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排序方式: 共有107条查询结果,搜索用时 15 毫秒
81.
82.
83.
SUPERMAN regulates floral whorl boundaries through control of auxin biosynthesis 总被引:1,自引:0,他引:1
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Yifeng Xu Nathanaël Prunet Eng‐Seng Gan Yanbin Wang Darragh Stewart Frank Wellmer Jiangbo Huang Nobutoshi Yamaguchi Yoshitaka Tatsumi Mikiko Kojima Takatoshi Kiba Hitoshi Sakakibara Thomas P Jack Elliot M Meyerowitz Toshiro Ito 《The EMBO journal》2018,37(11)
Proper floral patterning, including the number and position of floral organs in most plant species, is tightly controlled by the precise regulation of the persistence and size of floral meristems (FMs). In Arabidopsis, two known feedback pathways, one composed of WUSCHEL (WUS) and CLAVATA3 (CLV3) and the other composed of AGAMOUS (AG) and WUS, spatially and temporally control floral stem cells, respectively. However, mounting evidence suggests that other factors, including phytohormones, are also involved in floral meristem regulation. Here, we show that the boundary gene SUPERMAN (SUP) bridges floral organogenesis and floral meristem determinacy in another pathway that involves auxin signaling. SUP interacts with components of polycomb repressive complex 2 (PRC2) and fine‐tunes local auxin signaling by negatively regulating the expression of the auxin biosynthesis genes YUCCA1/4 (YUC1/4). In sup mutants, derepressed local YUC1/4 activity elevates auxin levels at the boundary between whorls 3 and 4, which leads to an increase in the number and the prolonged maintenance of floral stem cells, and consequently an increase in the number of reproductive organs. Our work presents a new floral meristem regulatory mechanism, in which SUP, a boundary gene, coordinates floral organogenesis and floral meristem size through fine‐tuning auxin biosynthesis. 相似文献
84.
Satoshi Numazawa Masa-Aki Shinoki Hisatomi Ito Takemi Yoshida Yukio Kuroiwa 《Journal of cellular physiology》1994,160(1):113-120
Human leukemia K562 cell differentiation induction by naturally occurring bufadienolides purified from the Chinese drug Senso and synthetic bufalin derivatives was examined by a nitro blue tetrazolium reduction assay. Bufalin showed the strongest activity among all the bufadienolides tested in this study. The degree of the induction of nitro blue diformazan positive cells by the bufadienolides correlated well with their inhibitory activities against Na+, K+ -ATPase prepared from K562 cells in vitro. N+, K+ -ATPases from a variant K562 clone (ouabain resistant, OuaR) and murine leukemia cell line M1-T22, which were insensitive to the bufadienolides in terms of growth inhibition and cell differentiation, appeared to be refractory to bufalin in vitro. A binding study of 3H-bufalin and 3H-ouabain revealed that saturated levels of both ligands associated with K562 cells were virtually similar; however, affinity of 3H-bufalin was considerably higher than 3H-ouabain. The saturated level of 3H-bufalin observed in the OuaR cells was approximately half of that observed in K562 cells without a change in its affinity. Association of 3H-bufalin with K562 cells was completely blocked by pretreatment of the cells with cold ouabain at concentrations saturating the binding sites. These results suggest that bufalin acts on the cells by binding to sites on the cell membrane which also bind ouabain. It is thus proposed that N+, K+ -ATPase inhibition is closely related to the initiation process in the induction of K562 cell differentiation induced by bufalin. © 1994 Wiley-Liss, Inc. 相似文献
85.
Effect of endothelin-1 and chemically induced hypoxia on Na+−K+−Cl− cotransport activity in cultured rat brain capillary endothelial cells was examined by using86Rb+ as a tracer for K+; bumetanide-sensitive K+ uptake was defined as Na+−K+−Cl− cotransport activity. Endothelin-1, phorbol 12-myristate 13-acetate (PMA), or thapsigargin increased Na+−K+−Cl− cotransport activity. A protein kinase C inhibitor, bisindolylmaleimide, inhibited PMA- and endothelin-1- (but not thapsigargin-)
induced Na+−K+−Cl− cotransport activity, indicating the presence of both protein kinase C-dependent regulatory mechanisms and protein kinase
C-independent mechanisms which involve intracellular Ca2+. Oligomycin, sodium azide, or antimycin A increased Na+−K+−Cl− cotransport activity by 80–200%. Oligomycin-induced Na+−K+−Cl− cotransport activity was reduced by an intracellular Ca2+ chelator (BAPTA/AM) but not affected by bisindolylmaleimide, suggesting the involvement of intracellular Ca2+, and not protein kinase C, in hypoxia-induced Na+−K+−Cl− cotransport activity.
Portions were presented at “27th Annual Meeting, The American Society for Neurochemistry” Philadelphia, Pennsylvania, March
2–6, 1996. 相似文献
86.
