Search results for "MICROSCOPY"

The response of Trissolcus basalis to footprint contact kairomones from Nezara viridula females is mediated by leaf epicuticular waxes.

2009

Chemical footprints left behind by true bugs are perceived as contact kairomones by scelionid egg parasitoids. Female wasps encountering a contaminated artificial substrate display a characteristic arrestment posture, holding the body motionless and antennating the surface. In the system Nezara viridula (L.) and its egg parasitoid Trissolcus basalis (Wollaston), previous studies have shown that the kairomone mediating such behavior is part of N. viridula's cuticular hydrocarbons (CHC) and furthermore that the wasp's ability to discriminate host male and female footprints is mainly based on the presence/absence of nonadecane (nC(19)). In this study, the effect of epicuticular waxes of leaves…

Toxicity of 4-chloro-o-cresol to fish. Light microscopy and chemical analysis of the tissue

1979

Surface Defects as a Tool to Solubilize and Functionalize WS 2 Nanotubes

2017

Layered transition metal dichalcogenides contain a number of crystal defects which significantly change their properties may be beneficial or detrimental for a specific application. We have prepared defect-rich multiwalled WS2 nanotubes by reductive sulfidization of W18O49 nanowires that were obtained solvothermally from tungsten chloride in different alcohols. The synthesis of the W18O49 nanowires was monitored and their morphological characteristics (e. g. length, rigidity and aspect ratio) are described in detail. The effect of morphology of the nanowires on the synthesis of WS2 nanotubes was investigated in order to obtain WS2 nanotubes that are highly solvent dispersible. Dispersions o…

Allosterism of Nautilus pompilius hemocyanin as deduced from 8 Å cryo-EM structures obtained under oxy and deoxy conditions

2008

Hemocyanins are the blue copper-containing respiratory proteins of many molluscs. Nautilus pompilius hemocyanin (NpH) is a cylindrical decamer composed of ten copies of a 350 kDa polypeptide subunit, in turn consisting of seven O2-binding functional units (FUs, termed NpH-a to NpH-g). Ten copies of the subunit segment NpH-a to NpH-f form the cylinder wall (ca. 35 nm in diameter), whereas the ten copies of NpH-g build the internal collar. Recently we published a 9A cryo-EM structure and molecular model of NpH that solved the principal architecture of this protein [1]. Hemocyanins are highly allosteric, and the cooperativity of oxygen binding should be transferred between functional units by …

Supramolecular self-assembly on the B-Si(111)-(√3x√3) R30° surface: From single molecules to multicomponent networks

2017

Abstract Understanding the physical and chemical processes in which local interactions lead to ordered structures is of particular relevance to the realization of supramolecular architectures on surfaces. While spectacular patterns have been demonstrated on metal surfaces, there have been fewer studies of the spontaneous organization of supramolecular networks on semiconductor surfaces, where the formation of covalent bonds between organics and adatoms usually hamper the diffusion of molecules and their subsequent interactions with each other. However, the saturation of the dangling bonds at a semiconductor surface is known to make them inert and offers a unique way for the engineering of m…

Induction of rapid and reversible cytokeratin filament network remodeling by inhibition of tyrosine phosphatases

2002

The cytokeratin filament network is intrinsically dynamic, continuously exchanging subunits over its entire surface, while conferring structural stability on epithelial cells. However, it is not known how cytokeratin filaments are remodeled in situations where the network is temporarily and spatially restricted. Using the tyrosine phosphatase inhibitor orthovanadate we observed rapid and reversible restructuring in living cells, which may provide the basis for such dynamics. By examining cells stably expressing fluorescent cytokeratin chimeras, we found that cytokeratin filaments were broken down and then formed into granular aggregates within a few minutes of orthovanadate addition. After …

Immunoelectron microscopy labeling for the identification of oligodendrocytes and their precursor cells

2021

Los oligodendrocitos son las células mielinizantes del sistema nervioso central. Además de la mielinización, proporcionan apoyo metabólico y trófico a las neuronas. Estas células se originan a partir de células progenitoras de oligodendrocitos (OPC) que están ampliamente distribuidas en la sustancia blanca y gris. Los oligodendrocitos y las OPC se ven gravemente afectados en diferentes patologías del cerebro humano. Estas enfermedades son causadas por patologías con diferentes mecanismos, como mutaciones genéticas, infecciones, mutaciones que dan lugar a neoplasias, autoinmunidad y lesiones traumáticas. La mayoría de estas disfunciones resultan en desmielinización. De entre las múltiples té…

A new efficient, highly dispersed, Pd nanoparticulate silica supported catalyst synthesized from an organometallic precursor. Study of the homogeneou…

2018

[EN] A new Pd(0) catalyst supported on silica UVM-7 has been synthesized from the organometallic [Pd-2(mu-(C6H4) Pp(2))(2)(CH3CN)(4)](BF4)(2) precursor, characterized by the high dispersion, activity, and small size of the palladium nanoclusters fixed on the silica surface. The catalyst was tested for the Suzuki-Miyaura (SM) reaction of different 4-substitutedphenyl halides with phenylboronic acid. The kinetic study concurs with most of the catalytic action was carried out by Pd species originated by the partial solubilization of Pd immobilized on mesoporous silica. The Schmidt's analysis of differential selectivity (SADS) in several competitive SM reactions, together the STEM-HAADF and HRT…

Pyrrolo[2,3-h]quinolinones: A new ring system with potent photoantiproliferative activity

2006

A new class of compounds, the pyrrolo[2,3-h]quinolin-2-ones, nitrogen isosters of the angular furocoumarin Angelicin, was synthesized with the aim of obtaining new photochemotherapeutic agents with increased antiproliferative activity and lower undesired toxic effects than the lead compound. Two synthetic pathways were approached to allow the isolation both of the dihydroderivatives 10-17 and of the aromatic ring system 23. Compounds 10-17 showed a remarkable phototoxicity and a great UVA dose dependence reaching IC(50) values at submicromolar level. Intracellular localization of these compounds has been evaluated by means of fluorescence microscopy using tetramethylrhodamine methyl ester a…

Reconstruction of Peritoneal-like Structure in Three-Dimensional Collagen Gel Matrix Culture

1997

The peritoneum is a serous membrane consisting of different kinds of cells and extracellular matrix components (ECM). The aim of the present study was to develop a three-dimensional (3D) in vitro culture system for possible investigation of pathological conditions of the peritoneum. Human omental mesothelial cells (MC) and endothelial cells from the umbilical vein (EC) were cultivated either on (MC) or in (EC) a preformed type I collagen matrix. In 3D culture mesothelial cells showed their phenotypical in vivo characteristics and the synthesis of a new basal membrane (BM). Endothelial cells developed vessel-like structures, produce a BM and express E-selectin after TNF-alpha stimulation. Th…