Inoue Shinya

No Thumbnail Available
Last Name
Inoue
First Name
Shinya
ORCID

Filters

2006 - 2009 4
2 2
4
Reset filters

Settings

Search Results

Now showing 1 - 4 of 4
  • Article
    Calyculin-A induces cleavage in a random plane in unfertilized sea urchin eggs
    (Marine Biological Laboratory, 2009-02) Goda, Makoto ; Inoue, Shinya ; Mabuchi, Issei
    Calyculin-A (CLA), a protein phosphatase inhibitor, has been known to induce cleavage resembling normal furrowing in unfertilized sea urchin eggs. In CLA-treated eggs, actin filaments and myosin assemble to form a contractile ring-like structure in the egg cortex; however, this occurs in the absence of a mitotic spindle or asters. Here, we investigated the relationship between the plane of CLA-induced cleavage and the intrinsic animal-vegetal polar axis in sea urchin eggs. The animal-vegetal axis was established using black ink to visualize the jelly canal located at the animal pole in the jelly coat surrounding the egg. We measured the acute angle between the jelly canal axis and the cleavage plane for both fertilized eggs and CLA-treated unfertilized eggs. Although the acute angle lay within 10 degrees for most of the fertilized eggs, it varied widely for CLA-treated unfertilized eggs. Measurements of the diameter of blastomeres revealed that cleavage of fertilized eggs took place in the mid-plane of the egg, but that CLA-induced divisions were unequal. These results suggest that neither the orientation nor the location of the CLA-induced cleavage furrow is related to the animal-vegetal polar axis of the egg, even though the furrowing mechanism itself is not dissimilar to that in fertilized eggs.
  • Preprint
    Orientation-independent differential interference contrast microscopy
    ( 2006) Shribak, Michael ; Inoue, Shinya
    The image in a regular DIC microscope reflects the orientation of the prism shear direction and the optical path gradients in a phase specimen. If the shear direction lies parallel to the specimen boundary no contrast is generated. Also a bias retardance is generally introduced, which creates a gray background and reduces image contrast. Here we describe the theoretical foundation for a new DIC technique, which records phase gradients independently of their orientation and with the digitally generated gradient magnitude image as well as the optical path distribution image free from the gray background. Separate images can show the magnitude distribution of the optical path gradients and of the azimuths, or the two images can be combined into one picture e.g., with the brightness representing magnitudes and color showing azimuths respectively. For experimental verification of the proposed technique we investigated various specimens such as glass rods embedded in Permount, Siemens star nano-fabricated in 90-nm thick silicon oxide layer, Bovine pulmonary artery endothelial cell, etc, using regular DIC optics on a microscope equipped with a precision rotating stage. Several images were recorded with the specimen oriented in different directions, but with the prism bias unchanged, followed by digital alignment and processing of the images. The results demonstrate that the proposed DIC technique can successfully image and measure phase gradients of transparent specimens, independent of the directions of the gradient. The orientation-independent DIC data obtained can also be used to compute the quantitative distribution of specimen phase or to generate enhanced, regular DIC images with any desired shear direction. We are currently developing a new device using special DIC prisms, which allows the bias and shear directions to be switched rapidly without the need to mechanically rotate the specimen or the prism (US Patent Application 2005-0152030). With the new system an orientation independent DIC image should be obtained in a fraction of a second. A detailed description of the new system will be given in a future publication.
  • Preprint
    Microtubule dynamics in cell division : exploring living cells with polarized light microscopy
    ( 2008-04-11) Inoue, Shinya
    This Perspective is an account of my early experience while I studied the dynamic organization and behavior of the mitotic spindle and its submicroscopic filaments using polarized light microscopy. The birefringence of spindle filaments in normally dividing plant and animal cells, and those treated by various agents, revealed: A) the reality of spindle fibers and fibrils in healthy living cells; B) the labile, dynamic nature of the molecular filaments making up the spindle fibers; C) the mode of fibrogenesis and action of orienting centers; and D) force-generating properties based on the disassembly and assembly of the fibrils. These studies, which were carried out directly on living cells using improved polarizing microscopes, in fact, predicted the reversible assembly properties of isolated microtubules.
  • Article
    Quantitative orientation-independent differential interference contrast (DIC) microscopy coupled with orientation-independent Polarization microscopy
    (Cambridge University Press, 2007-08-05) Shribak, Michael ; LaFountain, James R. ; Biggs, David ; Inoue, Shinya
    Differential interference contrast (DIC) microscopy is widely used to observe structure and motion in unstained, transparent living cells and isolated organelles, producing a monochromatic shadowcast image of optical phase gradient. Polarized light microscopy (Pol) reveals structural anisotropy due to form birefringence, intrinsic birefringence, stress birefringence, etc. DIC and Pol complement each other as, for example, in a live dividing cell, the DIC image will clearly show the chromosomes while the Pol image will depict the distribution of the birefringent microtubules in the spindle. Both methods, however, have the same shortcomings: they require the proper orientation of a specimen in relation to the optical system in order to achieve best results.