"Dicranin" in the Membrane Phospholipids of a Dicranaceae and Pottiaceae Moss Member of the Eastern Himalayan Biodiversity Hotspot

Fatty Acid Profiles of Some Siberian Bryophytes and Prospects of Their Use in Chemotaxonomy

The composition of fatty acids (FAs) in gametophyte samples of 20 Siberian bryophyte species from four orders of mosses and four orders of liverworts collected in relatively cold months (April and/or October) was examined. FA profiles were obtained using gas chromatography. Thirty-seven FAs were found, from 12:0 to 26:0; they included mono-, polyunsaturated (PUFAs) and rare FAs, such as 22:5n-3 and two acetylenic FAs, 6a,9,12-18:3 and 6a,9,12,15-18:4 (dicranin). Acetylenic FAs were found in all examined species of the Bryales and Dicranales orders, dicranin being the predominant FA. The role of particular PUFAs in mosses and liverworts is discussed. Multivariate discriminant analysis (MDA) was performed to determine whether FAs can be used in the chemotaxonomy of bryophytes. Based on the MDA results, FA composition is related to the taxonomic status of species. Thus, several individual FAs were identified as chemotaxonomic markers at the level of bryophyte orders. These were 18:3n-3; 18:4n-3; 6a,9,12-18:3; 6a,9,12,15-18:4; 20:4n-3 and EPA in mosses and 16:3n-3; 16:2n-6; 18:2n-6; 18:3n-3 and EPA in liverworts. These findings indicate that further research into bryophyte FA profiles can shed light on phylogenetic relationships within this group of plants and the evolution of their metabolic pathways.

Lipidomes of Icelandic bryophytes and screening of high contents of polyunsaturated fatty acids by using lipidomics approach

Bryophytes (mosses, liverworts, and hornworts) have interested researchers because of their high chemical diversity and their potential uses in pharmaceutical, food, and cosmetic industries. Specifically, long-chain polyunsaturated fatty acids (l-PUFA) such as arachidonic acid (AA) and eicosapentaenoic acid (EPA) are commonly found in bryophytes, but not in vascular plants. Bryophytes accumulate PUFAs in cold or even freezing temperature to keep the cell fluidity. Iceland has a long history of bryophyte vegetation. These bryophytes are highly adapted to the harsh environment in Iceland and therefore are expected to produce high amounts of PUFAs. However, despite the fact that hundreds of mosses and liverworts have been found in Iceland, their lipid profiles largely remain unknown. In this study, we performed untargeted lipidomics by using UPLC-ESI-QTOF-MS as a rapid screening strategy to examine the lipid compositions of 39 local bryophyte species in Iceland and aimed to find high AA and EPA producers. A total of 280 lipid molecular species from 15 lipid classes were quantified with isotope-labeled internal standards. AA and EPA were abundantly distributed in the phospholipids (mainly PC and PE) and glycerolipids (MGDG and DGDG) in six moss species, namely Racomotrium lanuginosum, R. ericoides, Bryum psedotriquetrium, Plagiomnium ellipticum, Hylocomium splendens, and Rhytidiadelphus triquetrus. Two of the six species (B. psedotriquetrium and H. splendens) also accumulated high concentrations of PUFA-containing-triacylglycerols.

Chemotaxonomic and evolutionary perspectives of Bryophyta based on multivariate analysis of fatty acid fingerprints of Eastern Himalayan mosses

Bryophyta comprises one of the earliest lineages of land plants that had implemented remarkable innovations to their lipid metabolic systems for successful adaptation to terrestrial habitat. This study presents a comprehensive investigation of fatty acid profiles of mosses from Eastern Himalayas with an aim to trace their chemotaxonomic and evolutionary implications. Fatty acid compositions of 40 random mosses belonging to major families of Bryophyta were explored by gas chromatographic analysis. A diverse array of saturated, monounsaturated and polyunsaturated fatty acids including rare acetylenic fatty acids were detected. Hexadecanoic acid (C16:0), 9,12 (Z,Z)-octadecadienoic acid (C18:2n6) and 9,12,15 (Z,Z,Z)-octadecatrienoic acid (C18:3n3) were the predominant fatty acids in all the mosses. However, quantitative variation of C20 polyunsaturated fatty acids (PUFAs), specifically 5,8,11,14 (Z,Z,Z,Z)-eicosatetraenoic acid (C20:4n6), among the investigated mosses was the most prominent outcome. The diplolepidous members of Bryidae, especially the mosses of Hypnales, Bryales and Bartramiales contained higher amount of C20 PUFAs compared with the haplolepidous orders. Principal component analyses based on individual fatty acids and other related parameters validated C20:4n6 content and the ratio of C20:4n6/C18:2n6 as the apparent chemotaxonomic discriminants. The prevalent notion of considering 9,12,15-octadecatrien-6-ynoic acid (C18:4a) as the chemomarker of Dicranaceae has also been challenged, since the compound was detected not only in different families of Dicranales, but also in a Pottiales member, Leptodontium viticulosoides. Therefore, an ensemble of fatty acids instead of a single one can be considered as the chemical signature for taxonomic interpretation which may also be vital from an evolutionary standpoint.

Metabolic impairment in response to early induction of C/EBPβ leads to compromised cardiac function during pathological hypertrophy

Chronic pressure overload-induced left ventricular hypertrophy in heart is preceded by a metabolic perturbation that prefers glucose over lipid as substrate for energy requirement. Here, we establish C/EBPβ (CCAAT/enhancer-binding protein β) as an early marker of the metabolic derangement that triggers the imbalance in fatty acid (FA) oxidation and glucose uptake with increased lipid accumulation in cardiomyocytes during pathological hypertrophy, leading to contractile dysfunction and endoplasmic reticulum (ER) stress. This is the first study that shows that myocardium-targeted C/EBPβ knockdown prevents the impaired cardiac function during cardiac hypertrophy led by maladaptive metabolic response with persistent hypertrophic stimuli, whereas its targeted overexpression in control increases lipid accumulation significantly compared to control hearts. A new observation from this study was the dual and opposite transcriptional regulation of the alpha and gamma isoforms of Peroxisomal proliferator activated receptors (PPARα and PPARγ) by C/EBPβ in hypertrophied cardiomyocytes. Before the functional and structural remodeling sets in the diseased myocardium, C/EBPβ aggravates lipid accumulation with the aid of the increased FA uptake involving induced PPARγ expression and decreased fatty acid oxidation (FAO) by suppressing PPARα expression. Glucose uptake into cardiomyocytes was greatly increased by C/EBPβ via PPARα suppression. The activation of mammalian target of rapamycin complex-1 (mTORC1) during increased workload in presence of glucose as the only substrate was prevented by C/EBPβ knockdown, thereby abating contractile dysfunction in cardiomyocytes. Our study thus suggests that C/EBPβ may be considered as a novel cellular marker for deranged metabolic milieu before the heart pathologically remodels itself during hypertrophy.