Naoki Miyamoto Miho Yoshimura Yuji Okubo Kayo Suzuki-Nagata Takeshi Tsumuraya Nobutoshi Ito Ikuo Fujii 《Bioorganic & medicinal chemistry》2018,26(8):1412-1417
Catalytic antibody 7B9, which was elicited against p-nitrobenzyl phosphonate transition-state analogue (TSA) 1, hydrolyzes a wide range of p-nitrobenzyl monoesters and thus shows broad substrate tolerance. To reveal the molecular basis of this substrate tolerance, the 7B9 Fab fragment complexed with p-nitrobenzyl ethylphosphonate 2 was crystallized and the three-dimensional structure was determined. The crystal structure showed that the strongly antigenic p-nitrobenzyl moiety occupied a relatively shallow antigen-combining site and therefore the alkyl moiety was located outside the pocket. These results support the observed broad substrate tolerance of 7B9 and help rationalize how 7B9 can catalyze various p-nitrobenzyl ester derivatives. The crystal structure also showed that three amino acid residues (AsnH33, SerH95, and ArgL96) were placed in key positions to form hydrogen bonds with the phosphonate oxygens of the transitions-state analogue. In addition, the role of these amino acid residues was examined by site-directed mutagenesis to alanine: all mutants (AsnH33Ala, SerH95Ala, and ArgL96Ala) showed no detectable catalytic activity. Coupling the findings from our structural studies with these mutagenesis results clarified the structural basis of the observed broad substrate tolerance of antibody 7B9-catalyzed hydrolyses. Our findings provide new strategies for the generation of catalytic antibodies that accept a broad range of substrates, aiding their practical application in synthetic organic chemistry. 相似文献
87.
Synaptic activity causes reductions in cleft [Ca(2+)] that may impact subsequent synaptic efficacy. Using modified patch-clamp techniques to record from single neocortical nerve terminals, we report that physiologically relevant reductions of extracellular [Ca(2+)] ([Ca(2+)](o)) activate voltage-dependent outward currents. These outward currents are carried by a novel nonselective cation (NSC) channel that is indirectly inhibited by various extracellular agents (rank order potency, Gd(3+) > spermidine > Ca(2+) > Mg(2+), typical for [Ca(2+)](o) receptors). The identification of a Ca(2+) sensor-NSC channel pathway establishes the existence of a mechanism by which presynaptic terminals can detect and respond to reductions in cleft [Ca(2+)]. Activation of NSC channels by falls in [Ca(2+)](o) would be expected during periods of high activity in the neocortex and may modulate the excitability of the presynaptic terminal. 相似文献
88.
Mitsuaki Sato Shinya Maekawa Nobutoshi Komatsu Akihisa Tatsumi Mika Miura Masaru Muraoka Yuichiro Suzuki Fumitake Amemiya Shinichi Takano Mitsuharu Fukasawa Yasuhiro Nakayama Tatsuya Yamaguchi Tomoyoshi Uetake Taisuke Inoue Tadashi Sato Minoru Sakamoto Atsuya Yamashita Kohji Moriishi Nobuyuki Enomoto 《Journal of virology》2015,89(11):6105-6116
89.
Characterization of a Facultatively Psychrophilic Bacterium, Vibrio rumoiensis sp. nov., That Exhibits High Catalase Activity 总被引:1,自引:0,他引:1
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Isao Yumoto Hideaki Iwata Tomoo Sawabe Keisuke Ueno Nobutoshi Ichise Hidetoshi Matsuyama Hidetoshi Okuyama Kosei Kawasaki 《Applied microbiology》1999,65(1):67-72
A novel facultatively psychrophilic bacterium, strain S-1, which exhibits extraordinarily high catalase activity was isolated from the drain pool of a fish product processing plant that uses H2O2 as a bleaching and microbicidal agent. The catalase activity of the isolate was 1 or 2 orders of magnitude higher than those of Corynebacterium glutamicum, Staphylococcus aureus, Pseudomonas fluorescens, and five other species tested in this study. The strain seemed to possess only one kind of catalase, according to the results of polyacrylamide gel electrophoresis of the cell extract. The optimum temperature for catalase activity was about 30°C, which was about 20°C lower than that for bovine catalase activity. Electron microscopic observation revealed that the surface of the microorganism was covered by blebs. Although the isolate was nonflagellated, its taxonomic position on the basis of physiological and biochemical characteristics and analysis of 16S rRNA sequence and DNA-DNA relatedness data indicated that strain S-1 is a new species belonging to the genus Vibrio. Accordingly, we propose the name Vibrio rumoiensis. The type strain is S-1 (FERM P-14531). 相似文献
90.
Nobutoshi Kawai Toshifumi Yamamoto Hideko Yamamoto Richard M. McCarron Maria Spatz 《Journal of neurochemistry》1995,65(4):1588-1596
Abstract: The effect of endothelins (ET-1 and ET-3) on 86Rb+ uptake as a measure of K+ uptake was investigated in cultured rat brain capillary endothelium. ET-1 or ET-3 dose-dependently enhanced K+ uptake (EC50 = 0.60 ± 0.15 and 21.5 ± 4.1 nM, respectively), which was inhibited by the selective ETA receptor antagonist BQ 123 (cyclo-d -Trp-d -Asp-Pro-d -Val-Leu). Neither the selective ETB agonists IRL 1620 [N-succinyl-(Glu9,-Ala11,15)-ET-1] and sarafotoxin S6c, nor the ETB receptor antagonist IRL 1038 [(Cys11,Cys15)-ET-1] had any effect on K+ uptake. Ouabain (inhibitor of Na+,K+-ATPase) and bumetanide (inhibitor of Na+-K+-Cl? cotransport) reduced (up to 40% and up to 70%, respectively) the ET-1-stimulated K+ uptake. Complete inhibition was seen with both agents. Phorbol 12-myristate 13-acetate (PMA), activator of protein kinase C (PKC), stimulated Na+,K+-ATPase and Na+-K+-Cl? cotransport. ET-1-but not PMA-stimulated K+ uptake was inhibited by 5-(N-ethyl-N-isopropyl)amiloride (inhibitor of Na+/H+ exchange system), suggesting a linkage of Na+/H+ exchange with ET-1-stimulated Na+,K+-ATPase and Na+-K+-Cl? cotransport activity that is not mediated by PKC. 相似文献