects of dietary enrichment

Characterization of phospholipid profiles of egg yolks: Newly classified plasmalogens, distribution of polyunsaturated fatty acids, and the effects of dietary enrichment

Coal Worker's Pneumoconiosis-Targeted Lipidomics Reveals Aberrant Phospholipid Metabolism for Early-Stage Diagnosis.

Pneumoconiosis is the most prevalent occupational disease in China, with coal worker pneumoconiosis (CWP) demonstrating the highest incidence. Studies have indicated that phospholipids may be associated with CWP. In this study, serum was obtained from 62 patients with pneumoconiosis, 105 coal dust-exposed workers, and 50 healthy individuals and analyzed via targeted lipidomics using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). After initially identifying phospholipids with significant differences through univariate and multivariate statistical analyses, receiver operating characteristic (ROC) analysis was performed. The differential phospholipids identified in patient samples were then integrated to assess their diagnostic potential for CWP using a support vector machine (SVM). Compared with healthy subjects, the levels of Lyso-PS (18:0) were decreased, while PC (16:0), PC (18:0), PC (16:0/18:1), PI (16:0/18:1), PS (18:1), PG (16:0), and PG (18:0/18:1) were significantly increased in the pneumoconiosis group, with an area under the curve (AUC)>0.7. Moreover, compared with the dust-exposed group, Lyso-PC (16:0), PC (16:0), PC (16:0/18:1), PI (16:0/18:1), and PG (16:0) were significantly elevated in the pneumoconiosis group, with an AUC>0.7. The diagnostic model, including PC (16:0), PC (16:0/18:1), PI (16:0/18:1), and PG (16:0), demonstrated excellent performance with an AUC of 0.956. The serum phospholipid profiles of patients with pneumoconiosis differed significantly from those of controls, including differences in PC, Lyso-PC, PI, PS, Lyso-PS, and PG. Among these, a diagnostic model incorporating PC (16:0), PC (16:0/18:1), PI (16:0/18:1), and PG (16:0) demonstrated superior screening efficiency.

Targeted and untargeted cross-sectional study for sex-specific identification of plasma biomarkers of COVID-19 severity.

Coronavirus disease 2019 is a highly contagious respiratory illness caused by the coronavirus SARS-CoV-2. Symptoms can range from mild to severe and typically appear 2-14days after virus exposure. While vaccination has significantly reduced the incidence of severe complications, strategies for the identification of new biomarkers to assess disease severity remains a critical area of research. Severity biomarkers are essential for personalizing treatment strategies and improving patient outcomes. This study aimed to identify sex-specific biomarkers for COVID-19 severity in a Chilean population (n = 123 female, n = 115 male), categorized as control, mild, moderate, or severe. Data were collected using clinical biochemistry parameters and mass spectrometry-based metabolomics and lipidomics to detect alterations in plasma cytokines, metabolites, and lipid profiles related to disease severity. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed to select significant characteristic features for each group. The results revealed distinct biomarkers for males and females. In males, COVID-19 severity of was associated with inflammation parameters, triglycerides content, and phospholipids profiles. For females, liver damage parameters, triglycerides content, cholesterol derivatives, and phosphatidylcholine were identified as severity biomarkers. For both sexes, most of the biomarker combinations evaluated got areas under the ROC curve greater than 0.8 and low prediction errors. These findings suggest that sex-specific biomarkers can help differentiate the levels of COVID-19 severity, potentially aiding in the development of tailored treatment approaches.

Impact of ERG6 Gene Deletion on Membrane Composition and Properties in the Pathogenic Yeast Candida glabrata.

