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1.
Adventitious shoot regeneration was compared among leaf, stem and petal explants of carnation (Dianthus caryophyllus L.) cv. Scania on MS medium containing different concentrations of 6-benzyladenine (BA) and -naphthaleneacetic acid (NAA). High frequency regeneration was obtained only from petal explants on the media containing 5 to 10 M BA with or without 5 M NAA. Among the cytokinins tested, N-2-chloro-4-pyridyl-N-phenylurea and N-1,2,3-thiadiazol-5-yl-N-N-phenylurea were more effective than BA, kinetin, N6-2-isopentenyl adenine and zeatin on regeneration from petal explants. Although, high frequency shoot regeneration was obtained from all petal explants harvested from various developmental stages of buds, a significant decrease in regeneration capacity was observed in the explants obtained from fully-opened flowers. High frequency shoot regeneration was also obtained from the petal explants of cvs. Coral. Lena, Nora and White Sim, and an interspecific cultivar Eolo using the method developed in this study.Abbreviations NAA
-naphthaleneacetic acid
- BA
6-benzyladenine
- GA3
gibberellic acid
- 2iP
N6-2-isopentenyl adenine
- KT-30
N-2-chloro-4-pyridyl-N-phenylurea (also called 4PU)
- TDZ
N-1,2,3-thiadiazol-5-yl-N-phenylurea (also called thidiazuron) 相似文献
2.
The effect of N-(2-chloro-4-pyridyl)-N-phenylurea (4PU-30) on the growth and content of endogenous cytokinins of adenine type in tobacco (Nicotiana tabacum L.) callus was investigated. Biomass accumulation in calli grown on Murashige and Skoog (MS) medium with 4PU-30 was higher than that on MS medium with kinetin. The obvious presence of isopentenyladenine type cytokinins and traces of zeatin type cytokinins supposes modification in the endogenous cytokinin metabolism of the tobacco callus grown on 4PU-30. 相似文献
3.
Nodule cultures were induced from shoot tips of aseptically grownEucalyptus botryoides in a vertically rotated incubator. N-(2-chloro-4-pyridyl)-N-phenylurea (4PU) was a very effective cytokinin for induction of nodules in liquid B5 basal medium supplemented with naphthalene acetic acid and 3% sucrose.The effective concentration of 4PU ranged from 0.2 to 0.5mg/l. The nodule had a very smooth surface and was composed of small meristematic cells outside and large vacuolated cells inside. Shoots were regenerated from these cultures on media supplemented with 6-benzyladenine at 0.2mg/l in place of 4PU. These regenerated shoots were successfully rooted and cultivated in the field. Nodule cultures were maintained for 3–4 years with monthly subcultures without losing proliferation and regeneration abilities. Nodules were also successfully induced from other eucalypts, namelyE. camaldulensis, E. deglupta andE.grandis with slightly modified media. Furthermore, nodule cultures were also induced from shoot tips of field-grown plants inE.camaldulensis. This system is beneficial for both mass propagation of selected elite clones and creation of genetically engineered plants.Abbreviations 4PU
N-(2-chloro-4-pyridyl)-N-phenylurea
- BA
6-benzyladenine
- NAA
naphthalene acetic acid
- B5
Gamborg et al.(1968)'s basal medium
- PVP
polyvinylpyrrolidone 相似文献
4.
A soluble protein that interacts with a range of cytokinins was extensively purified from wheat (Triticum aestivum L.) germ. This protein has a K
d
for kinetin of 2×10-7 M. The binding of kinetin to the protein is inhibited by low concentrations of synthetic and naturally-occurring cytokinins including N6-benzyladenine, N6-benzyladenosine, kinetin riboside, N6-dimethylallyladenine, N6-dimethylallyladenosine, zeatin, zeatin riboside, N6-dimethyladenine and N6-dimethyladenosine. Adenine, adenosine and several non-N6-substituted adenine derivatives were ineffective as inhibitors of kinetin binding. While N6-butyryl-3,5-cyclic AMP, N6,2-O-dibutyryl-3,5-cyclic AMP and 2,3-cyclic AMP inhibited binding of kinetin to the protein, 3,5-cyclic AMP was ineffective. The kinetin-binding protein is heat-labile and pronase-sensitive. Kinetin-binding activity exactly co-chromatographs with a single peak of carbohydrate and protein on gel-filtration and is displaced from concanavalin A-Sepharose 4B by -methylglucoside. On gel filtration, the kinetin-binding protein behaves as a soluble protein with an apparent molecular weight of 180,000 daltons. 相似文献
5.
