Phospholipid Based Nano Drug Delivery Systems of Phytoconstituents

The development of phytochemistry and phyto-pharmacology has enabled elucidation of composition and biological activities of several medicinal plant constituents. However phytoconstituents are poorly absorbed due to their low aqueous solubility, large molecular size and poor membrane permeability when taken orally. Nanotechnology based drug delivery systems can be used to improve the dissolution rate, permeability and stability of these phytoconstituents. The current chapter aims to present the extraction of phytoconstituents, their identifications, and development/utilization of phospholipid based nano drug delivery systems (PBNDDS). The content of the chapter also provides characteristic features, in-vitro, in-vivo evaluations and stability performance of PBNDDS. The results from the UHPLC and GC-MS showed different phytoconstituents in the extracted samples with quantitative value. Dynamic light scattering (DLS) data showed PBNDDS of different phytoconstituents in the range of 50–250 nm with PDI value of 0.02–0.5, which was also confirmed by the electron microscopic data. Phytoconstituents loading or entrapment for PBNDDS was in the range of 60–95%. PBNDDS exhibited better in-vitro and in-vivo performance with improved Physico-chemical stability.

The Influences of Aqueous Dispersion Media on the Cytotoxic Effect of Zinc Oxide Nanoparticles

Zinc oxide nanoparticles (ZnO-NPs) are widely utilized in many applications due to distinct physical and chemical characteristics. There are growing concerns that abundant use of ZnO-NPs can cause harm to humans and the environment. There is a substantial problem with reproducibility in nanotoxicology research due to the inherent properties of nanoparticles. Dispersion media are used for the preparation of nanoparticles. However, the physical and biological behaviors of ZnO-NPs in aqueous dispersion media are poorly understood. In this study, we investigated the effect of ZnO-NPs on the viability of SH-SY5Y cells. Our results showed that ZnO-NPs diluted from water-dispersed stock solution caused significant cell death at a much lower dose compared to their counterpart diluted from the phosphate-buffered saline (PBS)-dispersed stock solution. Electron microscopic data indicated that ZnO-NPs from the PBS-dispersed stock solution form much larger agglomerates compared to the one from the water-dispersed stock solution. From these data, we can conclude that the types of media used for particle dispersion impact the change in the physical property and cytotoxicity of ZnO-NPs.

Reticulon 3 regulates very low density lipoprotein secretion by controlling very low density lipoprotein transport vesicle biogenesis

Secretion of very low density lipoprotein (VLDL) by the liver is an important physiological process; however, the rate of VLDL secretion is determined by its transport from the endoplasmic reticulum (ER) to the Golgi. This transport event is facilitated by a specialized ER-derived vesicle, the VLDL transport vesicle (VTV). We have reported earlier a detailed VTV proteome, which revealed that reticulon 3 (RTN3) is uniquely present in the VTV. Our immunoblotting and electron microscopic data demonstrate that RTN3 is enriched in the VTV; however, other ER-derived vesicles do not contain RTN3. Co-immunoprecipitation data coupled with confocal microscopic analyses strongly suggest that RTN3 interacts with VLDL core protein, apoB100, at the ER level. Our data show that either blocking of RTN3 using specific antibodies or RTN3 knockdown resulted in significant reduction in VTV biogenesis from hepatic ER membranes. Additionally, VLDL secretion from hepatocytes was significantly decreased when RTN3 was silenced by RTN3 siRNA. We conclude that RTN3 regulates VLDL secretion by controlling VTV-mediated ER-to-Golgi transport of nascent VLDL.