The ERG6 gene is crucial for the biosynthesis of ergosterol, a key component of yeast cell membranes. Our study examines the impact of ERG6 gene deletion on the membrane composition and physicochemical properties of the pathogenic yeast Candida glabrata. Specifically, we investigated changes in selected sterol content, phospholipid composition, transmembrane potential, and PDR16 gene activity. Sterol levels were measured using high-performance liquid chromatography, the phospholipid profile was analysed via thin-layer chromatography, transmembrane potential was assessed with fluorescence spectroscopy, and gene expression levels were determined by quantitative PCR. Our findings revealed a depletion of ergosterol, increased zymosterol and eburicol content, an increased phosphatidylcholine and a reduced phosphatidylethanolamine content in the Δerg6 strain compared to the wt. Additionally, the Δerg6 strain exhibited membrane hyperpolarization without changes in PDR16 expression. Furthermore, the Δerg6 strain showed increased sensitivity to the antifungals myriocin and aureobasidine A. These results suggest that ERG6 gene deletion leads to significant alterations in membrane composition and may activates an alternative ergosterol synthesis pathway in the C. glabrata Δerg6 deletion mutant.

Amycolatopsis melonis sp. nov., a novel protease-producing and cellulose-degrading actinobacterium isolated from soil.

A novel protease-producing and cellulose-degrading actinobacterium, designated strain NEAU-NG30T, was isolated from a melon rhizosphere soil sample collected in Harbin, Heilongjiang Province, China, and established its status using a polyphasic taxonomic study. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NEAU-NG30T was closely related to Amycolatopsis bullii DSM 45802T (98.7%) and Amycolatopsis vancoresmycina DSM 44592T (98.3%). The phospholipid profile contained diphosphatidylglycerol, phosphatidyl methylethanolamine, phosphatidylethanolamine and phosphatidylinositol. The diagnostic sugars in cell hydrolysates were determined to be galactose and arabinose. Cell walls contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinone was MK-9(H4). The major fatty acids were iso-C15:0 and iso-C16:0. Meanwhile, genome analysis of sequences revealed a genome size of 9 338 250 bp and a DNA G+C content of 71.6%. In addition, the average nucleotide identity values and the level of digital DNA-DNA hybridization between strain NEAU-NG30T and its reference strains fall below the thresholds typically used for delineating prokaryote species. According to phenotypic, chemotaxonomic and genotypic studies, it is indicated that strain NEAU-NG30T is considered to be a novel species of the genus Amycolatopsis, for which the name Amycolatopsis melonis sp. nov. is proposed, with NEAU-NG30T (=MCCC 1K08677T=JCM 35654T) as the type strain.

Relationship between systemic biomarker of lipid peroxidation 4-hydroxynonenal and lipidomic profile of morbidly obese patients undergoing bariatric surgery

Obesity is characterized by fat accumulation, impaired metabolism and oxidative stress, frequently associated with lipid peroxidation and generation of bioactive 4-hydroxynonenal (4-HNE). This study aimed to evaluate the impact of bariatric surgery-induced weight loss on lipid peroxidation and associated perturbations in lipid profile. Plasma samples of twenty obese individuals before and 6 months after bariatric surgery were collected in addition to samples of ten healthy controls. HILIC-LC-MS/MS platform was used to characterize phospholipid profile, while lipid peroxidation markers 15-F2t-IsoP, 10-F4t-NeuroP and reactive aldehyde 4-HNE were quantified by RP-LC-MS/MS and GC-MS, respectively. Six months post-surgery lipid peroxidation markers decreased significantly and the BMI of morbidly obese patients decreased by 13 on average. Lipidomics analysis, identified 117 phospholipid species from seven classes, and showed obesity-associated lipidome perturbations, particularly in ether-linked phosphatidylethanolamines (PEo). A total of 45 lipid species were found to be significantly altered with obesity, while 10 lipid species correlated with lipid peroxidation markers. Sample pairwise analyses indicated an interesting link between 4-HNE and the amount of two PEos, PEo (38:2) and PEo (36:2). The results indicate that weight loss-induced improvement of redox homeostasis together with changes in lipid metabolites may serve as markers of metabolic improvement. However, further studies are needed to understand the role of obesity-induced oxidative stress on ether lipid biosynthesis and lipidome perturbations, as well as the impact of bariatric surgery on metabolic improvement.

