scholarly journals Sunscreen Effect Exerted by Secondary Carotenoids and Mycosporine-Like Amino Acids in the Aeroterrestrial Chlorophyte Coelastrella rubescens under High Light and UV-A Irradiation

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2601
Author(s):  
Anna Zaytseva ◽  
Konstantin Chekanov ◽  
Petr Zaytsev ◽  
Daria Bakhareva ◽  
Olga Gorelova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Amino Acids ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Visible Light ◽  
High Light ◽  
Solar Irradiation ◽  
Transmission Electron ◽  
Secondary Carotenoids ◽  
Layer Chromatography

The microalga Coelastrella rubescens dwells in habitats with excessive solar irradiation; consequently, it must accumulate diverse compounds to protect itself. We characterized the array of photoprotective compounds in C. rubescens. Toward this goal, we exposed the cells to high fluxes of visible light and UV-A and analyzed the ability of hydrophilic and hydrophobic extracts from the cells to absorb radiation. Potential light-screening compounds were profiled by thin layer chromatography and UPLC-MS. Coelastrella accumulated diverse carotenoids that absorbed visible light in the blue–green part of the spectrum and mycosporine-like amino acids (MAA) that absorbed the UV-A. It is the first report on the occurrence of MAA in Coelastrella. Two new MAA, named coelastrin A and coelastrin B, were identified. Transmission electron microscopy revealed the development of hydrophobic subcompartments under the high light and UV-A exposition. We also evaluate and discuss sporopollenin-like compounds in the cell wall and autophagy-like processes as the possible reason for the decrease in sunlight absorption by cells, in addition to inducible sunscreen accumulation. The results suggested that C. rubescens NAMSU R1 accumulates a broad range of valuable photoprotective compounds in response to UV-A and visible light irradiation, which indicates this strain as a potential producer for biotechnology.

scholarly journals Chemical composition, anatomy, lignin distribution, and cell wall structure of Malaysian plant waste fibers

BioResources ◽  
2006 ◽  
Vol 1 (2) ◽  
pp. 220-232 ◽  
Author(s):  
H. P. S. Abdul Khalil ◽  
M. Siti Alwani ◽  
A. K. Mohd Omar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Chemical Composition ◽  
Cell Wall Structure ◽  
Wall Structure ◽  
Anatomical Characteristics ◽  
Lignin Distribution ◽  
Transmission Electron ◽  
Palm Frond

The chemical composition, anatomical characteristics, lignin distribution, and cell wall structure of oil palm frond (OPF), coconut (COIR), pine-apple leaf (PALF), and banana stem (BS) fibers were analyzed. The chemical composition of fiber was analyzed according to TAPPI Methods. Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe and determine the cell wall structure and lignin distribution of various agro-waste fibers. The results revealed differences in anatomical characteristics, lignin distributions, and cell wall structure of the different types of fibers investigated. Nevertheless, transmission electron microscopy (TEM) micrographs have confirmed that the well wall structure, in each case, could be described in terms of a classical cell wall structure, consisting of primary (P) and secondary (S 1 , S 2 , and S 3 ) layers.

Hydrothermal Synthesis of Visible Light Active SnO2-SnS2 Nanocomposite Photocatalyst for the Reduction of Cr(VI) in Water

2013 ◽  
Vol 709 ◽  
pp. 7-10
Author(s):  
Jing Li ◽  
Xi Hua Du ◽  
Wei Min Dai ◽  
Yong Cai Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Sno2 Nanoparticles ◽  
High Photocatalytic Activity ◽  
X Ray ◽  
Transmission Electron ◽  
Visible Light Active ◽  
Composition Structure

A low temperature (130 °C) hydrothermal method was proposed for the synthesis of SnO2-SnS2 nanocomposite. The composition, structure and optical property of the as-synthesized SnO2-SnS2 nanocomposite were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy and UV-vis diffuse reflectance spectra, and its photocatalytic activity was tested by the reduction of Cr(VI) in water under visible light (λ > 420 nm) irradiation. It was found that the as-synthesized SnO2-SnS2 nanocomposite exhibited high photocatalytic activity in the reduction of Cr(VI) in water under visible light (λ > 420 nm) irradiation, whereas SnO2 nanoparticles displayed no photocatalytic activity in the reduction of Cr(VI) in water under visible light (λ > 420 nm) irradiation.

