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OBJECTIVE: This study aimed to investigate the performance of generative pre-trained transformer-4 (GPT-4) on the Certification Test for Mental Health Management and whether tuned prompts could improve its performance. METHODS: This study used a 3 × 2 factorial design to examine the performance according to test difficulty (courses) and prompt conditions. We prepared 200 multiple-choice questions (600 questions overall) for each course using the Certification Test for Mental Health Management (levels I-III) and essay questions from the level I test for the previous four examinations. Two conditions were used: a simple prompt condition using the questions as prompts and tuned prompt condition using techniques to obtain better answers. GPT-4 (gpt-4-0613) was adopted and implemented using the OpenAI API. RESULTS: The simple prompt condition scores were 74.5, 71.5, and 64.0 for levels III, II, and I, respectively. The tuned and simple prompt condition scores had no significant differences (OR = 1.03, 95% CI; 0.65-1.62, p = 0.908). Incorrect answers were observed in the simple prompt condition because of the inability to make choices, whereas no incorrect answers were observed in the tuned prompt condition. The average score for the essay questions under the simple prompt condition was 22.5 out of 50 points (45.0%). CONCLUSION: GPT-4 had a sufficient knowledge network for occupational mental health, surpassing the criteria for levels II and III tests. For the level I test, which required the ability to describe more advanced knowledge accurately, GPT-4 did not meet the criteria. External information may be needed when using GPT-4 at this level. Although the tuned prompts did not significantly improve the performance, they were promising in avoiding unintended outputs and organizing output formats. UMIN trial registration: UMIN-CTR ID = UMIN000053582.
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OBJECTIVES: Low back pain (LBP) among caregivers in Japanese nursing homes has long been considered an occupational health issue. This study aimed to verify the reliability and validity of our developed Japanese version of the Movement and Assistance for Hospitalized Patients (J-MAPO) index, a risk assessment tool for LBP, in nursing homes. METHODS: Two inspectors assessed 15 nursing homes using J-MAPO, and deduced 3 LBP risk levels as follows: low, moderate, and high risk. Caregivers in nursing homes responded to a self-administered questionnaire on LBP over the past 12 months. Data from 296 caregivers with no missing data were used. We further used logistic regression models to analyze the association between LBP as a dependent variable, and J-MAPO risk level as an independent variable. We used Cohen kappa coefficient to assess interrater reliability to further assess the agreement between the 2 inspectors. RESULTS: The multivariate logistic regression analysis showed that the adjusted odds ratio and 95% CIs for LBP increased progressively with J-MAPO risk level (Low-risk: 1.00; Moderate-risk: 1.70 [0.74-3.91]; High-risk: 2.67 [1.28-5.56]). Furthermore, the J-MAPO risk levels assessed by the 2 inspectors were in perfect agreement (κ = 1) observed for interrater reliability using Cohen kappa coefficient. CONCLUSIONS: There was high interrater reliability, and J-MAPO risk levels were associated with LBP. Therefore, our results suggest that the J-MAPO is a useful risk assessment tool for LBP in Japanese nursing homes.