OsPLDα1 mediates cadmium stress response in rice by regulating reactive oxygen species accumulation and lipid remodeling

Lipid remodeling is crucial for various cellular activities and the stress tolerance of plants; however, little is known about the lipid dynamics induced by the heavy metal cadmium (Cd). In this study, we investigated the phospholipid profiles in rice (Oryza sativa) under Cd exposure. We observed a significant decline in the total amounts of phosphatidylcholine and phosphatidylserine, contrasted with an elevation in phosphatidic acid (PA) due to Cd stress. Additionally, Cd stress prompted the activation of phospholipase D (PLD) and induced the expression of PLDα1. OsPLDα1 knockout mutants (Ospldα1) showed increased sensitivity to Cd, characterized by a heightened accumulation of hydrogen peroxide in roots and diminished PA production following Cd treatment. Conversely, PLDα1-overexpressing (OsPLDα1-OE) lines demonstrated enhanced tolerance to Cd, with suppressed transcription of the respiratory burst oxidase homolog (Rboh) genes. The transcription levels of genes associated with Cd uptake and transport were accordingly modulated in Ospldα1 and OsPLDα1-OE plants relative to the wild-type. Taken together, our findings underscore the pivotal role of OsPLDα1 in conferring tolerance to Cd by modulating reactive oxygen species homeostasis and lipid remodeling in rice.

Comprehensive analysis of phospholipids in pumpkin (Cucurbita maxima) seeds: Comparison with cashew nuts and almonds

Pumpkin (Cucurbita maxima) seeds have gained increasing attention due to their high nutraceutical value; however, data regarding the phospholipid (PL) profile of this oily seed are scarce. Through the combination of RPLC-MS/MS, HILIC-MS, and Paternò-Büchi photochemical reaction, we comprehensively characterized PLs in three accessions of pumpkin seeds. We identified a total of 183 PL molecular species across eight classes. Phosphatidylcholine (PC) represents the most abundant class, followed by phosphatidylinositol (PI), phosphatidylglycerol (PG), and phosphatidic acid (PA). The total PL content is comparable to that of almonds and cashew nuts. In terms of PL structures, pumpkin seeds feature a higher abundance of C18:2-containing PL isomers, a preferential esterification of C18:1 and C18:2 at the sn-2 position as well as a predominant Δ9/Δ9,12 double bond locations for C18:1 and C18:2 respectively. This is the first systematic study on PLs of pumpkin seeds to our knowledge. Our findings add further evidence on the potential value of pumpkin seeds as a functional food or as a source material for making plant-based drink.

Nickel-induced oxidative stress and phospholipid remodeling in cucumber leaves

Nickel phytotoxicity has been attributed, among others, to oxidative stress. However, little is known about Ni-induced phospholipid modifications, including the oxidative ones. Accumulation of reactive oxygen species (ROS), antioxidative enzyme activities, malondialdehyde and the early lipid oxidation products contents, membrane permeability, phospholipid profile as well as phospholipid unsaturation degree were studied in the 1st and the 2nd leaves of hydroponically grown cucumber seedlings subjected to Ni stress. Compared to the 2nd leaf the 1st one showed stronger visual Ni toxicity symptoms, higher Ni, O2.- and H2O2 accumulation as well as greater enhancement in membrane permeability. Enzyme activities were differently influenced by Ni stress, however most pronounced changes were generally found in the 1st leaf. Ni treatment resulted in oxidation of leaf lipids, which was evidenced by appearance of increased contents of MDA and the early produced oxylipins. Among the latter 9-hydroxyoctadecatrienoic acid (9-HOTrE) and 13-hydroxyoctadecatrienoic acid (13-HOTrE) contents showed the most pronounced increase in response to Ni treatment. Exposure to the metal led to the changes in the leaf phospholipid profile and increased degree of phospholipid unsaturation. The obtained results have been discussed in relation to the difference in Ni stress severity between the 1st and the 2nd leaves.

Actinomycetospora aeridis sp. nov., Actinomycetospora flava sp. nov. and Actinomycetospora aurantiaca sp. nov., endophytic actinobacteria isolated from wild orchid (Aerides multiflora Roxb).

