Noboru Higashi

Electron microscope study of development of Chikungunya virus in green monkey kidney stable (VERO) cells

Abstract In an electron microscope study, Chikungunya virus (CHV) grown in VERO cell cultures revealed a shape, size, and structure characteristic of members of the arbovirus group. In thin sections, the virus displayed a roughly spherical or somewhat polygonal profile with a mean diameter of 42 mμ, and consisted of a 25 to 30-mμ core, exhibing substructures in the form of fine dots and thread-like elements, separated by a zone of diminished density from a well-defined envelope having fine projections. Intracytoplasmic, characteristic, dense particles 22 to 25 mμ in diameter having the same substructures as the viral core were presumed to represent virus precursors. The following stages in viral morphogenesis were deduced from the observations: virus precursors formed in the cytoplasmic matrix, and became aligned under regions of cell membranes or apposed to vacuolar membranes. Assembly of virus particles at the cell surface occurred by a budding process involving the incorporation of the virus precursors into virus particles to form their cores. Host cell membranes, which had been modified during infection so as to contain viral antigen, seemed to be elaborated into viral envelopes. Occasionally virus rods and giant forms were observed. They appeared to react with ferritin-conjugated specific antibody.

ELECTRON MICROSCOPIC STUDIES ON THE MODE OF REPRODUCTION OF TRACHOMA VIRUS AND PSITTACOSIS VIRUS IN CELL CULTURES.

Abstract The mode of reproduction of trachoma and psittacosis virus in cell cultures may be summarized as follows: The mechanism by which the infective particles enter the host cells is viropexis. The engulfed small particles retain their integrity in the vacuoles bounded by membranes which were derived from the cell surface membranes. There is no evidence for morphologic eclipse. Without loss of their individuality, the small particles become transformed or reorganized immediately into large particles. In other words, the origin of the large particles (initial bodies) is in the small particles (elementary bodies). There is no evidence for the formation of viral matrix in the cell cytoplasm as a precursor of large particles. In the vacuoles, the large particles increase in size and multiply by means of division. Large particles undergo repeated division before maturation occurs. It seems that large particles have an organelle acting as a division centrum. The sequence of steps in the elaboration of the small particles from the large particles is described.

An electronmicroscopic study on copper precipitation by copper-resistant yeast cells

SummaryBy electronmicroscopic observation of ultrathin sections, it was revealed that sulfide of copper was precipitated richly in the cell wall of copper-resistant yeast cells cultured in a copper-containing medium. The ratio Cu:S of the precipitation seems to range from about 1.8 to 1.

Purification and chemical composition of meningopneumonitis virus

Abstract Meningopneumonitis virus preparations contain two types of particle: one type is 0.25-0.3 μ in diameter and the other is 0.5-1.0 μ. Only the small particle is infective. By a combination of differential centrifugation, nuclease and trypsin treatment, and sucrose density gradient centrifugation, the large particles were nearly completely eliminated from the preparations; analysis of the small particle showed that it contained approximately equal amounts of ribo- and deoxyribonucleic acid.

Freeze-fracture studies of gap junctions of normal and neoplastic astrocytes

SummaryGap junctions of normal and neoplastic astrocytes were studied by the use of freeze-fracture or-etching technique. The gap junctions between normal astrocytes generally revealed a structure composed of small particles on fracture face A and associated pits on fracture face B. The particles and pits had presumably a complementary correlation: however, the pits were usually more regularly oriented—often in hexagonal array—than the particles. In the astrocytoma, the gap junctions were abundant and the pits were occasionally in tetragonal array. In the glioblastoma multiforme, the number of gap junctions was markedly decreased and the space between the particles sometimes increased, indicating a loose arrangement of the particles. The gap junctions in normal and neoplastic astrocytes demonstrated discontinuous macular plaques and did not exhibit continuous zones around the astrocytes. There was no evidence of tight junction in the fracture replicas of astrocytes. The present study might suggest that the malignancy of neoplastic astrocytes is represented by the decrease of the gap junction or by the loose orientation of the particles in the gap junction.

Atypical cristae in mitochondria of human glioblastoma multiforme cells.

