Rate of exchange of Cl− between the aqueous phase and its action site in the O2 evolving reaction of photosystem II studied by rapid, ionic-jump-induced Cl− depletion

AbstractRates of release and binding of Cl− from/to its action site in the O2 evolving reaction in photosystem II particles derived from spinach chloroplasts were estimated by measuring the suppression of O2 evolution by salt addition (ionic-jump) and its recovery by the readdition of Cl−. It was estimated that depletion and rebinding of Cl− were completed within a few seconds. These results suggest that the Cl−-action site is located in a space which is almost freely accessible to various ions in the outer medium, with no barrier to ion movements. These results can be explained by electrostatic attraction of Cl− to its action site, as was proposed in a study of anion effects on O2 evolution [(1986) Plant Cell Physiol. 27, in press]

Antifungal Activities of The Extracts From Some Tropical and Temperate Woods

Empat flavonoids (Sciadopitysin) (1), Ginkgetin (2), Ishorhamnetin (3), dan Quercetin (4), dua Texanes (Taxinine) (5) dan Taxol (6), dan Phenylisoserine methyl ester (7) dapat diisolasi dari Taxus cuspadata var. nana. Senyawa (7) juga dapat diisolasi dari Taxus chinensis. Senyawa (7) dapat diisolasi untuk pertama kalinya masing-masing dari T. cuspidata var. nana dan T. chinensis.Aktivitas antifungus senyawa-senyawa yang terisolasi tersebut dan tujuh turunan taxinine terhadap tujuh fungi patogenik tanaman (Cochliobolus miyabeanus, Alternaria kikuchiana, Giberella fujikuroi, Cladosporium cucumenium, Fusarium oxysporum, Colletotrichum fragariae dan Corynespora cassiicola) telah diukur. Taxinine dan tujuh turunan taxinine menunjukkan adanya aktivitas antifungus terhadap lima jenis fungi. Diantara tiga jenis kayu tropis (Amboyna,Kempas,Angsana),kayu Amboyna menunjukkan aktivitas antifungus terhadap empat fungi dari basidiomycetes (Le,Pp,G3,dan PLI). Selanjutnya, ekstrak methanolic dan fraksi larutnya nhexane dan ethyl ether dari kayu Amboyna menunjukkan aktivitas antifungus terhadap fungus Pp.Kata kunci: Antifungi, flavonoid, Texanes, phenylisoserine methyl ester, kayu tropis dan temperate, fungi patogenik tanaman, basidiomycetes

Antifungal Activities of The Extracts From Some Tropical and Temperate Woods

Empat flavonoids (Sciadopitysin) (1), Ginkgetin (2), Ishorhamnetin (3), dan Quercetin (4), dua Texanes (Taxinine) (5) dan Taxol (6), dan Phenylisoserine methyl ester (7) dapat diisolasi dari Taxus cuspadata var. nana. Senyawa (7) juga dapat diisolasi dari Taxus chinensis. Senyawa (7) dapat diisolasi untuk pertama kalinya masing-masing dari T. cuspidata var. nana dan T. chinensis.Aktivitas antifungus senyawa-senyawa yang terisolasi tersebut dan tujuh turunan taxinine terhadap tujuh fungi patogenik tanaman (Cochliobolus miyabeanus, Alternaria kikuchiana, Giberella fujikuroi, Cladosporium cucumenium, Fusarium oxysporum, Colletotrichum fragariae dan Corynespora cassiicola) telah diukur. Taxinine dan tujuh turunan taxinine menunjukkan adanya aktivitas antifungus terhadap lima jenis fungi. Diantara tiga jenis kayu tropis (Amboyna,Kempas,Angsana),kayu Amboyna menunjukkan aktivitas antifungus terhadap empat fungi dari basidiomycetes (Le,Pp,G3,dan PLI). Selanjutnya, ekstrak methanolic dan fraksi larutnya nhexane dan ethyl ether dari kayu Amboyna menunjukkan aktivitas antifungus terhadap fungus Pp.Kata kunci: Antifungi, flavonoid, Texanes, phenylisoserine methyl ester, kayu tropis dan temperate, fungi patogenik tanaman, basidiomycetes

Screening Corrections to the Electron Capture Rates in Dense Stars by the Relativistically Degenerate Electron Liquid

We calculate the screening corrections to the electron capture rates in dense stars by the relativistically degenerate electron liquid. In order to calculate the screening corrections we adopt the linear response theory which is widely used in the field of solid state physics and liquid metal physics. In particular, we use the longitudinal dielectric function for the relativistically degenerate electron liquid derived by Jancovici. We calculate the screening potential at the position of the nucleus. By using this screening potential one can calculate the screening corrections to the electron capture rates. We will present accurate analytic fitting formulae which summarize our numerical results. These fitting formulae will facilitate the application of the present results. The screening corrections to the electron capture rates are typically a few percent.Comment: uses AAS LaTeX macro package (Ver. 5.0), 8 pages, 2 tables, 4 figures, 2 subroutines, published in ApJ 579, 380-385 (2002

