Slotting Allowance: an Overlooked Angle in Grocery Retailing

Ever wonder why one product brand enjoys a more prominent shelf location in a particular retail establishment than another brand? Would such arrangement have any impact on the price one pays for a particular product? Answers to these are related to the relatively unexplored business phenomenon known as slotting allowances or fees for store shelf space. Read more about it...slotting allowance, retail market, distribution market, intermediate market, shelf space rental fee, product brand, store shelf space

Advances in cellular and sub-cellular level localization of lipids and metabolites using two- and three dimensional high-spatial resolution MALDI mass spectrometry imaging

This thesis presents efforts in the advancement and application of high-spatial resolution matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) for the mapping of small metabolites and lipids at the cellular and sub-cellular level. The following work presents a number of advances, using both 2- and 3-dimensional MALDI-MSI to enable visualization at the sub-cellular level. The first chapter consists of a general introduction to the technique of MALDI-MSI, and the seventh and final chapter provides a brief summary of the presented work and possible future directions. The second chapter presents a technology development for the optimization and application of matrix recrystallization to improve lipid ion signals in maize embryos and leaves. Using the optimized recrystallization conditions, the ion signals were improved three times, enhancing the image quality of lipid species with no apparent changes in their localization. Additionally, when methanol was used as a recrystallization solvent, unexpected side reactions were observed between phosphatidic acid and methanol vapor, suggesting recrystallization solvent should be carefully selected to avoid side reactions. The third chapter presents an application using 5- and 10-um high spatial resolution MALDI-MSI to explore quantitative fatty acyl distributions of two classes of thylakoid membrane lipids along the developmental gradient of maize leaves in two inbred lines, B73 and Mo17, and the reciprocal hybrid lines, B73xMo17 and Mo17xB73. This study demonstrated that high-resolution MALDI-MSI analysis can be directly applied to multicellular plant tissues to uncover cell-specific metabolic biology that has not been possible using traditional metabolomics methodologies. For example, certain thylakoid membrane lipids (e.g. phosphatidylglycerol (PG) 32:0) show genotype-specific differences in cellular distributions. Inbred B73 shows preferential localization of PG 32:0 in bundle sheath cells, while a more uniform distribution between bundle sheath and mesophyll cells in inbred Mo17. The fourth chapter present the first time MALDI-MSI has been applied for three dimensional chemical imaging of a single cell using newly fertilized individual zebrafish embryos as a model system. High-spatial resolution MALDI-MSI was used to map and visualize the three-dimensional spatial distribution of phospholipid classes, phosphatidylcholines (PC), phosphatidylethanolamines (PE), and phosphatidylinositols (PI), in the zebrafish embryo. The 3D MALDI-MSI volumetric reconstructions were then used to compare four different normalization approaches to find reliable relative quantification in 2D- and 3D- MALDI MSI data sets. Furthermore, two-dimensional MSI was studied for embryos at different cell developmental stages (1-, 2-, 4-, 8-, and 16-cell stage) to investigate the localization changes of some lipids, revealing heterogeneous localizations of different classes of lipids in the embryo. The fifth chapter discusses the development of a high-throughput MALDI-MS based metabolomics platform using a microarray of nanoparticles and organic matrices. Five matrices that provide broad metabolite coverage were selected and used to analyze turkey gut microbiome samples. Over two thousand unique metabolite features were reproducibly detected across intestinal samples from turkeys fed a diet amended with therapeutic or sub-therapeutic antibiotics, or non-amended feed. This protocol was applied to fifty two turkey cecal samples at three different time points from the antibiotic feed trial, which allowed distinct metabolite profiles to be discovered. The sixth chapter presents an on-tissue chemical modification strategy for high-spatial resolution MALDI-MSI. A mass spectrometry imaging methodology was use to selectively enhance the metabolite signals for a sub-metabolome at a time by performing on tissue derivatizations. Three well-known on-tissue derivatization methods were used: coniferyl aldehyde for primary amines, Girard’s reagent T for carbonyl groups, and 2-picolylamine for carboxylic acids. This proof of concept experiment was applied to cross-sections of maize leaves and roots, and enabled the identification of over five hundred new unique metabolite features. Combined, this approach facilitated the visualization of various classes of compounds, which can eventually allow high-spatial resolution MSI in the metabolomics scale

Gas-Electricity Coordination in Competitive Markets under Renewable Energy Uncertainty

