共查询到20条相似文献,搜索用时 31 毫秒
1.
D. B. Sattelle K. H. Langley A. L. Obaid B. M. Salzberg 《European biophysics journal : EBJ》1987,15(2):71-76
Quasi-elastic laser light scattering has been used to investigate the size and dispersity of synaptosomes and synaptic vesicles isolated from optic lobes of the squid Loligo pealei. Synaptosomal fractions were highly polydisperse (
) and the mean diameter (
) ranged from 0.5–2.0 m. Size distribution histograms yielded two major components — smaller particles (
) and a larger group of particles (
). The heterogeneity of the synaptosomal particles detected in solution is in agreement with published data obtained using electron microscopy. Purified synaptic vesicle fractions also yielded complex particle size distribution data. A component with a mean diameter in the range 150–250 nm was detected, though a smaller particle (
) dominated the scattering signal. This smaller particle closely resembles in size the electron lucent vesicles seen in the majority of squid optic lobe nerve terminals when examined by electron microscopy. Osmotically-induced shirnkage and swelling of the synptosomes was detected. Depolarization by veratridine (1.0×10–4
M) did not result in a detectable change in the size of synaptosomal particles. 相似文献
2.
Henrik Laasch 《Planta》1989,178(4):553-560
A series of tertiary amines was investigated for effects on the transmembrane proton potential difference (
H), on photophosphorylation and on electron-flux control related to the intrathylakoid proton potential (
HI), using isolated chloroplasts ofSpinacia oleracea L. As indicated by 9-aminoacridine fluorescence and [14C]methylamine uptake, all amines studied inhibited a build-up of
H and, in parallel, ATP synthesis. Even when
H was low, strong
H1-dependent electron-flux control was observed under the influence of tertiary amines. The strength of flux control in the presence of low
H and the effectiveness of inhibition of ATP synthesis linearly increased with the lipophilicity of the amines. The most effective of the amines tested caused 50% inhibition of ATP synthesis at a concentration of 6 M, which is about 1000-fold lower than the concentration required for inhibition by methylamine. The data presented indicate the existence of two proton domains in the thylakoid vesicles, one of them feeding the ATP-synthase, the other the sites of pH-dependent electron-flux control. It is concluded that tertiary amines develop their action in a lipophilic domain of the thylakoid membrane, in the vicinity of the ATP-synthase complex. A mechanism for selective uncoupling and for the maintenance of
HI-dependent electron flux control in the presence of low
H is discussed.Abbreviations and symbols
coefficient for pH-dependent electron flux control
- 9-AA
9-aminoacridine
- Chl
chlorophyll
- I50
amine concentration producing 50% inhibition of ATP-synthesis
- Je
flux of photosynthetic electron transport
-
k
H
apparent rate constant for proton efflux
-
H1
proton potential in the thylakoid lumen
-
H1
transthylakoid proton potential difference
-
p
partition coefficient
-
q
AA
coefficient for 9-aminoacridine fluorescence quenching
- PS
photosystem
- Q
quantum flux of photosynthetically active light
Dedicated to Professor Wilhelm Simonis, on the occasion of his 80th birthday 相似文献
3.
Summary The complete sequence of the 5S rRNA from the bioluminescent bacterium,Beneckea harveyi has been determined to be p U G C U U G G C G
C C A U A G C G A
U U-G G A C C C A
C U G A (U) C U U C
A U U C C-G A A C
C A G A A G U G A
A C G A A U U A-G
G C C G A U G G U
G U G U G G G G C
U-C C C C A U G U
A G A G U A G G A
A U C G-C C A G G
U (U)OH.Two sites of sensitivity to ribonuclease T2 cleavage were identified; at A41 and either A54 or A55. Comparison with existing sequence information fromEscherichia coli andPhotobacterium phosphoreum clarifies the amount of diversity among the bioluminescent bacteria and provides further insight into their phylogenetic position. Sequence heterogeneities were encountered and the importance of these in interpreting 5S rRNA data is discussed. 相似文献
4.
