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881.
Genetic identification of FIN2, a far red light-specific signaling component of
Arabidopsis thaliana 总被引:5,自引:3,他引:2
Moon Soo Soh Sung Hyun Hong Hiroko Hanzawa Masaki Furuya Hong Gil Nam 《The Plant journal : for cell and molecular biology》1998,16(4):411-419
Phytochrome A (PhyA) mediates most, if not all various plant responses to far-red (FR) light. Here, we report a novel genetic mutation that impairs a variety of responses in the PhyA-signaling pathway of Arabidopsis thaliana . The mutation was isolated by screening seedlings that show reduced sensitivity to continuous far-red (FRc) light irradiation, but not to continuous red (Rc) light irradiation. The mutation named fin2–1 is not allelic to a PHYA mutation. Furthermore, immunoblot analysis indicated that the amount of the phytochrome A apoprotein in the fin2–1 mutant was comparable to that in wild type. Seedling of the fin2–1 mutant showed defects in hypocotyl growth inhibition and apical hook and cotyledon opening in FRc light but not in Rc light. The results showed that the mutation occurred in a downstream signaling component potentially specific to PhyA. Other PhyAmediated responses such as FR-preconditioned blocking of greening, anthocyanin accumulation, reduction of gravitropic response, and expression of the CAB and CHS genes were impaired by the fin2–1 mutation: the degree of the mutant effect on the responses was variable. However, FR light-mediated seed germination and photoperiodic flowering responses were not affected significantly in the mutant. These results showed that FIN2 defines an upstream branch point in the PhyA signaling pathway. 相似文献
882.
Up-Dong Yeo Woong-Young Soh Naoki Nakagawa Naoki Sakurai Kazuyoshi Takeda 《Journal of Plant Biology》1998,41(3):219-226
To clarify a low level of cellulose biosynthesis of thein vitro cultured cells, the effects of several biochemical factors such as carbon sources (sucrose, maltose, and UDPG), antioxidants
(ascorbic acid and glutathione) and physical factors such as artificial pressure, high gravity, on the cellulose production
in barley callus and suspension cultures were investigated. In the suspension culture of two barley strains, the supplement
of different concentrations (0, 1.5, 3.0, and 4.5%) of sucrose or maltose into the medium for 30 days did not promote the
cellulose production and 4.5% of sugar supplement was rather inhibitory in one strain. However, in the presence of sucrose
at 3%, UDPG (3 or 10 mM) supplement, as a precursor for cellulose, promoted 1.2–13 fold of the production in two strains.
A low concentration (3 mM) of ascorbic acid and glutathione promoted 1.5 and 1.2 fold of the production in two strains, respectively.
These results suggest that low cellulose biosynthesis of thein vitro cultured cells is due to a decreased level of the UDPG in the cytosol, and that the oxidative condition of external medium
impedes cellulose synthesis in some manners. Artificial pressure applied to the callus promoted 1.4 fold of the cellulose
production. High gravity (5,000 or 10,000g) applied to the suspension-cultured cells by centrifugation did not cause a substantial change. 相似文献
883.
In order to investigate the effect of ABA on secondary embryogenesis from somatic embryos inAralia cordata Thunb., embryogenic callus and somatic embryos were induced from inflorescence on solid MS basal medium supplemented with 1.5 mg/L 2,4-D after eight weeks without subculture. For mass production of somatic embryos, embryogenic cell clumps were maintained in liquid MS medium supplemented with 1.0 mg/L 2,4-D, and then transferred to 2, 4-D-free medium. When developing embryos at various stages were cultured separately in liquid medium with ABA (0 to 2.0 mg/L) for three weeks, and then cultured in ABA-free liquid medium for two weeks, torpedo-shaped embryos exhibited secondary embryogenesis of 65.9% in only 0.2 mg/L ABA pretreatment. Cotyledonary embryos in cultures by 0.2, 0.5 and 1.0 mg/L ABA pretreatment also exhibited secondary embryogenesis (73%, 9.4% and 6.0%, respectively). However, globular and heart-shaped somatic embryos treated with ABA did not form secondary embryos on their hypocotyl surfaces. When cotyledonary embryos were cultured in ABA-free medium or 0.2 mg/L ABA treated medium for three weeks, and then in ABA-free liquid medium for 6 weeks, the germination frequency was lower in medium with 0.2 mg/L ABA (45.9%) than in hormone-free medium (56.8%). This result seems to be related to the high frequency of secondary embryogenesis. It is suggested that secondary embryogenesis by ABA application depends upon the stage of embryo cultured and the ABA concentration. 相似文献
884.
Spathoglottis plicata seeds were encapsulated in 4-mm-diameter capsules of alginate-chitosan or alginate-gelatin and infected with the mycorrhizal
fungus Rhizoctonia AM9. The encapsulated seeds were placed directly on Rhizoctonia culture. About 66% of the seeds encapsulated in sucrose-free chitosan-alginate established a symbiotic relationship with
the mycorrhizal fungus after co-culturing for 2 weeks. The highest percentage of infection observed was about 84%. Addition
of sucrose or using gelatin-alginate for encapsulation reduced the percentage of infection by about half. The growth of Rhizoctonia AM9 in sucrose-free alginate, chitosan and gelatin was found to be minimal. The advantages of germinating orchid seeds, encapsulated
in sucrose-free polymers, through mycorrhizal infection is discussed.