As climate concerns, low natural gas prices, and renewable technologies increase the electric power sector’s dependence on natural gas-fired power plants, operational and investment models for gas and electric power systems will need to incorporate the interdependencies between these two systems to accurately capture the impacts of one on the other. Currently, few hybrid gas-electricity models exist. This paper reviews the state of the art for hybrid gas-electricity models and presents a new model and case study to illustrate a few potential coupling effects between gas and electric power systems. Specifically, the proposed model analyzes the optimal operation of gas-fired power plants in a competitive electricity market taking into consideration gas purchases, gas capacity contracting, and residual demand uncertainty for the generation company due to renewable energy sources

3D MALDI Mass Spectrometry Imaging of a Single Cell: Spatial Mapping of Lipids in the Embryonic Development of Zebrafish

The zebrafish (Danio rerio) has been widely used as a model vertebrate system to study lipid metabolism, the roles of lipids in diseases, and lipid dynamics in embryonic development. Here, we applied high-spatial resolution matrix-assisted laser desorption/ionization (MALDI)-mass spectrometry imaging (MSI) to map and visualize the three-dimensional spatial distribution of phospholipid classes, phosphatidylcholine (PC), phosphatidylethanolamines (PE), and phosphatidylinositol (PI), in newly fertilized individual zebrafish embryos. This is the first time MALDI-MSI has been applied for three dimensional chemical imaging of a single cell. PC molecular species are present inside the yolk in addition to the blastodisc, while PE and PI species are mostly absent in the yolk. Two-dimensional MSI was also studied for embryos at different cell stages (1-, 2-, 4-, 8-, and 16-cell stage) to investigate the localization changes of some lipids at various cell developmental stages. Four different normalization approaches were compared to find reliable relative quantification in 2D- and 3D- MALDI MSI data sets

Saturation Mutagenesis of the HIV-1 Envelope CD4 Binding Loop Reveals Residues Controlling Distinct Trimer Conformations

The conformation of HIV-1 envelope (Env) glycoprotein trimers is key in ensuring protection against waves of neutralizing antibodies generated during infection, while maintaining sufficient exposure of the CD4 binding site (CD4bs) for viral entry. The CD4 binding loop on Env is an early contact site for CD4 while penetration of a proximal cavity by CD4 triggers Env conformational changes for entry. The role of residues in the CD4 binding loop in regulating the conformation of the trimer and trimer association domain (TAD) was investigated using a novel saturation mutagenesis approach. Single mutations identified, resulted in distinct trimer conformations affecting CD4bs exposure, the glycan shield and the TAD across diverse HIV-1 clades. Importantly, mutations that improve access to the CD4bs without exposing the immunodominant V3 loop were identified. The different trimer conformations identified will affect the specificity and breadth of nabs elicited in vivo and are important to consider in design of Env immunogens for vaccines

Nanoparticle microarray for high-throughput microbiome metabolomics using matrix-assisted laser desorption ionization mass spectrometry

A high-throughput matrix-assisted laser desorption/ionization mass spectrometry (MALDI)-MS-based metabolomics platform was developed using a pre-fabricated microarray of nanoparticles and organic matrices. Selected organic matrices, inorganic nanoparticle (NP) suspensions, and sputter coated metal NPs, as well as various additives, were tested for metabolomics analysis of the turkey gut microbiome. Four NPs and one organic matrix were selected as the optimal matrix set: α-cyano-4-hydroycinnamic acid, Fe3O4 and Au NPs in positive ion mode with 10 mM sodium acetate, and Cu and Ag NPs in negative ion mode with no additive. Using this set of five matrices, over two thousand unique metabolite features were reproducibly detected across intestinal samples from turkeys fed a diet amended with therapeutic or sub-therapeutic antibiotics (200 g/ton or 50 g/ton bacitracin methylene disalicylate (BMD), respectively), or non-amended feed. Among the thousands of unique features, 56 of them were chemically identified using MALDI-MS/MS, with the help of in-parallel liquid chromatography (LC)-MS/MS analysis. Lastly, as a proof of concept application, this protocol was applied to 52 turkey cecal samples at three different time points from the antibiotic feed trial. Statistical analysis indicated variations in the metabolome of turkeys with different ages or treatments

Rational modification of an HIV-1 gp120 results in enhanced neutralization breadth when used as a DNA prime

