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41.
Bård Smedsrød Marie Malmgren Jan Ericsson Torvard C. Laurent 《Cell and tissue research》1988,253(1):39-45
Summary Endocytosis via the hyaluronic acid/chondroitin sulphate receptor of rat liver endothelial cells was studied ultrastructurally, by use of a probe consisting of chondroitin sulphate proteoglycan attached to 15-nm gold particles. The probe bound to the surface of the cells exclusively in coated regions of the plasma membrane. Internalization at 37° C took place in less than one minute during which time interval the bound probe was transferred to coated vesicles. Further transfer to lysosomes was delayed in association with an accumulation of probes in a prelysosomal compartment consisting of large vacuoles in which probes lined the inner aspect of the membrane. Transport to lysosomes occurred only after a lag phase of at least 40–60 min at 37° C.Abbreviations
CS
chondroitin sulphate
-
CSPG
chondroitin sulphate proteoglycan
-
CSPG-Au
CSPG-gold complex
-
EM
electronmicroscopical or electron microscopy
-
HA
hyaluronic acid
-
KC
Kuppfer cells
-
LEC
liver endothelial cells
-
PC
parenchymal cells
-
RES
reticuloendothelial system 相似文献
42.
43.
The transfer of excitation energy in intact cells of the thermophilic green photosynthetic bacterium Chloroflexus aurantiacus was studied both at low temperature and under more physiological conditions. Analysis of excitation spectra measured at 4K indicates that the minor fraction of bacteriochlorophyll a present in the chlorosome functions as an intermediate in energy transfer between the main light-harvesting pigment BChl c and the membrane-bound B808-866 antenna complex. This supports the hypothesis that BChl a is associated with the base plate which connects the chlorosome with the membrane. The overall efficiency for energy transfer from the chlorosome to the membrane is only 15% at 4K. High efficiencies of close to 100% are observed above 40°C near the temperature where the cultures are grown. Cooling to 20°C resulted in a sudden drop of the transfer efficiency which appeared to originate in the chlorosome. This decrease may be related to a lipid phase transition. Further cooling mainly affected the efficiency of transfer between the chlorosome and the membrane. This effect can only partially be explained by a decreased Förster overlap between the chlorosomal BChl a and BChl a 808 associated with the membrane-bound antenna system. The temperature dependence of the fluorescence yield of BChl a 866 also appeared to be affected by lipid phase transitions, suggesting that this fluorescence can be used as a native probe of the physical state of the membrane. 相似文献
44.
Summary The on-line estimation of biomass concentration and of three variable parameters of the non-linear model of continuous cultivation by an extended Kalman filter is demonstrated. Yeast growth in aerobic conditions on an ethanol substrate is represented by an unstructured non-linear stochastic t-variant dynamic model. The filter algorithm uses easily accessible data concerning the input substrate concentration, its concentration in the fermentor and dilution rate, and estimates the biomass concentration, maximum specific growth rate, saturation constant and substrate yield coefficient. The microorganismCandida utilis, strain Vratimov, was cultivated on the ethanol substrate. The filter results obtained with the real data from one cultivation experiment are presented. The practical possibility of using this method for on-line estimation of biomass concentration, which is difficult to measure, is discussed.Nomenclature
D
dilution rate (h-1)
- DO2
dissolved oxygen concentration (%)
-
E
identity matrix
-
F
Jacobi matrix of the deterministic part of the system equations g
-
g
continuousn-vector non-linear real function
-
h
m-vector non-linear real function
-
K
Kalman filter gain matrix
-
K
S
saturation constant (kgm-3)
- KS
expectation of the saturation constant estimate
-
M
Jacobi matrix of the deterministic part of the measurement equations h
-
P(t0)
co-variance matrix of the initial values of the state
-
P(tk/tk)
c-variance matrix of the error in
(t
k|t
k)
-
P(tk+1/tk)
co-variance matrix of the error in
(t
k+1|t
k
-
Q
co-variance matrix of the state noise
-
R
co-variance matrix of the output noise
-
S
substrate concentration (kgm-3)
-
S
i
input substrate concentration
-
t
time
-
t
k
discrete time instant with indexk=0, 1, 2,...
