16-Hydroxyhexadecanoic acid

Characterization of Glossy Spike Mutants and Identification of Candidate Genes Regulating Cuticular Wax Synthesis in Barley (Hordeum vulgare L.).[Pubmed:36361814]

Int J Mol Sci. 2022 Oct 27;23(21):13025.

Cuticular waxes comprise the hydrophobic layer that protects crops against nonstomatal water loss and biotic and abiotic stresses. Expanding on our current knowledge of the genes that are involved in cuticular wax biosynthesis and regulation plays an important role in dissecting the processes of cuticular wax metabolism. In this study, we identified the Cer-GN1 barley (Hordeum vulgare L.) mutant that is generated by ethyl methanesulfonate mutagenesis with a glossy spike phenotype that is controlled by a single recessive nuclear gene. A physiological analysis showed that the total cuticular wax loads of Cer-GN1 were one-third that of the progenitor wild-type (WT), and its water loss rate was significantly accelerated (p < 0.05). In addition, Cer-GN1 was defective in the glume's cuticle according to the toluidine blue dye test, and it was deficient in the tubule-shaped crystals which were observed on the glume surfaces by scanning electron microscopy. Using metabolomics and transcriptomics, we investigated the impacts of cuticular wax composition and waxy regulatory genes on the loss of the glaucous wax in the spikes of Cer-GN1. Among the differential metabolites, we found that 16-Hydroxyhexadecanoic acid, which is one of the predominant C16 and C18 fatty acid-derived cutin monomers, was significantly downregulated in Cer-GN1 when it was compared to that of WT. We identified two novel genes that are located on chromosome 4H and are downregulated in Cer-GN1 (HvMSTRG.29184 and HvMSTRG.29185) that encode long-chain fatty acid omega-monooxygenase CYP704B1, which regulates the conversion of C16 palmitic acid to 16-Hydroxyhexadecanoic acid. A quantitative real-time PCR revealed that the expression levels of HvMSTRG.29184 and HvMSTRG.29185 were downregulated at 1, 4, 8, 12, and 16 days after the heading stage in Cer-GN1 when it was compared to those of WT. These results suggested that HvMSTRG.29184 and HvMSTRG.29185 have CYP704B1 activity, which could regulate the conversion of C16 palmitic acid to 16-Hydroxyhexadecanoic acid in barley. Their downregulation in Cer-GN1 reduced the synthesis of the cuticular wax components and ultimately caused the loss of the glaucous wax in the spikes. It is necessary to verify whether HvMSTRG.29184 and HvMSTRG.29185 truly encode a CYP704B1 that regulates the conversion of C16 palmitic acid to 16-Hydroxyhexadecanoic acid in barley.

Gas Chromatography-Mass Spectrometry Metabolite Analysis Combined with Transcriptomic and Proteomic Provide New Insights into Revealing Cuticle Formation during Pepper Development.[Pubmed:36148491]

J Agric Food Chem. 2022 Oct 5;70(39):12383-12397.

The cuticle plays an important role for the quality of pepper fruit. However, the molecular mechanism of cuticle formation in pepper fruit remains unclear. Our results showed that the wax was continuously accumulated during pepper development, while the cutin monomer first increased and then decreased. Hexadecanoic acid and 10,16-Hydroxyhexadecanoic acid were the main components of wax and cutin, respectively. Combined with transcriptome and proteome, the formation patterns of wax and cutin polyester network for pepper cuticle was proposed. The 18 pairs of consistent expression genes and proteins involved in cuticle formation were revealed. Meanwhile, 12 key genes were screened from fatty acid biosynthesis, biosynthesis of unsaturated fatty acids, fatty acid elongation, cutin, suberine, and wax biosynthesis, glycerolipid metabolism, and transport pathway. This study would provide important candidate genes and theoretical basis for the molecular mechanism of cuticle formation, which is essential for the breeding of peppers.

Investigation of Metabolome Underlying the Biological Mechanisms of Acute Heat Stressed Granulosa Cells.[Pubmed:35216260]

Int J Mol Sci. 2022 Feb 15;23(4):2146.

