The DNA polymerase activity of Pol ε holoenzyme is required for rapid and efficient chromosomal DNA replication in Xenopus egg extracts

BACKGROUND: DNA polymerase ε (Pol ε) is involved in DNA replication, repair, and cell-cycle checkpoint control in eukaryotic cells. Although the roles of replicative Pol α and Pol δ in chromosomal DNA replication are relatively well understood and well documented, the precise role of Pol ε in chromosomal DNA replication is not well understood. RESULTS: This study uses a Xenopus egg extract DNA replication system to further elucidate the replicative role(s) played by Pol ε. Previous studies show that the initiation timing and elongation of chromosomal DNA replication are markedly impaired in Pol ε-depleted Xenopus egg extracts, with reduced accumulation of replicative intermediates and products. This study shows that normal replication is restored by addition of Pol ε holoenzyme to Pol ε-depleted extracts, but not by addition of polymerase-deficient forms of Pol ε, including polymerase point or deletion mutants or incomplete enzyme complexes. Evidence is also provided that Pol ε holoenzyme interacts directly with GINS, Cdc45p and Cut5p, each of which plays an important role in initiation of chromosomal DNA replication in eukaryotic cells. CONCLUSION: These results indicate that the DNA polymerase activity of Pol ε holoenzyme plays an essential role in normal chromosomal DNA replication in Xenopus egg extracts. These are the first biochemical data to show the DNA polymerase activity of Pol ε holoenzyme is essential for chromosomal DNA replication in higher eukaryotes, unlike in yeasts

Crystal structure of pathogenic Staphylococcus aureus lipase complex with the anti-obesity drug orlistat

抗肥満薬が黄色ブドウ球菌の病原因子を阻害するメカニズムを解明. 京都大学プレスリリース. 2020-03-31.Staphylococcus aureus lipase (SAL), a triacylglycerol esterase, is an important virulence factor and may be a therapeutic target for infectious diseases. Herein, we determined the 3D structure of native SAL, the mutated S116A inactive form, and the inhibitor complex using the anti-obesity drug orlistat to aid in drug development. The determined crystal structures showed a typical α/β hydrolase motif with a dimeric form. Fatty acids bound near the active site in native SAL and inactive S116A mutant structures. We found that orlistat potently inhibits SAL activity, and it covalently bound to the catalytic Ser116 residue. This is the first report detailing orlistat–lipase binding. It provides structure-based information on the production of potent anti-SAL drugs and lipase inhibitors. These results also indicated that orlistat can be repositioned to treat bacterial diseases

漢字圏学習者の「の」の脱落における言語転移の様相 : 「の」「의」「的」の対応関係に着目して

横浜国立大学Yokohama National University本研究は「の」の脱落による誤用をターゲットとして言語転移の様相を探ろうとするものである。日本語学習者の名詞句における「の」の脱落は,複数の母語を対象とした作文及び発話データから,母語にかかわらず生じる誤用であることが明らかとなっているが,上のレベルになるにつれ漢字圏学習者により多く見られることが指摘されている。そこで本研究では韓国語と中国語を母語とする上級日本語学習者に対して文法性判断テストによる調査を実施し,日本語と同様に修飾部と被修飾部をつなぐ働きをする「의 (韓国語)」「的(中国語)」の有無が,日本語でも母語でも必要な「一致」か,日本語では必要であるが母語では不要な「不一致」か,母語ではあってもなくてもどちらでもよい「任意」かという観点から,「の」の脱落に対する正答率の差を検討した。その結果,中国語母語話者は,「一致」が「不一致」「任意」よりも有意に高く,母語との対応関係が一致しているほど正しく判断していることが明らかとなった。一方,韓国語母語話者は「任意」が「一致」「不一致」よりも有意に高く,母語との対応関係以外の要因が関与している可能性が示された。韓国語では「任意」であるケースが日本語と比較して非常に多く存在することから,韓国語で「任意」の場合には日本語では「の」が必要であるとする,学習者なりの認知的判断が関与している可能性が示された。従来の「正と負の転移」の枠組みでは説明しきれない言語転移のメカニズムの一端として報告する。This study investigated linguistic aspects of language transfer, focusing on the erroneous omission of the Japanese particle no (の). Grammaticality judgments of Japanese examples with no omitted were elicited from advanced-level Japanese learners whose L1 is Korean or Chinese. Three categories were used: (a) MATCHING - The no particle in L2 Japanese and the ui (의) particle in L1 Korean or de (的) particle in L1 Chinese are required. (b) NON-MATCHING - The no is required in L2, but the ui or de is not normally used in L1. (c) OPTIONAL - The L2 particle is required, but the L1 particle is optional. The results show that L1 Chinese learners had a significantly higher rate of correct responses to MATCHING items than to NON-MATCHING or OPTIONAL items, which suggests that learners judge more accurately when the correspondence between L1 and L2 is better. On the other hand, the L1 Korean learners did significantly better on OPTIONAL items than on MATCHING or NON-MATCHING items, which suggests that factors other than the correspondence between L1 and L2 may be involved

Synthesis, oxygen activation, and DNA-cleaving property of a histidine-pyridine-histidine ligand

A novel metal-chelating system comprising a 4-dimethylamino-　pyridine and two histidine appendages was synthesized. The two histidines were introduced by different manners; one through an amide linkage and other via a secondary amino linkage. ESR spectrum suggested a distorted pentacoordinate configuration of the copper complex of the ligand. The iron complex of the ligand had oxygen-activating property as shown by ESR spin trapping and DNA-cleaving activity as evaluated by experiments using pUC19 DNA