Somatic embryo formation occurred on leaf callus of grape (Vitis vinifera cv. Koshusanjaku). An embryogenic callus was induced from somatic embryo clusters cultured on vitamin-, inositol- and glycine-free Nitsch and Nitsch (1969) medium supplemented with 1.0M 2,4-D. This callus has retained a high embryogenic activity after repeated subculture on the same medium for over two years, and has produced numerous embryos after transfer to a hormone-free medium. The effect of cytokinin treatment on somatic embryogenesis from leaf callus was also examined. N-(2-chloro-4-pyridyl)-N-phenylurea (KT-30) and N-(1,2,3-thiadiazol-5-yl)-N-phenylurea (TAG), both synthetic cytokinins, were found to be effective for the induction of somatic embryogenesis. When leaf callus was induced by these cytokinins combined with 2,4-D at either 5.0 or 10.0M, somatic embryos were produced.Abbreviations B5
Basal medium, Gamborg et al. (1968)
- BA
6-benzylaminopurine
- 2,4-D
2,4- dichlorophenoxyacetic acid
- IAA
indole-3-acetic acid
- 2iP
(2-isopentenyl)adenine
- KIN
kinetin
- KT-30
N-(2-chloro-4-pyridyl)-N'-phenylurea, also called 4PU-30, Kyowa Hakko Kogyo Co., Japan
- NAA
1-naphthaleneacetic acid
- NN
Basal medium, Nitsch and Nitsch (1969)
- MS
Basal medium, Murashige and Skoog (1962)
- TAG
N-(1,2,3-thiadiazol-5-yl)-N'-phenylurea, also called thidiazuron or TDZ, Tomono Noyaku Co., Japan
- ZEA
zeatin 相似文献
6.
The response of a cytokinin resistant mutant is highly specific and permits a new cytokinin bioassay
We have previously isolated six independent cytokinin-resistant mutants of Nicotiana plumbaginifolia which define three complementation groups, zeal, zea2 and zea3. We report here the characterization of the phenotypic response to cytokinin treatment of the mutant 1–64, belonging to the zeal group, and the result of the study of the specificity of this response. The phenotype of this mutant grown in the presence of cytokinin concentrations higher than 0.1 M is characterized by a hypertrophy of the cotyledons and hypocotyl which results in an increase of plantlet fresh weight. This hypertrophy is correlated to cytokinin concentration in a range between 0.01 to 10 M. The specificity of this response has been verified by using adenine and urea type cytokinins, as well as enantiomers of methylzeatin and methylbenzyladenine which differ widely in their cytokinin activities. We show that the high specificity of the hypertrophic response to cytokinins can be used as a convenient bioassay to screen the cytokinin activity of adenine or urea type molecules.Abbreviations zeatin
[6-(4-hydroxy-3-methylbut-trans-2-enylamino)purine]
- iP
isopentenyladenine [6-(3-methylbut-2-enylamino)purine]
- BA
benzyladenine [6-(benzylamino)purine]
- (R)-(+)-MeZea
[(R)--methylzeatin]
- (S)-(–)-MeZea
[(S)--methylzeatin]
- (R)-(+)-MeBA
[(R)--methylbenzyladenine]
- (S)-(–)-MeBA
[(S)--methylbenzyladenine]
- CPPU
N-(2-chloro-4-pyridyl)-N-phenylurea
- thidiazuron
N-(1,2,3-thiadiazol-5-pyridyl)-N-phenylurea
The authors dedicate this paper to the memory of Jean-Pierre Bourgin, Director of the Laboratoire de Biologie Cellulaire, who died suddenly on October 29, 1994. 相似文献
7.
