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31.
Conversion of 15-hydroxyeicosatetraenoic acid to 11-hydroxyhexadecatrienoic acid by endothelial cells 总被引:1,自引:0,他引:1
Cultured endothelial cells take up 15-hydroxyeicosatetraenoic acid (15-HETE), a lipoxygenase product formed from arachidonic acid, and incorporate it into cellular phospholipids and glycerides. Uptake can occur from either the apical or basolateral surface. A substantial amount of the 15-HETE incorporated into phospholipids is present in the inositol phosphoglycerides. 15-HETE is converted into several metabolic products that accumulate in teh extracellular fluid; this conversion does not require stimulation by agonists. The main product has been identified as 11-hydroxyhexadecatrienoic acid [16:3(11-OH)], a metabolite of 15-HETE that has not been described previously. Formation of 16:3(11-OH) decreases when 4-pentenoic acid is present, suggesting that it is produced by beta-oxidation. The endothelial cells can take up 16:3(11-OH) only 25% as effectively as 15-HETE, and 16:3(11-OH) is almost entirely excluded from the inositol phosphoglycerides. These results suggest that the endothelial cells can incorporate 15-HETE when it is released into their environment. Through partial oxidation, the endothelium can process 15-HETE to a novel metabolite that is less effectively taken up and, in particular, is excluded from the inositol phosphoglycerides. 相似文献
32.
用~(14)C-Pro和~3H_2-Tyr离体暗培养黄瓜子叶,发现细胞质、SECW和RCW中的Hyp/Pro和Idt/Tyr都随时间呈线性增加。这两种比值后两者高于前者,而两种比值增加速度之比在胞质部分最大、RCW中最小。表明在胞质和胞壁中都有Pro羟化和Tyr异联化过程,但羟化作用主要发生在胞质中,异联化主要在RCW中。 理化处理(高渗溶液和CHM)和放射性示踪证明胞质中存在HRGP库;它被分泌到胞壁后,先以离子键与壁结合,后转变为共价键与壁结合的伸展素。 相似文献
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棉纤维细胞伸长生长与过氧化物酶和IAA氧化酶的关系 总被引:7,自引:0,他引:7
棉纤维细胞于开花当天从棉胚珠表皮上发生,随即开始伸长生长,星S型生长曲线。棉纤维细胞的可溶性蛋白、过氧化物酶活性和IAA氧化酶活性同伸长生长的关系不大;而离子型结合的细胞壁蛋白质含量、过氧化物酶活性和IAA氧化酶活性同棉纤维细胞的伸长生长关系较大,表现在棉纤维细胞快速伸长期活性较低,而在伸长生长停止时出现活性高峰,同棉纤维细胞的伸长生长有负相关现象。 相似文献
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Eugene Y. F. Shen 《The Journal of cell biology》1967,35(2):377-384
Microspectrophotometric analysis of the DNA content of nuclei in various parts of Chara zeylanica Willd. revealed that the amount of DNA in the nucleus of an internodal cell equals twice the amount of DNA in the nucleus of a sperm, while the half-anaphase stage of the same nodal cells contains the same amount of DNA as the nuclei of the male gametes. The DNA content of the nuclei of internodal cells may rise as much as 50 times higher than that of the gametes. However, in the oldest (most basal) internodal cells, the DNA content of the minute nuclei falls again to the basic (1 C) amount. Measurements of sister nuclei derived by amitosis indicated that both nuclei have equal amounts of DNA; this was interpreted as further evidence that amitosis is not a disorganized process or manifestation of degeneration. The bearing of these analyses on the question of the site of meiosis in these plants is discussed. 相似文献
39.
Summary A study of the behaviour of the photosynthetic products assimilated at different growth stages was conducted in the field and in the greenhouse using C14 tracer.In general, the assimilated carbon is translocated to and accumulates in the growing organs. The carbon assimilated at the maximum tiller number stage is distributed mostly to the lower leaves. The carbon assimilated at the booting stage is distributed mostly to the spikelet, certain leaf sheaths and culms. The carbon accumulated in the form of carbohydrates in the leaf sheaths and the culm before flowering is retranslocated to the panicle after flowering. However, because of the consumption by respiration, the efficiency of this type of carbohydrate in grain production is not very high. The carbon assimilated after flowering accumulated mostly and efficiently in the brown rice.The release of the assimilated carbon as CO2 is most intense immediately after assimilation. Thirty-five to 60 per cent of the assimilated carbon is consumed through respiration under the conditions of this experiment. As the carbon, which is in the form of sugars, rapidly changes to other forms, and also is consumed by respiration, the consumption declines rapidly. The retention percentage of assimilated carbon decreases as mutual shading increases.The large proportion of carbon released through respiration indicates the importance of studies on the significance of respiration in relation to growth.A portion of the thesis for the Master of Science degree submitted by Mr. Shen Lian to the Graduate School, University of the Philippines, College of Agriculture. 相似文献
40.
S. Laganire E. Kwong D. D. Shen 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1989,488(2)
A simple and sensitive stereoselective high-performance liquid chromatographic assay for the quantitation of propranolol enantiomers in serum is described. The method involves conversion of the propranolol enantiomers to diastereomeric urea derivatives by reaction with the chiral reagent (+)-phenylethylisocyanate, followed by chromatographic separation of the diastereomeric products. Conditions of the derivatization reaction were optimized to achieve rapid and quantitative yield with either of the enantiomers. Baseline resolution of the diastereomers was achieved on a reversed phase C8 column with an isocratic mobile phase. Fluorescence detection afforded an absolute on-column detection limit of 100 pg. The assay has been applied to pharmacokinetic studies in humans and small laboratory animals. 相似文献