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  • 1
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The influence of 2,6-dichlorobenzonitrile (DCB), an inhibitor of the synthesis of glucans, on the differentiation to tracheary elements of isolated mesophyll cells of Zinnia elegans and the formation of secondary cell walls was investigated. DCB caused a decrease in viability of the cells. The number of tracheary elements and the amount of lignin decreased with increasing concentrations of DCB in the medium. However, lignified tracheary elements were observed even in the presence of 5 μM DCB. In the presence of DCB, peroxidase activity and deposition of lignin were not always restricted to secondary cell-wall thickenings but were observed all over the walls of tracheary elements. In addition, some of the cells without any obvious cell-wall thickening were also lignified. The amount of total carbohydrate in cell walls decreased in the presence of DCB but the amount of uronic acids was barely affected. The amount of extracellular polysaccharide (ECP) increased in the presence of DCB. The effect of DCB on the incorporation of radiolabel from [14C]-glucose into cell-wall polysaccharides was examined. DCB specifically inhibited the synthesis of cellulose. These results suggest that the increase in the amount of ECP and the aberrant deposition of lignin caused by DCB were results of the perturbation of the assembly of cell-wall materials caused by interference by DCB in the synthesis of cellulose.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The effects of inhibition of the synthesis of protein, mRNA or rRNA on the progression of the cell cycle have been analyzed in cultures of Catharanthus roseus in which cells were induced to divide in synchrony by the double phosphate starvation method. The partial inhibition of protein synthesis at the G1 phase by anisoniycio or cycloheximide caused the arrest of cells in the G1 phase or delayed the entry of cells into the S phase. When protein synthesis was partially inhibited at the S phase, cell division occurred to about the same extent as in the control. When asynchronously dividing cells were treated with cycloheximide, cells accumulated in the G1 phase, as shown by flow-cytometric analysis. The partial inhibition of mRNA synthesis by α-amanitin at the G1 phase caused the arrest of cells in the G1 phase, although partial inhibition of mRNA synthesis at the S phase had little effect on cell division. In the case of inhibition of synthesis of rRNA by actinomycin D at the G1 phase, initiation of DNA synthesis was observed, but no subsequent DNA synthesis or the division of cells occurred. However, the addition of actinomycin D during the S phase had no effect on cell division. These results suggest that specific protein(s), required for the progression of the cell cycle, are synthesized in the G1 phase, and that the mRNA(s) that encode these proteins are also synthesized at the G1 phase.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 64 (1985), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: UDP-sugar contents were measured using high performance liquid chromatography and gas chromatography during the cell cycle in a synchronous culture of Catharanthus roseus (L.) G. Don. UDP-glucose, UDP-galactose, UDP-glucuronic acid, UDP-xylose and UDP-arabinose could be determined, and 75–90% of the UDP-sugars were UDP-glucose. The contents of UDP-glucose and UDP-galactose increased in the late G2-M and the late S-M phases, respectively, whereas UDP-glucoronic acid and UDP-arabinose increased in amount in the G1 phase. These changes in the levels of UDP-sugars during the cell cycle generally correlated well with the changes in cell wall constituents and in the activities of the enzyme involved in synthesis and interconversion of UDP-sugars reported by S. Amino et al. (Physiol. Plant. 1985. 64: 111–117).
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 62 (1984), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Cell elongation occurred when carrot (Daucus carota L. ev. Kurodagosun) cells subcultured through sieving (Y. Ozeki and A. Komamine, Physiol. Plant. 53: 570-577. 1981) were transferred to a medium lacking auxin, while the cells showed no elongation in a medium containing 2, 4-D. Changes in polysaccharides of the cell walls and in their sugar composition during elongation were investigated. All wall components, EDTA-soluble pectic substance, 5 and 24%, KOH-soluble hemicelluloses and cellulose increased markedly during elongation. The increase of hemicelluloses correlated especially with elongation. In the 5% KOH-soluble hemicellulose, galactose and arabinose contents in the walls increased significantly both in amounts (per fresh weight) and relative contents (% in total neutral sugars) during elongation, while the relative contents of glucose and xylose decreased rapidly in the 5 and 24% KOH-soluble hemicelluloses. The methylation analysis tentatively indicated that larger amounts of galactan and/or arabinogalactan and lower amount of xyloglucan were found as components of the two hemicelluloses of elongating cells than those of non-elongating cells. The amounts of total carbohydrate and of uronic acid of extracellular polysaccharides secreted into the medium increased to a larger extent in the elongation culture than in the non-elongation culture. The contents of galactose and arabinose in extracellular polysaccharides increased rapidly in the elongation culture. The biochemical aspects of cell elongation in the absence of auxin were discussed from the viewpoint of the results obtained here.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 50 (1980), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Five-day-cultured cells of Vinca rosea suspension culture were labelled with D-[U-14C]glucose for 3 h and were then incubated in a medium containing unlabelled glucose for 24 h. Before and after chasing, extra-cellular polysaccharides (ECP) and the cell walls were isolated from the medium and cells, respectively. ECP and polysaccharides in the hemicellulose fraction of cell walls were fractionated into a fraction precipitated as copper salt and one not precipitated as copper salt, and the latter was further fractionated using cellulose-powder chromatography. From the results of analyses of the sugar composition and methylation analyses, components of polysaccharides contained in each fraction were deduced. In ECP, the percentage of radioactivity in the arabinogalactan fraction increased during chasing, while in the cell wall radioactivity in the fraction containing arabinogalactan decreased during chasing. These results confirm the view that arabinogalactan in the cell wall is degraded, and secreted into the medium as a part of ECP.