Summary Barley plants (Hordeum vulgare L.) grown from seed for 28 days in flowing solution culture were subjected to different root temperatures (3, 5, 7, 9, 11, 13, 17, 25°C) for 14 days with a common air temperature of 25/15°C (day/night). Uptake of NH4 and NO3 ions was monitored separately and continuously from solutions maintained at 10 M NH4NO3 and pH 6.0. Effects of root temperature on unit absorption rate
, flux
and inflow
were compared. After 5 days
,
and
increased with temperature over the range 3–11°C for NH4 ions and over the range 3–13°C for NO3 ions, with little change for either ion above these temperatures. Q10 temperature coefficients for NH4 ions (3–13°C) were 1.9, 1.7 and 1.6 for
,
and
respectively, the corresponding values for NO3 ions being 5.0, 4.5 and 4.6. For both ions,
,
and
changed with time as did their temperature dependence over the range 3–25°C, suggesting that rates of ontogenetic development and the extent of adaptation to temperature may have varied among treatments. 相似文献
5.
P. A. Dibrov R. L. Lazarova V. P. Skulachev M. L. Verkhovskaya 《Journal of bioenergetics and biomembranes》1989,21(3):347-357
Addition of Na+ to the K+-loadedVibrio alginolyticus cells, creating a 250-fold Na+ gradient, is shown to induce a transient increase in the intracellular ATP concentration, which is abolished by the Na+/H+ antiporter, monensin. The pNa-supported ATP synthesis requires an additional driving force supplied by endogenous respiration or, alternatively, by a K+ gradient (high [K+] inside). In the former case, ATP formation is resistant to the protonophorous uncoupler. Dicyclohexylcarbodiimide and diethylstilbestrol, but not vanadate, completely inhibit Na+ pulse-induced ATP formation. The data agree with the assumption that Na+-ATP-synthase is involved in oxidative phosphorylation inV. alginolyticus. Interrelation of H+ and Na+ cycles in bacteria is discussed.Abbreviations
and
electrochemical gradients of H+ and Na+, respectively
-
transmembrane electric potential difference
- pH, pNa, and pK
concentration gradients of H+, Na+, and K+, respectively
- CCCP
carbonyl cyanidem-chlorophenylhydrazone
- DCCD
N,N-dicyclohexylcarbodiimide
- DES
diesthylstilbestrol
- HQNO
2-heptyl-4-hydroxyquinolineN-oxide
- Tricine
N[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine 相似文献
6.
Boniface S. Moses 《Environmental Biology of Fishes》2001,61(1):99-109
This paper investigates the relationship between the hydroclimatic parameters (rainfall and flood index) and the catch, stock abundance and recruitment of the catfish, Chrysichthys nigrodigitatus (Bagridae) and the bonga, Ethmalosa fimbriata (Clupeidae) of southeastern Nigeria's inshore waters. For C. nigrodigitatus, most peaks in the mean biomass
and recruitment
curves occurred during the 'wet' years, i.e., years for which the percentage deviations of rainfall
and flood index
from their means remained above their averages. Catch and abundance respectively showed good positive linear correlation with the flood index. E. fimbriata behaved differently; some peaks in the
and
curves occurred in the 'wet' and some in the 'dry' years; and there was no correlation between the annual catch of bonga and either the rainfall or the flood index. The hypothesis, that linear relationships exist between the interannual variations in the hydroregime and the yearly fluctuations in the catch and population structure of some coastal and estuarine fishes, holds true for the catfish, C. nigrodigitatus, but not for bonga, E. fimbriata. 相似文献
7.
