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81.
The present study examines the indispensability of a nucleus or nucleus-deriving factors in the induction of cleavage in Xenopus eggs by testing cleavage in Xenopus eggs fertilized with ultraviolet (UV)-damaged sperm and deprived of the female nucleus. These eggs, which contain only one UV-damaged nucleus with one set of centrioles, undergo unique cleavages. Cleavage takes place in only one of the two blastomeres formed by the immediately preceding cleavage. Histologically, only one nucleus, which does not appear to be organized into typical chromosomes, is found in one of the two blastomeres formed by the immediately preceding cleavage. The typical bipolar spindle and the diastema, or a slit of astral rays, are formed in the blastomere that contains the nucleus. By contrast, only asters lacking the spindle and the diastema are formed in the remaining blastomeres, which do not contain a nucleus. The same results are obtained in eggs that contain two UV-damaged nuclei with one set of centrioles. In these eggs, cleavage appears to occur in one or two blastomeres that contain either or both of the nuclei and one bipolar spindle. In eggs that contain one intact and one UV-damaged nuclei, cleavage takes place quite normally with each blastomere containing one nucleus or one set of chromosomes as well as one bipolar spindle. Thus, there is a very close correlation between the presence of a nucleus and the formation of the mitotic spindle, the diastema and the cleavage furrow in the blastomeres of Xenopus embryos. We conclude that the presence of a nucleus or nucleus-deriving factors is indispensable for the formation of the bipolar spindle, the diastema and the cleavage furrow in the blastomeres of the Xenopus embryos. 相似文献
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83.
Yuping Li Tomohiro Nishimura Kiichiro Teruya Tei Maki Takaaki Komatsu Takeki Hamasaki Taichi Kashiwagi Shigeru Kabayama Sun-Yup Shim Yoshinori Katakura Kazuhiro Osada Takeshi Kawahara Kazumichi Otsubo Shinkatsu Morisawa Yoshitoki Ishii Zbigniew Gadek Sanetaka Shirahata 《Cytotechnology》2002,40(1-3):139-149
Reactive oxygen species (ROS) cause irreversible damage to biological macromolecules, resulting in many diseases. Reduced
water (RW) such as hydrogen-rich electrolyzed reduced water and natural reduced waters like Hita Tenryosui water in Japan
and Nordenau water in Germany that are known to improve various diseases, could protect a hamster pancreatic β cell line,
HIT-T15 from alloxan-induced cell damage. Alloxan, a diabetogenic compound, is used to induce type 1 diabetes mellitus in
animals. Its diabetogenic effect is exerted via the production of ROS. Alloxan-treated HIT-T15 cells exhibited lowered viability,
increased intracellular ROS levels, elevated cytosolic free Ca2+ concentration, DNA fragmentation, decreased intracellular ATP levels and lowering of glucose-stimulated release of insulin.
RW completely prevented the generation of alloxan-induced ROS, increase of cytosolic Ca2+ concentration, decrease of intracellular ATP level, and lowering of glucose-stimulated insulin release, and strongly blocked
DNA fragmentation, partially suppressing the lowering of viability of alloxan-treated cells. Intracellular ATP levels and
glucose-stimulated insulin secretion were increased by RW to 2–3.5 times and 2–4 times, respectively, suggesting that RW enhances
the glucose-sensitivity and glucose response of β-cells. The protective activity of RW was stable at 4 °C for over a month,
but was lost by autoclaving. These results suggest that RW protects pancreatic β-cells from alloxan-induced cell damage by
preventing alloxan-derived ROS generation. RW may be useful in preventing alloxan-induced type 1-diabetes mellitus.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
84.
K Hara T Kashiwagi Y Ohtsu K Masunaga Y Akasu-Tsuji N Tsumura H Kato J Iwahashi N Hamada M Toyoda T Toyoda 《Microbiology and immunology》2001,45(10):717-720
An epidemic of aseptic meningitis caused by human echovirus 9 (E-9) occurred in the summer of 1997 in northern Kyushu, Japan. Sequences of genome position 2504-3358, which encoded a part of VP1, of the nine isolated viruses were determined. An RGD motif and B-C loop were found in all. They were almost identical and closely related to the virulent strain Barty. 相似文献
85.
Yoichiro Fujioka Shinya Nishide Toyoyuki Ose Tadaki Suzuki Izumi Kato Hideo Fukuhara Mari Fujioka Kosui Horiuchi Aya O. Satoh Prabha Nepal Sayaka Kashiwagi Jing Wang Mika Horiguchi Yuko Sato Sarad Paudel Asuka Nanbo Tadaaki Miyazaki Hideki Hasegawa Yusuke Ohba 《Cell host & microbe》2018,23(6):809-818.e5
86.
87.
Kazuhiro Kashiwagi Tomoaki Shigeta Hiroaki Imataka Takuhiro Ito Shigeyuki Yokoyama 《Journal of structural and functional genomics》2016,17(1):33-38
Tight control of protein synthesis is necessary for cells to respond and adapt to environmental changes rapidly. Eukaryotic translation initiation factor (eIF) 2B, the guanine nucleotide exchange factor for eIF2, is a key target of translation control at the initiation step. The nucleotide exchange activity of eIF2B is inhibited by the stress-induced phosphorylation of eIF2. As a result, the level of active GTP-bound eIF2 is lowered, and protein synthesis is attenuated. eIF2B is a large multi-subunit complex composed of five different subunits, and all five of the subunits are the gene products responsible for the neurodegenerative disease, leukoencephalopathy with vanishing white matter. However, the overall structure of eIF2B has remained unresolved, due to the difficulty in preparing a sufficient amount of the eIF2B complex. To overcome this problem, we established the recombinant expression and purification method for eIF2B from the fission yeast Schizosaccharomyces pombe. All five of the eIF2B subunits were co-expressed and reconstructed into the complex in Escherichia coli cells. The complex was successfully purified with a high yield. This recombinant eIF2B complex contains each subunit in an equimolar ratio, and the size exclusion chromatography analysis suggests it forms a heterodecamer, consistent with recent reports. This eIF2B increased protein synthesis in the reconstituted in vitro human translation system. In addition, disease-linked mutations led to subunit dissociation. Furthermore, we crystallized this functional recombinant eIF2B, and the crystals diffracted to 3.0 Å resolution. 相似文献
88.
Motif-programming is a method for creating artificial proteins by combining functional peptide motifs in a combinatorial manner. This method is particularly well suited for developing liaison molecules that interface between cells and inorganic materials. Here we describe our creation of artificial proteins through the programming of two motifs, a natural cell attachment motif (RGD) and an artificial Ti-binding motif (minTBP-1). The created proteins were found to reversibly bind Ti and to bind MC3T3-E1 osteoblast-like cells. Moreover, although the interaction with Ti was not covalent, the proteins recapitulated several functions of fibronectin, and thus, could serve as an artificial ECM on Ti materials. Because this motif-programming system could be easily extended to create artificial proteins having other biological functions and material specificities, it should be highly useful for application to tissue engineering and regenerative medicine. 相似文献
89.