Ultrastructure of hyperparasitism of Coniothyrium minitans on sclerotia of Sclerotinia sclerotiorum

1987 ◽  
Vol 65 (12) ◽  
pp. 2483-2489 ◽  
Author(s):  
H. C. Huang ◽  
E. G. Kokko
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Sclerotinia Sclerotiorum ◽  
Cell Walls ◽  
Chemical Activity ◽  
Coniothyrium Minitans ◽  
Medullary Tissue ◽  
Transmission Electron

Transmission electron microscopy revealed that hyphae of the hyperparasite Coniothyrium minitans invade sclerotia of Sclerotinia sclerotiorum, resulting in the destruction and disintegration of the sclerotium tissues. The dark-pigmented rind tissue is more resistant to invasion by the hyperparasite than the unpigmented cortical and medullary tissues. Evidence from cell wall etching at the penetration site suggests that chemical activity is required for hyphae of C. minitans to penetrate the thick, melanized rind walls. The medullary tissue infected by C. minitans shows signs of plasmolysis, aggregation, and vacuolization of cytoplasm and dissolution of the cell walls. While most of the hyphal cells of C. minitans in the infected sclerotium tissue are normal, some younger hyphal cells in the rind tissue were lysed and devoid of normal contents.

Poly(β-hydroxybutyrate) extrusion from pleomorphic cells ofAzotobacter vinelandiiUWD

1995 ◽  
Vol 41 (13) ◽  
pp. 22-31 ◽  
Author(s):  
William J. Page ◽  
Luis D'elia ◽  
Richard Sherburne ◽  
Lori L. Graham
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Azotobacter Vinelandii ◽  
Intact Cell ◽  
Viable Cell ◽  
Transmission Electron ◽  
Polymer Expansion ◽  
Chemical Dehydration ◽  
Pleomorphic Cells

Azotobacter vinelandii UWD cells fill with up to 80% (per dry mass) poly(β-hydroxybutyrate) (PHB) after 24 h growth in medium containing sugars and fish peptone. However, peptones were not usually added to Azotobacter culture as they induced pleomorphism and compromised cell wall strength. This study examines the morphology of these PHB-producing pleomorphic cells in the transmission electron microscope. PHB-producing cells incubated for 18–24 h were most frequently 2–3 μm diameter spheres containing up to 20 PHB inclusions/cross section, or a calculated ≈ 100 inclusions/cell volume. These inclusions tended to be of small size (≈ 0.5 μm diameter) and became fewer and larger in older cells. The most striking feature of these pleomorphic cells was the apparent extrusion of polymer from the cells. It is unlikely that PHB extrusion is an active process from a viable cell as there was considerable cell wall damage at the point of polymer extrusion. The results suggest that the extrusion of PHB may be the result of polymer expansion, caused by the dehydration of the specimen for transmission electron microscopy, coupled with the inability of the pleomorphic cell wall to retain the expanding polymer. Thus, freeze-substituted sections of similar cells that were prepared without chemical dehydration did not extrude PHB. However, lysed cells prepared for transmission electron microscopy by chemical dehydration also did not extrude PHB, which suggests differences in the fluidity of the PHB in intact cell inclusions and lysed cell granules.Key words: poly(β-hydroxybutyrate), inclusions, polymer expansion, dehydration artifact.