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Dor Lombar , Movimentação e Reposicionamento de Pacientes , Casas de Saúde , Humanos , Masculino , Japão , Feminino , Reprodutibilidade dos Testes , Pessoa de Meia-Idade , Inquéritos e Questionários/normas , Medição de Risco/métodos , Idoso , Adulto , Doenças Profissionais , Modelos Logísticos , Cuidadores , População do Leste AsiáticoRESUMO
BACKGROUND: Maintaining immovable postures for long durations might be a cause of low back pain. However, the relation between low back pain and the maintenance of postures for long durations has been unclear. Therefore, the durations of several postures in one working day should be measured to evaluate the risk of low back pain, although the available measuring methods are limited. To the best of our knowledge, no study has reported the development and investigation of a foot plantar pressure sensor for measurement of standing, sitting, and moving durations in daily work routines. Thus, in this study, we aimed to develop a foot plantar pressure sensor that could withstand long-term loads in the workplace. Furthermore, we aimed to evaluate the estimated results of standing, sitting, and moving durations among factory workers using the developed foot plantar pressure sensor. METHODS: The developed foot plantar pressure sensor obtained a percentage difference within ±5% to estimate standing, sitting, and moving durations in the laboratory. We measured foot plantar pressures of 20 factory workers to estimate standing, sitting, and moving activity in one working day using data obtained by the foot plantar pressure sensor. The estimated standing, sitting, and moving durations were compared with the human estimation of photo data obtained by a wearable camera. RESULTS: The agreement rate (Cohen's kappa coefficient) was 0.75 between the evaluation using the foot plantar pressure sensor data and human estimation using a wearable camera. Cohen's kappa coefficient was 0.81 in subjects who sat for ≥30% during daily work and 0.68 in subjects who sat for <30%. CONCLUSION: Our foot plantar pressure sensor effectively measured the standing, sitting, and moving durations in daily work that requires various movements and assumption of postures.
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Dor Lombar , Postura Sentada , Humanos , Pé , Postura , Posição OrtostáticaRESUMO
In the original publication of the article, the title was incorrectly published.
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OBJECTIVES: The Blalock-Taussig shunt (BTS) operation is a cornerstone as initial palliative surgery for congenital heart disease with severely reduced pulmonary blood flow (PBF). The ideal PBF provided by BTS is crucial for an uneventful postoperative course, since excess PBF results in acute distress of the systemic circulation and insufficient PBF requires another BTS surgery. Therefore, the goal of this study was to develop a simple device to control the shunt graft flow percutaneously using a constrictor balloon connected to a subcutaneous port. METHODS: The device consists of a cylindrical balloon and an anti-bending structure extension connected to the balloon center. A PTFE vascular graft wrapped by the device was connected to a simulated closed circuit to measure the relationship between pressure and blood flow while changing the inner volume of the balloon. In a beagle model of replacement of the right carotid artery, blood flow velocity was measured in the carotid artery after saline injection into the balloon. The blood flow velocity before and after balloon inflation was compared immediately after implantation of the device and at 3 months after implantation. RESULTS: The device provided good flow control by inflating and deflating the balloon ex vivo and in vivo for up to 3 months in a canine model with a small graft wrapped with the device. CONCLUSIONS: The simple device developed in this study may enable regulation of PBF through a small vascular graft and help to prevent severe morbidity and mortality in the clinical setting of BTS.
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Procedimento de Blalock-Taussig , Implante de Prótese Vascular , Procedimentos Cirúrgicos Cardíacos , Cardiopatias Congênitas/cirurgia , Artéria Pulmonar/cirurgia , Circulação Pulmonar/fisiologia , Animais , Artéria Carótida Primitiva/cirurgia , Cães , Cardiopatias Congênitas/fisiopatologia , Hemodinâmica , Masculino , Modelos Animais , Cuidados Paliativos , Procedimentos Cirúrgicos VascularesRESUMO
In organisms with circular chromosomes, such as bacteria and archaea, an odd number of homologous recombination events can generate a chromosome dimer. Such chromosome dimers cannot be segregated unless they are converted to monomers before cell division. In Escherichia coli, dimer-to-monomer conversion is mediated by the paralogous XerC and XerD recombinases at a specific dif site in the replication termination region. Dimer resolution requires the highly conserved cell division protein/chromosome translocase FtsK, and this site-specific chromosome resolution system is present or predicted in most bacteria. However, most archaea have only XerA, a homologue of the bacterial XerC/D proteins, but no homologues of FtsK. In addition, the molecular mechanism of XerA-mediated chromosome resolution in archaea has been less thoroughly elucidated than those of the corresponding bacterial systems. In this study, we identified two XerA-binding sites (dif1 and dif2) in the Thermoplasma acidophilum chromosome. In vitro site-specific recombination assays showed that dif2, but not dif1, serves as a target site for XerA-mediated chromosome resolution. Mutational analysis indicated that not only the core consensus sequence of dif2, but also its flanking regions play important roles in the recognition and recombination reactions mediated by XerA.
