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91.
Catherine Curie Thierry Liboz Marie-Hélène Montané Dominique Rouan Michèle Axelos Bernard Lescure 《Plant molecular biology》1992,18(6):1083-1089
In Arabidopsis thaliana, the activation process of the A1 EF-1 gene depends on several elements. Using the GUS reporter gene, transient expression experiments have shown that mutations of upstream cis-acting elements of the A1 promoter, or the deletion of an intron located within the 5 non-coding region, similarly affect expression in dicot or monocot protoplasts. The results reported here strongly suggest that this 5 intron is properly spliced in Zea mays. We show that two trans-acting factors, specifically interacting with an upstream activating sequence (the TEF 1 box), are present in nuclear extracts prepared from A. thaliana, Brassica rapa, Nicotiana tabacum and Z. mays. In addition, a DNA sequence homologous to the TEF 1 box, found at approximately the same location within a Lycopersicon esculentum EF-1 promoter, interacts with the same trans-acting factors. Homologies found between the A. thaliana and L. esculentum TEF 1 box sequences have allowed us to define mutations of this upstream element which affect the interaction with the corresponding trans-acting factors. These results support the notion that the activation processes of A. thaliana EF-1 genes have been conserved among angiosperms and provide interesting data on the functional structure of the TEF 1 box. 相似文献
92.
Khalid M. Chraibi B. Alain Latche Jean-Paul Roustan Jean Fallot 《Plant cell reports》1991,10(4):204-207
The effects of CoCl2, AgNO3 and ethylene released by exogenous 2-chloroethylphosphonic acid (Ethephon), were studied on shoot regeneration from cotyledons of Helianthus annuus cv. E8206R, a poorly regenerative cultivar. Inhibition of ethylene biosynthesis by CoCl2, at concentrations of 20 K, provoked a substantial enhancement of shoot regeneration (30 %): the control was poorly regenerative. However, CoCl2 had no effect when Ethephon was supplied. Inhibition of ethylene action by AgNO3, at concentrations of 10–25 M, caused a significant increase in plant regeneration: 25 % instead of 1.2 % in the control. Furthermore, addition of Ethephon to AgNO3-treated tissues failed to reduce the stimulation of shoot regeneration caused by AgNO3. On the basis of these findings, it is suggested that ethylene inhibits the regeneration process from cotyledons of sunflower.Abbreviations NAA
1-naphthalene acetic acid
- BAP
6-benzylamino-purine
- GA3
gibberellic acid
- Ethephon
2-chloroethylphosphonic acid
- MS
Murashige and Skoog medium
- AVG
aminoethoxyvinylglycine 相似文献
93.
Barry S. Cooperman Alain Expert-Bezançon Lawrence Kahan Jacques Dondon Marianne Grunberg-Manago 《Archives of biochemistry and biophysics》1981,208(2):554-562
We here report the results of using three light-dependent procedures for crosslinking IF-3 to 30 S proteins within an IF-3·30 S complex. In the first procedure, employing FMN as a photosensitizer, protein S12 is found to be the only major crosslinked protein. In the second procedure, IF-3 is first reacted with the new two-stage crosslinking reagent, p-nitrobenzylmaleimide (PNBM), and the PNBM—IF-3·30 S complex is irradiated. The major crosslinked proteins are S3 > S2, S12, S18. Small amounts of crosslinked S11 and S21 are also found. In the third procedure, the IF-3·30 S complex is reacted with PNBM and then irradiated. The major crosslinked proteins are S12 > S3 > S11 and small amounts of crosslinked S1, S13, and S21 are also found. These results are compared with results obtained by others using different crosslinking procedures and are used to discuss the Lake and Kahan model (J. A. Lake and L. Kahan, 1975, J. Mol. Biol., 99, 631–644, and J. A. Lake, 1978, in Advanced Techniques in Biological Electron Microscopy II, Koehler, J. K., ed., pp. 173–211, Springer-Verlag, Berlin) for IF-3 binding to 30 S subunits. 相似文献
94.
The authors recall some data concerning the distribution, the ecology and the taxonomy of Nuia and describe in detail its mode of growth, distinguished by 6 different growth-forms. 相似文献
95.
In extracts from Zea mays shoots, the presence of thiol compoundsin the extraction buffer was necessary to get an active 3 deoxy-D-arabinoheptulosonic acid 7-phosphate (DAHP) synthase. Its pH optimumfor activity was about 7.5. Of the different cations tested,only Mn++ was an activator. Enzyme stability was optimal inTris-HCl buffer, pH 7.5, that contained a reducing agent, Mn++and a polyol. Contrary to other reports, phosphoenolpyruvate(PEP) did not stabilize the preparation significantly. The synthaseexhibited high affinities for both erythrose-4-phosphate (Km:0.24 mM) and PEP (Km: 0.31 mM). Its specific activity was highestin young shoots. Corn DAHP synthase was inhibited in vitro by tryptophan. Moreover,the enzyme was retarded on a tryptophan agarose affinity column,but it was removed with the bulk of protein from the same supportwhen eluted with buffer containing tryptophan. Inhibition whichwas easily lost during storage at 4°C was pH dependent andincreased during development. Maximal inhibition, about 60%with 1 mM tryptophan, was observed in extracts from 8 day-oldshoots. Phenylalanine and tyrosine were not inhibitory, andno synergistic effects were observed when the aromatic aminoacids were tested in combination. Isoenzymes could not be demonstrated. (Received April 23, 1980; ) 相似文献
96.
97.
Alain B. Schreiber Johan Hoebeke Bernard Vray A. Donny Strosberg 《Experimental cell research》1981,132(2)
The association and dissociation mechanisms of lectin membrane receptor microclustering on HeLa cells have been studied by measuring resonance energy transfer between fluoresceinated and rhodaminated lentil lectin. Compounds known to affect membrane receptor mobility, such as Ca2+ ions, methylamine, cytochalasin D and nocodazole, did not modify the association kinetics nor the maximal energy transfer values at 4 and 37 °C. Dissociation of the membrane receptor microclusters was followed by measuring the temporal decrease in energy transfer values at 4 °C after preincubation for different time intervals at 37 °C. The rate of dissociation of the lectin receptors decreased in the presence of Ca2+ ions (10−3 M) and after cross-linking with anti-lectin antibodies. An increase was observed in the presence of cytochalasin D (10−6 M) and, to a lesser extent, of methylamine (10−2 M). When cytochalasin D and methylamine were combined at subliminal concentrations, a partial synergistic effect was observed. Nocodazole (10−6 M) had no effect. The results suggest that the association of lectin membrane receptors in microclusters is mediated only by physicochemical parameters. Ca2+ ions, cytochalasin D (microfilaments) and methylamine (transglutaminase)-sensitive components appear, however, to play an important role in the stabilization of the receptor microclusters. 相似文献
98.
Four strains of both Taphrina pruni and T. institiae were cultivated under identical conditions and and lipids and fatty acids were quantitatively analysed at two stages of their development. Tri- and diglycerides are the major neutral lipids in both species. Phosphatidylcholine and phosphatidylethanolamine are the most abundant polar lipids. Qualitatively, the two species show identical fatty acid contents, except for margaric acid (17:0) which was only found in Taphrine pruni. Quantitatively there are several differences: palmitoleic acid (16:1) occurs in reasonable amounts regularly and only in Taphrina pruni. The ratios 16:0/18:0 and 18:1/18:2 are generally higher for T. insititiae whereas the degree of unsaturation of fatty acids is higher in the former. The results are discussed with regard to data on other fungal species. 相似文献
99.
100.