Background The identification of phenotypic features of the HIV-1 envelope glycoprotein that correlate with neutralization breadth is an important goal of HIV vaccine research. Recently we compared the immunogenic potential of two gp120s differing in their ability to utilize CD4; B33 (highly macrophage topic) and LN40 (non-macrophage tropic). Using a DNA prime protein boost regimen in New Zealand White Rabbits, LN40-primed sera displayed enhanced breadth compared to the B33-primed group, with differences in immunogenicity between groups modulated by specific residues within and flanking the V3 loop and the CD4bs. To better understand the role of these residues in eliciting breadth, we introduced reciprocal mutations between LN40 and B33 at these critical positions. Methods Three groups of four rabbits were primed with one of three chimeric LN40/B33 gp120 DNAs, followed by a polyvalent protein boost. Time course and endpoint titers were determined via ELISA. Neutralization breadth was analyzed by Monogram against a panel of sixteen viruses using a Phenosense neutralization assay. Anti-gp120 serum specificities were determined using a set of overlapping peptides spanning the entire gp120 via ELISA. Results We found that sera primed with a B33 chimera containing specific LN40 residues within the V3 loop and the CD4 binding loop displayed enhanced neutralization breadth against a cross-clade panel of Tier 1 and 2 viruses compared to the B33-primed group. Interestingly, a second B33 chimera containing two additional LN40 substitutions (Stu-Bsu R373/N386) within C3/V4 primed the broadest response, being broader than even the LN40-primed group. Additionally, peptide ELISAs showed differences in reactivity between priming groups which were most pronounced for the C3/V4 region, suggesting an important role for these regions in modulating serum antibody responses against gp120

High spatial resolution mass spectrometry imaging reveals the genetically programmed, developmental modification of the distribution of thylakoid membrane lipids among individual cells of maize leaf

Metabolism in plants is compartmentalized among different tissues, cells and subcellular organelles. Mass spectrometry imaging (MSI) with matrix-assisted laser desorption ionization (MALDI) has recently advanced to allow for the visualization of metabolites at single cell resolution. Here we applied 5 and 10 m high-spatial resolution MALDI-MSI to the asymmetric Kranz anatomy of maize leaves to study the differential localization of two major anionic lipids in thylakoid membranes, sulfoquinovosyldiacylglycerols (SQDG) and phosphatidylglycerols (PG). The quantification and localization of SQDG and PG molecular species, among mesophyll (M) and bundle sheath (BS) cells, are compared across the leaf developmental gradient from four maize genotypes (the inbreds B73 and Mo17, and reciprocal hybrids B73xMo17 and Mo17xB73). SQDG species are uniformly distributed in both photosynthetic cell types regardless of leaf development or genotype. However, PG shows photosynthetic cell-specific differential localization depending on the genotype and the fatty acyl chain constituent. Overall, 16:1-containing PGs primarily contribute to the thylakoid membranes of M cells while BS chloroplasts are mostly composed of 16:0-containing PGs. Furthermore, PG 32:0 shows genotype-specific differences in cellular distribution, with preferential localization in BS cells for B73, but more uniform distribution between BS and M cells in Mo17. Maternal inheritance is exhibited within the hybrids such that localization of PG 32:0 in B73xMo17 is similar to the distribution in the B73 parental inbred, whereas that of Mo17xB73 resembles the Mo17 parent. This study demonstrates the power of MALDI-MSI to reveal unprecedented insights on metabolic outcomes in multicellular organisms at single cell resolution

Chemical characterization and bioactive properties of Prunus avium L.: The widely studied fruits and the unexplored stems

The aim of this study was to characterize sweet cherry regarding nutritional composition of the fruits, and individual phytochemicals and bioactive properties of fruits and stems. The chromatographic profiles in sugars, organic acids, fatty acids, tocopherols and phenolic compounds were established. All the preparations (extracts, infusions and decoctions) obtained using stems revealed higher antioxidant potential than the fruits extract, which is certainly related with its higher phenolic compounds (phenolic acids and flavonoids) concentration. The fruits extract was the only one showing antitumor potential, revealing selectivity against HCT-15 (colon carcinoma) (GI50~74 μg/mL). This could be related with anthocyanins that were only found in fruits and not in stems. None of the preparations have shown hepatotoxicity against normal primary cells. Overall, this study reports innovative results regarding chemical and bioactive properties of sweet cherry stems, and confirmed the nutritional and antioxidant characteristics of their fruits.The authors are grateful to Foundation for Science and Technology (FCT, Portugal) for financial support to the research centre CIMO (strategic project PEst OE/AGR/UI0690/2011) and L. Barros researcher contract under “Programa Compromisso com Ciência – 2008”