the cytokinins of tobacco crown-gall tissue have been analysed by quantitative mass spectrometry using 2H2-labelled cytokinin riboside 5-monophosphates and 15N4-labelled cytokinin glycosides as internal standards. The principal endogenous cytokinin of this tissue is zeatin riboside 5-monophosphate. The biologically inactive 7-glucoside of zeatin is the most abundant basic cytokinin in the tissue. These findings expose the limitations of previously reported analyses of similar tissues, which were restricted to biologically active basic cytokinins. The present study demonstrates that the endogenous cytokinins of tobacco crowngall tissue show a clear correspondence to the range of metabolites formed when exogenous cytokinins are supplied to nontumorous tobacco cells.Abbreviations DHZ
dihydrozeatin
- DHZ7G
dihydrozeatin 7-glucoside
- DHZMP
dihydrozeatin 9-riboside 5-monophosphate
- DHZR
dihydrozeatin 9-riboside
- GC-MS
coupled gas chromatography-mass spectrometry
- HPLC
high-performance liquid chromatography
- Z7G
zeatin 7-glucoside
- Z9G
zeatin 9-glucoside
- ZOG
zeatin O-glucoside
- ZMP
zeatin 9-riboside 5-monophosphate
- ZR
zeatin 9-riboside
- ZROG
zeatin 9-riboside O-glucoside 相似文献
8.
The rate of CO2- and p-benzoquione-dependent photosynthetic O2 evolution by Anabaena variabilis cells remained unaltered and the rate of O2 uptake observed after switching off the light (endogenous respiration) was enhanced by a factor of 6–8 when the O2 concentration was increased from 200 to 400 M. Photosystem-I-linked O2 uptake and respiration of the cells incubated with ascorbate and N,N,NN-tetramethyl-p-phenylenediamine was not appreciable influenced by the O2 concentration. 2-Iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether, blocking electron transfer at the plastoquinone level, suppressed O2 evolution and had no influence on endogenous respiration. 2-n-Heptyl-4-hydroxyquinoline-N-oxide, an inhibitor of electron transfer between photosystems II and I, as well as the cytochrome-oxidase inhibitors N
3
-
, CN- and NH2OH, caused a 35–50% retardation of endogenous respiration and blocked photosynthetic O2 evolution. The molar ratio of cytochromes b6, f, c-553, aa3 and photosystem-I reaction centers in the isolated membranes equalled approx. 2:1:2:0.7:2. It is inferred that endogenous respiration of A. variabilis cells is inhibited by the light-induced electron flow through both photosystems at the level of the plastoquinone-plastocyanin-oxidoreductase complex.Abbreviations DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DNP-INT
2-iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether
- Hepes
4-(2-hydroxyethyl)-1-piperazine ethansulfonic acid
- TMPD
N,N,NN-tetramethyl-p-phenylenediamine 相似文献
9.
Differences in endogenous levels of abscisic acid and gibberellinsbetween Betula platyphylla and Populusalba leaf protoplasts were determined using micro-scale extractionand purification steps, including thin layer chromatography ormicro-high-performance-liquid-chromatography and quantification by enzymelinkedimmunosorbent assay or micro-bioassay. The content of abscisic acid was tentimes higher in B. platyphylla than in P.alba on the basis of both cell number and dry weight; in contrast,levels of gibberellins were lower in the former. Leaf protoplasts of bothspecies are competent for plant regeneration through the exogenous supply ofauxins and cytokinins. The function of abscisic acid in these protoplastcultures is discussed in relation to the need for a strong cytokinin,N-(2-chloro-4-pyridyl)-N-phenylurea (4-CPPU) for colony proliferation inB. platyphylla, in contrast to a weak cytokininrequirementin P. alba. 相似文献
10.
Brian A. McGaw Roger Horgan Jim K. Heald George J. Wullems Rob A. Schilperoort 《Planta》1988,176(2):230-234
The levels of the major cytokinins, zeatin, zeatin riboside, zeatin riboside-5-monophosphate and zeatin-7-glucoside were measured in tobacco (Nicotiana tabacum L.) crown-gall tissues carrying insertion and deletion mutations in the T-DNA. Measurements were made by combined gas chromatography-mass spectrometry using selected ion monitoring with 15N- and 2H-labelled internal standards. The results demonstrate that, relative to wild-type tumour tissue, cytokinin levels are considerably elevated in tissues lacking functional T-DNA auxin-biosynthetic genes. From a detailed analysis of the major cytokinin metabolites it is concluded that a reduction in the extent of cytokinin degradation via N6-side-chain cleavage is an important factor leading to increased cytokinin levels in these tissues.Abbreviations IAA
indole-3-acetic acid
- SIM
selected ion monitoring
- Z
zeatin
- [7G]Z
zeatin-7-glucoside
- [9R]Z
zeatin-9-riboside
- [9R-5P]Z
zeatin riboside-5-monophosphate 相似文献
11.