Three novel mycelium-forming actinobacteria, designated OC33-EN06T, OC33-EN07T, and OC33-EN08T, were isolated from wild orchid (Aerides multiflora Roxb), collected from a hill evergreen forest in Northern Thailand. Strains OC33-EN06T and OC33-EN07T showed the highest 16S rRNA gene similarity with Actinomycetospora lutea TT00-04T, 99.17 and 99.45%, respectively. Strain OC33-EN08T showed high similarity with four species, namely 'Actinomycetospora termitidis Odt1-22T' (99.37%), Actinomycetospora chiangmaiensis DSM 45062T (99.02%), Actinomycetospora corticicola 014-5T (99.02%), and Actinomycetospora soli SF1T (98.81%). Comparative genome analysis of OC33-EN06T, OC33-EN07T, and OC33-EN08T with the closely related type strains showed that average nucleotide identity (ANI) based on blast, ANI based on MUMmer, and average amino acid identity values were less than 95% and the digital DNA-DNA hybridization values were less than 70%, all below the thresholds for species demarcation. The digital G+C content of OC33-EN06T, OC33-EN07T, and OC33-EN08T were 74.5, 74, and 74 mol%, respectively. These three strains developed bud-like chains of non-motile cylindrical spores with a smooth surface. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, arabinose, and galactose. The predominant menaquinone was MK-8(H4). The phospholipid profile included phosphatidylcholine, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylinositol. Based on comparative analysis of genotypic, phenotypic and chemotaxonomic data, strains OC33-EN06T (=TBRC 18349T=NBRC 116543T), OC33-EN07T (=TBRC 18350T=NBRC 116544T), and OC33-EN08T (=TBRC 18318T=NBRC 116542T) represent the type strains of three novel species of the genus Actinomycetospora for which the names Actinomycetospora aeridis sp. nov., Actinomycetospora flava sp. nov., and Actinomycetospora aurantiaca sp. nov., are proposed.

LC–MS/MS-based phospholipid profiling of plant-pathogenic bacteria with tailored separation of methyl-branched species

Plant-pathogenic bacteria are one of the major constraints on agricultural yield. In order to selectively treat these bacteria, it is essential to understand the molecular structure of their cell membrane. Previous studies have focused on analyzing hydrolyzed fatty acids (FA) due to the complexity of bacterial membrane lipids. These studies have highlighted the occurrence of branched-chain fatty acids (BCFA) alongside normal-chain fatty acids (NCFA) in many bacteria. As several FA are bound in the intact phospholipids of the bacterial membrane, the presence of isomeric FA complicates lipid analysis. Furthermore, commercially available reference standards do not fully cover potential lipid isomers. To address this issue, we have developed a reversed-phase high-performance liquid chromatography (RP-HPLC) method with tandem mass spectrometry (MS/MS) to analyze the phospholipids of various plant-pathogenic bacteria with a focus on BCFA containing phospholipids. The study revealed the separation of three isomeric phosphatidylethanolamines (PE) depending on the number of bound BCFA to NCFA. The validation of the retention order was based on available reference standards in combination with the analysis of hydrolyzed fatty acids through gas chromatography with mass spectrometry (GC/MS) after fractionation. Additionally, the transferability of the retention order to other major lipid classes, such as phosphatidylglycerols (PG) and cardiolipins (CL), was thoroughly examined. Using the information regarding the retention behavior, the phospholipid profile of six plant-pathogenic bacteria was structurally elucidated. Furthermore, the developed LC–MS/MS method was used to classify the plant-pathogenic bacteria based on the number of bound BCFA in the phospholipidome.Graphical

Combined UPLC-QqQ-MS/MS and AP-MALDI Mass Spectrometry Imaging Method for Phospholipidomics in Obese Mouse Kidneys: Alleviation by Feeding Sea Cucumber Phospholipids.

Sea cucumber phospholipids have ameliorative effects on various diseases related to lipid metabolism. However, it is unclear whether it can ameliorate obesity-associated glomerulopathy (ORG) induced by a high-fat diet (HFD). The present study applied UPLC-QqQ-MS/MS and atmospheric pressure matrix-assisted laser desorption ionization mass spectrometry imaging (AP-MALDI MSI) to investigate the effects of sea cucumber phospholipids, including plasmalogen PlsEtn and plasmanylcholine PakCho, on phospholipid profiles in the HFD-induced ORG mouse kidney. Quantitative analysis of 135 phospholipids revealed that PlsEtn and PakCho significantly modulated phospholipid levels. Notably, PlsEtn modulated kidney overall phospholipids better than PakCho. Imaging the "space-content" of 9 phospholipids indicated that HFD significantly increased phospholipid content within the renal cortex. Furthermore, PlsEtn and PakCho significantly decreased the expression of transport-related proteins CD36, while elevating the expression of fatty acid β-oxidation-related protein PPAR-α in the renal cortex. In conclusion, sea cucumber phospholipids reduced renal lipid accumulation, ameliorated renal damage, effectively regulated the content and distribution of renal phospholipids, and improved phospholipid homeostasis, exerting an anti-OGR effect.

