Search PubMed⌕ Search

Biomedical subjects

H Washioka

Publications and source records attributed to H Washioka.

15 recordsLinked to original sources
PubMed1994

The ability of influenza C virus to generate cord-like structures is influenced by the gene coding for M protein.

We observed previously that cord-like structures which had lengths up to 500 microns or greater were protruding from the surface of HMV-II cells infected with influenza C/Yamagata/1/88 virus (Nishimura et al., 1990, Virology 179, 179-188). Comparison of the cord-forming ability among a number of influenza C isolates revealed that the C/Taylor/1233/47 strain was unique in lacking the ability. It was also found that the major structural proteins, hemagglutinin-esterase (HE), nucleoprotein (NP), and matrix (M), could each be distinguished between C/Yamagata/1/88 and C/Taylor/1233/47 viruses by SDS-polyacrylamide gel electrophoresis. To determine the genes involved in the cord formation, a series of reassortant viruses were prepared between C/Yamagata/1/88 and C/Taylor/1233/47, and parental derivation of genes coding for HE, NP, and M was determined by gel electrophoresis. All reassortants which derived M gene from C/Yamagata/1/88, irrespective of derivation of genes coding for HE and NP, had the ability to generate cords, whereas none of reassortants which derived M gene from C/Taylor/1233/47 were capable of producing cords. With respect to several representative reassortants, the origins of genes encoding the polymerase proteins (PB2, PB1, P3) and the nonstructural proteins (NS1, NS2) were determined by T1-oligonucleotide fingerprinting of the isolated RNA segments. The results suggested that none of genes coding for these proteins are exclusively associated with the cord formation. Thus, it is likely that the M gene is the key determinant of the cord-forming ability of influenza C viruses. Nucleotide sequence analysis of the M genes revealed that compared to C/Yamagata/1/88, C/Taylor/1233/47 had two amino acid substitutions in the M molecule at positions 24 (Ala-->Thr) and 133 (Asp-->Asn).

Base Sequence↗
PubMed1991

Regional orientation of actin filaments in the pericanalicular cytoplasm of rat hepatocytes.

To elucidate how actin filaments participate in bile formation, polarity of actin filaments in the pericanalicular cytoplasm was determined with myosin subfragment 1 by transmission electron microscopy of ultrathin sections and deep-etching replicas. Densely concentrated actin filaments were identified around the bile canaliculi in the forms of microvillous core filaments, pericanalicular web filaments, and filaments on the junctional complex. They bound subfragment 1 to form double-helical strands on the deep-etching replica or typical arrowheads on the ultrathin section. All microvillous core filaments showed their arrowheads pointing basally, suggesting the molecular growth occurring at their apical ends. In contrast, filaments of the pericanalicular web, running in parallel to the cell surface, showed unfixed polarities as indicated by their arrowheads. Furthermore, neighboring filament pairs often showed opposite polarities, an alignment necessary for filament sliding. The junctional complex had filaments with arrowheads pointed mostly at the cell center with a small number in opposite direction. In addition, a group of sporadic filaments appeared to be installed to link to both the canalicular membrane and coated vesicles. Such regionally specialized actin filaments are considered inclusively to form a cytoskeletal system that is in charge of (a) maintenance of length of the microvilli, (b) contraction of the canalicular walls, and (c) translocation of coated vesicles in the pericanalicular cytoplasm.

Actin Cytoskeleton↗
PubMed1991

Horizontal-cell gap junction in the goldfish retina: area and density of particles as revealed by complementary freeze replicas.

Aiming at a morphological evaluation of horizontal cell gap junctions under intraocularly injected dopamine and 6-OH-dopamine influences as compared with those in the light and dark periods, the percentage of the junctional areas was computed by planimetry, and the distribution density of connexon particles by visual counting, on complementary freeze-replica electron micrographs. The outer plexiform layer was tentatively divided into the external-horizontal-somatic, intermediate-mixed-fibrous and internal-axon-terminal sublayers. The total number of connexon particles per cell seemed relatively unchanged, because the density of the particles was lower in the light period and after the dopamine treatment than in the dark and after the 6-OH-dopamine treatment; the percentage of the junctional area was conversely greater in the former than in the latter. The mode of response of the gap junction was presumed to occur in parallel with each of the sublayers after the chemical interference.

Animals↗
PubMed1989

Innervation and gap junctions of intestinal striated and smooth muscle cells in the loach. Thin section and freeze-fracture study.