Suzuki Hisanori Buonamassa Daniela Tornese Weisz Alessandro 《Molecular and cellular biochemistry》1990,99(1):33-39
Summary The activity of poly (ADP-ribose) polymerase (ADPRP) and the content of 2,5-oligodenylates core (2,5An; n = 2,3 and 4) were measured in homogenates of the uterus and of the liver of immature rats immediately before (time 0) or at different times after injection of estradiol-valerate. ADPRP activity increased gradualy, starting 6 hours after estrogen injection, for about 4 days. Instead, the content of 2,5 An decreased by about 50% within 6 hours, and thereafter more slowly for 4 days to about 20% of starting values. Estrogen increased ADPRP activity and decreased 2,5An concentration also in the kidney and in the cardiac muscle of the same animals, but not in the skeletal muscle, where neither of the two parameters was affected. Injection of vehicle only (sesame oil) had no effect on ADPRP activity nor on 2,5An content of immature rat tissues. 相似文献
12.
S. Schleicher I. Boekhoff U. Konietzko H. Breer 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,164(1):76-80
Protein kinase C inhibitors, such a calphostin C, abolish the transient nature of pheromone-induced rapid inositol 1,4,5-triphosphate (IP3) responses, suggesting that pheromone signalling is terminated by phosphorylation of specific proteins. Challenging antennal preparations fromHeliothis virescens with species-specific pheromones in the presence of [32P]--ATP led to a rapid, stimulus-dependent incorporation of32Pi into antennal proteins. Pheromone-induced phosphorylation was completely abolished by a blockade of protein kinase C. Electrophoretic analysis revealed that upon stimulation with a pheromone blend two polypeptide bands were labelled; stimulation solely with the major compound (Z-11-hexadecenal) resulted in only a single labelled band. The data indicate that pheromones cause phosphorylation of specific antennal proteins which may be receptors for pheromones.Abbreviations ATP
adenosine 5-triphosphate
- DMSO
dimethylsulphoxide
- DPM
disintigrations per minute
- DTT
dithiothreitol
- EDTA
ethylenediaminetetra-acetic acid
- EGTA
ethyleneglycol-bis(-aminoethyl ether)N,N,N,N-tetra-acetic acid
- GTP
guanosine 5-triphosphate
- IP3
inositol 1,4,5-trisphosphate
- MOPS
3-(N-morpholino)propanesulphinic acid
- Pi
inorganic phosphate
- PDBu
phorbol-dibutyrate
- SDS
sodium dodecyl sulphate 相似文献
13.
Cecilia PC Soh Alastair SR Donald James Feeney Walter TJ Morgan Winifred M Watkins 《Glycoconjugate journal》1989,6(3):319-332
The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and1H-500 MHz NMR spectroscopy. In Sda serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity. 相似文献
14.
Uptake of 35S-labelled sulfate and thiosulfate was studied in twenty sulfate-reducing bacteria. Micromolar additions of these substrates were highly accumulated by washed cells of freshwater and marine strains. In marine strains accumulation required Na+. Generally, the uptake capacity was increased after sulfate limitation during growth. With two marine species, Desulfovibrio salexigens and Desulfobacterium autotrophicum, the effects of various ionophores and inhibitors affecting the transmembrane pH or Na+ gradient or the membrane potential were studied. In both strains transport was reversible. There was no discrimination between sulfate and thiosulfate. With increasing additions the amount taken up increased, while the accumulation factor (Cin/Cout) decreased. Uptake was not directly correlated with the ATP level inside the cells. From these results and the action patterns of the inhibitors tested it is concluded that marine sulfate-reducing bacteria accumulate sulfate and thiosulfate electrogenically in symport with Na+ ions, while in freshwater strains protons are symported. The high-accumulating systems are induced only at low sulfate concentration, while low-accumulating systems are active at sulfate-sufficient conditions.Abbreviations CCCP
carbonyl cyanide m-chlorophenylhydrazone
- DCCD
dicyclohexylcarbodiimide
- ETH 157
N, N-dibenzyl-N,N-diphenyl-1,2-diphenylendioxydiacetamide
- TCS
3,3,4,5-tetrachlorosalicylanilide 相似文献
15.