Summary The cellular mechanism of K-stimulated Cl transport in locust hindgut was studied using double-barrelled ionsensitive microelectrodes and electrophysiological techniques. Steady-state net electrochemical potentials for Cl and K and the conductances of apical and basal membranes and paracellular pathway were determined under control conditions, during exposure to 1mm cAMP, and following ion substitutions. Under control open-circuit conditions, intracellular Cl activity (a
Cl
c
) was 3.5 times that predicted for passive equilibrium across the apical membrane. The net electrochemical potential opposing Cl entry from the mucosal side
increased by 50% during cAMP stimulation of transepithelial Cl absorption whereas the net electrochemical potential favoring Cl exit across the basal membrane
was unchanged. No correlation was observed between
and the net electrochemical potential across the apical membrane for Na. The net electrochemical potential favoring K entry across the apical membrane
was negligible underI
sc conditions when Cl transport rate was approximately 10 eq cm–2 hr–1. Locust rectal cells showed electrical and dye coupling. The results also indicate that most transepithelial diffusion of ions is transcellular and that epithelial tightness effectively increases during exposure to cAMP becauseR
a andR
b both decrease, by 80% whileR
j is unchanged. The cAMP-induced R
b was abolished in Cl-free saline whereas R
a was insensitive to Cl removal, but was blocked by removing K from the saline. Based on these findings, our model for Cl absorption in locust hindgut features i) an active entry step for Cl at the apical membrane which is stimulated by cAMP and by low levels of K on the mucosal side, but is not energized by
or
a large cAMP-stimulated Cl conductance in the basal membrane and a similar cAMP-stimulated K conductance in the apical membrane. cAMP dose-response curves are similar for the stimulation of active Cl absorption and Cl-independent (i. e. K) conductance, indicating that cAMP exerts dual control over active Cl transport and counter-ion permeability. 相似文献
8.
Gregory K. Snyder Wesley W. Weathers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1977,117(3):291-301
Summary Resting rates of O2 consumption
against
, exercise endurance times and
during recovery from vigorous exercise were measured inSceloporus occidentalis captured near sea level and inS. graciosus captured above 2850 m. Oxygen consumption against
was also measured inS. occidentalis captured above 2850 m. When
was recorded continuously, as ambient
was slowly reduced from 155 Torr, it became directly dependent upon ambient
between 110 and 120 Torr. The critical
for the high altitude lizards was lower than that for the lowland lizards, which enabled the former to maintain relatively higher
's when ambient
was reduced below 120 Torr. The high altitude lizards also had significantly greater endurance when stimulated to exercise at 1600 m (
130 Torr). Both the higher
under hypoxia and the greater endurance roughly parallel a significantly greater maximum
in the high altitude lizards. At a simulated altitude of 3600 m (
100 Torr), maximum
and rate of recovery of the O2 debt calculated from post active
were significantly reduced in the lowland but not the high altitude lizards. The effects of simulated altitude conditions on the lowland but not the mountaine animals indicate adaptations to altitude in these sceloporine lizards. We did not find any consistent relationship between organ/body weight ratios or hematocrit and our measures of
endurance or the altitude at which the lizards were captured. 相似文献
9.
Hisako Sakiyama Noriyuki Inaba Toru Toyoguchi Yasunori Okada Misako Matsumoto Hideshige Moriya Hiroshi Ohtsu 《Cell and tissue research》1994,277(2):239-245
The first component of complement
has been shown to degrade type I and type II collagens (Yamaguchi et al. 1990), the latter of which is a major constituent of the cartilage matrix. In order to understand the physiological roles of
in cartilage resorption, the expression of C1s was examined by immunohistochemistry in the primary ossification center where the matrix is removed and replaced by bone marrow. Hypertrophic chondrocytes, endothelium and hematogenous elements in the capillary buds were intensely stained by a monoclonal antibody against C1s. Matrix metalloproteinase 9 (MMP-9, 92kDa gelatinase/type IV collagenase) was also immunolocalized in hypertrophic chondrocytes, mesenchymal cells in the primitive bone marrow and the cartilage matrix adjacent to the marrow. In addition,
was found to activate the zymogen of MMP-9. These observations suggest that
and MMP-9 coordinately participate in matrix degradation in cartilage.Abbreviations
MMP
Matrix metalloproteinase
-
APMA
4-aminophenylmercuric acetate
-
DFP
diisopropyl fluorophosphate, HE hematoxylin and eosin
-
C1s
inactive C1s
-
activated C1s 相似文献
10.
L. I. Churikova 《Neurophysiology》1992,24(6):425-432
A study was made of the effect of reciprocal inhibition on individual firing motoneurons in the extensor carpi ulnaris and soleus muscle in human subjects. Peristimulus histograms (PSH) were plotted at different average frequency of motoneuron firing (
) and the change in duration of interspike intervals (ISI) was analyzed. For reciprocal inhibition, as for other types of inhibition,
is a factor in the effectiveness of motoneuron inhibition. The duration of inhibition apparent in the PSH, the sizes of zones of inhibition effectiveness in the ISIs and lengthening of the intervals are dependent on
. For all motoneurons, the low
range is most favorable for effective inhibition. The dependence of effectiveness of a volley on the time of its arrival within the ISI is also analyzed.Institute for Problems of Information Transmission, Russian Academy of Sciences, Moscow. Translated from Neirofiziologiya, Vol. 24, No. 6, pp. 643–653, November–December, 1992. 相似文献
11.