The tunica muscularis of the proximal intestine of the loach consisted of intermingling striated and smooth muscle cells without forming any distinct sublayers. Close contacts devoid of intervention by a basal lamina sometimes occurred between these different types of muscle cells. Gap junctions were occasionally found between heterologous as well as homologous muscle cells. In freeze-fracture replicas, striated muscle cells were distinguished from smooth muscle cells by numerous, evenly distributed subsurface caveolae. These were relatively rare and linearly arranged in smooth muscle cells. Variously-sized and -formed aggregations of connexon particles were found in the protoplasmic fracture-face of both muscle cells. Striated muscle cells had aggregates of connexon particles taking the form of either a small solid polygon or an annulus with a particle-free central region. In smooth muscle cells, the particles were arranged either in variously-sized patches or in straight lines. Topologically, heterologous gap junctions observed in ultrathin section were thought to correspond to the small patchy aggregations. Striated muscle cells in the gut had neuromuscular junctions, which differed morphologically from "cholinergic" nerve terminals at neuromuscular junctions of typical skeletal muscle cells. The smooth muscle cells had close apposition with axonal terminals containing many granular vesicles and a variable number of small, clear vesicles. Occasionally, a "cholinergic"-type axonal terminal with a presynaptic active site was found close to a smooth muscle cell.

Animals↗
PubMed1989

Photoreceptor disk membranes of Lampetra japonica.

With the aim of characterizing photoreceptor outer segments and obtaining in situ observation of macromolecular variations due to cell types as well as adaption, we counted the number of outer segment disk membranes using electron micrographs of ultrathin sections as well as intramembrane particles on the complementary replicas of the retina of Lampetra japonica. Long photoreceptor cells (LPCs, cone-type cells) numbered 10,000/mm2 in the central as well as peripheral regions, while short ones (SPCs, rod-type cells) numbered 30,000/mm2 in the same regions. The LPC outer segment exhibited 306 disks on average during the light cycle versus 364 during the dark cycle. 12.0% of the LPC disks during the light cycle versus 13.4% during the dark cycle represented the "open" disks. The SPC outer segment exhibited 470 disks on average during the light cycle versus 507 during the dark cycle. 11.1% of the SPC disks during the light cycle versus 13.6% during the dark cycle represented the "open" disks. The LPC disk membrane contained 44.3 particles/0.01 microns 2 during the light cycle versus 39.5 particles during the dark cycle, 95% of which were derived from the protoplasmic fracture (PF) face. The SPCs contained 36.0 particles/0.01 micron 2 during the light cycle versus 43.6 during the dark cycle, 90% of which were derived from the PF-face. The present findings contradict the frequently cited hypothesis that an "open" disk, retaining continuity with the plasmalemma, is preserved characteristically into later stages by the cone outer segment. The significance of the intramembrane particles for the activity of the photoreceptor membrane is discussed.

Animals↗
PubMed1988

Gap junction and its cytoskeletal undercoats as involved in invagination-endocytosis.

Plasmamembrane and its cytoskeletal undercoat were characterized by electron microscopy in gap junctions (GJs) of steroidogenic cells of the guinea pig and bullfrog adrenal glands. In both species GJs varied in shape considerably and measured 0.1-4 microns in diameter. Planar GJs were not provided with any distinct form of the undercoat. In contrast, variably invaginating GJs had a network of actin-containing microfilaments located in the protruding cytoplasm arising from either one of adjoining cells. In the deeper invaginations, on the contrary, parallel arrays of actin-containing microfilaments formed a submembranous sheath in the withdrawing cytoplasm. The microfilaments were arranged at right angles for the long axis of the invagination. In completely internalized GJs, the network and sheath became less organized or obscured. A mechanical force driving the invagination-endocytosis involving GJ areas is presumably generated by the microfilament network and sheath, organized differently in forms, but working in concert together. It is also likely that there is another dissolving process for GJs via clathrin-coated vesicles.

Adrenal Glands↗
PubMed1987

Demonstration of rod and cone photoreceptors in the lamprey retina by freeze-replication and immunofluorescence.

In common with other cyclostomata, the Japanese river lamprey (Lampetra japonica) has a retina consisting of distinct types of photoreceptor cells called long and short photoreceptor cells. After freeze-fracture, disc membranes of these photoreceptor cells were characterized in common by a homogeneous distribution of intramembrane particles on the protoplasmic fracture faces, in contrast to those of the myeloid bodies bearing scattering particles. Immunofluorescent examination was applied to the retina with monoclonal antibodies raised against bovine and chicken rhodopsins. Positive immunoreactivity was found to be limited to outer segments of the short cell, leaving the entire body of the long cell and all other components of the retina negative. The results suggest that the short cell is more closely related to a rod-type photoreceptor cell characterized by rhodopsin as its visual pigment.

Animals↗
PubMed1986

"Cholinergic" postsynaptic membranes of bullfrog sympathetic ganglia: electron microscopy of thin sections and freeze-fracture replicas.