Transmission Electron Microscopy of Unfrozen and Frozen/Thawed Cells of Listeria monocytogenes Treated With Lipase and Lysozyme

1992 ◽  
Vol 55 (9) ◽  
pp. 687-696 ◽  
Author(s):  
SOUZAN E. EL-KEST ◽  
ELMER H. MARTH
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Listeria Monocytogenes ◽  
Storage Time ◽  
Frozen Storage ◽  
Activity Type ◽  
Protoplast Formation ◽  
Transmission Electron ◽  
Three Stages

Unfrozen cells of Listeria monocytogenes typically contained no preplasma space exterior to the plasma membrane (PM) when viewed by transmission electron microscopy. Cells of L. monocytogenes strains Scott A, V7, and California (CA), after freezing and frozen storage, exhibited one or more of the following when viewed with transmission electron microscopy: (a) retraction of cytoplasm and infolding of the PM to form mesosomes, (b) extra-and intracellular rupture of the cell wall (CW), (c) formation of intracellular “bubbles,” and (d) damage to the CW and PM that could have resulted from autolysin activity. Type and degree of effect depended on frozen storage time and strain of L. monocytogenes. Lysozyme treatment of unfrozen or frozen/stored (19 d)/thawed cells of strains Scott A, V7, and CA resulted in protoplast formation and damage to the CW. Three stages of protoplast formation were observed when cells of strain CA were frozen, stored 2 weeks, thawed, and treated with lysozyme. More damage to the CW and PM occurred when frozen storage time was extended for up to 6 weeks before treatment with lysozyme. Lipase and lysozyme treatment of unfrozen or frozen/stored (19 d)/thawed cells of strain Scott A resulted in protoplast formation with some damage to the PM and irregularity in shape of cells. Damage to the PM increased with increasing frozen storage time for up to 6 weeks. Some cells of strain CA resisted freezing, frozen storage for 6 weeks, thawing, and treatment with lipase and lysozyme.

scholarly journals Swelling of Valonia cellulose microfibrils in amine oxide systems

2008 ◽  
Vol 86 (6) ◽  
pp. 520-524 ◽  
Author(s):  
Pierre Noé ◽  
Henri Chanzy
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Electron Diffraction ◽  
Amine Oxide ◽  
Cellulose Microfibrils ◽  
Electron Diffraction Analysis ◽  
Oxide Systems ◽  
Transmission Electron ◽  
Valonia Ventricosa

Cellulose microfibrils from Valonia ventricosa cell-wall fragments were immersed into molten N-methylmorpholine-N-oxide monohydrate (NMMO·H2O), stabilized with n-propyl gallate and kept at 80 °C. The resulting ultrastructural modifications, which were followed by transmission electron microscopy and electron diffraction analysis, showed that within minutes the solvent slowly penetrated inside the crystalline microfibrils and progressed as a wedge in between the cellulose chains without cutting them. Prior to dissolution, a longitudinal subfibrillation of the initial microfibrils occurred, leading to the observation of highly swollen microfibrils, which could reach diameters up to three times larger than those of the initial samples. This mode of swelling is compared with those occurring in other systems, where the intracrystalline swelling of cellulose has been described at the ultrastructural level.Key words: cellulose swelling, Valonia cellulose, N-methylmorpholine-N-oxide.

scholarly journals RrgA and RrgB Are Components of a Multisubunit Pilus Encoded by the Streptococcus pneumoniae rlrA Pathogenicity Islet

2006 ◽  
Vol 74 (4) ◽  
pp. 2453-2456 ◽  
Author(s):  
Julianna LeMieux ◽  
David L. Hava ◽  
Alan Basset ◽  
Andrew Camilli
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Streptococcus Pneumoniae ◽  
Western Blotting ◽  
Surface Proteins ◽  
Domain Swapping ◽  
Cell Fractionation ◽  
Sorting Signal ◽  
Transmission Electron

ABSTRACT The rlrA pathogenicity islet in Streptococcus pneumoniae TIGR4 encodes three surface proteins, RrgA, RrgB, and RrgC, and three sortase enzymes. Using transmission electron microscopy, cell fractionation, cell wall sorting signal domain swapping, and Western blotting, we show that RrgA and RrgB are incorporated into a multisubunit pilus in S. pneumoniae.