The
and the Gp have been measured in whole cells ofMethylophilus methylotrophus during the oxidation of various respiratory chain substrates. The magnitude of the
depended on the external pH and the composition of the assay medium, and varied from-109 to-165 mV. The relative contributions of the and the pH to the
were found to vary with the external pH such that the internal pH remained constant; depending on the composition of the assay medium, this value was between 6.6 and 7.0. A Gp of approximately-46 kJ/mol was generated during the oxidation of methanol, and either the or pH alone was fully competent to drive ATP synthesis. Respiration and ATP synthesis were found to be poised far from equilibrium under the conditions of these experiments, and the value of the Gp was thus controlled kinetically. Comparison of the
with the Gp yielded an H+/ATP quotient >2.6 g-ion H+/mol ATP.Abbreviations TMPD
N,N,N,N-tetramethyl-p-phenylenediamine
- FCCP
carbonylcyanidep-trifluoromethoxyphenylhydrazone
- DMO
5,5-dimethyloxazolidine-2,4-dione
- TPMP+
triphenylmethylphosphonium (iodide salt); Tween 20, polyoxyethylenesorbitan monolaurate
- TPP+
tetraphenylphosphonium (bromide salt)
-
bulk phase transmembrane electrochemical potential difference of protons (
)
- pH
bulk phase transmembrane pH difference (pHin-pHout)
-
bulk phase transmembrane electrical potential difference (in-out)
- p
true protonmotive force (incorporating both bulk phase and localised protons;
) 相似文献
12.
To evaluate the order and the values of Markov properties of the time series of events, we have proposed a statistical measure dependency:D
m
= (H
0
–H
m
)/H
0
, whereH
0 andH
m are Shannon's entropy and them-th order conditional entropy, respectively. It is indicated that
is a better point estimator ofD
m, giving a total value of them-th order Markov process. Here
and
are the estimate ofD
m and the arithmetic mean of
when them-th order shuffling is made many times for a given observed series, respectively. The value
represents Markov value of the orderm. Under the assumption that the series has continuous variables and the normal distribution, simplified dependency is defined by, where |S
m
| is the determinant of serial correlation coefficients. It is shown that is practically useful for the estimation of the order and the values of Markov processes with small sample size. It is also indicated that analysis is basically equivalent to the least mean-square analysis of autoregressive models. 相似文献
13.
Patterns of carbon assimilation in a microalgal community from annual sea ice,east Antarctica 总被引:1,自引:0,他引:1
Summary Patterns of carbon assimilation into photosynthetic end products were measured in annual sea ice near the Antarctic stations of Davis and Mawson, during December 1982, following the peak of the spring ice algal bloom. Rates of14C assimilation in the ice communities, measured with an in situ sampler-incubation chamber ranged from 1.58–32.92 mg Cm-2h-1
during this period.The partitioning of14C bicarbonate into four subcellular fractions (chloroform-soluble, methanol/water (MeOH/H2O)-soluble, trichloroacetic acid (TCA)-soluble, and TCA-residue) and the efficacy of extraction was determined. During in situ incubations (3–4 h), it was found that a major proportion of the label
was incorporated into a (13)-glucan which was distributed between the neutral MeOH/H2O-and TCA-soluble fractions. The remainder of the label was found in the chloroform-(lipid;
), charged MeOH/H2O-soluble (amino/organic acids;
) and TCA-residue (protein;
). The glucan accounted for 93% of the cellular carbohydrate of ice algae and had a linkage composition similar to the reserve (13)--D-glucan found in cultured diatoms. High14C-incorporation into MeOH/H2O- and TCA-soluble fractions also occurred over a 24 h in vitro incubation, although incorporation into protein, at the expense of the other fractions, continued during the night.While primary productivity in the ice communities was still appreciable during December, the prominent synthesis of reserve glucan and the decreasing cellular ratios of protein/carbohydrate suggests that the ice algae may be nutrient limited during this period. 相似文献
14.
