18 research outputs found
Tolerance of the freeze-dried mouse sperm nucleus to temperatures ranging from −196 °C to 150 °C
It has long been believed that tolerance against extreme environments is possible only for ‘lower’ groups, such as archaea, bacteria or tardigrades, and not for more ‘advanced’ species. Here, we demonstrated that the mammalian sperm nucleus also exhibited strong tolerance to cold and hot temperatures. When mouse spermatozoa were freeze-dried (FD), similar to the anhydrobiosis of Tardigrades, all spermatozoa were ostensibly dead after rehydration. However, offspring were obtained from recovered FD sperm nuclei, even after repeated treatment with conditions from liquid nitrogen to room temperature. Conversely, when FD spermatozoa were heated at 95 °C, although the birth rate was decreased with increasing duration of the treatment, offspring were obtained even for FD spermatozoa that had been heat-treated for 2 h. This period was improved up to 6 h when glucose was replaced with trehalose in the freeze-drying medium, and the resistance temperature was extended up to 150 °C for short periods of treatment. Randomly selected offspring grew into healthy adults. Our results suggest that, when considering the sperm nucleus/DNA as the material that is used as a blueprint of life, rather than cell viability, a significant tolerance to extreme temperatures is present even in ‘higher’ species, such as mammals
Characterization of monocyte/macrophage subsets in the skin and peripheral blood derived from patients with systemic sclerosis
Mammalian Fat and Dachsous cadherins regulate apical membrane organization in the embryonic cerebral cortex
Compartmentalization of the plasma membrane in a cell is fundamental for its proper functions. In this study, we present evidence that mammalian Fat4 and Dachsous1 cadherins regulate the apical plasma membrane organization in the embryonic cerebral cortex. In neural progenitor cells of the cortex, Fat4 and Dachsous1 were concentrated together in a cell–cell contact area positioned more apically than the adherens junction (AJ). These molecules interacted in a heterophilic fashion, affecting their respective protein levels. We further found that Fat4 associated and colocalized with the Pals1 complex. Ultrastructurally, the apical junctions of the progenitor cells comprised the AJ and a stretch of plasma membrane apposition extending apically from the AJ, which positionally corresponded to the Fat4–Dachsous1-positive zone. Depletion of Fat4 or Pals1 abolished this membrane apposition. These results highlight the importance of the Fat4–Dachsous1–Pals1 complex in organizing the apical membrane architecture of neural progenitor cells
Single Event Tolerance of X-ray SOI Pixel Sensors
We evaluate the single event tolerance of the X-ray silicon-on-insulator
(SOI) pixel sensor named XRPIX, developed for the future X-ray astronomical
satellite FORCE. In this work, we measure the cross-section of single event
upset (SEU) of the shift register on XRPIX by irradiating heavy ion beams with
linear energy transfer (LET) ranging from 0.022 MeV/(mg/cm2) to 68
MeV/(mg/cm2). From the SEU cross-section curve, the saturation cross-section
and threshold LET are successfully obtained to be and ,
respectively. Using these values, the SEU rate in orbit is estimated to be
0.1 event/year primarily due to the secondary particles induced by
cosmic-ray protons. This SEU rate of the shift register on XRPIX is negligible
in the FORCE orbit.Comment: 9 pages, 5 figures, accepted for publication in JATI
Mechanosensitive EPLIN-dependent remodeling of adherens junctions regulates epithelial reshaping
The F-actin–stabilizing protein EPLIN is a mechanosensitive regulator of adherens junction remodeling in epithelial cells
X-ray Radiation Damage Effects on Double-SOI Pixel Detectors for the Future Astronomical Satellite "FORCE"
We have been developing the monolithic active pixel detector "XRPIX" onboard
the future X-ray astronomical satellite "FORCE". XRPIX is composed of CMOS
pixel circuits, SiO2 insulator, and Si sensor by utilizing the
silicon-on-insulator (SOI) technology. When the semiconductor detector is
operated in orbit, it suffers from radiation damage due to X-rays emitted from
the celestial objects as well as cosmic rays. From previous studies, positive
charges trapped in the SiO2 insulator are known to cause the degradation of the
detector performance. To improve the radiation hardness, we developed XRPIX
equipped with Double-SOI (D-SOI) structure, introducing an additional silicon
layer in the SiO2 insulator. This structure is aimed at compensating for the
effect of the trapped positive charges. Although the radiation hardness to
cosmic rays of the D-SOI detectors has been evaluated, the radiation effect due
to the X-ray irradiation has not been evaluated. Then, we conduct an X-ray
irradiation experiment using an X-ray generator with a total dose of 10 krad at
the SiO2 insulator, equivalent to 7 years in orbit. As a result of this
experiment, the energy resolution in full-width half maximum for the 5.9 keV
X-ray degrades by 17.8 2.8% and the dark current increases by 89
13%. We also investigate the physical mechanism of the increase in the dark
current due to X-ray irradiation using TCAD simulation. It is found that the
increase in the dark current can be explained by the increase in the interface
state density at the Si/SiO2 interface.Comment: 15 pages, 12 figures, accepted for publication in Journal of
Astronomical Telescopes, Instruments, and System