OIST Institutional Repository
Not a member yet
2744 research outputs found
Sort by
Mannich Reactions of Carbohydrate Derivatives with Ketones To Afford Polyoxy-Functionalized Piperidines
Get PDFMannich reactions of carbohydrate derivatives with ketones that afford polyoxy-functionalized piperidines are reported. Ketone nucleophiles (enamines/enolates) were generated in the presence of the amines used for the formation of the iminium ions of sugar derivatives with or without an additive. Conditions to preferentially generate piperidine derivatives rather than tetrahydrofurans were identified. Products from the reactions of allyl ketones were readily transformed to bicyclic piperidines.journal articl
The Bacterial DNA Binding Protein MatP Involved in Linking the Nucleoid Terminal Domain to the Divisome at Midcell Interacts with Lipid Membranes
Get PDFDivision ring formation at midcell is controlled by various mechanisms in Escherichia coli, one of them being the linkage between the chromosomal Ter macrodomain and the Z-ring mediated by MatP, a DNA binding protein that organizes this macrodomain and contributes to the prevention of premature chromosome segregation. Here we show that, during cell division, just before splitting the daughter cells, MatP seems to localize close to the cytoplasmic membrane, suggesting that this protein might interact with lipids. To test this hypothesis, we investigated MatP interaction with lipids in vitro. We found that, when encapsulated inside vesicles and microdroplets generated by microfluidics, MatP accumulates at phospholipid bilayers and monolayers matching the lipid composition in the E. coli inner membrane. MatP binding to lipids was independently confirmed using lipid-coated microbeads and biolayer interferometry assays, which suggested that the recognition is mainly hydrophobic. Interaction of MatP with the lipid membranes also occurs in the presence of the DNA sequences specifically targeted by the protein, but there is no evidence of ternary membrane/protein/DNA complexes. We propose that the association of MatP with lipids may modulate its spatiotemporal localization and its recognition of other ligands.journal articl
Hollow Whispering Gallery Mode Resonators: from Fabrication to Application
Get PDFOkinawa Institute of Science and Technology Graduate UniversityDoctor of PhilosophyWhispering gallery mode resonators (WGMRs) are ultrahigh quality optical resonators, where Q-factors higher than 107 are easily achieved. They can be used as compact optical sensors, laser sources, and experimental platforms to study optomechanics and nonlinear optics, for example. A type of WGMR with a hollow structure first appeared
in the literature in 2010. Such a WGMR is called a microbubble resonator (MBR) named after its geometrical structure. The wall thickness of an MBR is, typically, quite thin and this leads to several interesting properties: (i) the resonant frequency can be tuned by inserting air pressure, (ii) geometrical dispersion is changed from normal bulk
WGMRs, and (iii) when the bubble is filled with water (or other liquids), the resonant optical field can be distributed within, and have an interaction with, the liquid core. In this thesis, we discuss the fabrication method for MBRs and their application in a coupled cavity system, as a tunable laser, and for frequency comb generation at near
visible wavelengths. In future, transient sensing may be achieved in a liquid core MBR and different patterns of cascaded Raman scattering may be controlled by inserting air pressure into the MBR. Preliminary work on these topics is also included in this dissertation.doctoral thesi
Coordinated Roles of the Putative Ceramide-Conjugation Protein, Cwh43, and a Mn2+-Transporting, P-Type ATPase, Pmr1, in Fission Yeast
Get PDFGenetically controlled mechanisms of cell division and quiescence are vital for responding to changes in the nutritional environment and for cell survival. Previously, we have characterized temperature-sensitive (ts) mutants of the cwh43 gene in fission yeast, Schizosaccharomyces pombe, which is required for both cell proliferation and nitrogen starvation-induced G0 quiescence. Cwh43 encodes an evolutionarily conserved transmembrane protein that localizes in endoplasmic reticulum (ER). Defects in this protein fail to divide in low glucose and lose mitotic competence under nitrogen starvation, and also affect lipid metabolism. Here, we identified mutations of the pmr1 gene, which encodes an evolutionarily conserved Ca2+/Mn2+-transporting P-type ATPase, as potent extragenic suppressors of ts mutants of the cwh43 gene. Intriguingly, these pmr1 mutations specifically suppressed the ts phenotype of cwh43 mutants, among five P-type Ca2+- and/or Mn2+-ATPases reported in this organism. Cwh43 and Pmr1 co-localized in the ER. In cwh43 mutant cells, addition of excessive manganese to culture media enhanced the severe defect in cell morphology, and caused abnormal accumulation of a cell wall component, 1, 3-β-glucan. In contrast, these abnormal phenotypes were abolished by deletion of the pmr1+ gene, as well as by removal of Mn2+ from the culture medium. Furthermore, nutrition-related phenotypes of cwh43 mutant cells were rescued in the absence of Pmr1. Our findings indicate that the cellular processes regulated by Cwh43 are appropriately balanced with Pmr1-mediated Mn2+ transport into the ER.journal articl
Self-delivery of N-hydroxylethyl peptide assemblies to the cytosol inducing endoplasmic reticulum dilation in cancer cells
