710 research outputs found
Orientation-independent differential interference contrast microscopy
Author Posting. © The Authors, 2006. This is the author's version of the work. It is posted here by permission of Optical Society of America for personal use, not for redistribution. The definitive version was published in Applied Optics 45 (2006): 460-469, doi:10.1364/AO.45.000460.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
Triphenyl{(E)-4-[4-(phenyldiazenyl)phenyl]-4H-1,2,4-triazol-1-yl}boron
In the title compound, C32H26BN5 or [(C14H11N5)B(C6H5)3], the B atom is approximately tetrahedrally coordinated. The diazo unit is in a trans conformation, which is generally more stable than a cis one for aromatic azo compounds. The crystal structure features very weak C—H⋯π interactions. The dihedral angles between the central benzene ring and the terminal rings in the heterocycle are 62.64, 73.54 and 61.60°
Interaction of neuron-specific K+-Cl− cotransporter, KCC2, with brain-type creatine kinase
Abstractγ-Aminobutyric acid, a major inhibitory neurotransmitter within the adult central nervous system, is also known to be excitatory at early developmental stages due to the elevated intracellular Cl− concentration. This functional change is primarily attributable to a K+-Cl− cotransporter, KCC2, the expression of which is developmentally regulated in neurons. However, little detail information is available concerning the intracellular regulation of KCC2 function. Here, we identify an interaction between KCC2 and brain-type creatine kinase by means of yeast two-hybrid screening. This interaction, which was also detected in cultured cells and brain extracts, might contribute to KCC2-mediated modulation of Cl− homeostasis
Calyculin-A induces cleavage in a random plane in unfertilized sea urchin eggs
Author Posting. © Marine Biological Laboratory, 2009. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 216 (2009): 40-44.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.This study was supported by research grants
from the JSPS (#15207013) to I. M., and facilities provided
to S. I. by the Marine Biological Laboratory, Woods Hole,
Massachusetts
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (INBOX): Part 3. Mesoscale variability of dissolved oxygen concentrations observed by multiple floats during S1-INBOX
As part of the interdisciplinary project S1-INBOX (Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment conducted around the S1 biogeochemical mooring site), we used data from more than 18 floats and a biogeochemical mooring S1 (near 30° N, 145° E) to investigate temporal and spatial changes in the shallow oxygen maximum (SOM) associated with a mesoscale cyclonic eddy. On the northern edge of the cyclonic eddy, patches (linear dimensions of 20–40 km) with relatively high oxygen concentrations were observed around the SOM. The patterns of the oxygen concentrations reflected the fact that changes of the depths of the isopycnal surfaces were caused by small disturbances associated with the eddy structure along the eddy edge. The implication is that nutrient-rich water was supplied by upward isopycnal heaving at the edge of the eddy and contributed to the formation of the high-oxygen patches. As relatively high oxygen concentrations on the same isopycnal surfaces at greater depths were sometimes observed in the region downstream of the high-oxygen patches, we suggest that the patches were advected to the downstream region. The high-oxygen water seemed to extend into the eddy core from its edge. Ageostrophic secondary circulation around the edge of the eddy might have contributed to maintenance of the high oxygen concentrations in the eddy core, and these high oxygen concentrations may have been formed during spin-up of the eddy by heaving of isopycnal surfaces
Dichlorido[1-(8-quinolyliminomethyl)-2-naphtholato]iron(III)
The FeIII ion in the title complex, [FeCl2(C20H13N2O)], has a distorted square-pyramidal coordination formed by one O atom and two N atoms from a tridentate 1-(8-quinolyliminomethyl)-2-naphtholate ligand and two Cl atoms. In the crystal structure, molecules form a column structure along the a axis through π–π stacking interactions, with centroid–centroid distances of 3.657 (1) and 3.818 (2) Å. Weak C—H⋯Cl interactions are observed between the columns
Clinical significance of the expression of connexin26 in colorectal cancer
<p>Abstract</p> <p>Background</p> <p>Connexin26 (Cx26) is one of the connexins (Cxs) family members which form gap junction channels. Cx26 is considered to be a tumor suppressor gene. However, recent studies revealed that over expression of Cx26 is associated with a poor prognosis in several human cancers. This study investigated the correlation between Cx26 expression and the clinicopathological features and P53 expression in colorectal cancer.</p> <p>Methods</p> <p>One hundred and fifty-three patients who underwent a curative resection were studied. Tissue samples were investigated by immunohistochemical staining using antibodies for Cx26 and P53. Moreover, apoptotic cells were detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) staining.</p> <p>Results</p> <p>Cx26 expression was found in 83 cases (54.2%) and P53 expression in 71 cases (46.4%). A correlation was observed between the Cx26 expression and recurrence, histology, and p53 expression (P < 0.05). Cx26 positive tumors had significantly longer survival than Cx26 negative tumors (P < 0.05). A multivariate Cox analysis demonstrated that Cx26 expression was an independent prognostic factor (P < 0.05). However, no significant correlation was observed between Cx26 and AI.</p> <p>Conclusion</p> <p>This study suggests that Cx26 expression is an independent prognostic factor in patients that undergo a curative resection of colorectal cancer.</p
Prospect for Future MeV Gamma-ray Active Galactic Nuclei Population Studies
While the X-ray, GeV gamma-ray, and TeV gamma-ray skies have been extensively
studied, the MeV gamma-ray sky is not well investigated after the Imaging
Compton Telescope (COMPTEL) scanned the sky about two decades ago. In this
paper, we investigate prospects for active galactic nuclei population studies
with future MeV gamma-ray missions using recent spectral models and luminosity
functions of Seyfert and flat spectrum radio quasars (FSRQs). Both of them are
plausible candidates as the origins of the cosmic MeV gamma-ray background. If
the cosmic MeV gamma-ray background radiation is dominated by non-thermal
emission from Seyferts, the sensitivity of 10^-12 erg cm^-2 s^-1 is required to
detect several hundred Seyferts in the entire sky. If FSRQs make up the cosmic
MeV gamma-ray background, the sensitivity of ~4 x 10^-12 erg cm^-2 s^-1 is
required to detect several hundred FSRQs following the recent FSRQ X-ray
luminosity function. However, based on the latest FSRQ gamma-ray luminosity
function, with which FSRQs can explain up to ~30% of the MeV background, we can
expect several hundred FSRQs even with the sensitivity of 10^-11 erg cm^-2 s^-1
which is almost the same as the sensitivity goal of the next generation MeV
telescopes.Comment: 9 pages, 5 figures, accepted for publication in PAS
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