The human serine/threonine kinase Aurora-B is structurally related to the protein kinase Ipl1p from S cerevisiae and aurora from Drosophila melanogaster, which are key regulators of mitosis. The present study shows that human Aurora-B is activated by okadaic acid and forms complexes with the protein serine/threonine phosphatase type 1 (PP1) or PP2A, but not with PP5. These data identi®ed Aurora-B associated protein phosphatases as negative regulators of kinase activation. We then used a series of substrates based on a histone H3 phosphorylation site (residues 5 ± 15) to determine the substrate speci®city of human Aurora-B. We found that this enzyme is an arginine-directed kinase that can phosphorylate histone H3 at serines 10 and 28 in vitro, suggesting that human Aurora-B is a mitotic histone H3 kinase.
The neural circuit of the central nervous system (CNS) primarily determines brain functions and, as a consequence, controls animal behavior. This paper describes an X-ray microtomographic analysis of the Drosophila larvae CNS, visualizing the neural network embedded in the three-dimensional structure of the nerve tissue. In fluorescence confocal microscopy, absorbance at emission or excitation wavelengths interferes with the fluorescence detection. In contrast, transparency of the nerve tissue to hard X-rays enables tomographic analysis of the intact CNS without sectioning. Yet the nerve tissue is composed of light elements that give little contrast in a hard X-ray transmission image. The contrast was enhanced by staining neuropils in the CNS with metal elements. The obtained structure revealed the internal architecture of the CNS. This metal-staining microtomographic analysis can be applied to any nerve tissues, thereby shedding light on the underlying structural basis of neural functions.
alpha-Glucosidase inhibitors are useful for glycemic control in patients with NIDDM and the percentage of carbohydrate in all calorie sources is an important factor for the expression of their effects.
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