-
u(t)
input vector
-
v(tk)
measurement (output) noise sequence
-
w(t)
n-vector white Gaussian random process
-
x(t0)
initial state of the system
-
(t0)
expectation of the initial state values
-
x(t)
n-dimensional state vector
-
x(tk)
state vector at the time instantt
k
-
(tk|tk)
expectation of the state estimate at timet
k when measurements are known to the timet
k
-
(tk+1|tk)
expectation of the state prediction
-
X
biomass concentration (kgm-3)
-
expectation of the biomass concentration estimate
-
y(tk)
m-dimensional output vector at the time instantt
k
-
Y
XIS
substrate yield coefficient
-
X|S
expectation of the substrate yield coefficient estimate
-
specific growth rate (h-1)
- M
maximum specific growth rate (h-1)
-
expectation of the maximum specific growth rate estimate
-
state transition matrix 相似文献
45.
Summary Establishment of Plantago lanceolata and P. major ssp major among grass was studied in a field experiment in which survival and selection on date of seedling emergence and plant size was investigated in relation to the vegetation structure. P. major — in contrast to P. lanceolata — was not able to establish itself in grass because of its lower competitive ability caused by later germination, smaller seedling size, and shorter leaves. In both species there was selection for early germination. For P. lanceolata a significant correlation was found between the strength of selection and the light climate, determined by the structure of the grass sward. Plants that germinated early were at an advantage because they were larger, especially the leaves, when compared with plants that germinated late. It seems likely that selection was mainly by competition for light. Contrary to expectation P. major-seedlings had a higher shade tolerance than those of P. lanceolata. The performance of both species is discussed in relation to their different life strategies.Grassland species research group publication no 142 相似文献
46.
ent-Kaurene Synthesis and Endogenous Levels of Gibberellins in a Shoot Forming Tobacco Crown Gall Tissue 总被引:1,自引:0,他引:1
Mettrie Ren?e; de Greef Jan; Nakagawa Sachiko; Sakurai Akira 《Plant & cell physiology》1988,29(5):777-784
The in vitro ent-Mcaurene synthesizing capacity, as well asthe endogenous GA content of shoot-forming tobacco crown gallsinduced by a nopaline-type Ti plasmid, was studied. For determinationof the ent-kaurene synthesizing capacity, an HPLC procedurepreceded by sample clean-up was used and the GA content wasexamined by GC-SIM. Kaurene synthesis reached a maximum at thebeginning of the logarithmic phase of growth. There was a clearcorrelation between the ent-kaurene synthesizing capacity andthe content of C20-GAs. It seems that gibberellin synthesisis related to growth and development of the tissue. The natureof the GAs identified suggests, that the GA metabolism mightbe an unusual one. (Received October 12, 1987; Accepted April 11, 1988) 相似文献
47.
Simone Grinfeld Paul Jacquet Jan Gilles Lucile Baugnet-Mahieu 《Development genes and evolution》1988,197(5):302-304
Summary In some strains of mice, eggs when X irradiated during the pronuclear stage, undergo a mitotic block in the G2 phase of the first cell cycle and cleave when the second division takes place in controls. The importance of this effect varies considerably with the strain and depends exclusively on the maternal genotype. In previous work, two-dimensional electrophoresis showed that eggs blocked at the one-cell stage after irradiation, undergo the same modifications in polypeptide synthesis as two-cell controls of the same age, except at the time of normal first mitosis, where three polypeptide sets of 30, 35 and 45 kDa appear only in cleaving controls. In the present study, we have found phosphorylations in dividing controls, on polypeptides of 30, 35 and 45 kDa. These phosphorylations are not seen in blocked irradiated eggs. 相似文献
48.
