Diatoms were examined from a 13-m-long sediment core from the Misaka peatland, Gifu Prefecture, covering the late glacial through the Holocene (ca. 0-30 ka). Diatom records produce a history of ...paleoenvironmental changes as follows. During most of period between ca. 30 and ca. 12 ka of the late glacial, the lake was eutrophic and neutral or alkaline with an open water area. However, during two short periods (2.5-2.4, 1.6-1.5 ka) of the late glacial, the lake became oligotrophic and acid as bog pool or low moor, probably with enhanced hygrophytes. During the open water lake intervals water temperature was relatively lower. On the contrary, during the bog pool or low moor intervals, it was relatively higher. These environmental changes depend on air temperature fluctuations for the late glacial. Between ca. 12 and ca. 4 ka, the lake became oligotrophic and acid as bog pool or low moor with enhanced hygrophytes. Diatom assemblages during this interval indicate high water temperature, probably in response to Holocene warmth. The present study shows close correlation between paleoclimate change and a environmental history of the Misaka peatland.
Three pyroclastic flow deposits in the Takayama and Omine area, central Honshu, are correlated to the distal widespread volcanic ashes intercalated in the Plio-Pleistocene boundary strata in central ...Japan. The correlation is based on these stratigraphic relationships, facies, magnetostratigraphy, petrographic properties such as mineral assemblage, refractive index and chemical composition of the volcanic glasses and ortho-pyroxene. As the result of these correlation, the eruption age of the proximal pyroclastic flow deposits have become clear. And precise correlation between proximal eruption units and distal depositional units is now possible. Ho-Kd 39 Tephra erupted at about 1.76 Ma, forming a co-ignimbrite ash, which deposited in the Kanto sedimentary basin. Eb-Fukuda Tephra erupted at about 1.75 Ma, and distal volcaniclastic deposit sedimented in the Kinki, Niigata and Kanto sedimentary basins. The eruptional and depositional phase are divided into the stage 1, stage 2 (early), stage 2 (late) and stage 3. Stage 1 is phreato-plinian type eruption phase, forming distal ash fall deposit. Stage 2 (early) is plinian pumice fall, intra-plinian pyroclastic flow and plinian pumice fall eruption phase, forming distal ash fall. Stage 2 (late) is final eruptional phase of the biggest pyroclastic flow of the Eb-Fukuda Tephra, forming a co-ignimbrite ash fall. Stage 3 is resedimented stage after the end of the explosive eruption. It is notable that resedimented volcaniclastic deposit reached Osaka sedimentary basin 300 km away from the eruption center. Om-SK 110 Tephra erupted at about 1.65 Ma, divided into the stage 1, stage 2 and stage 3.Stage 1 is eruption phase of the plinian pumice fall and first pyroclastic flow. Stage 2 is pauses in eruption activity. Stage 3 is second pyroclastic flow phase, it is inferred that the pyroclastic flow of the stage 3 directly entered the Niigata sedimentary basin and simultaneously formed a co-ignimbrite ash.
Kd 38 pyroclastic key bed which is intercalated near the boundary of Pliocene-Pleistocene series is a widespread volcanic ash bed and important key bed for the stratigraphy of the Kazusa Group. ...Redefined Kd 38 pyroclastic key bed as the Kd 38 volcanic ash bed were reexamined for correlation in thirteen localities in the Boso Peninsula based on their lithofacies and petrographic properties. Thirteen localities are divided three areas, which are namely Sano-Kaisho, Yokoze-Oppara and Orikizawa-Koshikoma areas based on lithofacies of Kd 38 volcanic ash. Lithofacies and petrographic properties of Kd 38 volcanic ash are different at each area. However, Kd 38 volcanic ash bed in different localities can be correlated by correlation of the Kd 38.2 volcanic ash bed below the Kd 38 volcanic ash bed and relationship of lithofacies and petrographic properties. Their differences of lithofacies and petrographic properties of the Kd 38 volcanic ash bed at each localities reflects the difference in depositional processes of this volcanic ash after fallout.
The emergence of hepatitis C virus (HCV) with resistance-associated substitution (RAS), produced by mutations in the HCV genome, is a major problem in direct acting antivirals (DAA) treatment. This ...study aimed to clarify the mutational spectrum in HCV-RNA and the substitution pattern for the emergence of RASs in patients with chronic HCV infection. HCV-RNA from two HCV replicon cell lines and the serum HCV-RNA of four non-liver transplant and four post-liver transplant patients with unsuccessful DAA treatment were analyzed using high-accuracy single-molecule real-time long-read sequencing. Transition substitutions, especially A>G and U>C, occurred prominently under DAAs in both non-transplant and post-transplant patients, with a mutational bias identical to that occurring in HCV replicon cell lines during 10-year culturing. These mutational biases were reproduced in natural courses after DAA treatment. RASs emerged via both transition and transversion substitutions. NS3-D168 and NS5A-L31 RASs resulted from transversion mutations, while NS5A-Y93 RASs was caused by transition substitutions. The fidelity of the RNA-dependent RNA polymerase, HCV-NS5B, produces mutational bias in the HCV genome, characterized by dominant transition mutations, notably A>G and U>C substitutions. However, RASs are acquired by both transition and transversion substitutions, and the RASs-positive HCV clones are selected and proliferated under DAA treatment pressure.
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