Heat stress affects granulosa cells and the ovarian follicular microenvironment, ultimately resulting in poor oocyte developmental competence. This study aims to investigate the metabo-lomics response of bovine granulosa cells (bGCs) to in vitro acute heat stress of 43 degrees C. Heat stress triggers oxidative stress-mediated apoptosis in cultured bGCs. Heat-stressed bGCs exhibited a time-dependent recovery of proliferation potential by 48 h. A total of 119 metabolites were identified through LC-MS/MS-based metabolomics of the spent culture media, out of which, 37 metabolites were determined as differentially involved in metabolic pathways related to bioenergetics support mechanisms and the physical adaptations of bGCs. Multiple analyses of metabolome data identified choline, citric acid, 3-hydroxy-3-methylglutaric acid, glutamine, and glycocyamine as being upregulated, while galactosamine, AICAR, ciliatine, 16-Hydroxyhexadecanoic acid, lysine, succinic acid, uridine, xanthine, and uraconic acid were the important downregulated metabolites in acute heat stress. These differential metabolites were implicated in various important metabolic pathways directed towards bioenergetics support mechanisms including glycerophospholipid metabolism, the citrate cycle (TCA cycle), glyoxylate and dicarboxylate metabolism, and serine, threonine, and tyrosine metabolism. Our study presents important metabolites and metabolic pathways involved in the adaptation of bGCs to acute heat stress in vitro.

Biocatalytic Route for the Synthesis of Oligoesters of Hydroxy-Fatty acids and ϵ-Caprolactone.[Pubmed:29542861]

Biotechnol J. 2018 Jun;13(6):e1700629.

Developments of past years placed the bio-based polyesters as competitive substitutes for fossil-based polymers. Moreover, enzymatic polymerization using lipase catalysts has become an important green alternative to chemical polymerization for the synthesis of polyesters with biomedical applications, as several drawbacks related to the presence of traces of metal catalysts, toxicity and higher temperatures could be avoided. Copolymerization of ϵ-caprolactone (CL) with four hydroxy-fatty acids (HFA) from renewable sources, 10-hydroxystearic acid, 12-hydroxystearic acid, ricinoleic acid, and 16-Hydroxyhexadecanoic acid, was carried out using commercially available immobilized lipases from Candida antarctica B, Thermomyces lanuginosus, and Pseudomonas stutzeri, as well as a native lipase. MALDI-TOF-MS and 2D-NMR analysis confirmed the formation of linear/branched and cyclic oligomers with average molecular weight around 1200 and polymerization degree up to 15. The appropriate selection of the biocatalyst and reaction temperature allowed the tailoring of the non-cyclic/cyclic copolymer ratio and increase of the total copolymer content in the reaction product above 80%. The catalytic efficiency of the best performing biocatalyst (Lipozyme TL) is evaluated during four reaction cycles, showing excellent operational stability. The thermal stability of the reaction products is assessed based on TG and DSC analysis. This new synthetic route for biobased oligomers with novel functionalities and properties could have promising biomedical applications.

Structural profiling of wax biopolymer from Pinus roxburghii Sarg. needles using spectroscopic methods.[Pubmed:28596007]

Int J Biol Macromol. 2017 Nov;104(Pt A):261-273.

Pinus roxburghii Sarg. is the most abundant species in Himalayan region. The needles of the species largely contribute to the forest biomass and remain the major cause of forest fires leading to climate change, biodiversity loss, etc. Intriguingly, the layer of needles contains wax, a biomacromolecule with potential chemical functionalities for value addition. In the present study, a distinctive approach towards complete structural analysis of the isolated wax in its native state has been done using (1)H, (13)C, HSQC, HMBC, COSY, TOCSY along with GC-MS of the methyl esters of constituent fatty acids. The wax was isolated in a quantitative yield of 1.64% and analyses suggest that it is a polymer of linearly attached fatty acid esters which on hydrolysis yielded three types of omega-hydroxy fatty acids viz. 12-hydroxydodecanoic acid, 14-hydroxytetradecanoic acid and 16-Hydroxyhexadecanoic acid in a ratio of 1:1:2 respectively. Complete assignments for a carbonyl group, alpha-, beta- and other methylenes present in wax were achieved; corroborating the presence of polyester. In particular, identification of wax structure was accomplished through NMR; thereby providing a lead towards future structural analysis of waxes in their native form. The study would also be helpful to generate commercially important compounds derived from pine needle wax. This will offer an opportunity for utilisation of pine needle biomass: a root cause of Himalayan forest fires.