658 research outputs found

    The YlmG protein has a conserved function related to the distribution of nucleoids in chloroplasts and cyanobacteria

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    <p>Abstract</p> <p>Background</p> <p>Reminiscent of their free-living cyanobacterial ancestor, chloroplasts proliferate by division coupled with the partition of nucleoids (DNA-protein complexes). Division of the chloroplast envelope membrane is performed by constriction of the ring structures at the division site. During division, nucleoids also change their shape and are distributed essentially equally to the daughter chloroplasts. Although several components of the envelope division machinery have been identified and characterized, little is known about the molecular components/mechanisms underlying the change of the nucleoid structure.</p> <p>Results</p> <p>In order to identify new factors that are involved in the chloroplast division, we isolated <it>Arabidopsis thaliana </it>chloroplast division mutants from a pool of random cDNA-overexpressed lines. We found that the overexpression of a previously uncharacterized gene (<it>AtYLMG1-1</it>) of cyanobacterial origin results in the formation of an irregular network of chloroplast nucleoids, along with a defect in chloroplast division. In contrast, knockdown of <it>AtYLMG1-1 </it>resulted in a concentration of the nucleoids into a few large structures, but did not affect chloroplast division. Immunofluorescence microscopy showed that AtYLMG1-1 localizes in small puncta on thylakoid membranes, to which a subset of nucleoids colocalize. In addition, in the cyanobacterium <it>Synechococcus elongates</it>, overexpression and deletion of <it>ylmG </it>also displayed defects in nucleoid structure and cell division.</p> <p>Conclusions</p> <p>These results suggest that the proper distribution of nucleoids requires the YlmG protein, and the mechanism is conserved between cyanobacteria and chloroplasts. Given that <it>ylmG </it>exists in a cell division gene cluster downstream of <it>ftsZ </it>in gram-positive bacteria and that <it>ylmG </it>overexpression impaired the chloroplast division, the nucleoid partitioning by YlmG might be related to chloroplast and cyanobacterial division processes.</p

    A Genome-Wide Association Analysis Identified a Novel Susceptible Locus for Pathological Myopia at 11q24.1

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    Myopia is one of the most common ocular disorders worldwide. Pathological myopia, also called high myopia, comprises 1% to 5% of the general population and is one of the leading causes of legal blindness in developed countries. To identify genetic determinants associated with pathological myopia in Japanese, we conducted a genome-wide association study, analyzing 411,777 SNPs with 830 cases and 1,911 general population controls in a two-stage design (297 cases and 934 controls in the first stage and 533 cases and 977 controls in the second stage). We selected 22 SNPs that showed P-values smaller than 10−4 in the first stage and tested them for association in the second stage. The meta-analysis combining the first and second stages identified an SNP, rs577948, at chromosome 11q24.1, which was associated with the disease (P = 2.22×10−7 and OR of 1.37 with 95% confidence interval: 1.21–1.54). Two genes, BLID and LOC399959, were identified within a 200-kb DNA encompassing rs577948. RT–PCR analysis demonstrated that both genes were expressed in human retinal tissue. Our results strongly suggest that the region at 11q24.1 is a novel susceptibility locus for pathological myopia in Japanese

    A Survey on Cooperation between Early Childhood Facilities and Elementary Schools regarding Children with Disabilities

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    This survey aimed to reveal the current conditions of cooperation between early childhood facilities and elementary schools regarding children with disabilities. A nationwide questionnaire was administered to 172 nursery schools (public), 242 nursery schools (private), 200 kindergartens (public), 481 kindergartens (private), and 592 elementary schools. Overall, for cooperation with elementary school for children with disabilities, the percentage of practice with kindergarten (public) was highest among early childhood facilities. In particular, for “Exchange activities between early childhood facilities and elementary schools” and “Introduction of approach curriculum,” the percentage of practice with kindergarten (public) was higher when compared with that in other early childhood facilities. The newly found information in this survey was that nursery schools (public) were most likely to take advantage of the “Individual education program.” The major problem was that nursery school and kindergarten teachers were willing to cooperate on early childhood education and care with elementary school teachers, but elementary school teachers answered that it was difficult to cooperate with many of the early childhood facilities. The ideal method for cooperation between early childhood facilities and elementary schools needs to be considered within each community.本研究は平成26年度文部科学省委託「幼児教育の改善・充実調査研究」(研究代表者:山崎 晃)及び平成25~27年度科学研究費・基盤研究(C)(研究課題番号:25381325,研究代表者:山崎 晃)の助成を受けて行われた研究成果の一部である