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DNA Arqueal/genética , Recombinases/metabolismo , Recombinação Genética , Thermoplasma/genética , Tirosina/metabolismo , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Sítios de Ligação , Genoma Bacteriano , Técnicas In Vitro , Mutação , Plasmídeos , Especificidade por Substrato , Thermoplasma/enzimologia , Thermoplasma/crescimento & desenvolvimentoRESUMO
Fbh1, an F-box helicase related to bacterial UvrD, has been proposed to modulate homologous recombination in fission yeast. We provide several lines of evidence for such modulation. Fbh1, but not the related helicases Srs2 and Rqh1, suppressed the formation of crossover recombinants from single HO-induced DNA double-strand breaks. Purified Fbh1 in complex with Skp1 (Fbh1-Skp1 complex) inhibited Rad51-driven DNA strand exchange by disrupting Rad51 nucleoprotein filaments in an ATP-dependent manner; this disruption was alleviated by the Swi5-Sfr1 complex, an auxiliary activator of Rad51. In addition, the reconstituted SCFFbh1 complex, composed of purified Fbh1-Skp1 and Pcu1-Rbx1, displayed ubiquitin-ligase E3 activity toward Rad51. Furthermore, Fbh1 reduced the protein level of Rad51 in stationary phase in an F-box-dependent, but not in a helicase domain-independent manner. These results suggest that Fbh1 negatively regulates Rad51-mediated homologous recombination via its two putative, unrelated activities, namely DNA unwinding/translocation and ubiquitin ligation. In addition to its anti-recombinase activity, we tentatively suggest that Fbh1 might also have a pro-recombination role in vivo, because the Fbh1-Skp1 complex stimulated Rad51-mediated strand exchange in vitro after strand exchange had been initiated.
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DNA Helicases/genética , Recombinação Homóloga/genética , Rad51 Recombinase/biossíntese , Proteínas de Schizosaccharomyces pombe/biossíntese , Proteínas de Schizosaccharomyces pombe/genética , Schizosaccharomyces/genética , Citoesqueleto/genética , Quebras de DNA de Cadeia Dupla , DNA Helicases/metabolismo , Mutação , Nucleoproteínas/genética , Nucleoproteínas/metabolismo , Rad51 Recombinase/genética , Proteínas Ligases SKP Culina F-Box/genética , Proteínas Ligases SKP Culina F-Box/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Ubiquitina-Proteína Ligases/genéticaRESUMO
The Swi5-Sfr1 heterodimer protein stimulates the Rad51-promoted DNA strand exchange reaction, a crucial step in homologous recombination. To clarify how this accessory protein acts on the strand exchange reaction, we have analyzed how the structure of the primary reaction intermediate, the Rad51/single-stranded DNA (ssDNA) complex filament formed in the presence of ATP, is affected by Swi5-Sfr1. Using flow linear dichroism spectroscopy, we observe that the nucleobases of the ssDNA are more perpendicularly aligned to the filament axis in the presence of Swi5-Sfr1, whereas the bases are more randomly oriented in the absence of Swi5-Sfr1. When using a modified version of the natural protein where the N-terminal part of Sfr1 is deleted, which has no affinity for DNA but maintained ability to stimulate the strand exchange reaction, we still observe the improved perpendicular DNA base orientation. This indicates that Swi5-Sfr1 exerts its activating effect through interaction with the Rad51 filament mainly and not with the DNA. We propose that the role of a coplanar alignment of nucleobases induced by Swi5-Sfr1 in the presynaptic Rad51/ssDNA complex is to facilitate the critical matching with an invading double-stranded DNA, hence stimulating the strand exchange reaction.