A conformation and structure of atypical cristae was seen in some enlarged mitochondria in human glioblastoma multiforme. In the transformation into atypical cristae, normal cristae were markedly decreased in number or absent, and instead, few of them elongated and straightened, becoming intensified in density. Two major forms were discernible in the atypical cristae: close junction type and septate desmosome type. In the close junction type, the apposed cristal unit membranes, about 60 A in thickness, appeared to be arranged in a closely parallel manner analogous to the formation of close junction between epithelial cells, and the intracristal space, about 70 A wide, was of an intermediate density. In the septate desmosome type, the apposed cristal unit membranes were separated by an intracristal space, about 70 A wide, where a series of oriented parallel lamellae or septa spanned at a regular interval of about 160 A from center to center, similar in feature to septate desmosomes. The individual parallel lamellae or septa were mostly composed of electron opaque bodies.

DEVELOPMENTAL CYCLE AND REPRODUCTIVE MECHANISM OF THE MENINGOPNEUMONITIS VIRUS IN STRAIN L CELLS

For the past four years in our laboratory, attempts have been made to obtain some information on the complex nature of the growth of the meningopneumonitis virus, a member of the psittacosis group viruses, in strain L cells. Since the first studies of Bedson (1933) on the mode of multiplication of the psittacosis virus, results of studies with new virological and cytological techniques by many workers have provided additional information on the growth characteristics of the psittacosis group viruses. So far as the authors are aware, however, results and explanation of the mode of multiplication of the viruses in the cell have not always been clear. In the present paper, cell cultures infected with the meningopneumonitis virus were studied under a systematic combination of growth curve experiments, morphological examinations with the optical and electron microscope, and direct chemical analysis of nucleic acid content of the infected cells.

Electron microscopy of pox virus-to-cell adsorption and the ultrastructure of developmental forms of pox virus

Pox viruses adsorbed on the strain L cells or HeLa cells were photographed using ultrathin sectioning. The viral particles seemed to touch the host cell cytoplasmic membrane with oblique orientation and with their major axis towards the membrane. A striking feature was interminglement of much smaller bodies with viral particles around the cell surface where viral particle adsorption was seen. Most of the developmental forms of pox viruses were limited by a double membrane system, visible as an outer dense line measuring about 40 to 60 in width and an inner dense line measuring the same width. Forms without a membrane were sometimes noted. Coiled threads measuring about 30 to 50 in width were seen in the nucleoid or in the central area of the viroplasm of the developmental forms. The virological meanings of developmental forms from the point of view of dynamic infectivity are discussed.

Particle-lamella complex and lamellar crystalloid in human meningioma.

Two characteristic crystalloids were evident in the cytoplasm of human meningioma. The first type, tentatively designated as a particle—lamella complex, was shown as a slender and straight rod often with tapering ends, and usually composed of closely packed parallel arrays of dense lamellae which were closely associated with ribosome-like particles. The individual lamellae were 80–170 in thickness and aligned in the long axis of the crystalloid. The ribosome-like particles were arranged linearly in the interlamellar spaces at about 200–450 intervals. The particle layer was not composed of the ribosome-like particles alone, but often replaced by the lamellar structure. In the same way, the lamellar layer partly consisted of the ribosome-like particles. Thus, the particle layer and the lamellar layer were oriented in an alternating manner. In addition, the ribosome-like particles were often accumulated closely along the particle—lamella complex. The second type of crystalloid, a lamellar crystalloid, consisted of parallel lamellae which were oriented regularly at about 400 intervals. Usually, no ribosome-like particles were evident in the interlamellar spaces. However, a few lamellar crystalloids showed the ribosome-like particles which were oriented linearly for a short distance in the interlamellar spaces or along the outermost lamella, and revealed a close morphological relation to the particle—lamella complex. It might be suggested that the lamellar crystalloid was formed by the activity of the ribosome-like particles from the particle—lamella complex, or vice versa.

A plaque assay for meningopneumonitis virus in monolayers of strain L cells.

Abstract A technique has been devised for producing meningopneumonitis plaques in monolayers of L cells. There is a linear relationship between plaque count and virus input, and the reproducibility of the results suggests that this will be a useful assay method.