Preliminary Study on the Restoration of the Phospholipid Profile in Serum from Patients with COVID-19 by Treatment with Vitamin E.

SARS-CoV-2 is an obligatory intracellular pathogen that requires a lipid bilayer membrane for its transport to build its nucleocapsid envelope and fuse with the host cell. The biological membranes are constituted by phospholipids (PLs), and vitamin E (Vit E) protects them from oxidative stress (OS). The aim of this study was to demonstrate if treatment with Vit E restores the modified profile of the FA in PLs in serum from patients with coronavirus disease-19 (COVID-19). We evaluated Vit E, total fatty acids (TFAs), fatty acids of the phospholipids (FAPLs), total phospholipids (TPLs), 8-isoprostane, thromboxane B2 (TXB2), prostaglandins (PGE2 and 6-keto-PGF1α), interleukin-6 (IL-6), and C-reactive protein (CRP) in serum from 22 COVID-19 patients before and after treatment with Vit E and compared the values with those from 23 healthy subjects (HSs). COVID-19 patients showed a decrease in Vit E, TPLs, FAPLs, and TFAs in serum in comparison to HSs (p ≤ 0.01), and Vit E treatment restored their levels (p ≤ 0.04). Likewise, there was an increase in IL-6 and CRP in COVID-19 patients in comparison with HSs (p ≤ 0.001), and treatment with Vit E decreased their levels (p ≤ 0.001). Treatment with Vit E as monotherapy can contribute to restoring the modified FA profile of the PLs in the SARS-CoV-2 infection, and this leads to a decrease in lipid peroxidation, OS, and the inflammatory process.

PhosphoLipidome Alteration Induced by Clostridioides difficile Toxin B in Enteric Glial Cells.

Clostridioides difficile (C. difficile) is responsible for a spectrum of nosocomial/antibiotic-associated gastrointestinal diseases that are increasing in global incidence and mortality rates. The C. difficile pathogenesis is due to toxin A and B (TcdA/TcdB), both causing cytopathic and cytotoxic effects and inflammation. Recently, we demonstrated that TcdB induces cytopathic and cytotoxic (apoptosis and necrosis) effects in enteric glial cells (EGCs) in a dose/time-dependent manner and described the underlying signaling. Despite the role played by lipids in host processes activated by pathogens, to counter infection and/or induce cell death, to date no studies have investigated lipid changes induced by TcdB/TcdA. Here, we evaluated the modification of lipid composition in our in vitro model of TcdB infection. Apoptosis, cell cycle, cell viability, and lipidomic profiles were evaluated in EGCs treated for 24 h with two concentrations of TcdB (0.1 ng/mL; 10 ng/mL). In EGCs treated with the highest concentration of TcdB, not only an increased content of total lipids was observed, but also lipidome changes, allowing the separation of TcdB-treated cells and controls into different clusters. The statistical analyses also allowed us to ascertain which lipid classes and lipid molecular species determine the clusterization. Changes in lipid species containing inositol as polar head and plasmalogen phosphatidylethanolamine emerged as key indicators of altered lipid metabolism in TcdB-treated EGCs. These results not only provide a picture of the phospholipid profile changes but also give information regarding the lipid metabolism pathways altered by TcdB, and this might represent an important step for developing strategies against C. difficile infection.

