High-Resolution Petrographic Evidence Confirming Detrital and Biogenic Magnetites as Remanence Carriers for Zongpu Carbonates in the Gamba Area, South Tibet

Paleocene carbonates from the Gamba area of South Tibet provide the largest paleomagnetic dataset for constraining the paleogeography of the India-Asia collision in the early stage. Previous studies argued that the characteristic remanences (ChRMs) obtained from this unit were remagnetized via orogenic fluids. This study carries out a high-resolution petrographic study on the Paleocene carbonates from Gamba aiming to test the nature of the ChRMs. Electron microscopic observation on magnetic extracts identified a large amount of detrital magnetite that are multi- to single domain in sizes and nanoscale biogenic magnetite. Minor framboidal iron oxides were also identified, which were previously interpreted as authigenic magnetite that substitutes pyrite. However, our scanning and transmission electron microscopic (SEM/TEM) observations, along with optical microscope and Raman spectrum investigations further suggest that these magnetic minerals are pigmentary hematite and goethite that are incapable of carrying a stable primary magnetization. We therefore argue that the ChRMs of the limestones from the Zongpu Formation in the Gamba area are carried by detrital and biogenic magnetites rather than authigenic magnetite. The paleomagnetic data from the Gamba area are interpreted as primary origin and can thus be used for tectonic reconstructions. We emphasize that magnetic extraction, integrated with advanced mineralogic studies (e.g., electron backscatter diffraction and electron diffraction) are effective approaches for investigating the origin of magnetic carriers in carbonate rocks.

Relationship between IgA Nephropathy and Porphyromonas gingivalis; Red Complex of Periodontopathic Bacterial Species

IgA nephropathy (IgAN) has been considered to have a relationship with infection in the tonsil, because IgAN patients often manifest macro hematuria just after tonsillitis. In terms of oral-area infection, the red complex of periodontal bacteria (Porphyromonas gingivalis (P. gingivalis), Treponema denticol (T. denticola) and Tannerella forsythia (T. forsythia)) is important, but the relationship between these bacteria and IgAN remains unknown. In this study, the prevalence of the red complex of periodontal bacteria in tonsil was compared between IgAN and tonsillitis patients. The pathogenicity of IgAN induced by P. gingivalis was confirmed by the mice model treated with this bacterium. The prevalence of P. gingivalis and T. forsythia in IgAN patients was significantly higher than that in tonsillitis patients (p < 0.001 and p < 0.05, respectively). A total of 92% of tonsillitis patients were free from red complex bacteria, while only 48% of IgAN patients had any of these bacteria. Nasal administration of P. gingivalis in mice caused mesangial proliferation (p < 0.05 at days 28a nd 42; p < 0.01 at days 14 and 56) and IgA deposition (p < 0.001 at day 42 and 56 after administration). Scanning-electron-microscopic observation revealed that a high-density Electron-Dense Deposit was widely distributed in the mesangial region in the mice kidneys treated with P. gingivalis. These findings suggest that P. gingivalis is involved in the pathogenesis of IgAN.

Ultrastructural analysis in yeast reveals a meiosis-specific actin-containing nuclear bundle

Actin polymerises to form filaments/cables for motility, transport, and the structural framework in a cell. Recent studies show that actin polymers are present not only in the cytoplasm but also in the nuclei of vertebrate cells. Here, we show, by electron microscopic observation with rapid freezing and high-pressure freezing, a unique bundled structure containing actin in the nuclei of budding yeast cells undergoing meiosis. The nuclear bundle during meiosis consists of multiple filaments with a rectangular lattice arrangement, often showing a feather-like appearance. The bundle was immunolabelled with an anti-actin antibody and was sensitive to an actin-depolymerising drug. Similar to cytoplasmic bundles, nuclear bundles are rarely seen in premeiotic cells and spores and are induced during meiotic prophase-I. The formation of the nuclear bundle is independent of DNA double-stranded breaks. We speculate that nuclear bundles containing actin play a role in nuclear events during meiotic prophase I.

Metal atom–guided conformational analysis of single polynuclear coordination molecules

Microscopic observation of single molecules is a rapidly expanding field in chemistry and differs from conventional characterization techniques that require a large number of molecules. One of such form of single-molecule microscopy is high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), which is especially suitable for coordination compounds because of its atomic number–dependent contrast. However, to date, single-molecule observations using HAADF-STEM has limited to simple planar molecules. In the present study, we demonstrate a direct structural investigation of nonplanar dendronized polynuclear Ir complexes with subnanometer resolution using Ir as an atomic label. Decreasing the electron dose to the dendrimer complexes is critical for the single-molecule observation. A comparison with simulated STEM images of conformational isomers is performed to determine the most plausible conformation. Our results enlarge the potential of electron microscopic observation to realize structural analysis of coordination macromolecules, which has been impossible with conventional methods.

