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1.
2.
Dual regulation of adenylate cyclase and guanylate cyclase: alpha 2-adrenergic signal transduction in adrenocortical carcinoma cells 总被引:1,自引:0,他引:1
Isolated adrenocortical carcinoma cells of rat contain alpha 2- and beta-adrenergic receptors. When these cells are incubated with alpha 2-adrenergic agonists, there is a concentration-dependent increase of cyclic GMP that is blocked by the alpha 2-adrenergic antagonist yohimbine but not by the beta-antagonist propranolol. Concomitantly, both p-aminoclonidine (20 microM) and clonidine (100 microM), the alpha 2-adrenergic agonists, stimulate membrane guanylate cyclase activity. In calcium free medium there is no alpha 2-agonist-dependent increase in cyclic GMP. Isoproterenol, a beta-agonist, and forskolin cause an increase in cyclic AMP but not cyclic GMP. The cyclic AMP increase induced by isoproterenol is blocked by propranolol but not by yohimbine. Isoproterenol- and forskolin-dependent increases in cyclic AMP are inhibited by p-aminoclonidine and the inhibition is relieved by yohimbine. These results indicate a dual regulation of guanylate cyclase and adenylate cyclase by the alpha 2-receptor signal: guanylate cyclase is coupled to the receptor in a positive fashion, whereas adenylate cyclase is coupled in a negative fashion. Calcium is obligatory in the cyclic GMP-mediated response. 相似文献
3.
Stem segments of adult plants of Ficus religiosa L. cultured on MS medium containing 1.0 mg/l 2,4-D produced callus. Shoots were regenerated when the induced calli were transferred to medium supplemented with 0.05 to 2.0 mg/l BAP. Callus derived shoots produced roots and developed into plantlets when transferred to medium supplemented with 1.0 mg/l NAA.Abbreviations MS
Murashige and Skoog (1962)
- BAP
6-benzylaminopurine
- NAA
naphthaleneacetic acid
- 2,4-D
2,4-dichlorophenoxyacetic acid 相似文献
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6.
Perng-Kuang Chang Jeffrey W. Cary Jiujiang Yu Deepak Bhatnagar Thomas E. Cleveland 《Molecular genetics and genomics : MGG》1995,248(3):270-277
Aflatoxins comprise a group of polyketide-derived carcinogenic mycotoxins produced byAspergillus parasiticus andAspergillus flavus. By transformation with a disruption construct, pXX, we disrupted the aflatoxin pathway inA. parasiticus SRRC 2043, resulting in the inability of this strain to produce aflatoxin intermediates as well as a major yellow pigment in the transformants. The disruption was attributed to a single-crossover, homologous integration event between pXX and the recipientA. parasiticus genome at a specific locus, designatedpksA. Sequence analysis suggest thatpksA is a homolog of theAspergillus nidulans wA gene, a polyketide synthase gene involved in conidial wall pigment biosynthesis. The conservedβ-ketoacyl synthase, acyltransferase and acyl carrier-protein domains were present in the deduced amino acid sequence of thepksA product. Noβ-ketoacyl reductase and enoyl reductase domains were found, suggesting thatpksA does not encode catalytic activities for processingβ-carbon similar to those required for long chain fatty acid synthesis. ThepksA gene is located in the aflatoxin pathway gene cluster and is linked to thenor-1 gene, an aflatoxin pathway gene required for converting norsolorinic acid to averantin. These two genes are divergently transcribed from a 1.5 kb intergenic region. We propose thatpksA is a polyketide synthase gene required for the early steps of aflatoxin biosynthesis. 相似文献
7.