Self-organization of actin networks by a monomeric myosin

The organization of actomyosin networks lies at the center of many types of cellular motility, including cell polarization and collective cell migration during development and morphogenesis. Myosin-IXa is critically involved in these processes. Using total internal reflection fluorescence microscopy, we resolved actin bundles assembled by myosin-IXa. Electron microscopic data revealed that the bundles consisted of highly ordered lattices with parallel actin polarity. The myosin-IXa motor domains aligned across the network, forming cross-links at a repeat distance of precisely 36 nm, matching the helical repeat of actin. Single-particle image processing resolved three distinct conformations of myosin-IXa in the absence of nucleotide. Using cross-correlation of a modeled actomyosin crystal structure, we identified sites of additional mass, which can only be accounted for by the large insert in loop 2 exclusively found in the motor domain of class IX myosins. We show that the large insert in loop 2 binds calmodulin and creates two coordinated actin-binding sites that constrain the actomyosin interactions generating the actin lattices. The actin lattices introduce orientated tracks at specific sites in the cell, which might install platforms allowing Rho-GTPase–activating protein (RhoGAP) activity to be focused at a definite locus. In addition, the lattices might introduce a myosin-related, force-sensing mechanism into the cytoskeleton in cell polarization and collective cell migration.

FLOWER DEVELOPMENT OF EMPETRUM HERMAPHRODITUM (ERICACEAE), "БОТАНИЧЕСКИЙ ЖУРНАЛ"

Flowers of most Ericaceae are characterized by pentamery and sympetaly. Empetrum is one of the members of Ericaceae that deviate from this flower groundplan. Due to differences in floral morphology, earlier classifications places Empetrum in a distinct family, Empetraceae belonging to various orders. Perianth of Empetrum is composed by two trimerous whorls of free phyllomes. Different authors interpret it as either simple (with tepals) or double (with sepias and petals). The paper presents scanning electron microscopic data on flower development in Empetrum hermaphroditum. Developmental data suggest that the perianth should be interpreted as double one. Petals are free in anthetic flower and rudiments of corolla tube are not found in early stages of flower development. In this respect, Empetrum differs from some other Ericaceae with free petals in anthetic flowers (such as Rhodonendron tomentosum- Leins, 1964) where rudiments of corolla tube can be traced early in development. In both cases, secondary loss of sympetaly should be assumed. In contrast to another, unrelated genus of Ericaceae bearing flowers with three petals (Tripetaleia-Nishino, 1988) no signs of 'cryptic pentamery' can be traced in flowers of Empetrum. Different patterns of carpel arrangement are documented in Empetrum. Polymerous gynoecium of Empetrum is interpreted as an apomorphic character state derived from a gynoecium isomerous to perianth whorls.

Acyl Enzyme Intermediates in Sortase-Catalyzed Pilus Morphogenesis in Gram-Positive Bacteria

ABSTRACT In gram-positive bacteria, covalently linked pilus polymers are assembled by a specific transpeptidase enzyme called pilus-specific sortase. This sortase is postulated to cleave the LPXTG motif of a pilin precursor between threonine and glycine and to form an acyl enzyme intermediate with the substrate. Pilus polymerization is believed to occur through the resolution of this intermediate upon specific nucleophilic attack by the conserved lysine located within the pilin motif of another pilin monomer, which joins two pilins with an isopeptide bond formed between threonine and lysine. Here, we present evidence for sortase reaction intermediates in Corynebacterium diphtheriae. We show that truncated SrtA mutants that are loosely bound to the cytoplasmic membrane form high-molecular-weight complexes with SpaA polymers secreted into the extracellular milieu. These complexes are not formed with SpaA pilin mutants that have alanine substitutions in place of threonine in the LPXTG motif or lysine in the pilin motif. The same phenotype is observed with alanine substitutions of either the conserved cysteine or histidine residue of SrtA known to be required for catalysis. Remarkably, the assembly of SpaA pili, or the formation of intermediates, is abolished with a SrtA mutant missing the membrane-anchoring domain. We infer that pilus polymerization involves the formation of covalent pilin-sortase intermediates, which occurs within a molecular platform on the exoplasmic face of the cytoplasmic membrane that brings together both sortase and its cognate substrates in close proximity to each other, likely surrounding a secretion apparatus. We present electron microscopic data in support of this picture.