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11.
Yoshifumi Kawana Raiki Yamamoto Yukira Mochida Kunio Suzuki Shigeyuki Baba Hamako Sasamoto 《Plant biotechnology reports》2007,1(4):219-226
Liquid cultures were successfully generated from cotyledons of two Sonneratia species, S. alba and S. caseolaris in Murashige and Skoog (MS) medium containing 0.1 μmol L−1 2,4-dichlorophenoxyacetic acid (2,4-D). Adventitious roots differentiated from cotyledons of S. alba. Proliferated cells were subcultured and a large volume of suspension cells was subsequently established in 100-mL flasks.
All the cytokinins tested inhibited cell proliferation. After three years of culture, the potential to differentiate was tested
as indicated by greening of the cells. Greening occurred when suspension cells were transferred to solid MS medium with and
without 0.1 μmol L−1 2,4-D. Greening was stimulated by low concentrations of the weak auxins indolebutyric acid (IBA) and naphthaleneacetic acid
(NAA) while 2,4-D stimulated late-stage greening. Abscisic acid (ABA) inhibited greening. Gibberellic acid (GA3) at 1.0 μmol L−1 stimulated callus greening and was not inhibitory even when tested at high concentrations. Cytokinins were inhibitory in
combination with 0.1 μmol L−1 of either IBA or NAA. The cause of different effects of plant hormones on growth and differentiation was discussed. Small-scale
liquid media and 24-well culture plates of solid media methods developed in this paper are suitable for the optimization of
hormonal conditions for cell proliferation and differentiation. 相似文献
12.
Junya Sato Ippei Takahashi Takashi Umeda Masashi Matsuzaka Kazuma Danjyo Ryosuke Tsuya Kazuyuki Kida Hideki Takami Shigeyuki Nakaji 《Luminescence》2011,26(6):557-564
In recent years, the effects of smoking and excessive alcohol consumption on immune function have been studied, due to a high prevalence of infection or cancer in heavy drinkers, and the combination of smoking and drinking was considered to be a carcinogenic risk. However, the effect of smoking and drinking on systemic immune function has yet to be clearly understood. In this study, we investigated neutrophil functions (reactive oxygen species (ROS) productive activity, phagocytic ability and serum opsonic activity) and their relationship with alcohol consumption or amount of smoking. In total there were 731 male and female adult subjects who participated in the Iwaki Health Promotion Project in 2005. Multiple regression analysis showed a trend of increased ROS production in male subjects and a statistically significant decrease was observed in phagocytic activity caused by smoking in female subjects. In other words, oxidative stress caused by smoking in male subjects may be involved in ROS production from neutrophils. Decreased phagocytic activity of neutrophils caused by smoking suggests that host defense functions were impaired in female subjects. A relationship between neutrophil functions and the amount of alcohol consumption was not observed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
13.
In the cultures of the alga Chlamydomonas reinhardtii, division rhythms of any length from 12 to 75 h were found at a range of different growth rates that were set by the intensity
of light as the sole source of energy. The responses to light intensity differed in terms of altered duration of the phase
from the beginning of the cell cycle to the commitment to divide, and of the phase after commitment to cell division. The
duration of the pre-commitment phase was determined by the time required to attain critical cell size and sufficient energy
reserves (starch), and thus was inversely proportional to growth rate. If growth was stopped by interposing a period of darkness,
the pre-commitment phase was prolonged corresponding to the duration of the dark interval. The duration of the post-commitment
phase, during which the processes leading to cell division occurred, was constant and independent of growth rate (light intensity)
in the cells of the same division number, or prolonged with increasing division number. It appeared that different regulatory
mechanisms operated through these two phases, both of which were inconsistent with gating of cell division at any constant
time interval. No evidence was found to support any hypothetical timer, suggested to be triggered at the time of daughter
cell release. 相似文献
14.
15.
Yuzuru Itoh Shun-ichi Sekine Shiro Suetsugu Shigeyuki Yokoyama 《Nucleic acids research》2013,41(13):6729-6738
Selenocysteine (Sec) is translationally incorporated into proteins in response to the UGA codon. The tRNA specific to Sec (tRNASec) is first ligated with serine by seryl-tRNA synthetase (SerRS). In the present study, we determined the 3.1 Å crystal structure of the tRNASec from the bacterium Aquifex aeolicus, in complex with the heterologous SerRS from the archaeon Methanopyrus kandleri. The bacterial tRNASec assumes the L-shaped structure, from which the long extra arm protrudes. Although the D-arm conformation and the extra-arm orientation are similar to those of eukaryal/archaeal tRNASecs, A. aeolicus tRNASec has unique base triples, G14:C21:U8 and C15:G20a:G48, which occupy the positions corresponding to the U8:A14 and R15:Y48 tertiary base pairs of canonical tRNAs. Methanopyrus kandleri SerRS exhibited serine ligation activity toward A. aeolicus tRNASec
in vitro. The SerRS N-terminal domain interacts with the extra-arm stem and the outer corner of tRNASec. Similar interactions exist in the reported tRNASer and SerRS complex structure from the bacterium Thermus thermophilus. Although the catalytic C-terminal domain of M. kandleri SerRS lacks interactions with A. aeolicus tRNASec in the present complex structure, the conformational flexibility of SerRS is likely to allow the CCA terminal region of tRNASec to enter the SerRS catalytic site. 相似文献
16.