Stefan Highsmith Mark Kubinec Devendra K. Jaiswal Hiromi Morimoto Philip G. Williams David E. Wemmer 《Journal of biomolecular NMR》1993,3(3):325-334
Summary The synthesis of [2-3H]ATP with specific activity high enough to use for 3H NMR spectroscopy at micromolar concentrations was accomplished by tritiodehalogenation of 2-Br-ATP. ATP with greater than 80% substitution at the 2-position and negligible tritium levels at other positions had a single 3H NMR peak at 8.20 ppm in 1D spectra obtained at 533 MHz. This result enables the application of tritium NMR spectroscopy to ATP utilizing enzymes.The proteolytic fragment of skeletal muscle myosin, called S1, consists of a heavy chain (95 kDa) and one alkali light chain (16 or 21 kDa) complex that retains myosin ATPase activity. In the presence of Mg2+, S1 converts [2-3H]ATP to [2-3H]ADP and the complex S1.Mg[2-3H]ADP has ADP bound in the active site. At 0°C, 1D 3H NMR spectra of S1.Mg[2-3H]ADP have two broadened peaks shifted 0.55 and 0.90 ppm upfield from the peak due to free [2-3H]ADP. Spectra with good signal-to-noise for 0.10 mM S1.Mg[2-3H]ADP were obtained in 180 min. The magnitude of the chemical shift caused by binding is consistent with the presence of an aromatic side chain being in the active site. Spectra were the same for S1 with either of the alkali light chains present, suggesting that the alkali light chains do not interact differently with the active site. The two broad peaks appear to be due to the two conformations of S1 that have been observed previously by other techniques. Raising the temperature to 20 °C causes small changes in the chemical shifts, narrows the peak widths from 150 to 80 Hz, and increases the relative area under the more upfield peak. Addition of orthovanadate (Vi) to produce S1.Mg[2-3H]ADP.Vi shifts both peaks slightly more upfield without chaning their widths or relative areas. 相似文献
8.
Human and animal mesenchymal progenitor cells from bone marrow: Identification of serum for optimal selection and proliferation 总被引:14,自引:0,他引:14
Donald P. Lennon Stephen E. Haynesworth Scott P. Bruder Neelam Jaiswal Arnold I. Caplan 《In vitro cellular & developmental biology. Animal》1996,32(10):602-611
Summary An undifferentiated subset of cells within the stromal cell population of bone marrow in postnatal mammals retains the capacity
to differentiate along osteogenic, adipogenic, fibroblastic, and chondrogenic lines. These cells, which are referred to as
mesenchymal stem cells (MSCs), can be maintainedin vitro and expanded in number through a process of subculturing. MSCs are maintained in culture in medium supplemented with 10%
fetal bovine serum (FBS). It is believed that certain, as yet unidentified, serum components play critical roles in the attachment
and proliferation of MSCs. Commercially available FBS is poorly characterized and may vary in composition and quality from
lot to lot. This study describes a method for the selection of lots of FBS that best support maintenance of the undifferentiated
state, mitotic expansion of MSCsin vitro, and retention of multilineage developmental potential in response to appropriate cues. 相似文献
9.
Tamal K. Roy Sarita Agarwal Deepak K. Agarwal 《Biochemical and biophysical research communications》1982,106(3):888-894
Centperazine or diethylcarbamazine, administered at various dose levels to rats inhibited the activity of succinate dehydrogenase significantly in 4 hrs in liver. Centperazine also inhibited the activity of cytochrome-c oxidase but stimulated the activity of benzo (a) pyrene hydroxylase in liver. In kidneys, activities of succinate dehydrogenase, cytochrome-c oxidase and aniline hydroxylase were significantly inhibited by centperazine only, however, the activity of benzo (a) pyrene hydroxylase was inhibited by both the drugs. These drugs had no effect on the activity of aminopyrene N-demethylase and cytochrome P-450 contents of liver and kidneys. 相似文献
10.
A K Jaiswal S N Upadhyay S K Bhattacharya 《Indian journal of experimental biology》1991,29(6):532-537
The study was conducted on 64 Charles Foster strain albino rats, which were equally distributed into 8 evenly matched groups, following a 2 x 2 x 2 factorial design, by varying three independent factors at two levels: nutrition--normal and undernutrition; environment--enrichment and impoverishment, and drug treatment--vehicle and dihydroergotoxine (3 mg/kg, i.p.). Prenatal undernutrition was induced by restricting the mother's food intake. The environmental enrichment/impoverishment and the vehicle/dihydroergotoxine treatments were given during the postweaning period of the pups. The rats were subjected to original and subsequent reversal brightness discrimination learning tests in a single unit T-maze at 8-9 weeks of age. Thereafter, the animals were tested for passive avoidance learning. The results indicate that undernutrition caused significant original and reversal discrimination learning, deficits whereas environmental deprivation attenuated only the original discrimination learning performance. Dihydroergotoxine treatment facilitated the learning performance of rats in both the original and reversal learning tests. Nutritional, environmental and dihydroergotoxine treatments had no effect on the retention of the passive avoidance learning, both at 24 hr and 1 week intervals. Dihydroergotoxine treatment attenuated the learning deficits induced by prenatal undernutrition. The results indicate that dihydroergotoxine is not likely to be useful in cognitive deficits, induced by malnutrition, though it facilitated learning acquisition, since it had no effect on retention. 相似文献