Shih-fang Fan M. M. Dewey B. Gaylinn B. Chu 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(6):508-512
Summary In dynamic light scattering, measurements of the intensity-intensity time correlation function from a suspension of rod-like particles of length L could reveal dynamical information related to translational and internal motions of those particles. For a suspension of thick filaments isolated from the myosin-regulated, striated muscles of Limulus at KL>1 (where K is the scattering vector), the average characteristic linewidth (
) increased with the addition of Ca2+ or with the depletion of ATP. The increase in the
with the addition of Ca2+ could be due to the presence of energy-requiring, high-frequency motions of the crossbridges activated by Ca2+. The increase in
which occurred with the depletion of ATP was assumed to be mainly due to the thermal motions of the crossbridges after they had moved radially away from the filament backbone. The percentage increase in
following the addition of Ca2+ was found to be seasonal, i.e., values of
obtained from thick filaments isolated between the middle of June and the middle of September were smaller than those obtained during the rest of the year. The effect of temperature on the percentage increase in
was also different. The increase showed a maximum at about 35°C during the summer and at about 25°C at other times. However, the percentage increase in
developed under ATP-depleted conditions showed no temperature-related maximum. The number of bound Ca2+ per myosin molecule was 1 during the summer and 2 at other times.Abbreviations DLS
dynamic light scattering
- L
length
- K
scattering vector
- SDS-PAGE
sodium dodecyl sulfate polyacrylamide gel electrophoresis
-
average characteristic line width
Deceased 相似文献
15.
Christiane Wloczyk Achim Kröger Thomas Göbel Gabriele Holdt Ralf Steudel 《Archives of microbiology》1989,152(6):600-605
Wolinella succinogenes grown on formate and elemental sulphur was found to use the polysulphide derivatives 2,2-tetrathiobispropionate (R2S4) or pentathionate (S5O
6
=
) as acceptors for formate oxidation. The specific activities of formate oxidation with these acceptors were similar to those with elemental sulphur. The main reaction products of R2S4 reduction were 2,2-dithiobispropionate (R2S2) and sulphide. Pentathionate was converted to thiosulphate and some elemental sulphur. The electrochemical proton potential
across the cytoplasmic membrane of the bacterium was measured in the steady state of electron transport from formate to R2S4. The electrical proportion () of the
determined through the distribution of labeled tetraphenylphosphonium cation was obtained as 0.17 Volt. The was zero, when a protonophore was present. The pH-difference across the membrane was negligible. Thus the
generated by sulphur respiration is close to that measured earlier with fumarate as the terminal acceptor of electron transport.Abbreviations DMO
5,5-dimethyloxazolidine-2,4-dione
- R2Sn (n=2–5)
2,2-polythiobispropionate
- TTFB
4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazol
- TPP
tetraphenylphosphonium cation 相似文献
16.
Spondyloepiphyseal dysplasia tarda: linkage with genetic markers from the distal short arm of the X chromosome 总被引:4,自引:0,他引:4
S. Szpiro-Tapia A. Sefiani M. Guilloud-Bataille S. Heuertz B. Le Marec J. Frézal P. Maroteaux M. C. Hors-Cayla 《Human genetics》1988,81(1):61-63
Summary A linkage study of six families with spondyloepiphyseal dysplasia tarda (SEDL) has been performed. A linkage to site DXS41 (
=0.08; =3.07) and DXS92 (
=0.05; =2.95) has been established. We propose, that the SEDL locus lies on the distal part of the short arm of the X chromosome. 相似文献
17.
