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Ten of twelve spiroplasma strains from different sources carried multiple covalently closed circular duplex deoxyribonucleic acid molecules, as shown by ethidium bromide-cesium chloride gradient centrifugation of cell lysates and examination of resulting bands by electron microscopy and agarose gel electrophoresis. Two to eight size classes per strain,(More)
A double mutant of Cryptococcus neoformans which lacked the ability to produce melanin (Mel-) on media containing diphenols and failed to grow at 37 degrees C (temperature sensitive, Tem-) was obtained by UV irradiation and subsequent cloning. The mutant showed two lesions in melanogenesis in that it lacked the active transport system for diphenolic(More)
The cytoplasmic antigen and ultrastructural changes we described previously for chimpanzees (Pan troglodytes) infected with hepatitis C virus (HCV) or with hepatitis D virus have recently been shown to be indirect measures of viral replication and appear to represent a host response to the expression or action of interferon. The time of appearance of these(More)
The approximate size of the H strain of non-A, non-B (NANB) hepatitis virus was determined by filtration through polycarbonate membranes. The accuracy and reproducibility of such filtrations were monitored by filtering selected reference viruses. These studies indicate that strain H, representative of the principal blood-borne NANB hepatitis virus, is 30-60(More)
The mycoplasma-like organism Spiroplasma citri gen. nov., sp. nov., isolated from citrus infected with "Stubborn" disease and carried in serial cultures in several media, was examined by dark-field microscopy and electron microscopy of negatively-stained and shadowed preparations and of sections. It grows as motile, helical filaments in liquid, but as(More)
Mutant 168ts-200B, resulting from nitrosoguanidine treatment of Bacillus subtilis 168 (trp(-) C2), exhibits a rod-to-sphere morphogenetic interconversion when the incubation temperature is 30 or 45 C, respectively. Ultrathin sections of rods grown at 30 C, after glutaraldehyde-osmium uranium-lead fixation and staining, show trilaminar cell walls with a(More)
This paper presents a computationally efficient algorithm for smoothly space-variant Gaussian blurring of images. The proposed algorithm uses a specialized filter bank with optimal filters computed through principal component analysis. This filter bank approximates perfect space-variant Gaussian blurring to arbitrarily high accuracy and at greatly reduced(More)
Electron microscopy of Filobasidiella neoformans, the perfect state of Cryptococcus neoformans, revealed basidiomycete doliporesepta between hyphal cells and also between clamp connections and adjacent cells. The pore-occluding material was a heterogeneous flattened plate with dark margins and a lighter center, as seen in the species of Filobasidium.(More)
WhenHistoplasma capsulatum yeast cells were grown in the presence of partially inhibitory concentrations of saramycetin, electron microscopy revealed that the proportion of apparently damaged cells was a function of the concentration of the antibiotic. Evidence of early damage consisted of irregularity of outline, followed by progressive lysis of internal(More)
Hepatitis E virus (HEV), a positive-strand RNA agent, has been associated with enterically transmitted non-A, non-B hepatitis in Asia, Africa, and Mexico. To evaluate the role of HEV in an outbreak of hepatitis in Pakistan, we used immune electron microscopy to detect 1) antibody to HEV, for evidence of infection, and 2) virus, to determine the pattern of(More)