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91.
Hartmut Linden M. Mercedes Lucas Maria Rosario de Felipe Gerhard Sandmann 《Physiologia plantarum》1993,88(2):229-236
In situ location of phytoene desaturase, a key enzyme in the carotenoid biosynthesis pathway, has been investigated in chloroplasts from higher plants. For this purpose, an antiserum has been raised against the phytoene desaturase from the cyanobacterium Synechococcus PCC 7942 overexpressed in E. coli . The specifity of this antiserum was demonstrated by inhibition of the enzymatic desaturation reaction in vitro. The antiserum was further purified and immunoabsorbed with E. coli proteins. The resulting IgG-fraction was tested by western blotting against membrane proteins from chloroplasts of tobacco ( Nicotiana tabacum L. cv. Samsun) and spinach ( Spinacia oleracea L. cv. Atlanta). Apparent molecular masses of immunoreactive proteins were 62 and 64 kDa. A western blot of different membrane fractions of spinach chloroplasts (inner and outer envelopes, and thylakoids) indicated a localization of the phytoene desaturase in thylakoids. A post embedding immunogold microscopy procedure was employed. In these experiments the main labelling (79%) was associated with thylakoid membranes of tobacco chloroplasts. Of the counted colloidal gold particles, 16% were found in the stroma. Only 5% were detected in the envelope membranes. These results give clear evidence that at least the majority of phytoene desaturase molecules is localized within thylakoid membranes of higher plant chloroplasts and that the presence of the enzyme in the envelope is of minor significance. 相似文献
92.
Claude Penel Guy Auderset Nicola Bernardini Federico J. Castillo Hubert Greppin D. James Morré 《Physiologia plantarum》1988,73(1):134-146
Floral induction in the long-day plant spinach ( Spinacia oleracea L. cv. Nobel) was accompanied by a thickening of the plasma membrane. Densitometry analyses showed that the light space of the dark-light-dark pattern of the membrane was not changed upon photoinduction. Rather, the increase was due to an enhancement of the dark layer adjacent to the cell wall. Parallel analyses of protein and phospholipid composition revealed no marked changes in protein composition or biosynthetic rate, protein phosphorylation, glycolipids and/or phospholipids as a result of the 24 h of continuous light sufficient to induce flowering. Photoinduction, however, was accompanied by an increase in the relative amount of plasma membrane sterols which may be related to the membrane thickening. 相似文献
93.
Abstract Thylakoids isolated from cold-acclimated spinach (Spinacia oleracea L.) leaves were more resistant against mechanical freeze-thaw injury measured as plastocyanin release, than thylakoids from non-acclimated leaves. They were more resistant against solute influx during freezing and they were able to re-expand to a larger volume in comparison to non-hardy controls. Likewise, plastocyanin was released from thylakoids of non-acclimated but not of frost-hardy leaves under conditions of mild in situ freezing stress for several days. 相似文献
94.
Some characteristics of U-937 and HL-60 leukemia cell lines treated with a fraction of non-dialyzable extract of spinach are reported. The absorbed fraction separated by a DEAE-Tyopearl 650 column chromatography of the non-dialyzable extract induced NBT reducing activity of U-937 and HL-60 cells. This fraction also induced substrate adhesion of U-937 cells, and the non-specific esterase activity of HL-60 cells. The expression of CD11b, CD11c and CD36 antigens on the U-937 cell surface was enhanced by the treatment with the fraction, whereas CD24 antigen was not. The treatment of HL-60 cells with the fraction also induced the expression of CD11b and CD11c antigens, but CD24 and CD36 were not expressed. These results indicated that the non-dialyzable extract of spinach induced immature differentiation of U-937 and HL-60 cells into monocyte/macrophages.Abbreviations NBT
nitroblue tetrazolium
- TPA
12-O-tetradecanoyl-phorbol-13-acerate
- PBS
phosphate buffered saline
- FITC
fluorescein isothiocyanate 相似文献
95.
96.