Low-frequency maternal novel MYH7 mosaicism mutation in recurrent fetal-onset severe left ventricular noncompaction: a case report

BackgroundLeft ventricular noncompaction (LVNC) is a rare inherited cardiomyopathy with a broad phenotypic spectrum. The genotype-phenotype correlations in fetal-onset LVNC have not yet been fully elucidated. In this report, we present the first case of severe fetal-onset LVNC caused by maternal low-frequency somatic mosaicism of the novel myosin heavy chain 7 (MYH7) mutation.Case presentationA 35-year-old pregnant Japanese woman, gravida 4, para 2, with no significant medical or family history of genetic disorders, presented to our hospital. In her previous pregnancy at 33 years of age, she delivered a male neonate at 30 weeks of gestation with cardiogenic hydrops fetalis. Fetal echocardiography confirmed LVNC prenatally. The neonate died shortly after birth. In the current pregnancy, she again delivered a male neonate with cardiogenic hydrops fetalis caused by LVNC at 32 weeks of gestation. The neonate died shortly after birth. Genetic screening of cardiac disorder-related genes by next-generation sequencing (NGS) was performed which revealed a novel heterozygous missense MYH7 variant, NM_000257.3: c.2729A > T, p.Lys910Ile. After targeted and deep sequencing by NGS, the same MYH7 variant (NM_000257.3: c.2729A > T, p.Lys910Ile) was detected in 6% of the variant allele fraction in the maternal sequence but not in the paternal sequence. The MYH7 variant was not detected by conventional direct sequencing (Sanger sequencing) in either parent.ConclusionsThis case demonstrates that maternal low-frequency somatic mosaicism of an MYH7 mutation can cause fetal-onset severe LVNC in the offspring. To differentiate hereditary MYH7 mutations from de novo MYH7 mutations, parental targeted and deep sequencing by NGS should be considered in addition to Sanger sequencing

Lipophilic Compound-Mediated Gene Expression and Implication for Intervention in Reactive Oxygen Species (ROS)-Related Diseases: Mini-review

In addition to exhibiting antioxidant properties, conjugated linoleic acid (CLA) and vitamin E may modulate gene expression of endogenous antioxidant enzymes. Depending on cellular microenvironments, such modulation reflects either antioxidant or prooxidant outcomes. Although epidemiological/experimental studies have indicated that CLA and vitamin E have health promoting properties, recent findings from clinical trials have been inconclusive. Discrepancies between the results found from prospective studies and recent clinical trials might be attributed to concentration-dependent cellular microenvironment alterations. We give a perspective of possible molecular mechanisms of actions of these lipophilic compounds and their implications for interventions of reactive oxygen species (ROS)-related diseases

The Kinase Inhibitor SFV785 Dislocates Dengue Virus Envelope Protein from the Replication Complex and Blocks Virus Assembly

Dengue virus (DENV) is the etiologic agent for dengue fever, for which there is no approved vaccine or specific anti-viral drug. As a remedy for this, we explored the use of compounds that interfere with the action of required host factors and describe here the characterization of a kinase inhibitor (SFV785), which has selective effects on NTRK1 and MAPKAPK5 kinase activity, and anti-viral activity on Hepatitis C, DENV and yellow fever viruses. SFV785 inhibited DENV propagation without inhibiting DENV RNA synthesis or translation. The compound did not cause any changes in the cellular distribution of non-structural 3, a protein critical for DENV RNA synthesis, but altered the distribution of the structural envelope protein from a reticulate network to enlarged discrete vesicles, which altered the co-localization with the DENV replication complex. Ultrastructural electron microscopy analyses of DENV-infected SFV785-treated cells showed the presence of viral particles that were distinctly different from viable enveloped virions within enlarged ER cisternae. These viral particles were devoid of the dense nucleocapsid. The secretion of the viral particles was not inhibited by SFV785, however a reduction in the amount of secreted infectious virions, DENV RNA and capsid were observed. Collectively, these observations suggest that SFV785 inhibited the recruitment and assembly of the nucleocapsid in specific ER compartments during the DENV assembly process and hence the production of infectious DENV. SFV785 and derivative compounds could be useful biochemical probes to explore the DENV lifecycle and could also represent a new class of anti-virals

第二言語としての日本語習得過程における言語転移の研究 : 「の」の過剰使用を中心として

広島大学(Hiroshima University)博士(教育学)Pedagogydoctora

A Study of Overuse of "NO" in the Acquisition of Japanese as a Second Language : A Longitudinal Study Based on Oral Interviews

It is a relatively known fact that children acquiring Japanese as a first language (L1)tend to overuse "NO" as in "*ookii no kuruma" instead of the correct form, "ookii kuruma(=a big car)". This overgeneralization is also reported to have been observed in the utterances of adult learners of Japanese as a second language (L2).There are two different opinions about this phenomenon. First, this is one of the developmental errors so that learners make mistakes in spite of their native languages. Second, it could be the possibility of language transfer from the Chinese language. This paper discusses these two different opinions by conducting an investigation includ-ing 22 adult learners of Japanese learning in Japan. They were interviewed individually twice, at the beginning and at the end of the course. Each interview took about thirty minutes. These are the findings; (1) Some learners take "unit formation strategy", one of the language processing strate- gies, in the overuse "NO". (2) For Chinese learners, more errors are found by the end of the semester of the ad- vanced level compared to the beginning of the intermediate level. (3) Chinese learners overuse" NO" as the modifier for all I-adj., Na-adj. and verbs. The study concludes that (1)shows some of the errors could not be caused by language transfer and it supports the first hypothesis. On the other hand, (2)and(3)show the evidence that might be caused by transfer from their native language, Chinese, which supports the second hypothesis