P. Pärt C. M. Wood 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1996,166(1):37-45
Using primary cultures of gill pavement cells from freshwater rainbow trout, a method is described for achieving confluent monolayers of the cells on glass coverslips. A continuous record of intracellular pH was obtained by loading the cells with the pH-sensitive flourescent dye 2,7-bis(2-carboxyethyl)-5(6)-carboxyfluorescein and mounting the coverslips in the flowthrough cuvette of a spectrofluorimeter. Experiments were performed in HEPES-buffered media nominally free of HCO3. Resting intracellular pH (7.43 at extracellular pH=7.70) was insensitive to the removal of Cl– or the application of 4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid (0.1 mmol·l–1), but fell by about 0.3 units when Na+ was removed or in the presence of amiloride (0.2 mmol·l–1). Exposure to elevated ammonia (ammonia prepulse; 30 mmol·l–1 as NH4Cl for 6–9 min) produced an increase in intracellular pH (to about 8.1) followed by a slow decay, and washout of the pulse caused intracellular pH to fall to about 6.5. Intracellular non-HCO
3
–
buffer capacity was about 13.4 slykes. Rapid recovery of intracellular pH from intracellular acidosis induced by ammonia prepulse was inhibited more than 80% in Na+-free conditions or in the presence of amiloride (0.2 mmol·l–1). Neither bafilomycin A1 (3 mol·l–1) nor Cl removal altered the intracellular pH recovery rate. The K
m for Na+ of the intracellular pH recovery mechanism was 8.3 mmol·l–1, and the rate constant at V
max was 0.008·s–1 (equivalent to 5.60 mmol H+·l–1 cell water·min–1), which was achieved at external Na+ levels from 25 to 140 mmol·l–1. We conclude that intracellular pH in cultured gill pavement cells in HEPES-buffered, HCO
3
–
-free media, both at rest and during acidosis, is regulated by a Na+/H+ antiport and not by anion-dependent mechanisms or a vacuolar H+-ATPase.Abbreviations
BCECF
2,7-bis(2-carboxyethyl)-5(6)-carboxy-fluorescein
-
BCECF/AM
2,7-bis(2-carboxyethyl)-5(6)-carboxy-fluorescein, acetoxymethylester
-
Cholin-Cl
choline chloride
-
DMSO
dimethyl sulfoxide
-
EDTA
ethylene diamine tetra-acetic acid
-
FBS
foetal bovine serum
-
H
+
-ATPase
Proton-dependent adenosine triphosphatase
-
HEPES
N-[2-hydroxyethyl]piperazine-N[2-ethanesulfonic acid]
-
pH
i
intracellular pH
-
pH
e
extracellular pH
-
PBS
phosphate-buffered saline
-
SITS
4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid 相似文献
16.
Summary The plasmalemma ofNitella internode was made freely permeable to solutes by treating the cell with detergent and EGTA under plasmolysis. After the treatment, the cytoplasmic streaming was stopped by bathing the cell in a medium lacking ATP. The streaming was reactivated by perfusing the exterior of the permeabilized cell with a medium containing both Mg2+ and ATP. The reactivated streaming could be reversibly stopped by depletion of ATP. However, depletion of Mg2+ irreversibly inhibited the streaming.Cytochalasin B at 5 g/ml irreversibly inhibited the reactivated streaming within a minute, showing that microfilaments are involved in the streaming.Abbreviations ATP
adenosine-5-triphosphoric acid
- CB
cytochalasin B
- CyDTA
cyclohexanediamine-N,N-tetraacetic acid
- DMSO
dimethylsulfooxide
- DTT
dithiothreitol
- EGTA
ethyleneglycol-bis(-aminoethylether)-N,N tetraacetic acid
- PIPES
piperazine-N,N-bis(2-ethanesulfonic acid)
- PMSF
phenylmethyl-sulfonylfluoride 相似文献
17.
R. Lohrmann 《Journal of molecular evolution》1976,8(3):197-210
Summary Aqueous solutions of linear inorganic polyphosphates incubated in presence of Mg ions depolymerize to give trimetaphosphate. The presence of a nucleoside 5-phosphate has little influence upon the reaction. Drying the products obtained by incubating a linear polyphosphate with Mg ions in the presence of a nucleoside 5-phosphate yields nucleoside 5-polyphos-phates. The prebiological relevance of the reactions is discussed.Abbreviations Pn(n=1,2,3,)
linear polyphosphate containing n phosphate residues
- P3!
trimetaphosphate
- A
adenosine
- pnN
nucleoside 5-polyphosphate containing n phosphate residues, e.g. with N = A, n = 4
- p4N
adenosine 5-tetraphosphate
-
P
*
lpmA
pnA, (n = 1 + m); adenosine 5-polyphosphate containing n phosphate units with33p-label on terminal 1 phosphate groups 相似文献
18.
