Screening of tenuazonic acid production-inducing compounds and identification of NPD938 as a regulator of fungal secondary metabolism.

The control of secondary metabolism in fungi is essential for the regulation of various cellular functions. In this study, we searched the RIKEN Natural Products Depository (NPDepo) chemical library for inducers of tenuazonic acid (TeA) production in the rice blast fungus Pyricularia oryzae and identified NPD938. NPD938 transcriptionally induced TeA production. We explored the mode of action of NPD938 and observed that this compound enhanced TeA production via LAE1, a global regulator of fungal secondary metabolism. NPD938 could also induce production of terpendoles and pyridoxatins in Tolypocladium album RK99-F33. Terpendole production was induced transcriptionally. We identified the pyridoxatin biosynthetic gene cluster among transcriptionally induced secondary metabolite biosynthetic gene clusters. Therefore, NPD938 is useful for the control of fungal secondary metabolism.

FABP5 Is a Sensitive Marker for Lipid-Rich Macrophages in the Luminal Side of Atherosclerotic Lesions.

Lipid-rich macrophages in atherosclerotic lesions are thought to be derived from myeloid and vascular smooth muscle cells. A series of studies with genetic and pharmacological inhibition of fatty acid binding protein 4 (FABP4) and FABP5 and bone marrow transplant experiments with FABP4/5 deficient cells in mice have demonstrated that these play an important role in the development of atherosclerosis. However, it is still uncertain about the differential cell-type specificity and distribution between FABP4- and FABP5-expressing cells in early- and late-stage atherosclerotic lesions. In this study, we first explored spatial distribution of FABP4/5 in atherosclerotic lesions in apolipoprotein E deficient (ApoE-/-) mice. FABP4 was only marginally detected in early and advanced lesions, whereas FABP5 was abundantly expressed in these lesions. In advanced lesions, the FABP5-positive area was mostly restricted to the foam cell layer adjacent to the lumen above collagen and elastic fibers with a high signal/noise ratio. Oil red O (ORO) staining revealed that FABP5-positive cells were lipid-rich in early and advanced lesions. Together, most of lipid-rich FABP5-positive cells reside adjacent to the lumen above collagen and elastic fibers. We next studied involvement of FABP5 in lesion formation of atherosclerosis using ApoE-/- FABP5-/- mice. However, deletion of FABP5 did not affect the development of atherosclerosis. These findings, along with previous reports, suggest a novel notion that FABP5 is a sensitive marker for bone marrow-derived lipid-rich macrophages in the luminal side of atherosclerotic lesions, although its functional significance remains elusive.

Ultrafast magnetization modulation induced by the electric field component of a terahertz pulse in a ferromagnetic-semiconductor thin film.

High-speed magnetization control of ferromagnetic films using light pulses is attracting considerable attention and is increasingly important for the development of spintronic devices. Irradiation with a nearly monocyclic terahertz pulse, which can induce strong electromagnetic fields in ferromagnetic films within an extremely short time of less than ~1 ps, is promising for damping-free high-speed coherent control of the magnetization. Here, we successfully observe a terahertz response in a ferromagnetic-semiconductor thin film. In addition, we find that a similar terahertz response is observed even in a non-magnetic semiconductor and reveal that the electric-field component of the terahertz pulse plays a crucial role in the magnetization response through the spin-carrier interactions in a ferromagnetic-semiconductor thin film. Our findings will provide new guidelines for designing materials suitable for ultrafast magnetization reversal.

Synthesis and Magnetic Properties of Stable Radical Derivatives Carrying a Phenylacetylene Unit.

A nitronyl nitroxide derivative, 2-phenylethynyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-oxide (1), and two verdazyl derivatives carrying a phenylacetylene unit, 1,5-diphenyl-3-phenylethynyl-6-oxo-1,2,4,5-tetrazin-2-yl (2) and 1,5-diisopropyl-3-phenylethynyl-6-oxo-1,2,4,5-tetrazin-2-yl (3), were synthesized and their packing structures were studied by X-ray crystallographic analysis and magnetically characterized in the solid state. While 1 and 3 had an isolated doublet spin state, 2 formed an antiferromagnetically coupled pair (2J/kB = -118 K). Density functional theory (DFT) calculations reveal that the spin density polarized in the phenyl group decreases as the dihedral angle between the phenyl ring and radical plane increases.