Jan Van Parijs Hilde M. Joosen Willy J. Peumans Jan M. Geuns André J. Van Laere 《Archives of microbiology》1992,158(1):19-25
The lectin from stinging nettle rhizomes, Urtica dioica agglutinin (UDA), did not affect the evolution of wet and dry weight, protein, nucleic acid, ATP, cAMP and glycerol content during early germination of Phycomyces blakesleeanus spores. However, earlier investigations established a strongly reduced mycelial growth of several phytopathogenic fungi by this small plant lectin. Total uptake and incorporation of radioactive precursors showed no differences between UDA or control hyphae, but UDA significantly altered the distribution patterns of [14C]-glucose incorporated into the walls of Phycomyces blakesleeanus (more label was recovered in the chitin fraction). Moreover, a small but significant stimulation of chitin synthase and a similar inhibition of chitin deacetylase was found in cell wall preparations. These observations could lead to a better understanding of plant-pathogen interrelationships and to a further elucidation of cell wall structure in fungi.Abbreviations GlcNAc
N-Acetylglucosamine
- PDB
potato dextrose broth
- PMM
Phycomyces minimal medium
- UDA
Urtica dioica agglutinin
- TEA
tri-ethyl-amine
- DAB
1,4-diaminobutanone 相似文献
49.
Comamonas acidovorans NBA-10 was previously shown to degrade 4-nitrobenzoate via 4-hydroxylaminobenzoate and 3,4-dihydroxybenzoate. Washed cells, grown on a mixture of 4-nitrobenzoate and ethanol, stoichiometrically produced ammonium and 3,4-dihydroxybenzoate from 4-nitrobenzoate under anaerobic conditions provided ethanol was present. In cell extracts 4-hydroxylaminobenzoate was degraded to ammonium and 3,4-dihydroxybenzoate, but this activity was lost upon dialysis. No requirement for a cofactor was found, but rather reduced incubation conditions were necessary to restore enzyme activity. The 4-hydroxylamino-degrading enzyme was purified and the role of this novel type of enzyme in the degradation of nitroaromatic compounds is discussed.Abbreviation 4-ABA
4-aminobenzoate
- 4-NBA
4-nitrobenzoate
- 4-HABA
4-hydroxylaminobenzoate
- 3,4-diHBA
3,4-dihydroxybenzoate 相似文献
50.
Tjakko Abee Jan Knol Klaas J. Hellingwerf Evert P. Bakker Annette Siebers Wil N. Konings 《Archives of microbiology》1992,158(5):374-380
Cells of the purple non-sulphur bacterium Rhodobacter sphaeroides express a high-affinity K+ uptake system when grown in media with low K+ concentrations. Antibodies againts the catalytic KdpB protein or the whole KdpABC complex of Escherichia coli crossreact with a 70.0 kDa R. sphaeroides protein that was expressed only in cells grown in media with low K+ concentrations. In membranes derived from R. sphaeroides cells grown with low K+ concentrations (induced cells), a high ATPase activity could be detected when assayed in Tris-HCl pH 8.0 containing 1 mM MgSO4. This ATPase activity increased upon addition of 1 mM KCl from 166 to 289 mol ATP hydrolysed x min-1 x g protein-1 (1.7-fold stimulation). The K+-stimulated ATPase activity was inhibited approximately 93% by 0.5 mM vanadate but hardly by N,N-dicyclohexylcarbo-diimide (DCCD). These results indicate that the inducible K+-ATPase in R. sphaeroides resembles the Kdp K+-translocating ATPase of Escherichia coli. This Kdp-like transport system is also expressed in R. capsulatus and Rhodospirillum rubrum during growth in media with low K+ concentrations suggesting a wide distribution of this transport system among phototrophic bacteria.Abbreviations
electrical potential difference across the cytoplasmic membrane
- pH
pH difference across the cytoplasmic membrane
- BSA
bovine serum albumine
- PAGE
polyacrylamide gel electrophoresis
- HEPES
4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid
- PMSF
phenyl-methyl-sulfonyl fluoride
- DCCD
N,N-dicyclohexylcarbodiimide
- AIB
2--aminoisobutyric acid
- TMG
methyl--d-thiogalactopyranoside 相似文献