Yuzuru Itoh Markus J. Bröcker Shun-ichi Sekine Dieter Söll Shigeyuki Yokoyama 《Journal of molecular biology》2014
The 21st amino acid, selenocysteine (Sec), is incorporated translationally into proteins and is synthesized on its specific tRNA (tRNASec). In Bacteria, the selenocysteine synthase SelA converts Ser-tRNASec, formed by seryl-tRNA synthetase, to Sec-tRNASec. SelA, a member of the fold-type-I pyridoxal 5′-phosphate-dependent enzyme superfamily, has an exceptional homodecameric quaternary structure with a molecular mass of about 500 kDa. Our previously determined crystal structures of Aquifex aeolicus SelA complexed with tRNASec revealed that the ring-shaped decamer is composed of pentamerized SelA dimers, with two SelA dimers arranged to collaboratively interact with one Ser-tRNASec. The SelA catalytic site is close to the dimer–dimer interface, but the significance of the dimer pentamerization in the catalytic site formation remained elusive. In the present study, we examined the quaternary interactions and demonstrated their importance for SelA activity by systematic mutagenesis. Furthermore, we determined the crystal structures of “depentamerized” SelA variants with mutations at the dimer–dimer interface that prevent pentamerization. These dimeric SelA variants formed a distorted and inactivated catalytic site and confirmed that the pentamer interactions are essential for productive catalytic site formation. Intriguingly, the conformation of the non-functional active site of dimeric SelA shares structural features with other fold-type-I pyridoxal 5′-phosphate-dependent enzymes with native dimer or tetramer (dimer-of-dimers) quaternary structures. 相似文献
17.
Kiba A Sangawa Y Ohnishi K Yao N Park P Nakayashiki H Tosa Y Mayama S Hikichi Y 《Molecular plant-microbe interactions : MPMI》2006,19(2):112-122
Pseudomonas cichorii is the major causal agent of bacterial rot of lettuce. Collapse and browning symptoms were observed in lettuce leaf tissue from 15 to 24 h after inoculation (HAI) with P. cichorii; superoxide anion generation was detected at 1 to 6 HAI; and cell death was induced at 6 HAI, reaching a maximum at approximately 9 and 12 HAI. Heterochromatin condensation and DNA laddering also were observed within 3 HAI. Pharmacological studies showed that induction of cell death and DNA laddering was closely associated with de novo protein synthesis, protein kinase, intracellular reactive oxygen species, DNase, serine protease, and caspase III-like protease. Moreover, chemicals, which inhibited the induction of cell death and DNA laddering, also suppressed the development of disease symptoms. These results suggest that apoptotic cell death might be closely associated with the development of bacterial rot caused by P. cichorii. 相似文献
18.
Ohashi K Yamazaki T Kitamura S Ohta S Izumi S Kominami S 《Biochimica et biophysica acta》2007,1770(2):231-240
A sigmoid-type dependence on the inhibitor concentration was observed in the cytochrome c reductase activity for peptide inhibitors (mastoparan and melittin), calmodulin antagonists (W-7 and tamoxifen) and monobutyltin in a reconstituted system comprised of recombinant rat neuronal nitric-oxide synthase (nNOS) and calmodulin (CaM). The increase in the concentration of CaM in the system induced a decrease in the inhibitory effect, indicating that the inhibitors might interfere with the interaction between nNOS and CaM. The changes in the fluorescence spectra of dansylated CaM caused by the addition of mastoparan, melittin and monobutyltin indicated complex formation between CaM and those compounds, which led to the decrease in the effective concentration of CaM available to nNOS. The sigmoid-type inhibition of mastoparan and melittin fit the theoretical equations quite well, assuming that two CaM molecules bind cooperatively to one nNOS homodimer. Monobutyltin, tamoxifen and W-7 were found to inhibit nNOS activity by binding to the CaM binding site of the nNOS homodimer, in addition to the binding of the inhibitors to calmodulin. These compounds inhibited the L-citrulline formation of nNOS from L-arginine, and the inhibitory effects were abrogated by raising the concentration of calmodulin. It became clear that the binding of calmodulin to nNOS can be interfered with in two ways: (1) via a decrease in the effective concentration of calmodulin caused by complex formation between the inhibitor and calmodulin, and (2) via the inhibition of the binding of calmodulin to nNOS caused by the occupation of the binding site by the inhibitor. 相似文献
19.
20.
H. Yoshida Shigeyuki Fujita Tadahiko Iizuka Toshimichi Yoshida Teruyo Sakakura 《Histochemistry and cell biology》1997,107(6):479-484
The expression of tenascin (TN) in the temporomandibular joint (TMJ) disc and synovial membrane was examined in 18 human
TMJ samples from patients with internal derangement of the TMJ and ten control specimens by an immunohistological technique
using paraffin-embedded tissue and specific anti-human TN monoclonal antibody (RCB-1). The expression of TN was observed in
all 28 samples, but it was limited to the walls of blood vessels, the perineurium, and the surface of the TMJ disc. The expression
of TN was diffuse in the stroma of mildly hypertrophic synovial membranes and focal in the surface of severely hypertrophic
synovial membranes. The clinical symptoms of internal derangement of the TMJ are thought to be related to the degree of synovitis.
The present study demonstrates that TN is expressed specifically in the portion of the TMJ synovial membrane affected with
internal derangement.
Accepted: 17 December 1996 相似文献