The r-process in supernova explosions from the collapse of O-Ne-Mg cores

We examine r-process nucleosynthesis in a "prompt supernova explosion" from an 8-10 Msun progenitor star, as an alternative scenario to the "neutrino wind" mechanism. In the present model, the progenitor star has formed an oxygen-neon-magnesium core at its center. The core-collapse simulations are performed with a one-dimension, Newtonian hydrodynamic code. We obtain a very weak prompt explosion, in which no r-processing occurs. We further simulate energetic prompt explosions by enhancement of the shock-heating energy, in order to investigate conditions necessary for the production of r-process nuclei in such events. The highly neutronized ejecta (Ye = 0.14-0.20) leads to robust production of r-process nuclei; their relative abundances are in excellent agreement with the solar r-process pattern. Our results suggest that prompt explosions of 8-10 Msun stars with oxygen-neon-magnesium cores can be a promising site of r-process nuclei.Comment: 32 pages, 9 figures, accepted for publication in Ap

N-Sulfanylethylanilide-based traceable linker for enrichment and selective labelling of target proteins

An N-sulfanylethylanilide-based traceable linker, developed to facilitate identification of target proteins of bioactive compounds, was introduced into an alkynylated target protein. Subsequent adsorption onto streptavidin beads allowed it to be treated with a cysteine-fluorophore conjugate in the presence of phosphate. This induced the N-S acyl transfer reaction of the N-sulfanylethylanilide unit. The subsequent native chemical ligation of the fluorophore resulted in cleavage of the linker for target elution and fluorescent labelling of the target, allowing it to be distinguished from non-target proteins

Design and synthesis of caged ceramide : UV-responsive ceramide releasing system based on UV-induced amide bond cleavage followed by O–N acyl transfer

Sphingolipids, recognized as membrane constructs and as key signaling molecules, have been studied to examine intracellular function. Some caged sphingolipids that release parent sphingolipids after exposure to UV-irradiation have been previously developed, but caged ceramide has yet to be reported. In this study, we report the design and synthesis of a caged ceramide. Photo-irradiation experiment clarified that the caged ceramide can be successfully converted to the parent ceramide by UV-irradiation. Introduction of an alkyne-handle moiety for further modification of the caged ceramide is also reported

Development of a Chemical Methodology for the Preparation of Peptide Thioesters Applicable to Naturally Occurring Peptides Using a Sequential Quadruple Acyl Transfer System

Peptide thioesters are very useful in protein chemistry, and chemistry- and biochemistry-based protocols are used for the preparation of thioesters. Among such protocols, only a few biochemistry-based approaches have been use for naturally occurring peptide sequences. The development of chemistry-based protocols applicable to natural sequences remains a challenge, and the development of such methods would be a major contribution to protein science. Here, we describe the preparation of peptide thioesters using innovative methodology that features nickel(II)-mediated alcoholysis of a naturally occurring peptide sequence, followed by O-N and N-S acyl transfers. This protocol involves sequential quadruple acyl transfer, termed SQAT. Notably, the SQAT system consists of sequential chemical reactions that allow naturally occurring peptide sequences to be converted to thioesters without requiring an artificial chemical unit

Prevalence of and risk factors for postoperative complications after lower third molar extraction : A multicenter prospective observational study in Japan

Lower third molar extraction is the most common surgical treatment among routine dental and oral surgical procedures. while the surgical procedures for lower third molar extraction are well established, the difficulty of tooth extraction and the frequency of postoperative complications differ depending on the patient’s background. To establish a management protocol for the lower third molars, the prevalence of and risk factors for postoperative complications after lower third molar extraction were investigated in a large number of Japanese patients in a multicenter prospective study. During 6 consecutive months in 2020, 1826 lower third molar extractions were performed at the 20 participating institutions. The medical records of the patients were reviewed, and relevant data were extracted. The prevalence of and risk factors for postoperative complications were analyzed. The prevalence of postoperative complications after lower third molar extraction was 10.0%. Multivariate analysis indicated that age (≤32 vs >32, odds ratio [OR]: 1.428, 95% confidence interval [95% CI]: 1.040–1.962, P < .05), the radiographic anatomical relationship between the tooth roots and mandibular canal (overlapping of the roots and canal vs no close anatomical relationship between the roots and the superior border of the canal, OR: 2.078, 95% CI: 1.333–3.238, P < .01; overlapping of the roots and canal vs roots impinging on the superior border of the canal, OR: 1.599, 95% CI: 1.050–2.435, P < .05), and impaction depth according to the Pell and Gregory classification (position C vs position A, OR: 3.7622, 95% CI: 2.079–6.310, P < .001; position C vs position B, OR: 2.574, 95% CI: 1.574–4.210, P < .001) are significant independent risk factors for postoperative complications after lower third molar extraction. These results suggested that higher age and a deeply impacted tooth might be significant independent risk factors for postoperative complications after lower third molar extraction