Metabolic insights into high-altitude adaptation of Himalayan ‘Horsetails’ [Equisetum diffusum D. Don] with special reference to the fatty acid dynamicity

Equisetum diffusum D. Don, a perennial herb of Equisetaceae, is considered as native to the Himalayan mountain range. This plant has prolific distribution along different altitudes of Eastern Himalayan region. Generally, mountain flora, like E. diffusum, experience a combination of contrasting abiotic stresses and may represent a unique natural model for investigating physiological resilience to address climate change. So, the present study has been framed to compare the metabolic responses in E. diffusum growing at different elevation belts with an aim to understand the underlying basis for their high-altitude adjustment ability. The biochemical profiles of this plant, collected from three different altitudinal transects of Darjeeling hills, were compared. The fatty acid profiles of neutral lipids, membrane phospholipids and glycolipids demonstrated palmitic acid and oleic acid as the predominant fatty acids. The major outcome was the substantial increase of polyunsaturated fatty acids (PUFAs) and unsaturation index in glycolipids of the samples collected from higher altitudes. Major proportion of changes in PUFA content was contributed by arachidonic acid. Therefore, the plants homeostatically control the membrane fluidity by enhancing the unsaturation of glycolipid fatty acids. Moreover, significantly higher antioxidant enzyme activities in higher altitude samples reflect the involvement of these enzymes in coping with the oxidative stress condition and membrane damage. The stress responsive effects may be further augmented by enhanced content of secondary metabolites. Therefore, a combination of biochemical responses along with the changes in membrane plasticity can be predicted as the metabolic adjustment strategies for high-altitude adaptation of E. diffusum.

Degradation ability of Trichoderma spp. in the presence of poly(butylene adipate-co-terephthalate) microparticles

Investigating the effects of microplastics remains a pertinent issue given the extensive biodiversity of exposed organisms, variations in the mechanisms of action among individual polymers, and their reliance on environmental conditions. Therefore, the objective of the study was to investigate some interactions of the popular biodegradable plastic poly(butylene adipate-co-terephthalate) (PBAT) on some aspects of the physiology of filamentous fungi Trichoderma spp., integral components of the soil microbiome known for promoting plant growth and aiding in pollution remediation. In the two Trichoderma strains examined, a positive influence on fungal growth was observed in the presence of microplastics (MPs). The capability to degrade MPs with the involvement of cytochrome P450 monooxygenases was confirmed through the detection of terephthalic acid (TPA) in postculture extractions. Additionally, inhibition of degradative activity in the presence of MPs was observed for metolachlor (MET) and 2,4-dichlorophenoxyacetic acid (2,4-D). Moreover, biodegradation pathways with the involvement several dechlorinated or hydroxylated metabolites were proposed for examined compunds. Concentration-dependent shifts in oxidative stress enzymes activity and slight modifications in phospholipid profiles were noted for the tested PBAT concentrations. In summary, this study enhances our understanding of PBAT's impact on the physiology of filamentous fungal and their degradative capacities important for mitigating environmental pollution by xenobiotics and plastics.

WED-226 An algorithm based on serum phospholipid profiles to predict liver fibrosis degree in metabolic dysfunction-associated steatotic liver disease

WED-226 An algorithm based on serum phospholipid profiles to predict liver fibrosis degree in metabolic dysfunction-associated steatotic liver disease

Characterization of phospholipidome in milk, yogurt and cream, and phospholipid differences related to various dairy processing methods

Milk phospholipids have multiple health benefits, but the deficiency of detailed phospholipid profiles in dairy products brings obstacles to intake calculation and function evaluation of dairy phospholipids. In present study, 306 phospholipid molecular species were identified and quantified among 207 milk, yogurt and cream products using a HILIC-ESI-Q-TOF MS and a HILIC-ESI-QQQ MS. The phospholipid profiles of five mammals' milk show that camel milk contains the most abundant phosphatidylethanolamine, phosphatidylserine and sphingomyelin; cow, yak and goat milk have similar phospholipidomes, while buffalo milk contains abundant phosphatidylinositol. Fewer plasmalogens but more lyso-glycerolphospholipids were found in ultra-high-temperature (UHT) sterilized milk than in pasteurized milk, and higher proportions of lyso-glycerolphospholipid/total phospholipid were observed in both cream and skimmed/semi-skimmed milk than whole milk, indicating that UHT and skimming processes improve glycerolphospholipid degradation and phospholipid nutrition loss. Meanwhile, more diacyl-glycerolphospholipids and less of their degradation products make yogurt a better phospholipid resource than whole milk.

