Major contribution of sulfide‐derived sulfur to the benthic food web in a large freshwater lake

In freshwater systems, contributions of chemosynthetic products by sulfur-oxidizing bacteria in sediments as nutritional resources in benthic food webs remain unclear, even though chemosynthetic products might be an important nutritional resource for benthic food webs in deep-sea hydrothermal vents and shallow marine systems. To study geochemical aspects of this trophic pathway, we sampled sediment cores and benthic animals at two sites (90 and 50 m water depths) in the largest freshwater (mesotrophic) lake in Japan: Lake Biwa. Stable carbon, nitrogen, and sulfur isotopes of the sediments and animals were measured to elucidate the sulfur nutritional resources for the benthic food web precisely by calculating the contributions of the incorporation of sulfide-derived sulfur to the biomass and of the biogeochemical sulfur cycle supporting the sulfur nutritional resource. The recovered sediment cores showed increases in ³⁴S-depleted sulfide at 5 cm sediment depth and showed low sulfide concentration with high δ³⁴S in deeper layers, suggesting an association of microbial activities with sulfate reduction and sulfide oxidation in the sediments. The sulfur-oxidizing bacteria may contribute to benthic animal biomass. Calculations based on the biomass, sulfur content, and contribution to sulfide-derived sulfur of each animal comprising the benthic food web revealed that 58%–67% of the total biomass sulfur in the benthic food web of Lake Biwa is occupied by sulfide-derived sulfur. Such a large contribution implies that the chemosynthetic products of sulfur-oxidizing bacteria are important nutritional resources supporting benthic food webs in the lake ecosystems, at least in terms of sulfur. The results present a new trophic pathway for sulfur that has been overlooked in lake ecosystems with low-sulfate concentrations

Spontaneous Production of Interleukin-5 and Its Heterogeneous Effect on Eosinophils in an Adult T-Cell Leukemia Patient

ABSTRACTWe examined the functional heterogeneity of eosinophils from an adult T-cell leukemia (ATL) patient with eosinophilia. A 63-year-old man was admitted to our hospital because of lymphadenopathy. The leukocyte count was 10 400 /mm3, with 36.0% eosinophils and 3.0% abnormal lymphocytes. The diagnosis of ATL was based on the presence in serum of anti- human T-cell lymphotrophic virus-1 antibody and on histologic demonstration of ATL cells. The mononuclear cells spontaneously produced eosinophil-related cytokines (granulocyte-macrophage colony stimulating factor, 5600pg/mL; interleukin (IL)-5, 375pg/mL). Peripheral eosinophils were fractionated into normodense eosinophils (NE) and hypodense eosinophils (HE) by a Percoll density gradient method, and these cells were compared in terms of several heterogeneous functions. The NE were more chemotactically attracted to IL-5 than the HE. More apoptotic cells appeared among the NE than among the HE and this difference was correlated with the positive rate of Fas antigen on eosinophils. Survival of the HE was longer than that of the NE. Survival of the HE was prolonged by IL-5 stimulation, but survival of the NE was not. These data suggest that functionally heterogeneous eosinophils were present in this ATL patient with eosinophilia and that IL-5 enhanced this heterogeneity. The response of eosinophils to IL-5 may have contributed to the patho- genesis of eosinophilia in this patient

miRNAs regulate SIRT1 expression during mouse embryonic stem cell differentiation and in adult mouse tissues

SIRT1 is increasingly recognized as a critical regulator of stress responses, replicative senescence, inflammation, metabolism, and aging. SIRT1 expression is regulated transcriptionally and post-transcriptionally, and its enzymatic activity is controlled by NAD+ levels and interacting proteins. We found that SIRT1 protein levels were much higher in mouse embryonic stem cells (mESCs) than in differentiated tissues. miRNAs post-transcriptionally downregulated SIRT1 during mESC differentiation and maintained low levels of SIRT1 expression in differentiated tissues. Specifically, miR-181a and b, miR-9, miR-204, miR-199b, and miR-135a suppressed SIRT1 protein expression. Inhibition of mir-9, the SIRT1-targeting miRNA induced earliest during mESC differentiation, prevented SIRT1 downregulation. Conversely, SIRT1 protein levels were upregulated post-transcriptionally during the reprogramming of mouse embryonic fibroblasts (MEFs) into induced pluripotent stem (iPS) cells. The regulation of SIRT1 protein levels by miRNAs might provide new opportunities for therapeutic tissue-specific modulation of SIRT1 expression and for reprogramming of somatic cells into iPS cells

Side-on measurement of hydrodynamics of laser-driven plasmas with high space- and time-resolution x-ray imaging technique

Copyright 2003 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Review of Scientific Instruments, 74(3), 2198-2201, 2003 and may be found at http://dx.doi.org/10.1063/1.153785

Improvement Map Analyzer of Kit-Build Concept Map for In-class Analysis by Teacher

