Dynamic product-precursor relationships underlie cuticular lipid accumulation on maize silks

ABSTRACTThe hydrophobic cuticle is the first line of defense between aerial portions of a plant and the external environment. On maize silks, the cuticular cutin matrix is infused with cuticular lipids, consisting of a homologous series of very-long-chain fatty acids (VLCFAs), aldehydes, and hydrocarbons that serve as precursors, intermediates, and end-products of the elongation, reduction, and decarbonylation reactions of the hydrocarbon-producing pathway. To deconvolute the potentially confounding impacts of the silk microenvironment and silk development on the hydrocarbon-producing pathway, spatio-temporal cuticular lipid profiling was conducted on the agronomically important inbreds B73 and Mo17, and their reciprocal hybrids. Statistical interrogation via multivariate analyses of the metabolite abundances of the hydrocarbon-producing pathway demonstrate that the cellular VLCFA pool is positively correlated with the cuticular lipid metabolome, and this metabolome is primarily affected by the silk microenvironment and the plant genotype. Moreover, genotype has a major effect on the pathway, with increased cuticular hydrocarbon and concomitant reduction of cuticular VLCFA accumulation on B73 silks, suggesting that conversion of VLCFAs to hydrocarbons is more effective in B73 than Mo17. Statistical modeling of the ratios between cuticular hydrocarbons and cuticular VLCFAs reveals the complexity of the product-precursor ratio relationship, demonstrating a significant role of precursor chain length. Longer-chain VLCFAs are preferentially utilized as precursors for hydrocarbon biosynthesis. Collectively, these findings demonstrate maize silks as an effective and novel system for dissection of the complex dynamics of cuticular lipid accumulation in plants.One-sentence SummaryThe product-precursor ratios in the cuticular hydrocarbon-producing pathway are impacted by fatty acid precursor chain length, plant genotype and the spatio-temporal dynamic gradients of maize silks.

Topology-dominated dynamic wetting of the precursor chain in a hydrophilic interior corner

The topology-dominated dynamic wetting of a droplet in a hydrophilic interior corner was explored using molecular dynamics simulations and molecular kinetic theory. A wetting transition in the interior corner of a single-file water-molecule precursor chain (PC), which eliminated the stress singularity and advanced much faster than the precursor film, was controlled by the interior angle. Owing to the confinement in the interior corner, the potential surface is lower and smoother. The one-dimensional hydrogen-bond chain transferred the disjoining pressure to drive the PC to slip-like ice. As an example, a stable and long metallic monatomic chain was formed using the unique transport properties of the PC for the first time. Our results may help in understanding the topology-dominated dynamic wetting in a hydrophilic interior corner, expand ‘Taylor conjecture’ to nanoscale and develop new applications at nanoscale.

Histochemical localization and analysis of blood group-related antigens in human pancreas using immunostaining with monoclonal antibodies and exoglycosidase digestion.

We examined the distribution of blood group-related antigens using an indirect immunoperoxidase method with monoclonal antibodies (MAb) directed to A, B, H, Lewis a (Lea), Lewis b (Leb), Lewis x (Lex), and Lewis y (Ley) antigens and Type 1 precursor chain in human pancreas. Effects of prior digestion with exoglycosidases on MAb stainings were simultaneously investigated. A, B, H, Leb, and Ley antigens were detected in acinar cells and interlobular duct cells but not in centroacinar cells, intercalated duct cells, and islet of Langerhans cells. The expression of these antigens in acinar cells was not dependent on Lewis type and secretor status of the tissue donors, whereas that in interlobular duct cells was strictly dependent on secretor status. The distribution pattern of these antigens in acinar cells was not homogeneous, i.e., cells producing H antigens expressed both Leb and Ley antigens but not A or B antigens, whereas those producing A or B antigens did not secrete Leb and Ley as well as H antigens. Digestion with alpha-N-acetylgalactosaminidase or alpha-galactosidase resulted in the appearance of Leb and Ley antigens as well as H antigen in acinar cells producing A and/or B antigens. Type 1 precursor chain was not detected in pancreatic tissues from secretors but appeared in acinar cells producing H antigen after alpha-L-fucosidase digestion, which also disclosed Lex but not Lea antigen in acinar cells expressing both Leb and Ley. In some non-secretors, MAb against Type 1 precursor chain reacted with acinar cells without enzyme digestion. Although Lea antigen was not detected in acinar cells, it was found in centroacinar cells, intercalated duct cells, and interlobular duct cells from all individuals examined except two Le(a-b-) secretors. After sialidase digestion, Lex antigen appeared in centroacinar and intercalated duct cells from some individuals. Sialidase digestion also elicited reactivity with MAb against Type 1 precursor chain in islet of Langerhans cells from some individuals. These results demonstrate the complexity in the pattern of expression and regulation of blood group-related antigens in different cell types of human pancreas. Such complexity may largely be ascribed to differences in individual genotypes and in gene expression patterns of different cell types.