46 research outputs found

    Theory of Ferromagnetic Superconductivity

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    It is argued that the pairing symmetry realized in a ferromagnetic superconductor UGe2_2 must be a non-unitary triplet pairing. This particular state is free from the Pauli limitation and can survive under a huge internal molecular filed. To check our identification we examine its basic properties and several experiments are proposed. In particular, the external field is used to raise TcT_c by controlling the internal spontaneous dipole field.Comment: 4 pages, no figure

    Biosynthetic study of FR-900848: unusual observation on polyketide biosynthesis that did not accept acetate as origin of acetyl-CoA

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    The biosynthetic pathway of a potent antifungal agent, FR-900848, has been examined by administration of several 13C-labeled precursors to Streptoverticillium fervens HP-891. Although none of the 13C-labeled acetate was incorporated into FR-900848, the labeling pattern of FR-900848 derived from d-[U-13C6]glucose revealed that the fatty acid backbone of FR-900848 has been biosynthesized via a polyketide pathway. These unusual results strongly show that the major pathway to provide acetyl-CoA in this microorganism is glycolysis. Feeding experiments with d-[U-13C6]glucose, [1,3-13C2]glycerol, and l-[Me-13C]methionine provided information on the biosynthetic origin of structurally unusual parts (polycyclopropane and aminonucleoside) in this antibiotic

    Analytical electron microscopy for materials science

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    Two-Step Regulation of LAX PANICLE1 Protein Accumulation in Axillary Meristem Formation in Rice[W]

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    Axillary meristem (AM) formation is an important determinant of plant architecture. In rice (Oryza sativa), LAX PANICLE1 (LAX1) function is required for the generation of AM throughout the plant's lifespan. Here, we show a close relationship between AM initiation and leaf development; specifically, the plastochron 4 (P4) stage of leaf development is crucial for the proliferation of meristematic cells. Coincident with this, LAX1 expression starts in the axils of leaves at P4 stage. LAX1 mRNA accumulates in two to three layers of cells in the boundary region between the initiating AM and the shoot apical meristem. In lax1 mutants, the proliferation of meristematic cells is initiated but fails to progress into the formation of AM. The difference in sites of LAX1 mRNA expression and its action suggests non-cell-autonomous characteristics of LAX1 function. We found that LAX1 protein is trafficked to AM in a stage- and direction-specific manner. Furthermore, we present evidence that LAX1 protein movement is required for the full function of LAX1. Thus, we propose that LAX1 protein accumulates transiently in the initiating AM at P4 stage by a strict regulation of mRNA expression and a subsequent control of protein trafficking. This two-step regulation is crucial to the establishment of the new AM

    Cyclization mechanism of phomopsene synthase : mass spectrometry based analysis of various site-specifically labeled terpenes

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    Elucidation of the cyclization mechanism catalyzed by terpene synthases is important for the rational engineering of terpene cyclases. We developed a chemoenzymatic method for the synthesis of systematically deuterium-labeled geranylgeranyl diphosphate ( GGPP), starting from site-specifically deuterium-labeled isopentenyl diphosphates (IPPs) using IPP isomerase and three prenyltransferases. We examined the cyclization mechanism of tetracyclic diterpene phomopsene with phomopsene synthase. A detailed EI-MS analysis of phomopsene labeled at various positions allowed us to propose the structures corresponding to the most intense peaks, and thus elucidate a cyclization mechanism involving double 1,2-alkyl shifts and a 1,2-hydride shift via a dolabelladien-15-yl cation. Our study demonstrated that this newly developed method is highly sensitive and provides sufficient information for a reliable assignment of the structures of fragmented ions

    Effects of Dietary Protein Levels on Production and Characteristics of Japanese Quail Eggs

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    Three different lines (normal, brown and crossbred) of Japanese quail were used in this study to examine the effects of dietary protein level on the production and quality of eggs. In all lines, poor egg production was evident throughout the experiment on a diet with 16% crude protein (CP). Egg production increased as the CP levels of diets increased. Until 32 weeks, normal (N) and brown (B) lines showed higher egg production at 24% CP, while the crossbred (BN) line showed higher egg production at 22% CP. The cumulative egg production at 24% CP was higher than or similar to that at 26% CP. A comparison of egg production among different lines showed that BN produced significantly (P<0.05) more eggs than N at the lower protein levels of 20% and 22% CP. Weight of eggs was lowest in all lines at 16% CP, and tended to increase with increasing protein level. No difference in egg weight was observed among lines. Egg weight and yolk color were significantly (P<0.05) affected by different levels of protein. It appears that 24% CP was optimal for higher egg production and egg weight for N and B lines and 22% CP for BN lines. Furthermore, our data indicate that heterosis was obtained in BN for egg production at the lower protein levels

    Biosynthetic Machinery of Diterpene Pleuromutilin Isolated from Basidiomycete Fungi

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    The diterpene pleuromutilin is a ribosome-targeting antibiotic isolated from basidiomycete fungi, such as Clitopilus pseudo-pinsitus. The functional characterization of all biosynthetic enzymes involved in pleuromutilin biosynthesis is reported and a biosynthetic pathway proposed. In vitro enzymatic reactions and mutational analysis revealed that a labdane-related diterpene synthase, Ple3, catalyzed two rounds of cyclization from geranylgeranyl diphosphate to premutilin possessing a characteristic 5-6-8-tricyclic carbon skeleton. Biotransformation experiments utilizing Aspergillus oryzae transformants possessing modification enzyme genes allowed the biosynthetic pathway from premutilin to pleuromutilin to be proposed. The present study sets the stage for the enzymatic synthesis of natural products isolated from basidiomycete fungi, which are a prolific source of structurally diverse and biologically active terpenoids
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