    ATR阻害は非相同末端結合および相同組換え修復と非依存的に5-FUを増感する

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    The anticancer agent 5-fluorouracil (5-FU) is cytotoxic and often used to treat various cancers. 5-FU is thought to inhibit the enzyme thymidylate synthase, which plays a role in nucleotide synthesis and has been found to induce single- and double-strand DNA breaks. ATR Ser/Thr kinase (ATR) is a principal kinase in the DNA damage response and is activated in response to UV- and chemotherapeutic drug-induced DNA replication stress, but its role in cellular responses to 5-FU is unclear. In this study, we examined the effect of ATR inhibition on 5-FU sensitivity of mammalian cells. Using immunoblotting, we found that 5-FU treatment dose-dependently induced the phosphorylation of ATR at the autophosphorylation site Thr-1989 and thereby activated its kinase. Administration of 5-FU with a specific ATR inhibitor remarkably decreased cell survival, compared with 5-FU treatment combined with other major DNA repair kinase inhibitors. Of note, the ATR inhibition enhanced induction of DNA double-strand breaks and apoptosis in 5-FU-treated cells. Using gene expression analysis, we found that 5-FU induced the activation of the intra-S cell-cycle checkpoint. Cells lacking BRCA2 were sensitive to 5-FU in the presence of ATR inhibitor. Moreover, ATR inhibition enhanced the efficacy of the 5-FU treatment, independently of the nonhomologous end-joining and homologous recombination repair pathways. These findings suggest that ATR could be a potential therapeutic target in 5-FU-based chemotherapy.博士(医学)・甲第791号・令和3年3月15日© 2020 Ito et al. Published under exclusive license by The American Society for Biochemistry and Molecular Biology, Inc.This is an Open Access article under the CC BY license(https://creativecommons.org/licenses/by/4.0/)

    27ヒドロキシコレステロールはエストロゲン受容体を介してヒトSLC22A12の発現を制御する

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    The excretion and reabsorption of uric acid both to and from urine are tightly regulated by uric acid transporters. Metabolic syndrome conditions, such as obesity, hypercholesterolemia, and insulin resistance, are believed to regulate the expression of uric acid transporters and decrease the excretion of uric acid. However, the mechanisms driving cholesterol impacts on uric acid transporters have been unknown. Here, we show that cholesterol metabolite 27-hydroxycholesterol (27HC) upregulates the uric acid reabsorption transporter URAT1 encoded by SLC22A12 via estrogen receptors (ER). Transcriptional motif analysis showed that the SLC22A12 gene promoter has more estrogen response elements (EREs) than other uric acid reabsorption transporters such as SLC22A11 and SLC22A13, and 27HC-activated SLC22A12 gene promoter via ER through EREs. Furthermore, 27HC increased SLC22A12 gene expression in human kidney organoids. Our results suggest that in hypercholesterolemic conditions, elevated levels of 27HC derived from cholesterol induce URAT1/SLC22A12 expression to increase uric acid reabsorption, and thereby, could increase serum uric acid levels.博士(医学)・甲第772号・令和3年3月15日© 2020 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License(https://creativecommons.org/licenses/by-nc/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes

    Improvement in Performance of Parallel Garbage Collector

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    スナップショット型(snapshot-at-beginning)と分類されるタイプの並列GCは, 無停止処理に向くが, ゴミの回収効率が悪い。筆者らは1982年以来このタイプの並列GCの効率の改善に取り組んできた。この成果が部分印づけ法と相補型GCという二つの方法である。本論文ではその研究の集大成として, スナップショット型の並列GCの問題点を解説し, この二つの方法について概説する。また, GC効率の測定法やCommon Lispを基にしたシステムへの応用例も報告する。A class of parallel garbage collectors called snapshot-at-beginning collectors have preferable properties such as predictable pause time and ease of implementation. However, these collectors had been known to be inefficient in terms of collection perform
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