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991.
992.
Masanori Sakaguchi Karam Kim Lily Mae Yee Yu Yoshiko Hashikawa Yukiko Sekine Yuki Okumura Masako Kawano Masanobu Hayashi Deependra Kumar Edward S. Boyden Thomas J. McHugh Yasunori Hayashi 《PloS one》2015,10(6)
The optogenetic manipulation of light-activated ion-channels/pumps (i.e., opsins) can reversibly activate or suppress neuronal activity with precise temporal control. Therefore, optogenetic techniques hold great potential to establish causal relationships between specific neuronal circuits and their function in freely moving animals. Due to the critical role of the hippocampal CA1 region in memory function, we explored the possibility of targeting an inhibitory opsin, ArchT, to CA1 pyramidal neurons in mice. We established a transgenic mouse line in which tetracycline trans-activator induces ArchT expression. By crossing this line with a CaMKIIα-tTA transgenic line, the delivery of light via an implanted optrode inhibits the activity of excitatory CA1 neurons. We found that light delivery to the hippocampus inhibited the recall of a contextual fear memory. Our results demonstrate that this optogenetic mouse line can be used to investigate the neuronal circuits underlying behavior. 相似文献
993.
Shinji Miwa Shuya Yano Hiroaki Kimura Mako Yamamoto Makoto Toneri Yasunori Matsumoto Fuminari Uehara Yukihiko Hiroshima Takashi Murakami Katsuhiro Hayashi Norio Yamamoto Michael Bouvet Toshiyoshi Fujiwara Hiroyuki Tsuchiya Robert M Hoffman 《Cell cycle (Georgetown, Tex.)》2015,14(4):621-629
Essentially every population of cancer cells within a tumor is heterogeneous, especially with regard to chemosensitivity and resistance. In the present study, we utilized the fluorescence ubiquitination-based cell cycle indicator (FUCCI) imaging system to investigate the correlation between cell-cycle behavior and apoptosis after treatment of cancer cells with chemotherapeutic drugs. HeLa cells expressing FUCCI were treated with doxorubicin (DOX) (5 μM) or cisplatinum (CDDP) (5 μM) for 3 h. Cell-cycle progression and apoptosis were monitored by time-lapse FUCCI imaging for 72 h. Time-lapse FUCCI imaging demonstrated that both DOX and CDDP could induce cell cycle arrest in S/G2/M in almost all the cells, but a subpopulation of the cells could escape the block and undergo mitosis. The subpopulation which went through mitosis subsequently underwent apoptosis, while the cells arrested in S/G2/M survived. The present results demonstrate that chemoresistant cells can be readily identified in a heterogeneous population of cancer cells by S/G2/M arrest, which can serve in future studies as a visible target for novel agents that kill cell-cycle-arrested cells. 相似文献
994.
995.
996.
Masayuki Yamashita Eriko Nitta Go Nagamatsu Yoshiko Matsumoto Ikushima Kentaro Hosokawa Fumio Arai Toshio Suda 《Biochemical and biophysical research communications》2013
Nucleostemin is a nucleolar protein known to play a variety of roles in cell-cycle progression, apoptosis inhibition, and DNA damage protection in embryonic stem cells and tissue stem cells. However, the role of nucleostemin in hematopoietic stem cells (HSCs) is yet to be determined. Here, we identified an indispensable role of nucleostemin in mouse HSCs. Depletion of nucleostemin using short hairpin RNA strikingly impaired the self-renewal activity of HSCs both in vitro and in vivo. Consistently, nucleostemin depletion triggered apoptosis rather than cell-cycle arrest in HSCs. Furthermore, DNA damage accumulated during cultivation upon depletion of nucleostemin. The impaired self-renewal activity of HSCs induced by nucleostemin depletion was partially rescued by p53 deficiency but not by p16Ink4a or p19Arf deficiency. Taken together, our study demonstrates that nucleostemin protects HSCs from DNA damage accumulation and is required for the maintenance of HSCs. 相似文献
997.
998.
Hitoshi Obata Michiaki Tatsuno Tai Tokuyama Yasunori Nitta Masanosuke Takagi Keitaro Hiromi 《Bioscience, biotechnology, and biochemistry》2013,77(5):1021-1023
The reduction of 2, 6-dichlorophenolindophenol by triose reductone was studied in a wide pH range (pH 2~11), using a stopped-flow apparatus. The apparent first-order rate constant, kapp, and the second-order rate constant, k, were obtained. The k-pH profile resembles that of l-ascorbic acid, though the rate of l-ascorbic acid is considerably larger than that of triose reductone. Determination of triose reductone by stopped-flow method is possible, even in the presence of various organic substances. 相似文献
999.
Setsuro Matsushita Masayo Kobayashi Yuki Nitta 《Bioscience, biotechnology, and biochemistry》2013,77(6):817-824
The inactivation of the enzymes by linoleic acid hydroperoxides (LAHPO) was tested in connection with the toxicity of oxidized fat. At the same time, the inhibition of enzyme activities by linoleic acid was also tested. Ribonuclease (RNase), trypsin, chymotrypsin and pepsin which are considered to be simple proteins and not to be SH-enzymes were chosen as the enzymes. RNase was largely inhibited by LAHPO, but the other enzymes were inhibited by linoleic acid as well as LAHPO. The inhibition of each enzyme occurred at different pH. This fact may show that the inhibition occurs by binding of such hydrophobic compounds to the enzyme, and that the surface exposition of hydrophobic region may depend on the pH. Not only the reaction of some specific amino acid residue in the protein molecules with LAHPO, but also the binding of these hydrophobic compounds must be remembered in the mechanism of inhibition. 相似文献
1000.
Shuichi Kaminogawa Norihiro Azuma Yasunori Suzuki 《Bioscience, biotechnology, and biochemistry》2013,77(12):3035-3040
A prolidase with a molecular weight of 43,000 was purified to homogeneity from a cell-free extract of Streptococcus cremoris H61. The optimum pH of the enzyme was in the range of 6.5 to 7.5. The hydrolyzing activity was specific for dipeptides of the X-Pro type. Kinetic constants for 4 dipeptides (Leu-Pro, Phe-Pro, Val-Pro and Ala-Pro) were estimated. Km values were not very different for these substrates, but Vmax values were quite different (Leu-Pro > Phe-Pro, Val-Pro > Ala-Pro). The enzyme was activated by cobalt ion and inactivated by metal-chelating agents or with 2-mercaptoethanol. 相似文献