First Isolation, Molecular Characterization, and Serological Survey of Bovine Adenovirus Type 2 in Japan

Bovine adenovirus type 2 (BAdV-2), a member of the Mastadenovirus genus of the Adenoviridae family, is involved in mild respiratory disease and is rarely isolated from cattle in the world. Here, we isolated BAdV-2 for the first time in Japan, from the feces of cattle with severe respiratory symptoms. The isolate, designated strain KY19-1, was identified morphologically and genetically. Electron microscopic observation of infected cells showed intranuclear, non-enveloped virus particles, approximately 70 nm in diameter and with typical adenoviral morphology. Whole-genome sequencing revealed that the viral genome is 33,175 bp long, with 105 bp inverted terminal repeats and encoding 32 predicted genes. KY19-1 has a similar genomic organization to the prototype BAdV-2 strain No. 19 with overall 99.1% nucleotide identity. Notable differences were found in the E3 region of the genome, which may affect various biological properties, including pathogenicity. The seroepidemiology of BAdV-2 was also investigated, using a virus-neutralization test, and 92.8 % of the Japanese cattle (n=1,325) were seropositive, with the positivity rate increased by age. Further experimental infections with KY19-1 may elucidate the pathogenic properties of BAdV-2 and the importance of this virus as a causal agent of bovine respiratory disease.

The performance of titanium composite coatings obtained through thermal spraying and microarc oxidation

The development of composite coatings essential to improve the wear and corrosion resistances of the materials employed in numerous applications, such as automobile, chemical, medicine, construction, aerospace, and biomedical industries. In this study, we presented a double-layer coating technique, which consisted of a thermal-sprayed titanium (Ti) layer and a micro-arc oxidation (MAO) film on AISI 1020 steel. The effect of the composite coatings (Ti/MAO) on wear and corrosion resistance was investigated. To obtain a coating thickness from 250 µm to 450 µm, the prepared specimens were coated with Ti (99.9% pure) by arc spraying. Then, the Ti/MAO films were deposited on Ti coatings. The current density of MAO was fixed at 35 A/dm2, the voltages were 250, 300, 350, 400, and 450 V, and the duration of the MAO process was 10 min, Measurements of film thickness, microstructure, microhardness, X-ray diffractometry analysis, and scanning electron microscopic observation were performed for determining the characteristics of the composite coatings (Ti/MAO). Potentiodynamic polarization curves were used to compare the corrosion resistance of these composite coatings. A ball-on-disc wear test, using an oscillation friction wear tester, was carried out at room temperature according to the ASTM G99 standard to determine the wear resistance. Among all the specimens, Ti/MAO (400 V) had the greatest hardness, lowest friction coefficient, least weight loss, and longest sliding distance. The sliding distance of Ti/MAO (400 V) was about 1.7 times higher than those of Ti. The open-circuit potential of Ti/MAO (400 V) was about 1.7 times better than those of Ti. The corrosion currents of Ti/MAO (250 V) and Ti/MAO (400 V) were decreased by MAO about 95% and 92%, respectively. Although the corrosion current of Ti/MAO (400 V) was higher than that of Ti/MAO (250 V), Ti/MAO (400 V) had better effects in other tests. According to the results, Ti/MAO (400 V) presented the best performance among all the specimens and provided improved protection to both Ti and substrate.

Three new deep-sea species of Thyasiridae (Mollusca: Bivalvia) from the abyssal plain of the northwestern Pacific Ocean and hadal depths of the Kuril-Kamchatka Trench

The Thyasiridae is the most species-rich family of bivalves in the abyssal and hadal zones of the northwestern Pacific Ocean. In recent years, with at least 14 thyasirid species found in that region at depths exceeding 3,000 m. Some of them are the numerically dominant species in bottom communities. However, all members in that family have not yet been identified to the species level. Based on the material collected from 1953 to 2016 by five deep-sea expeditions, three new species of Thyasiridae (Mollusca: Bivalvia) are described from the abyssal and hadal zones of the northwestern Pacific. “Axinulus” roseus sp. nov. was found in the Kuril-Kamchatka Trench at 9,000–9,583 m depth. This species has a large rhomboidal shell with strong commarginal sculpture, a well defined, long and deep lunule and escutcheon without an auricle, a ctenidium consisting of a single demibranch, extensively lobed lateral pouches, and a large prodissoconch with specific sculpture. It is one of the dominant species in terms of abundance in macrobenthic communities in the deepest basin of the Kuril-Kamchatka Trench with a population density of up to 396 ind. m−2. The species has a shell length of up to 9.0 mm and it is the largest thyasirid with a single demibranch. “Axinulus” oliveri sp. nov. was found in a vast region of the northwestern Pacific on the abyssal plain adjacent to the Kuril-Kamchatka Trench, on the abyssal slope of the Kuril Islands, and in the Kuril-Kamchatka Trench at 4,648–6,168 m depth. This species is characterized by its ovate-rhomboidal shell, a well defined, deep and long escutcheon with a distinct auricle, a ctenidium with a single demibranch, and extensively lobed lateral pouches. It is widespread in the northwestern Pacific and forms populations with a density of up to 36 ind. m−2. Scanning electron microscopic observation of the gills of “A.” roseus sp. nov. and “A.” oliveri sp. nov. revealed that these species are not chemosymbiotic. “Axinulus” roseus sp. nov. and “A.” oliveri sp. nov. are provisionally assigned to the genus Axinulus, because they differ from the type species of the genus in a number of morphological and anatomical features. Parathyasira fragilis sp. nov. was found on the abyssal plain adjacent to the Kuril-Kamchatka Trench at 5,249–5,399 m depth. This species is distinguished by its very thin, fragile, dorsoventrally elongated, rhomboidal shell with very long anterodorsal margin and a long, wide, flat lunule. The taxonomic position of the new species is discussed.