Get PDFInspired by clinical studies on alcohol abuse induced endoplasmic reticulum disruption, we designed a N-hydroxylethyl peptide assembly to regulate the ER stress response in cancer cells. Upon coupling with a coumarin derivative via an ester linkage, a prodrug was synthesized to promote esterase-facilitated self-delivery of N-hydroxylethyl peptide assemblies around the ER, inducing ER dilation. Following this, ER-specific apoptosis was effectively and efficiently activated in various types of cancer cells including drug resistant and metastatic ones.journal articl
Aptamer-based and aptazyme-based riboswitches in mammalian cells
Get PDFMolecular recognition by RNA aptamers has been exploited to control gene expression in response to small molecules in mammalian cells. These mammalian synthetic riboswitches offer attractive features such as small genetic size and lower risk of immunological complications compared to protein-based transcriptional gene switches. The diversity of gene regulatory mechanisms that involve RNA has also inspired the development of mammalian riboswitches that harness various regulatory mechanisms. In this report, recent advances in synthetic riboswitches that function in mammalian cells are reviewed focusing on the regulatory mechanisms they exploit such as mRNA degradation, microRNA processing, and programmed ribosomal frameshifting.journal articl
States of decay: The systems biology of mRNA stability
Get PDFAn appropriate equilibrium between transcription and mRNA decay is vital for the function of the cell. The RNA-binding complexes regulating mRNA degradation, such as carbon catabolite repression 4-negative on TATA-less, may also control several other stages of the mRNA life cycle, from transcription to translation. This pleiotropic control complicates the analysis of mRNA stability. Computational models have analysed the mechanisms underlying mRNA turnover and have been used to extract mRNA decay rates from high-throughput data sets. Multiomics studies have clarified the actions of RNA-binding complexes, and such studies allow the evolution of more accurate and complex computational models. This review discusses two complementary aspects of systems biology in the study of mRNA decay—computational modelling of mRNA turnover and recent ‘-omics’ studies of the function of RNA-binding proteins controlling mRNA stability.journal articl
Diallyl Disulfide Mitigates DNA Damage and Spleen Tissue Effects After Irradiation
Get PDFBACKGROUND Several factors found in foods are beneficial to human health and they may contribute to radiation protection. Taking food factors could be an easy way to reduce the effects of radiation after nuclear accidents, as well as secondary radiation risks after cancer radiotherapy or space missions. Here, diallyl disulfide (DADS), a component of garlic oil, was studied for its ability to mitigate radiation damage.
MATERIAL AND METHODS We investigated the effects of DADS on micronucleus (MN) formation and apoptosis in HepG2 cells by use of 4-Gy X-ray irradiation. We also assessed the effects of DADS on radiation damage in vivo by evaluating MN formation in bone marrow cells in mice (BALB/c, 8-week-old females) after oral intake of DADS prior to irradiation with 4 Gy. Several tissue effects were also investigated.
RESULTS The presence of DADS inhibited MN formation, whereas DADS had no influence on the radiation-induced inhibition of cell cycle progression in HepG2 cells. An increase in apoptosis in HepG2 cells was induced after irradiation, and this effect was stronger in the presence of DADS than in its absence. In mice, when DADS was administered daily for 3 days prior to irradiation, MN formation in irradiated mice was decreased. The decrease in MN formation in mice was greater with 0.5% DADS compared to 1% DADS. Moreover, an increase in spleen weight observed 3 weeks after irradiation was suppressed in mice administered DADS.
CONCLUSIONS DADS is a potential radiation-protective agent that effectively mitigates DNA damage, and its effects in the spleen observed after irradiation may be related to inflammation and carcinogenesis.journal articl
Rapid Action of Retinoic Acid on the Hypothalamic Pituitary Adrenal Axis
Get PDFRetinoic acid (RA) is the active metabolite of vitamin A but is also used as a medication, primarily for acne in which the treatment regime lasts several months. A number of studies have indicated that treatment with RA over this time period impacts the hypothalamic-pituitary-adrenal (HPA) axis and may contribute to a number of the side-effects of the drug. No studies though have investigated the short-term, early effects RA may have on the HPA axis via the transcriptional pathways activated by the RA receptor. This study investigated the action of RA over 3 days on regulatory components of the HPA axis. Several key genes involved in glucocorticoid feedback pathways in the hippocampus, hypothalamus and pituitary were unchanged after 3-days exposure to RA. Key elements though in the adrenal gland involved in corticosterone and aldosterone synthesis were altered in particular with the Cyp11b2 gene downregulated in vivo and ex vivo. The rapid, 5 h, change in Cyp11b2 expression suggested this activation may be direct. These results highlight the adrenal gland as a target of short-term action of RA and potentially a trigger component in the mechanisms by which the long-term adverse effects of RA treatment occur.journal articl
