Homologous very-long-chain 1,3-alkanediols and 3-hydroxyaldehydes in leaf cuticular waxes of Ricinus communis L

Surface extracts from primary leaves of Castor bean were found to contain 1.8 microg cm(-2) of cuticular waxes. The mixture comprised alkanes (C(26)-C(29)), primary alcohols (C(22)-C(38)), aldehydes (C(26) and C(28)), fatty acids (C(20)-C(34)) and triterpenoids (lupeol, beta- and alpha-amyrin). Besides, a series of n-alkane-1,3-diols was detected, with chain lengths ranging from C(22) to C(28), a strong predominance of even-numbered homologs, and a maximum for hexacosane-1,3-diol. Seven other compounds were assigned to a novel class of wax constituents and identified as homologous unbranched 3-hydroxyaldehydes ranging from C(22) to C(28). As the chain length distribution of this series closely paralleled the homolog pattern of 1,3-diols, it seems likely that both compound classes are biosynthetically related.     

A single HPLC-PAD-APCI/MS method for the quantitative comparison of phenolic compounds found in leaf, stem, root and fruit extracts of Vaccinium angustifolium

A method was developed for the analysis of Vaccinium angustifolium Ait. (Lowbush blueberry), which is a widely used natural health product, particularly for the treatment of diabetic symptoms. While the anthocyanin content of the fruit has been well characterized, the chemistry of the vegetative parts used in supportive therapy for diabetes has been largely ignored. Using a metabolomics-based approach for compound identification with an emphasis on phenolic metabolites, a single HPLC-PAD-APCI/ MS method was developed for the separation and quantitation of the major metabolites found in the 95% ethanol extracts of leaf, stem, root and fruit. The leaf extract contained high concentrations of chlorogenic acid (approximately 100 microg/mg extract) and a variety of quercetin glycosides that were also detected in the fruit and stem extracts. Flavan-3-ol monomers (+)-catechin and (-)-epicatechin were found in all plant parts but their procyanidin dimers were exclusively identified in the stem and root. The accuracy and precision of the presented method were corroborated by low intra- and inter-day variations in quantitative results in all plant part extracts. Further validation of the extraction and analytical protocols focused on identified compounds with reputed anti-diabetic activity, revealing recoveries greater than 80% and detection limits of 0.12-2.73 microg/mL.     

The Inhibitor of wax 1 locus (Iw1) prevents formation of β‐ and OH‐β‐diketones in wheat cuticular waxes and maps to a sub‐cM interval on chromosome arm 2BS

Glaucousness is described as the scattering effect of visible light from wax deposited on the cuticle of plant aerial organs. In wheat, two dominant genes lead to non‐glaucous phenotypes: Inhibitor of wax 1 (Iw1) and Iw2. The molecular mechanisms and the exact extent (beyond visual assessment) by which these genes affect the composition and quantity of cuticular wax is unclear. To describe the Iw1 locus we used a genetic approach with detailed biochemical characterization of wax compounds. Using synteny and a large number of F₂ gametes, Iw1 was fine‐mapped to a sub‐cM genetic interval on wheat chromosome arm 2BS, which includes a single collinear gene from the corresponding Brachypodium and rice physical maps. The major components of flag leaf and peduncle cuticular waxes included primary alcohols, β‐diketones and n‐alkanes. Small amounts of C19–C27 alkyl and methylalkylresorcinols that have not previously been described in wheat waxes were identified. Using six pairs of BC₂F₃ near‐isogenic lines, we show that Iw1 inhibits the formation of β‐ and hydroxy‐β‐diketones in the peduncle and flag leaf blade cuticles. This inhibitory effect is independent of genetic background or tissue, and is accompanied by minor but consistent increases in n‐alkanes and C₂₄ primary alcohols. No differences were found in cuticle thickness and carbon isotope discrimination in near‐isogenic lines differing at Iw1.     

Metabolic Enzyme Alterations and Astrocyte Dysfunction in a Murine Model of Alexander Disease With Severe Reactive Gliosis

Alexander disease (AxD) is a rare and fatal neurodegenerative disorder caused by mutations in the gene encoding glial fibrillary acidic protein (GFAP). In this report, a mouse model of AxD (GFAP^Tg;Gfap^+/R236H) was analyzed that contains a heterozygous R236H point mutation in murine Gfap as well as a transgene with a GFAP promoter to overexpress human GFAP. Using label-free quantitative proteomic comparisons of brain tissue from GFAP^Tg;Gfap^+/R236H versus wild-type mice confirmed upregulation of the glutathione metabolism pathway and indicated proteins were elevated in the peroxisome proliferator-activated receptor (PPAR) signaling pathway, which had not been reported previously in AxD. Relative protein-level differences were confirmed by a targeted proteomics assay, including proteins related to astrocytes and oligodendrocytes. Of particular interest was the decreased level of the oligodendrocyte protein, 2-hydroxyacylsphingosine 1-beta-galactosyltransferase (Ugt8), since Ugt8-deficient mice exhibit a phenotype similar to GFAP^Tg;Gfap^+/R236H mice (e.g., tremors, ataxia, hind-limb paralysis). In addition, decreased levels of myelin-associated proteins were found in the GFAP^Tg;Gfap^+/R236H mice, consistent with the role of Ugt8 in myelin synthesis. Fabp7 upregulation in GFAP^Tg;Gfap^+/R236H mice was also selected for further investigation due to its uncharacterized association to AxD, critical function in astrocyte proliferation, and functional ability to inhibit the anti-inflammatory PPAR signaling pathway in models of amyotrophic lateral sclerosis (ALS). Within Gfap⁺ astrocytes, Fabp7 was markedly increased in the hippocampus, a brain region subjected to extensive pathology and chronic reactive gliosis in GFAP^Tg;Gfap^+/R236H mice. Last, to determine whether the findings in GFAP^Tg;Gfap^+/R236H mice are present in the human condition, AxD patient and control samples were analyzed by Western blot, which indicated that Type I AxD patients have a significant fourfold upregulation of FABP7. However, immunohistochemistry analysis showed that UGT8 accumulates in AxD patient subpial brain regions where abundant amounts of Rosenthal fibers are located, which was not observed in the GFAP^Tg;Gfap^+/R236H mice.