Chellathai Jayabaskaran 《Plant Growth Regulation》1990,9(1):9-17
A protein which binds specifically to [3H]-zeatin has been isolated from cucumber cotyledons by chromatographic techniques. Its binding to [3H]-zeatin was inhibited remarkably by the addition of non-radioactive cytokinins and the order of inhibition was zeatin > -zeatin riboside > N6-(2-isopentenyl)adenine > N6-(2-isopentenyl)adenosine > N6-benzyl-adenosine > kinetin riboside. This protein behaved as a soluble protein with an apparent molecular size of 43,000 daltons on gel filtration through calibrated Sephadex G-100 column. The dissociation constant, Kd, of the protein-zeatin complex was about 4 × 10–7 M. 相似文献
19.
Fritz-Joachim Hüther Jan Berden Bernhard Kadenbach 《Journal of bioenergetics and biomembranes》1988,20(4):503-516
The effect of ATP and other anions on the kinetics of cytochromec oxidation by reconstituted bovine heart cytochromec oxidase was investigated. The following results were obtained: (1) ATP and other polyvalent anions increase theK
m
for cytochromec and theV
max (if assayed by the photometric method). The magnitude of the effect is proportional to the charge of the anion as follows from the series of increasing effectiveness: Piii. (2) The kinetic effects are obtained in the millimolar physiological concentration range. (3) The kinetic changes are not saturated at high concentrations. (4) A specific interaction site for ATP at the cytosolic domain of the enzyme is concluded from the increase ofK
m
for cytochromec after photolabelling of proteoliposomes with 8-azido-[-32P]-ATP, which is protected by ATP but not by ADP. (5) No specific binding site for ATP could be identified by photolabelling with 8-azido-[-32P]-ATP. The labelling is only partly protected by ATP or ADP.Abbreviations CCP
carbonylcyanide-m-chlorophenylhydrazone
- TMPD
N,N,N,N-tetramethyl-1,4-phenylenediamine dihydrochloride
- 8-N3-ATP
8-azido-adenosine-5-triphosphate
Dedicated to Professor Dr. Friedhelm Schneider on the occasion of his 60th birthday. 相似文献
20.
Takenori Miyamoto Diego Restrepo Edward J. Cragoe Jr. John H. Teeter 《The Journal of membrane biology》1992,127(3):173-183
Summary Olfactory receptor neurons enzymatically dissociated from channel catfish olfactory epithelium were depolarized transiently following dialysis of IP3 or cAMP (added to the patch pipette) into the cytoplasm. Voltage and current responses to IP3 were blocked by ruthenium red, a blocker of an IP3-gated Ca2+-release channel in sarcoplasmic reticulum. In contrast, the responses to cAMP were not blocked by extracellularly applied ruthenium red, nor by l-cis-diltiazem or amiloride and two of its derivatives. The current elicited by cytoplasmic IP3 in neurons under voltage clamp displayed a voltage dependence different from that of the cAMP response which showed marked outward rectification. A sustained depolarization was caused by increased cytoplasmic IP3 or cAMP when the buffering capacity for Ca2+ of the pipette solution was increased, when extracellular Ca2+ was removed or after addition of 20–200 nm charibdotoxin to the bathing solution, indicating that the repolarization was caused by an increase in [Ca
i
] that opened Ca2+-activated K+ channels. The results suggest that different conductances modulated by either IP3 or cAMP are involved in mediating olfactory transduction in catfish olfactory receptor neurons and that Ca2+-activated K+ channels contribute to the termination of the IP3 and cAMP responses.Abbreviations ATP
adenosine 5-triphosphate
- BAPTA
(bis-(o-aminophenoxy)-ethane-N-N-N-N)-tetraacetic acid
- cAMP
adenosine cyclic 3,5-monophosphate
- cGMP
guanosine cyclic 3,5-monophosphate
- CTX
charybdotoxin
- DCB
3,4-dichlorobenzamil
- EDTA
ethylenediaminetetraacetic acid
- EGTA
ethylenglycol-bis-(b-aminoethyl)-N-N-N-N-tetraacetic acid
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- IP3
inositol-1,4,5-triphosphate
- NMDG
N-methyl-d-glucamine
We would like to thank the Tanabe Seiyaku Co., Ltd., for their gift of l-cis-diltiazem. This work was supported by National Institutes of Health grants DC00566 and BRSG S07RR05825. 相似文献