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DNA de Cadeia Simples/química , Recombinação Homóloga , Rad51 Recombinase/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Cálcio/química , DNA de Cadeia Simples/metabolismoRESUMO
Both ubiquitously expressed Rad51 and meiosis-specific Dmc1 are required for crossover production during meiotic recombination. The budding yeast Rad52 and its fission yeast ortholog, Rad22, are "mediators;" i.e., they help load Rad51 onto ssDNA coated with replication protein A (RPA). Here we show that the Swi5-Sfr1 complex from fission yeast is both a mediator that loads Dmc1 onto ssDNA and a direct "activator" of DNA strand exchange by Dmc1. In stark contrast, Rad22 inhibits Dmc1 action by competing for its binding to RPA-coated ssDNA. Thus, Rad22 plays dual roles in regulating meiotic recombination: activating Rad51 and inhibiting Dmc1.
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DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Recombinases/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/metabolismo , Trifosfato de Adenosina/metabolismo , Troca Genética/genética , Quebras de DNA de Cadeia Dupla , Reparo do DNA/genética , Recombinação Homóloga , Meiose , Ligação Proteica , Estabilidade Proteica , Proteína Rad52 de Recombinação e Reparo de DNA/metabolismo , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
trans-acting small interfering RNAs (tasiRNAs) are plant-specific endogenous siRNAs produced via a unique pathway whose first step is the microRNA (miRNA)-programmed RNA-induced silencing complex (RISC)-mediated cleavage of tasiRNA gene (TAS) transcripts. One of the products is subsequently transformed into tasiRNAs by a pathway that requires several factors including SUPPRESSOR OF GENE SILENCING3 (SGS3) and RNA-DEPENDENT RNA POLYMERASE6. Here, using in vitro assembled ARGONAUTE (AGO)1-RISCs, we show that SGS3 is recruited onto RISCs only when they bind target RNA. Following cleavage by miRNA173 (miR173)-programmed RISC, SGS3 was found in complexes containing cleaved TAS2 RNA and RISC. The 3' cleavage fragment (the source of tasiRNAs) was protected from degradation in this complex. Depletion of SGS3 did not affect TAS2 RNA cleavage by miR173-programmed RISC, but did affect the stability of the 3' cleavage fragment. When the 3' nucleotide of 22-nt miR173 was deleted or the corresponding nucleotide in TAS2 RNA was mutated, the complex was not observed and the 3' cleavage fragment was degraded. Importantly, these changes in miR173 or TAS2 RNA are known to lead to a loss of tasiRNA production in vivo. These results suggest that (i) SGS3 associates with AGO1-RISC via the double-stranded RNA formed by the 3'-terminal nucleotides of 22-nt miR173 and corresponding target RNA, which probably protrudes from the AGO1-RISC molecular surface, (ii) SGS3 protects the 3' cleavage fragment of TAS2 RNA from degradation, and (iii) the observed SGS3-dependent stabilization of the 3' fragment of TAS2 RNA is key to tasiRNA production.
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Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , RNA de Plantas/genética , RNA de Plantas/metabolismo , Complexo de Inativação Induzido por RNA/metabolismo , Sequência de Aminoácidos , Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/genética , Sequência de Bases , Genes de Plantas , Dados de Sequência Molecular , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Plantas Geneticamente Modificadas , Estabilidade de RNA , Homologia de Sequência de AminoácidosRESUMO
Ago1, an effector protein of RNA interference (RNAi), regulates heterochromatin silencing and cell cycle arrest in fission yeast. However, the mechanism by which Ago1 controls cell cycle checkpoint following hydroxyurea (HU) treatment has not been elucidated. In this study, we show that Ago1 and other RNAi factors control cell cycle checkpoint following HU treatment via a mechanism independent of silencing. While silencing requires dcr1(+), the overexpression of ago1(+) alleviated the cell cycle defect in dcr1Δ. Ago1 interacted with the mRNA export factor, Ptr1. The ptr1-1 mutation impaired cell cycle checkpoint but gene silencing was unaffected. Genetic analysis revealed that the regulation of cell cycle checkpoint by ago1(+) is dependent on ptr1(+). Nuclear accumulation of poly(A)(+) RNAs was detected in mutants of ago1(+) and ptr1(+), suggesting there is a functional link between the cell cycle checkpoint and RNAi-mediated RNA quality control.