Received: 19 February 1998 / Revision received: 8 May 1998 / Accepted: 20 May 1998 相似文献
885.
I Sohár 《Acta biologica Hungarica》1991,42(1-3):183-201
Two weeks of immobilization in shortened state caused 50% decrease in muscle mass and an increase in lysosomal proteinase activities. In this study causes of elevated protease activities in muscle are studied. Many factors could play a role in these elevated proteinase activities. We have found that redox state, ATP content, fuel supply and glucocorticoid receptor number were important in this period. Testosterone, insulin or proteinase inhibitors were not proved to play role in elevated proteinase activities. These practical results are explained by the results achieved in other types of cells. We conclude that changes in redox potential and/or oxygen free radical content of muscle elements can cause a post-translational covalent modification of cysteine proteinases and -SH dependent metalloproteinases, leading thereby to their activation. Lysosomal cysteine proteinases can activate procathepsin D that can damage lysosomal cysteine proteinase inhibitors and in another path it activates procathepsin B, L and H reversely. This feed-back regulation and the activation of cysteine proteinases by metalloproteinases might accelerate the proteinase activities in skeletal muscles. 相似文献
886.
Accurate 1H, 15N, and 13C chemical shift assignments were determined for staphylococcal nuclease H124L (in the absence of inhibitor or activator ion). Backbone 1H and 15N assignments, obtained by analysis of three-dimensional 1H-15N HMQC-NOESY data [Wang, J., Mooberry, E.S., Walkenhorst, W.F., & Markley, J. L. (1992) Biochemistry (preceding paper in this issue)], were refined and extended by a combination of homo- and heteronuclear two-dimensional NMR experiments. Staphylococcal nuclease H124L samples used in the homonuclear 1H NMR studies were at natural isotopic abundance or labeled randomly with 2H (to an isotope level of 50%); nuclease H124L samples used for heteronuclear NMR experiments were labeled uniformly with 15N (to an isotope level greater than 95%) or uniformly with 13C (to an isotope level of 26%). Additional nuclease H124L samples were labeled selectively by incorporating single 15N- or 13C-labeled amino acids. The chemical shifts of uncomplexed enzyme were then compared with those determined previously for the nuclease H124L.pdTp.Ca2+ ternary complex [Wang, J., LeMaster, D. M., & Markley, J.L. (1990) Biochemistry 29, 88-101; Wang, J., Hinck, A.P., Loh, S. N., & Markley, J.L. (1990) Biochemistry 29, 102-113; Wang, J., Hinck, A.P., Loh, S.N., & Markley, J.L. (1990) Biochemistry 29, 4242-4253]. The results reveal that the binding of pdTp and Ca2+ induces large shifts in the resonances of several amino acid segments. These chemical shift changes are interpreted in terms of changes in backbone torsion angles that accompany the binding of pdTp and Ca2+; changes at the binding site appear to be transmitted to other regions of the molecule through networks of hydrogen bonds. 相似文献
887.
888.
Summary Second generation aposporous gametophytes were obtained from sporophytes derived from first generation aposporous gametophytes, which in turn came from the mature fronds grown from spores in the laboratory. Murashige and Skoog modified medium in 1% agar supplemented with sugar alcohols (sorbitol, mannitol), auxins (NAA, 2,4-D) and cytokinin (BA) promoted a higher percentage of aposporous development from mature fronds ofPyrrosia piloselloides derived from aseptically cultured spores as compared with those obtained from plants in the field. A method using 46-diamidino-2-phenyl indole and fluorescence microscopy correlated the deoxyribonucleic acid contents of the aposporous gametophytes and sporophytes derived from them with their ploidy level.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- DAPI
46-diamidino-2-phenyl indole
- DNA
deoxyribonucleic acid
- MS
Murashige and Skoog medium
- BA
benzyladenine
- NAA
1-naphthaleneacetic acid 相似文献
889.
Choy Theng Loh Luke A. Adams Bim Graham Gottfried Otting 《Journal of biomolecular NMR》2018,71(4):287-293
The amino acids 4-(tert-butyl)phenylalanine (Tbf) and 4-(trimethylsilyl)phenylalanine (TMSf), as well as a partially deuterated version of Tbf (dTbf), were chemically synthesized and site-specifically incorporated into different proteins, using an amber stop codon, suppressor tRNA and the broadband aminoacyl-tRNA synthetase originally evolved for the incorporation of p-cyano-phenylalanine. The 1H-NMR signals of the tert-butyl and TMS groups were compared to the 1H-NMR signal of tert-butyltyrosine (Tby) in protein systems with molecular weights ranging from 8 to 54 kDa. The 1H-NMR resonance of the TMS group appeared near 0 ppm in a spectral region with few protein resonances, facilitating the observation of signal changes in response to ligand binding. In all proteins, the R 2 relaxation rate of the tert-butyl group of Tbf was only little greater than that of Tby (less than two-fold). Deuteration of the phenyl ring of Tbf made only a relatively small difference. The effective T 2 relaxation time of the TMS signal was longer than 140 ms even in the 54 kDa system. 相似文献
890.