教授者が学習者に伝えようとした内容に対する学習者の理解状況を把握するための枠組みとして，統一された構成部品を用いて概念マップを作成させるキットビルド概念マップが提案されており，授業実践を通してその有用性が確認されている．本研究ではキットビルド概念マップを用いた授業内での形成的評価を可能にするための概念マップの分析ツール（マップアナライザ）を，教授者が単独で利用できるように改良した．従来も学習者の作成した概念マップを集計・分析するマップアナライザが実装されていたが，教授者による授業内での分析を前提として設計されたものではなかったため，授業での利用のためにはこのマップアナライザを分析専従者が操作する必要があり，教授者単独では用いることができていなかった．本研究では，教授者による授業内での分析目的が(1) 集団分析，と(2) 個人分析，の二つに大別でき，それらが一連の手順で行われることに着目し，この二つの分析目的を想定して機能を集約した二つのモードの実装として従来のマップアナライザの改良を行った．改良されたマップアナライザの評価として，同マップアナライザの実践利用実績，実践利用者に対するアンケート調査，及び改良前のマップアナライザとのユーザビリティの実験的比較についても報告する．なお，現在，キットビルド概念マップを用いた授業実践は全て改良後のマップアナライザを用いて行われている

Direct observation of reversible oxygen anion redox reaction in Li-rich manganese oxide, Li2MnO3, studied by soft X-ray absorption spectroscopy

Li-rich layered oxides have attracted attention as promising positive electrode materials for next-generation lithium-ion secondary batteries because of their high energy storage capacity. The participation of the oxygen anion has been hypothesized to contribute to these oxides' high capacity. In the present study, we used O K-edge and Mn L-edge X-ray absorption spectroscopy (XAS) to study the reversible redox reactions that occur in single-phase Li-rich layered manganese oxide, Li2MnO3. We semiquantitatively analyzed the oxygen and manganese reactions by dividing the charge/discharge voltage region into two parts. The O K-edge XAS indicated that the electrons at the oxygen site reversibly contributed to the charge compensation throughout the charge/discharge processes at operating voltages between 2.0 and 4.8 V vs. Li+/Li0. The Mn L-edge XAS spectra indicated that the Mn redox reaction occurred only in the lower-voltage region. Thus, at higher potentials, the electrons, mainly at the oxygen site, contributed to the charge compensation. Peaks whose energies were similar to peroxide appeared in and then disappeared from the O K-edge spectra obtained during the reversible redox cycles. These results indicate that the reorganization of the oxygen network in the crystal structure affects the redox components. By using two kinds of detection modes with different probing depths in XAS measurements, it was found that these redox reactions are bulk phenomena in the electrode

Spectra of V1405 Cas at the very beginning indicate a low-mass ONeMg white dwarf progenitor

The lowest possible mass of ONeMg white dwarfs (WDs) has not been clarified despite its importance in the formation and evolution of WDs. We tackle this issue by studying the properties of V1405 Cas (Nova Cassiopeiae 2021), which is an outlier given a combination of its very slow light-curve evolution and the recently reported neon-nova identification. We report its rapid spectral evolution in the initial phase, covering 9.88, 23.77, 33.94, 53.53, 71.79, and 81.90 hours after the discovery. The first spectrum is characterized by lines from highly-ionized species, most noticeably He II and N III. These lines are quickly replaced by lower-ionization lines, e.g., N II, Si II, and O I. In addition, Al II (6237 \r{A}) starts emerging as an emission line at the second epoch. We perform emission-line strength diagnostics, showing that the density and temperature quickly decrease toward later epochs. This behavior, together with the decreasing velocity seen in H$\alpha$, H$\beta$, and He I, indicates that the initial nova dynamics is reasonably well described by an expanding fireball on top of an expanding photosphere. Interestingly, the strengths of the N III and Al II indicate large abundance enhancement, pointing to an ONeMg WD progenitor as is consistent with its neon-nova classification. Given its low-mass nature inferred by the slow light-curve evolution and relatively narrow emission lines, it provides a challenge to the stellar evolution theory that predicts the lower limit of the ONeMg WD mass being $\sim$ 1.1 $M_\odot$.Comment: 15 pages, 5 figures, 2 tables, accepted to Ap

A Map-Based Cloning Strategy Employing a Residual Heterozygous Line Reveals that the GIGANTEA Gene Is Involved in Soybean Maturity and Flowering

Flowering is indicative of the transition from vegetative to reproductive phase, a critical event in the life cycle of plants. In soybean (Glycine max), a flowering quantitative trait locus, FT2, corresponding to the maturity locus E2, was detected in recombinant inbred lines (RILs) derived from the varieties “Misuzudaizu” (ft2/ft2; JP28856) and “Moshidou Gong 503” (FT2/FT2; JP27603). A map-based cloning strategy using the progeny of a residual heterozygous line (RHL) from the RIL was employed to isolate the gene responsible for this quantitative trait locus. A GIGANTEA ortholog, GmGIa (Glyma10g36600), was identified as a candidate gene. A common premature stop codon at the 10th exon was present in the Misuzudaizu allele and in other near isogenic lines (NILs) originating from Harosoy (e2/e2; PI548573). Furthermore, a mutant line harboring another premature stop codon showed an earlier flowering phenotype than the original variety, Bay (E2/E2; PI553043). The e2/e2 genotype exhibited elevated expression of GmFT2a, one of the florigen genes that leads to early flowering. The effects of the E2 allele on flowering time were similar among NILs and constant under high (43°N) and middle (36°N) latitudinal regions in Japan. These results indicate that GmGIa is the gene responsible for the E2 locus and that a null mutation in GmGIa may contribute to the geographic adaptation of soybean