Lipidomics reveals the reshaping of the mitochondrial phospholipid profile in cells lacking OPA1 and mitofusins

Depletion or mutations of key proteins for mitochondrial fusion, like optic atrophy 1 (OPA1) and mitofusins 1 and 2 (Mfn 1 and 2), are known to significantly impact the mitochondrial ultrastructure, suggesting alterations of their membranes’ lipid profiles. In order to make an insight into this issue, we used hydrophilic interaction liquid chromatography coupled with electrospray ionization–high resolution MS to investigate the mitochondrial phospholipid (PL) profile of mouse embryonic fibroblasts knocked out for OPA1 and Mfn1/2 genes. One hundred sixty-seven different sum compositions were recognized for the four major PL classes of mitochondria, namely phosphatidylcholines (PCs, 63), phosphatidylethanolamines (55), phosphatidylinositols (21), and cardiolipins (28). A slight decrease in the cardiolipin/PC ratio was found for Mfn1/2-knockout mitochondria. Principal component analysis and hierarchical cluster analysis were subsequently used to further process hydrophilic interaction liquid chromatography–ESI-MS data. A progressive decrease in the incidence of alk(en)yl/acyl species in PC and phosphatidylethanolamine classes and a general increase in the incidence of unsaturated acyl chains across all the investigated PL classes was inferred in OPA1 and Mfn1/2 knockouts compared to WT mouse embryonic fibroblasts. These findings suggest a reshaping of the PL profile consistent with the changes observed in the mitochondrial ultrastructure when fusion proteins are absent. Based on the existing knowledge on the metabolism of mitochondrial phospholipids, we propose that fusion proteins, especially Mfns, might influence the PL transfer between the mitochondria and the endoplasmic reticulum, likely in the context of mitochondria-associated membranes.

Melatonin Mitigates Lead-Induced Oxidative Stress and Modifies Phospholipid Profile in Tobacco BY-2 Suspension Cells.

Many studies have shown that melatonin (an indoleamine) is an important molecule in plant physiology. It is known that this indoleamine is crucial during plant stress responses, especially by counteracting secondary oxidative stress (efficient direct and indirect antioxidant) and switching on different defense plant strategies. In this report, we present exogenous melatonin's potential to protect lipid profile modification and membrane integrity in Nicotiana tabacum L. line Bright Yellow 2 (BY-2) cell culture exposed to lead. There are some reports of the positive effect of melatonin on animal cell membranes; ours is the first to report changes in the lipid profile in plant cells. The experiments were performed in the following variants: LS: cells cultured on unmodified LS medium-control; (ii) MEL: BY-2 cells cultured on LS medium with melatonin added from the beginning of culture; (iii) Pb: BY-2 cells cultured on LS medium with Pb2+ added on the 4th day of culture; (iv) MEL+Pb: BY-2 cells cultured on LS medium with melatonin added from the start of culture and stressed with Pb2+ added on the 4th day of culture. Lipidomic analysis of BY-2 cells revealed the presence of 40 different phospholipids. Exposing cells to lead led to the overproduction of ROS, altered fatty acid composition and increased PLD activity and subsequently elevated the level of phosphatidic acid at the cost of dropping the phosphatidylcholine. In the presence of lead, double-bond index elevation, mainly by higher quantities of linoleic (C18:2) and linolenic (C18:3) acids in the log phase of growth, was observed. In contrast, cells exposed to heavy metal but primed with melatonin showed more similarities with the control. Surprisingly, the overproduction of ROS caused of lipid peroxidation only in the stationary phase of growth, although considerable changes in lipid profiles were observed in the log phase of growth-just 4 h after lead administration. Our results indicate that the pretreatment of BY-2 with exogenous melatonin protected tobacco cells against membrane dysfunctions caused by oxidative stress (lipid oxidation), but also findings on a molecular level suggest the possible role of this indoleamine in the safeguarding of the membrane lipid composition that limited lead-provoked cell death. The presented research indicates a new mechanism of the defense strategy of plant cells generated by melatonin.