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排序方式: 共有435条查询结果,搜索用时 46 毫秒
1.
Hydroxycinnamoyl-CoA:Putrescine Hydroxycinnamoyltransferase in Tobacco Cell Cultures with High and Low Levels of Caffeoylputrescine 总被引:1,自引:0,他引:1
A new hydroxycinnamoyl-CoA:putrescine hydroxycinnamoyltransferase (PHT) was detected in two variant lines of Nicotiana tabacum L. (TX1, TX4) accumulating markedly different levels of caffeoylputrescine. The enzyme accepted only the aliphatic diamines putrescine, cadaverine and 1,3-diaminopropane at a ratio of 100:33:8. Caffeoyl- and feruloyl-CoAs were the best acyl donors. The apparent Km-values for caffeoyl-CoA and putrescine were near 3 and 10 micromolar, respectively, at the pH-optimum of 10.0. PHT activity was quite similar in low producing TX1 and high producing TX4 cells, while some other biosynthetic enzymes (phenylalanine ammonia-lyase, ornithine decarboxylase) were greatly enhanced in TX4 cells, suggesting that PHT does not catalyze the rate-limiting step in hydroxycinnamoylputrescine formation. 相似文献
2.
Characterization of a meta-Fluorotyrosine-Tolerant Cell Culture of Eschscholtzia californica Cham 下载免费PDF全文
A cell line of Eschscholtzia californica selected for meta-fluorotyrosine (MFT) tolerance was found to have 10-fold increased levels of phenylalanine and tyrosine compared to the parent line, while most other amino acids were only increased 2-fold. Tracer experiments with shikimic acid in the presence of MFT showed that the biosynthesis of the aromatic amino acids was not impaired in the tolerant line. Feeding experiments with phenylalanine, tyrosine, or shikimic acid also revealed a reduced turnover of the pools of the aromatic amino acids in the variant. Thus undisturbed de novo biosynthesis of the aromatic amino acids and dilution of toxic effects of MFT by the enlarged pool sizes seemed to be the main reason for the acquired tolerance. Despite the enlarged availability of the precursor tyrosine, formation of the benzophenanthridine alkaloids was enhanced neither in the growth nor in the production medium. 相似文献
3.
Cell cultures ofThalictrum
rugosum released their protoberberine alkaloids into the medium, when cells were transferred to fresh medium lacking phosphate. The nutritional factors required and the impact of the cells' physiological state for the alkaloid excretion were analyzed. Cell cultures, having released their alkaloids into the medium, continued to grow when the alkaloid containing medium was replaced by fresh growth medium. 相似文献
4.
Glycosaminoglycan synthesis is depressed during mitosis and elevated during early G1 总被引:3,自引:1,他引:2 下载免费PDF全文
S F Preston C S Regula P R Sager C B Pearson L S Daniels P A Brown R D Berlin 《The Journal of cell biology》1985,101(3):1086-1093
[35S]Sulfate incorporation was measured in populations of Chinese hamster ovary cells enriched for mitotics, early G1 cells, and interphase monolayers or suspensions. Incorporation was determined by biochemical analysis of extracts and quantitative autoradiography of thick sections. 90% of [35S]sulfate was incorporated into glycosaminoglycan (GAG). Incorporation was depressed fourfold in mitotics and stimulated by from two- to three-fold in early G1 cells relative to mixed interphase cells. GAG synthesis was maintained into late G2. Thus, the rate of GAG biosynthesis was correlated temporally with the detachment and reattachment of cells to substrate. Inhibitors of protein synthesis brought about the rapid arrest of GAG biosynthesis. However, xylosides, which bypass the requirement for core protein, did not bring oligosaccharide sulfation in mitotics to interphase levels. These observations indicate an inhibition of Golgi processing and are consistent with a generalized defect of membrane vesicle-mediated transport during mitosis. 相似文献
5.
Tryptophan decarboxylase (EC 4.2.1.27) is synthesized de-novo by Catharanthus roseus cells shortly after the cells have been transferred into culture medium in which monoterpenoid indole alkaloids are formed. The enzyme production, monitored by in-vivo labelling with [35S]methionine and immunoprecipitation, precedes the apparent maximal enzyme activity by 10–12 h. From the time course of the descending enzyme activity after induction, a half-life of 21 h for tryptophan decarboxylase in C. roseus cell suspensions is calculated. A comparison of the polyadenylated-RNA preparations from C. roseus cells indicates that mRNA activity for tryptophan decarboxylase is only detected in cells grown in the production medium. The importance of tryptophan decarboxylase induction with respect to the accumulation of th corresponding alkaloids is discussed.Abbreviation TDC
tryptophan decarboxylase 相似文献
6.
Norma L. Trolinder Jerry D. Berlin Joe R. Goodin 《In vitro cellular & developmental biology. Plant》1987,23(11):789-794
Summary A cotton cell suspension culture has been developed that provides unique opportunities for plant biologists to investigate
early developmental events regulating cotton fiber properties, plant cell elongation, and cell wall biogenesis. The suspension
culture was derived from cells of cotton (Gossypium hirsutum L.) ovule callus. These cells undergo the stages of fiber development
previously described for in vivo fiber development. Fibers range in length up to 11 mm and have secondary walls.
Supported by the U.S. Department of Agriculture, Agricultural Research Service, Southern Regional Research Laboratory, New
Orleans, Louisiana, and Cotton Incorporated, Raleigh, North Carolina. 相似文献
7.
8.
The ultrastructural localization of acid mucopolysaccharides in the intestine after irradiation 总被引:2,自引:0,他引:2
J D Berlin 《Radiation research》1968,34(2):347-356
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