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Proteínas Argonautas/metabolismo , Pontos de Checagem do Ciclo Celular/genética , Proteínas Associadas à Matriz Nuclear/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Interferência de RNA , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/fisiologia , Proteínas Argonautas/genética , Núcleo Celular/metabolismo , Heterocromatina/metabolismo , Hidroxiureia/farmacologia , Mutação , Proteínas Associadas à Matriz Nuclear/genética , Proteínas de Transporte Nucleocitoplasmático/genética , Edição de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Schizosaccharomyces/efeitos dos fármacos , Schizosaccharomyces/genética , Proteínas de Schizosaccharomyces pombe/genéticaRESUMO
INTRODUCTION: We verified the setup error (SE) in two persons' radiation therapist's team, which consist of staff and new face. We performed the significance test for SE by the staff group and the new face group. METHODS: One group consists of four staff therapists with at least 5 to 30 years of experience. The other group consists of new face radiation therapists that have 1 to 1.5 years of experience. Analyzed were 53 patients diagnosed with pelvic cancer (seven patients who underwent 3 dimensional conformal radiation therapy (3DCRT) and 46 patients who underwent intensity modulated radiation therapy (IMRT). Image verification was 1460 times. It was performed through setup verification by cone beam computed tomography (CBCT), and we measured SE of four directions (lateral, long, vertical, 3D). We performed the student's t-test to get the difference of the average error between the staff group and the new face group. RESULTS: The results of significance tests show that there is no difference between SE in the staff group and the new face group in radiotherapy.
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Competência Clínica/estatística & dados numéricos , Erros Médicos/estatística & dados numéricos , Corpo Clínico/estatística & dados numéricos , Equipe de Assistência ao Paciente/estatística & dados numéricos , Neoplasias Pélvicas/radioterapia , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , HumanosRESUMO
Rad51 forms a helical filament on single-stranded DNA and promotes strand exchange between two homologous DNA molecules during homologous recombination. The Swi5-Sfr1 complex interacts directly with Rad51 and stimulates strand exchange. Here we describe structural and functional aspects of the complex. Swi5 and the C-terminal core domain of Sfr1 form an essential activator complex with a parallel coiled-coil heterodimer joined firmly together via two previously uncharacterized leucine-zipper motifs and a bundle. The resultant coiled coil is sharply kinked, generating an elongated crescent-shaped structure suitable for transient binding within the helical groove of the Rad51 filament. The N-terminal region of Sfr1, meanwhile, has an interface for binding of Rad51. Our data suggest that the snug fit resulting from the complementary geometry of the heterodimer activates the Rad51 filament and that the N-terminal domain of Sfr1 plays a role in the efficient recruitment of the Swi5-Sfr1 complex to the Rad51 filaments.
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Modelos Moleculares , Complexos Multiproteicos/química , Conformação Proteica , Rad51 Recombinase/química , Proteínas de Schizosaccharomyces pombe/química , Cristalografia por Raios X , Ligação ProteicaRESUMO
In eukaryotes, DNA strand exchange is the central reaction of homologous recombination, which is promoted by Rad51 recombinases forming a right-handed nucleoprotein filament on single-stranded DNA, also known as a presynaptic filament. Accessory proteins known as recombination mediators are required for the formation of the active presynaptic filament. One such mediator in the fission yeast Schizosaccharomyces pombe is the Swi5-Sfr1 complex, which has been identified as an activator of Rad51 that assists in presynaptic filament formation and stimulates its strand exchange reaction. Here, we determined the 1:1 binding stoichiometry between the two subunits of the Swi5-Sfr1 complex using analytical ultracentrifugation and electrospray ionization mass spectrometry. Small-angle x-ray scattering experiments revealed that the Swi5-Sfr1 complex displays an extremely elongated dogleg-shaped structure in solution, which is consistent with its exceptionally high frictional ratio (f/f(0)) of 2.0 ± 0.2 obtained by analytical ultracentrifugation. Furthermore, we determined a rough topology of the complex by comparing the small-angle x-ray scattering-based structures of the Swi5-Sfr1 complex and four Swi5-Sfr1-Fab complexes, in which the Fab fragments of monoclonal antibodies were specifically bound to experimentally determined sites of Sfr1. We propose a model for how the Swi5-Sfr1 complex binds to the Rad51 filament, in which the Swi5-Sfr1 complex fits into the groove of the Rad51 filament, leading to an active and stable presynaptic filament.