Spinach plants ( Spinacia oleracea L. cv. Subito) were grown in a complete nutrient solution under ample light intensity (14 h day−1 at 660 μmol m−2 s−1 ) before being transferred either to a minus-N solution (experiment 1), or to limiting light conditions (6 h day−1 at 220 μmol m−2 s−1 ; experiment 2). Shoot growth in experiment 1 decreased significantly from 0.24 day−1 to 0.07 day−1 after the fourth day of transfer. Root relative growth rate increased after 1 day from 0.25 to 0.31 day−1 , but decreased on the fifth day after transfer to 0.11 day−1 . Shoot growth in experiment 2 decreased significantly from 0.25 to 0.17 day−1 after the fourth day of transfer, while root growth decreased to half of its original level (0.25 day−1 ) already on the second day. Growth substrate levels in the plants (free sugars, free amino acids) and starch levels depended on the plant age, the moment in the diurnal cycle, and the imposed treatment. Fluctuations in shoot growth or root growth resulting from the light or N limitation could not be explained by a correspondent increase or decrease in the levels of growth substrates. The hypotheses underlying the functional equilibrium theory, assuming shoot and root growth to be controlled by N- and C-containing substrates respectively, and several other growth and partitioning models are therefore questioned. A neglect of the osmotic role of the free sugars in these models might be the explanation for this. 相似文献
97.
A new model is presented to predict the plant uptake of nitrate supplied by diffusion and mass flow to its roots. Plant growth, root-shoot ratio and the plant's nitrate uptake capacity are all set dependent on the plant's N nutrition state. By thoroughly integrating processes occurring in both plant and soil, the model enables to control the relative importance of both under a wide range of different nutritional scenarios.Soil parameters D0
diffusion coefficient in water (m2 day-1)
- De
diffusion coefficient in soil (m2 day-1)
- C
nitrate concentration in soil (mol m-3)
- f
tortuosity (-)
-
volumetric moisture content (-)
- R
radial distance from root axis (m)
Plant parameters b1, b2
parameters of biomass partitioning Equation (10)
- IR
interroot distance (m)
- KmU
Michaelis-Menten constant of the uptake system (mol m-3)
- KmNRA
Michaelis-Menten constant of nitrogen reduction system (mol g-1)
- k1, k2, k3
parameters of growth model Equation (9)
- Lv
Root length density (m m-3)
- NO3 set
-
Set point of the cytoplasmatic nitrate pool (mol g-1 dw)
- NO3 c
-
cytoplasmatic nitrate concentration (mol g-1 dw)
- NO3 v
-
vacuolar nitrate concentration (mol g-1 dw)
- NRAmax
maximum nitrate reductase activity (mol g-1 dw day-1)
- Nre
reduced nitrogen content (mol)
- Nremax
maximum reduced N concentration in the plant (mol g-1 dw)
- P
partitioning coefficient of nitrate between cyplasm and vacuole
- R(1)
root radius (m)
- RGR
relative growth rate (day-1)
- U
uptake rate (mol day-1 m-2)
- Umax
maximum uptake rate (Eq. 6) (day-1 m-2)
- Vo
water flux at root surface (m day-1)
- Wr
root dry weight (g)
- Wsh
shoot dry weight (g)
- X
model parameter: number of root compartments
- Y
model parameter: number of nodes 相似文献
98.
Shi Lan-Xin Kim Soo J. Marchant Alan Robinson Colin Schröder Wolfgang P. 《Plant molecular biology》1999,40(4):737-744
The location and expression of the previously uncharacterised photosystem II subunit PsbX have been analysed in higher plants. We show that this protein is a component of photosystem II (PSII) core particles but absent from light-harvesting complexes or PSII reaction centres. PsbX is, however, localised to the near vicinity of the reaction centre because it can be cross-linked to cytochrome b559, which is known to be associated with the D1/D2 dimer. We also show that the expression of this protein is tightly regulated by light, since neither protein nor mRNA is found in dark-grown plants. 相似文献
99.
100.
Thelightharvestingchlorophylla/bproteincomplex(LHCII)associatedwithphotosystemIIisthemostabundantpigmentproteincomplexinchloroplastthylakoidofallgreenplants.Itcontainsabout50%ofthetotalamountofpigmentsinvolvedinplantphotosynthesis.LHCIIperformsimportantf… 相似文献