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 79 (1990), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Gene expression correlated with proliferation was investigated in Catharanthus roseus (L.) G. Don. cells. Polyadenylated RNAs were isolated from cells in proliferative states or in nonproliferative states and the variations in the population and levels of mRNA were analyzed by in vitro translation followed by separation of the corresponding polypeptides by two-dimensional gel electrophoresis. Levels of two mRNAs increased in the actively cycling cells, while they were hardly detected in cells in stationary phase or in cells arrested by starvation of phosphate, sucrose or nitrogen. The molecular masses of the translated products of these two mRNAs were 53 and 60 kDa. No mRNAs were specifically synthesized in common among the various cultures of cells whose growth was arrested by nutrient starvation.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Changes in the amounts of enzyme proteins and mRNAs for phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and chalcone synthase (CHS, EC 6.-.-.-) were investigated in suspension cultures of carrot (Daucus carola L. cv. Kurodagosun), in which anthocyanin synthesis was induced and repressed in the absence and presence of 2,4-dichrolophenoxyaeetic acid (2,4-D), respectively. The amounts of enzyme proteins were measured using anti-PAL and anti-CHS sera. In a medium lacking 2,4-D, enzyme proteins and mRNAs for both PAL and CHS were induced 5 days after transfer, when the anthocyanin synthesis was induced. They all increased coordinately during days 5-7 after transfer, when anthocyanin was rapidly synthesized, and then they decreased. In contrast, in a medium containing 2,4-D, the amount of enzyme protein and mRNA for CHS were below detectable levels throughout the culture time. As regards PAL, however, whether 2,4-D was present or not, both enzyme protein and mRNA rapidly increased after the transfer of cells to fresh medium, and then decreased and remained at low levels in a medium containing 2,4-D. The addition of 2,4-D to cells cultured for 6 days in a medium lacking 2,4-D caused an immediate decrease in the amounts of enzyme proteins and mRNAs for both PAL and CHS.All the results obtained here indicate that the induction and suppression of the synthesis of PAL and CHS were probably due lo increase and decrease, respectively, in the amounts of their mRNAs. Thus, it is suggested that the induction and suppression of anthocyanin in this system may be regulated at the transcriptional level by 2,4-D.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 71 (1987), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: In suspension cultures of Phytolacca americana L., betacyanin accumulation per cell increased with increasing total nitrogen concentration (initial NH+4:NO−3 ratio 1:2) in the range 0–40 mM and then remained almost constant in the range 40–80 mM. Increasing ammonium increased growth while betacyanin accumulation was reduced. On the other hand, betacyanin accumulation increased when nitrate was increased while growth was almost constant in the concentration range examined. A time-course study of ammonium and nitrate concentration changes in the medium showed that betacyanin accumulation was associated with nitrate uptake.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 71 (1987), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The effects of sucrose on betacyanin accumulation and growth in suspension cultures of Phytolacca americana L. were investigated. Maximal betacyanin accumulation was observed at 88 mM sucrose on cell number basis and at 175 mM sucrose on fresh weight basis. This is because cell size decreased as the initial sucrose concentration was increased. Supplementary studies using mannitol indicated that sucrose itself caused increased cell number and that cell size was affected by both sucrose concentration and water potential. Betacyanin accumulation per cell and per fresh weight at a constant concentration of sucrose (88 mM) decreased with decreasing water potential. When sucrose concentration increased at a constant water potential (–0.7 MPa), betacyanin accumulation per fresh weight increased up to 88 mM and remained at constant level at higher concentrations, while betacyanin accumulation per cell decreased remarkably, due to a dramatic increase in cell number.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 60 (1984), S. 0 
    ISSN: 1399-3054
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Changes in cell wall constituents during the cell cycle were investigated using a synchronous culture of Catharanthus roseus (L.) G. Don which was obtained by the double phosphate starvation method (S. Amino et al. 1983. Physiol. Plant. 59: 393–396). Cell walls isolated from the cells in each phase of the cell cycle were fractionated into EDTA-soluble (pectin), 5 and 24% KOH-soluble (hemicellulose) and 24% KOH-insoluble (cellulose) fractions. Their sugar compositions were investigated by gas chromatography and methylation analysis. The following changes were observed: (1) a significant increase in total cell walls in the G1 phase after cell division, (2) a temporary increase in the relative amount of the EDTA-soluble fraction during cytokinesis, (3) an increase in the relative amount of galactose, probably 4-linked galactose, in the EDTA-soluble fraction prior to cytokinesis, (4) a temporary increase in the relative amount of 3-linked glucose during cytokinesis, (5) little change in the composition of polysaccharides throughout the cell cycle in the 24% KOH-soluble fraction, which consisted mainly of xyloglucan. The changes observed are discussed in relation to the progression and physiological significance of each phase of the cell cycle.
    Materialart: Digitale Medien
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