scholarly journals A Three-Dimensional Model of the Yeast Transmembrane Sensor Wsc1 Obtained by SMA-Based Detergent-Free Purification and Transmission Electron Microscopy

2021 ◽  
Vol 7 (2) ◽  
pp. 118
Author(s):  
Natalia Voskoboynikova ◽  
Maria Karlova ◽  
Rainer Kurre ◽  
Armen Y. Mulkidjanian ◽  
Konstantin V. Shaitan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Transmembrane Domain ◽  
Three Dimensional ◽  
Water Soluble ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Water Soluble Polymer ◽  
Transmission Electron

The cell wall sensor Wsc1 belongs to a small family of transmembrane proteins, which are crucial to sustain cell integrity in yeast and other fungi. Wsc1 acts as a mechanosensor of the cell wall integrity (CWI) signal transduction pathway which responds to external stresses. Here we report on the purification of Wsc1 by its trapping in water-soluble polymer-stabilized lipid nanoparticles, obtained with an amphipathic styrene-maleic acid (SMA) copolymer. The latter was employed to transfer tagged sensors from their native yeast membranes into SMA/lipid particles (SMALPs), which allows their purification in a functional state, i.e., avoiding denaturation. The SMALPs composition was characterized by fluorescence correlation spectroscopy, followed by two-dimensional image acquisition from single particle transmission electron microscopy to build a three-dimensional model of the sensor. The latter confirms that Wsc1 consists of a large extracellular domain connected to a smaller intracellular part by a single transmembrane domain, which is embedded within the hydrophobic moiety of the lipid bilayer. The successful extraction of a sensor from the yeast plasma membrane by a detergent-free procedure into a native-like membrane environment provides new prospects for in vitro structural and functional studies of yeast plasma proteins which are likely to be applicable to other fungi, including plant and human pathogens.

scholarly journals Fabrication and Photocatalytic Properties of Electrospun Fe-Doped TiO2 Nanofibers Using Polyvinyl Pyrrolidone Precursors

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2634
Author(s):  
Kyeong-Han Na ◽  
Bo-Sung Kim ◽  
Han-Sol Yoon ◽  
Tae-Hyeob Song ◽  
Sung-Wook Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Visible Light ◽  
Crystal Phase ◽  
Acid Orange 7 ◽  
Tio2 Nanofibers ◽  
Doped Tio2 ◽  
Acid Orange ◽  
Photodegradation Rate ◽  
Transmission Electron

For the removal of pollutants, a modified TiO2 photocatalyst is attracting attention. Fe-doped TiO2 nanofibers were prepared through a combination of electrospinning and calcination. Morphological characterization of the sample was conducted using field-emission scanning electron and transmission electron microscopy. The crystal structure of each sample was analyzed using high-resolution transmission electron microscopy, selected area electron diffraction, and Fast Fourier Transform imaging. The average diameter of the Fe-doped TiO2 nanofibers was measured to be 161.5 nm and that of the pure TiO2 nanofibers was 181.5 nm. The crystal phase when heat treated at 350 °C was anatase for TiO2 nanofibers and rutile for Fe-doped TiO2 nanofibers. The crystal phase of the TiO2 matrix was easily transitioned to rutile by Fe-doping. The photocatalytic performance of each sample was compared via the photodegradation of methylene blue and acid orange 7 under ultraviolet and visible light irradiation. In the Fe-doped TiO2 nanofibers, photodegradation rates of 38.3% and 27.9% were measured under UV irradiation and visible light, respectively. Although other catalysts were not activated, the photodegradation rate in the Fe-doped TiO2 nanofibers was 9.6% using acid orange 7 and visible light. For improved photocatalytic activity, it is necessary to study the concentration control of the Fe dopant.

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