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Rad51 Recombinase/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/metabolismo , Reparo do DNA/genética , Reparo do DNA/fisiologia , Ligação Proteica , Estrutura Terciária de Proteína , Rad51 Recombinase/genética , Schizosaccharomyces/genética , Proteínas de Schizosaccharomyces pombe/química , Proteínas de Schizosaccharomyces pombe/genética , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
BACKGROUND: Prolonged compression of limb muscles and subsequent decompression are important in the development of crush syndrome (CS). We applied a simple rubber tourniquet to rat hind limbs to create a CS model. METHODS: Anesthetized rats were subjected to bilateral hind limb compression for 5 hours followed by decompression and reperfusion for 0 hour, 1 hour, 3 hours, and 24 hours under monitoring of arterial blood pressure and electrocardiography. Blood and tissue samples were collected for histology, biochemical analysis, and tissue myeloperoxidase activity assessment. RESULTS: The survival rates of the CS-model groups remained at 100% until 3 hours, however, dropped to 25% at 24 hours after reperfusion mainly because of hyperkalemia and consequent hypotension observed at 1 hour and deteriorated at 3 hours after reperfusion. Rhabdomyolysis evaluated by circulating and histologic markers of injury was found as early as 1 hour and more marked at 3 hours, resulting in impaired renal function 24 hours after reperfusion. Myeloperoxidase activities increased with incremental periods after reperfusion not only in injured limb muscles but also in kidney and lung, suggesting an abnormal interaction between the vascular endothelium and circulating leukocytes after rhabdomyolysis, possibly causing subsequent multiple organ dysfunction frequently encountered in CS. CONCLUSION: The findings from this study demonstrate the feasibility of a novel small animal model of extremity crush injury. By using this model, the impact of incremental periods of reperfusion on mortality and remote organ dysfunctions can be characterized. Future studies are necessary to better define a threshold for this injury pattern and the impact of other factors underlying this syndrome.
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Síndrome de Esmagamento/fisiopatologia , Animais , Síndrome de Esmagamento/patologia , Modelos Animais de Doenças , Eletrocardiografia , Estudos de Viabilidade , Membro Posterior/irrigação sanguínea , Testes de Função Renal , Masculino , Peroxidase/metabolismo , Ratos , Ratos Wistar , Reperfusão , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/fisiopatologia , Rabdomiólise/patologia , Rabdomiólise/fisiopatologia , Taxa de Sobrevida , TorniquetesRESUMO
Homologous recombination proceeds via the formation of several intermediates including Holliday junctions (HJs), which are important for creating crossover products. DNA strand exchange is a core reaction that produces these intermediates that is directly catalyzed by RecA family recombinases, of which there are two types in eukaryotes: universal Rad51 and meiosis-specific Dmc1. We demonstrated previously that Rad51 promotes four-strand exchange, mimicking the formation and branch migration of HJs. Here we show that Dmc1 from fission yeast has a similar activity, which requires ATP hydrolysis and is independent of an absolute requirement for the Swi5-Sfr1 complex. These features are critically different from three-strand exchange mediated by Dmc1, but similar to those of four-strand exchange mediated by Rad51, suggesting that strand exchange reactions between duplex-duplex and single-duplex DNAs are mechanistically different. Interestingly, despite similarities in protein structure and in reaction features, the preferential polarities of Dmc1 and Rad51 strand exchange are different (Dmc1 promotes exchange in the 5'-to-3' direction and Rad51 promotes exchange in the 3'-to-5' direction relative to the ssDNA region of the DNA substrate). The significance of the Dmc1 polarity is discussed within the context of the necessity for crossover production.
