Trichothecium roseum, a mycoparasite of Sclerotinia sclerotiorum

1993 ◽  
Vol 71 (12) ◽  
pp. 1631-1638 ◽  
Author(s):  
H. C. Huang ◽  
E. G. Kokko
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Cell Walls ◽  
Electron Microscopic ◽  
Trichothecium Roseum ◽  
Moist Sand ◽  
Dual Cultures ◽  
Transmission Electron ◽  
Bean Plants ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies

Among sclerotia of Sclerotinia sclerotiorum collected from diseased bean plants in a field near Lethbridge in 1987 and 1988, 30 and 16%, respectively, were contaminated by Trichothecium roseum. Laboratory studies showed that T. roseum is a mycoparasite of S. sclerotiorum, able to infect and destroy sclerotia in dual cultures on potato dextrose agar. Among sclerotia inoculated with spores of T. roseum and incubated for 4 weeks on moist sand, 54 and 43% were infected and killed by the isolates TR-4 and TR-6, respectively. Transmission electron microscopic studies of infected sclerotia revealed that hyphae of T. roseum entered the rind tissue by penetrating the melanized cell walls or via junctions between cells. Lysis of host cell walls occurred at penetration sites. Hyphae of T. roseum ramified in cortical and medullary tissues, destroying the sclerotium. In sclerotia with light infections of T. roseum, numerous cortical and (or) medullary cells showed cytoplasmic granulation and vacuolization without direct association with the mycoparasitic hyphae. Key words: biocontrol, hyperparasite, mycoparasitism.

Radial mass analysis of unstained STEM images of molluscan hemocyanins

1990 ◽  
Vol 48 (3) ◽  
pp. 810-811
Author(s):  
M.G. Hamilton ◽  
T.T. Herskovits ◽  
J.S. Wall
Keyword(s):  
Image Analysis ◽  
Hollow Cylinder ◽  
Electron Micrographs ◽  
Side View ◽  
Mass Analysis ◽  
Mass Measurements ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies

The hemocyanins of molluscs are aggregates of a cylindrical decameric subparticle that assembles into di-, tri-, tetra-, penta-, and larger multi-decameric particles with masses that are multiples of the 4.4 Md decamer. Electron micrographs of these hemocyanins typically show the particles with two profiles: circular representing the cylinder viewed from the end and rectangular representing the side-view of the hollow cylinder.The model proposed by Mellema and Klug from image analysis of a didecameric hemocyanin with the two decamers facing one another with collar (closed) ends outward fits the appearance of side-views of the negatively-stained cylinders. These authors also suggested that there might be caps at the ends. In one of a series of transmission electron microscopic studies of molluscan hemocyanins, Siezen and Van Bruggen supported the Mellema-Klug model, but stated that they had never observed a cap component. With STEM we have tested the end cap hypothesis by direct mass measurements across the end-views of unstained particles.

Synthesis of nanometer-sized particles of barium orthotitanate prepared through a modified reverse micellar route: Structural characterization, phase stability and dielectric properties

2004 ◽  
Vol 19 (10) ◽  
pp. 2905-2912 ◽  
Author(s):  
Tokeer Ahmad ◽  
Ashok K. Ganguli
Keyword(s):  
Martensitic Transition ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies ◽  
Size Of Particles ◽  
Reverse Micellar

Nanoparticles of barium orthotitanate (Ba2TiO4) was obtained using microemulsions (avoiding Ba-alkoxide). Powder x-ray diffraction studies of the powder after calcining at 800 °C resulted in a mixture of orthorhombic (70%) and monoclinic (30%) phases. The high-temperature orthorhombic form present at 800 °C was due to the small size of particles obtained by the reverse micellar route. Pure orthorhombic Ba2TiO4 was obtained on further sintering at 1000 °C with lattice parameters a = 6.101(2) Å, b =22.94(1) Å, c = 10.533(2) Å (space group, P21nb). The particle size obtained from x-ray line broadening studies and transmission electron microscopic studies was found to be 40–50 nm for the powder obtained after heating at 800 °C. Sintering at 1000 °C showed increase in grain size up to 150 nm. Our studies corroborate well with the presence of a martensitic transition in Ba2TiO4. The dielectric constant was found to be 40 for Ba2TiO4 (at 100 kHz) for samples sintered at 1000 °C. The dielectric loss obtained was low (0.06) at 100 kHz.

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