Identification of an amino acid residue on influenza C virus M1 protein responsible for formation of the cord-like structures of the virus.

Influenza C virus-like particles (VLPs) have been generated from cloned cDNAs. A cDNA of the green fluorescent protein (GFP) gene in antisense orientation was flanked by the 5' and 3' non-coding regions of RNA segment 5 of the influenza C virus. The cDNA cassette was inserted between an RNA polymerase I promoter and terminator of the Pol I vector.

Tegumentary papillae of Echinostoma caproni cercariae (Trematoda: Echinostomatidae).

Argentophilic staining and scanning electron microscopy were used to study the tegumentary papillae of Echinostoma caproni cercariae. The most abundant tegumentary papillae were uniciliate, but multiciliate papillae were also found, mainly on the ventral aspect of the oral collar. The distribution pattern of the papillae on the body and tail was in general similar to that seen in the cercariae of other 37-collar-spined Echinostoma species.

Comparative ultrastructure of eggs in Echinostoma paraensei, E. caproni, and E. trivolvis (Trematoda: Echinostomatidae).

The 37-collar-spined echinostomes Echinostoma paraensei, E. caproni, and E. trivolvis are digeneans that live in the intestine of small mammals and birds.

Comparative ultrastructure study of lamellar gastrodermal projections in Echinostoma paraensei, E. caproni, and E. trivolvis (Trematoda : Echinostomatidae).

A comparative ultrastructure study using transmission electron microscopy (TEM) of ultrathin sections, freeze-fracture replication, and scanning electron microscopy (SEM) was conducted on the gastrodermal lamellar microvilli in adults of Echinostoma paraensei, E. caproni, and E. trivolvis.

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.

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.

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.

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.

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.

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.

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.

"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.

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.

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.

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.

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.