Dr. R. V. Nair T. M. Masajo G. S. Khush 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1982,61(1):19-22
Summary The inheritance of resistance to whitebacked planthopper Sogatella furcifera (Horvath) was studied in 21 rice varieties. Reactions of F1; F2 and F3 progenies of the crosses of 21 resistant varieties with the susceptible variety TN 1 revealed that a single dominant gene governs resistance in Mushkan 41, Santhi, Siahnakidar 195, SM2-34, Tirisurkh 251, Zirijowaian 245, 18, 24A, 39, 76 S, 78, 180, 213 B, 267, 293, CI 6037-4, NP97, S39 JKW and Bansphul. In varieties 65 and 274 A, resistance is governed by one dominant and one recessive gene which segregate independently of each other. Tests for allelism with the Wbph 1 gene originally identified in N 22 revealed that the dominant gene present in all the test varieties is the same as Wbph 1. Further studies are required to determine the allelic relationships of the recessive gene found in varieties 65 and 274 A. 相似文献
18.
Anne-Spence M. Falk Catherine T. Neiswanger Katherine Leigh Field L. Marazita Mary L. Allen F. H. Siervogel Roger M. Roche Alex F. Crandall Barbara F. Sparkes Robert S. 《Human genetics》1984,67(2):183-186
Summary Two data sets are analyzed for linkage between the PTC and Kell blood group loci. The original report of close linkage for these loci was that of Conneally et al. (1976), where the maximum likelihood estimate of was 0.05. These two new data sets give a combined maximum likelihood estimate of
m=f
=0.28. Estimating the recombination frequency for the sexes separately gave
m
=0.29,
f
=0.23. The combined maximum likelihood estimate over all published data sets including this report is
m=f
=0.14,
max=8.94. There is statistically significant evidence of heterogeneity among the published studies. 相似文献
19.
Ivona Aksentijevich Luis Gruberg Elon Pras James E. Balow Jr. Michal Kovo Ephraim Gazit Michael Dean Mordechai Pras Daniel L. Kastner 《Human genetics》1993,91(6):527-534
Familial Mediterranean fever (FMF) is an autosomal recessive disorder of unknown pathogenesis, characterized by recurrent, selflimited attacks of fever with synovitis, peritonitis, or pleurisy. Using DNAs from affected Israeli families, we have recently mapped the gene causing FMF (designated MEF) to the short arm of chromosome 16, with two-point lod scores in excess of 20. In this report we consider the possibility of a second FMF susceptibility locus. Before discovering linkage to markers on chromosome 16, we had found suggestive evidence for linkage to chromosome 17q, with the following maximal two-point lod scores: D17S74 (pCMM86),
= 2.47, (
= 0.20); D17S40 (pLEW101),
= 2.15(
= 0.15); D17S35 (CRI-pP3-1),
= 1.78 (
= 0.15); D17S46 (pLEW108),
= 1.69 (
= 0.18), D17S254,
= 2.30 (
= 0.20). Moreover, multipoint linkage analysis using D17S74 and D17S40 as fixed loci gave
= 3.27 approximately 10 centimorgans (cM) telomeric to D17S40. Data with the chromosome 17 markers alone in our families suggested locus heterogeneity. Nevertheless, our families were not separable into complementary subsets showing linkage either to chromosome 16 or to chromosome 17. We also examined the possibility that the positive lod scores for chromosome 17 might reflect a secondary, modifying locus. By several measures of disease severity, families with positive lod scores for chromosome 17 loci had no worse disease than those with negative lod scores for these loci. We conclude that chromosome 17 does not encode a major FMF susceptibility gene for some of the families, nor does it encode a disease-modifying gene. Rather, it would appear that linkage to chromosome 17 is a false positive (type I) error. These results reemphasize the fact that a lod score of 3.0 corresponds to a posterior probability of linkage of 95%, with an attendant 1 in 20 chance of observing a false positive. 相似文献
20.
The effect of inhibitors of the cytochrome pathway and alternative oxidase on the rate of respiration and generation of reactive oxygen species by pea mitochondria was studied. Respiration of mitochondria from pea cotyledons was inhibited by 70-80% by salicylhydroxamate (SHAM). The rate of hydrogen peroxide production by pea cotyledon mitochondria during succinate oxidation was 0.15 nmol/min per mg protein. SHAM considerably accelerated the hydrogen peroxide production. The SHAM-dependent H2O2 production was stimulated by 2 M antimycin A and inhibited by 5 mM KCN and 1 M myxothiazol. The study of the rate of
generation by pea mitochondria using EPR spin traps and epinephrine oxidation showed that H2O2 accumulation can be accounted for by a significant increase in the rate of
production. 相似文献