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DNA Cruciforme/genética , Rad51 Recombinase/metabolismo , Recombinases/metabolismo , Recombinação Genética/genética , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/enzimologia , Schizosaccharomyces/genética , Trifosfato de Adenosina/metabolismo , Cálcio/metabolismo , Endodesoxirribonucleases/metabolismo , Hidrólise , Magnésio/metabolismo , Rad51 Recombinase/genética , Proteínas de Schizosaccharomyces pombe/genéticaRESUMO
When inappropriate DNA structures arise, they are sensed by DNA structure-dependent checkpoint pathways and subsequently repaired. Recruitment of checkpoint proteins to such structures precedes recruitment of proteins involved in DNA metabolism. Thus, checkpoints can regulate DNA metabolism. We show that fission yeast Rad9, a 9-1-1 heterotrimeric checkpoint-clamp component, is phosphorylated by Hsk1(Cdc7), the Schizosaccharomyces pombe Dbf4-dependent kinase (DDK) homolog, in response to replication-induced DNA damage. Phosphorylation of Rad9 disrupts its interaction with replication protein A (RPA) and is dependent on 9-1-1 chromatin loading, the Rad9-associated protein Rad4/Cut5(TopBP1), and prior phosphorylation by Rad3(ATR). rad9 mutants defective in DDK phosphorylation show wild-type checkpoint responses but abnormal DNA repair protein foci and decreased viability after replication stress. We propose that Rad9 phosphorylation by DDK releases Rad9 from DNA damage sites to facilitate DNA repair.
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Proteínas de Ciclo Celular/metabolismo , Ciclo Celular , Cromatina/metabolismo , Dano ao DNA , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/citologia , Schizosaccharomyces/enzimologia , Sequência de Aminoácidos , Camptotecina/farmacologia , Ciclo Celular/efeitos dos fármacos , Proteínas de Ciclo Celular/química , Cromatina/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Replicação do DNA/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Cinética , Modelos Biológicos , Dados de Sequência Molecular , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Fosforilação/efeitos dos fármacos , Fosfosserina/metabolismo , Fosfotreonina/metabolismo , Ligação Proteica/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Proteína de Replicação A/metabolismo , Schizosaccharomyces/efeitos dos fármacos , Solubilidade/efeitos dos fármacos , Frações Subcelulares/efeitos dos fármacos , Frações Subcelulares/metabolismo , Fatores de TempoRESUMO
Specialized chromatin exists at centromeres and must be precisely transmitted during DNA replication. The mechanisms involved in the propagation of these structures remain elusive. Fission yeast centromeres are composed of two chromatin domains: the central CENP-A(Cnp1) kinetochore domain and flanking heterochromatin domains. Here we show that fission yeast Mcl1, a DNA polymerase alpha (Pol alpha) accessory protein, is critical for maintenance of centromeric chromatin. In a screen for mutants that alleviate both central domain and outer repeat silencing, we isolated several cos mutants, of which cos1 is allelic to mcl1. The mcl1-101 mutation causes reduced CENP-A(Cnp1) in the central domain and an aberrant increase in histone acetylation in both domains. These phenotypes are also observed in a mutant of swi7(+), which encodes a catalytic subunit of Pol alpha. Mcl1 forms S-phase-specific nuclear foci, which colocalize with those of PCNA and Pol alpha. These results suggest that Mcl1 and Pol alpha are required for propagation of centromere chromatin structures during DNA replication.