"Cholinergic" synapses of the bullfrog sympathetic ganglion cells were investigated with thin sectioning, complementary freeze-fracturing, and deep-etching methods after glutaraldehyde fixation. The protoplasmic (-fracture) face (PF) of the postsynaptic membrane was characterized by intramembranous particles (IMPs), 3,500/micron 2 in density, consisting of larger particles, 10-12 nm in diameter, and smaller ones, 8-9 nm; the complementary exoplasmic (-fracture) face (EF) contained larger and smaller IMPs, 750/micron 2 in density, and numbers of pits. By close inspection of the sections and freeze-fracture replicas at high magnification and with deep-etching in particular, it was concluded that aggregated IMPs might represent transmembranous components and that the particulate entities existing in the postsynaptic active zones might be larger in number than those exposed to view and counted here in the "cholinergic" synapses. An individual IMP often appeared to consist of five or six subunits arranged in a rosette with a central pit. These findings suggest that the aggregated IMPs, particularly the larger ones, may be closely related to the structure of the nicotinic ACh receptor-ion channel complex.

Animals↗
PubMed1985

Monomolecular surface film and tubular myelin figures of the pulmonary surfactant in hamster lung.

Perfusion fixation via pulmonary trunk was applied to the alveolar lining layer in situ at different lung volumes using a fixative containing tannic acid-ferrocyanide osmium. The monomolecular surface film and hypophasic tubular myelin figures were enhanced. In the range of transpulmonary pressure (1-10 cmH2O), the surface film appeared in the form of a single, electron-dense leaflet, 2.7 +/- 0.6 nm (M +/- SD) in thickness while trilaminar membrane structure was retained in all parts of the tubular myelin figures of the hypophase. The surface film was attached underneath at right angles with trilaminar membranes which formed the outermost parts of the tubular myelin. Such structural continuity was taken to support a view that the phospholipid unit membrane of the tubular myelin figure would be transformed at the hydrophobic phase into a pair of monomolecular leaflets, eventually forming the surface film.

Animals↗
PubMed1982

Electron microscopic observation on phase transition of purple membrane.

Structural changes during the thermal phase transition of purple membrane were observed by freeze-fracture electron microscopy. Native Halobacterium halobium cells contain broad purple membrane areas about 1 micron in diameter. The boundary separating purple and red membranes is obvious. On warming at 80 degrees C, particles of red membrane spread out beyond the boundary. Then a purple membrane area is eventually divided into small areolae of similar size, about 0.1 micron in diameter. By cooling down slowly, the purple membrane area is reformed and the crystalline arrangement also restored.

Bacteriorhodopsins↗
PubMed1980

Double-replica topography of disk membrane structures in the carp (Cyprinus carpio).

By an improved freeze-fracture device, a number of double replicas were obtained from the rod disk membranes of the carp retina for investigation of complementary, continuing, and transitional relationships between fracture faces. Some separate particles found along the smooth edge bordering on the adjacent interdisk cytoplasm can be occasionally matched with gaps found between particles forming the complementary rough face edge. Consequently the particles on both faces can be derived from a single continuous layer, corresponding to the ad-cytoplasmic component of the disk membrane. This observation seems to agree with a prevailing disk-membrane model in which the visual pigment molecules are localized in the ad-cytoplasmic lipid lamella, but not to conform with a recent hypothesis, based upon single replicas, that the fracture plane might pass along either the inner or outer true surface of the membrane and the visual pigment molecules be attached to the latter.

Animals↗
PubMed1980

Complementary freeze fracture methods applied to cattle disk membranes.

The rod-outer-segment disk membranes were studied in cattle retinas by electron microscope observation of ultrathin resin sections and complementary freeze replicas. In sections, the membranes are characterized by discontinuous electron densities along the unit membrane structure, in which electron-less-dense globular substructures, forming an intermediate layer, are enhanced. Such substructures are estimated as 60 A in diameter. In freeze replicas, the membranous particles of 77 A in diameter are distributed quite densely in the P-face and scattered in the E-face. Like a number of preceding investigators who have failed to obtain convincing findings to correlate similar profiles with the visual pigment molecules, we should also raise a question about preparation involving chemical and thermal procedures affecting the dimensions of the final images. Our constant results obtained from the two methods, however, will suggest that the thin-section substructures and freeze-replica particles represent two different phases respectively of the same molecular existence rather than a complete profile of the visual pigment. It is also uncertain yet whether one membranous particle should be in fact associated to one molecular pigment or an aggregation of several molecules. The last problem will be resolved to some extent by topographical analyses of the complementary replicas in progress in our laboratory.

Animals↗