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1.
This study describes the isolation and characterization of p-fluorophenylalanine-resistant diploid tobacco (Nicotiana tabacum L.) and diploid carrot (Daucus carota L.) cultured cell lines. The p-fluorophenylalanine-resistant tobacco and carrot lines can grow in medium containing p-fluorophenylalanine concentrations 10 to more than 100 times those which inhibit the growth of susceptible cells, respectively. The resistance trait was retained when the cells were grown in a medium lacking the phenylalanine analog for 50 generations. All 14 single cell clones started from the resistant carrot line remained resistant. The resistant lines incorporated much less p-fluorophenylalanine into protein, partially due to a decrease in uptake. In carrots, an increase in the levels of free phenylalanine and tyrosine also apparently contributed to the decreased incorporation of p-fluorophenylalanine into protein by increasing the metabolic pool size which diluted the incoming analog and caused a lowered percentage of incorporation, which was observed. Apparently, phenylalanine and tyrosine synthesis was also increased in resistant tobacco lines, since chorismate mutase was found to have greater activity and to be less sensitive to inhibition by phenylalanine, tyrosine, and p-fluorophenylalanine. It appears, however, that phenylalanine and tyrosine do not accumulate above the normal levels in the resistant tobacco cells, as these amino acids were apparently converted into phenolic compounds which were found in higher levels (6 times). The low frequency of appearance, the stability of the trait, and the biochemical nature of the resistance, indicate that the p-fluorophenylalanine resistance found in the carrot and tobacco lines described here is due to a mutation. 相似文献
2.
Enzymes involved in malate metabolism, viz., glutamic-oxalacetictransaminase, malate dehydrogenase, malic enzyme and phosphoenolpyruvatecarboxylase, had severalfold higher specific activities in organ-formingcallus cultures of tobacco compared to non-organ-forming cultures.These activities increased considerably during the days precedingshoot and root differentiation. While malate accumulated untilday 15 in non-organ-forming callus, it accumulated up to day6 in shoot-and root-forming callus. Total and reducing sugarsaccumulated until day 3 and declined thereafter in all the cultures.Thus, tobacco callus may utilize this pathway for deriving reducingpower which is required for organogenetic processes. (Received April 30, 1987; Accepted December 1, 1987) 相似文献
3.
The theoretical pH dependence of enzyme activities in membranes of low dielectric constant is estimated. It is shown that in biological membranes some types of enzymes may attain a limiting pH sensitivity such that an increment of only 0.2 pH unit (sufficient to induce action potentials in squid axons) causes a relative activity change of over 25%. The transients of enzyme activity generated by membrane depolarization and by pH increments in the bathing solution are discussed in relation to the transients of nervous excitation. 相似文献
4.
龙眼果实采后果肉自溶过程中细胞壁组分及其降解酶活性的变化 总被引:9,自引:0,他引:9
在(10±1)℃下贮藏的‘福眼’龙眼果实果肉自溶指数和自溶程度随着贮藏时间的延长而增加。果肉细胞壁干重、原果胶、纤维素、半纤维素和细胞壁蛋白含量不断减少。果肉果胶酯酶(PE)活性下降;多聚半乳糖醛酸酶(PG)活性在贮藏6~12d以及纤维素酶活性在贮藏0~12d期间均明显增强,到第12天达到活性高峰,之后下降。但在贮藏0~24d期间,PE、PG和纤维素酶仍然保持较高活性,贮藏24d之后快速下降。β-半乳糖苷酶活性在贮藏0~24d期间略有下降,而在贮藏24d后,活性增强,尤其是贮藏30d后,活性急剧升高。 相似文献
5.
Succinic dehydrogenase and cytochrome oxidase have been assayed in permanent cell lines (HEP 1, HEP 2, and HLM), in short-term cultures of chick embryo heart cells, and in various tissues. Their activities in different cells are compared by relating them to deoxyribonucleic acid. They are very low in HEP 1, HEP 2, and HLM cells by comparison with the activities in any normal tissues examined. All the succinic dehydrogenase was shown to be located in the mitochondria of the permanent cell lines by staining with tetrazolium derivatives. Both enzymes were more active in tissues of 19-day chick embryos than in those of 11- or 14-day embryos. The increasing activities found during normal development were quickly curtailed or reversed when heart cells were grown as monolayer cultures. Digitonin-treated mitochondria produced preparations with much higher activities of cytochrome oxidase than untreated samples. Activities measured in this way were again very much lower in HEP 1, HEP 2, and HLM cells than in the normal tissues. From the derived ratio of cytochrome oxidase:succinic dehydrogenase, it was apparent that cytochrome oxidase is diminished to a greater extent than succinic dehydrogenase in both permanent cell lines and short-term cultures, by comparison with the corresponding activities in embryonic and adult tissues. The features common to the metabolism of proliferating cells in vitro and malignant cells are discussed. 相似文献
6.
Cell-density-dependent Changes in the Metabolism of Chloronema Cell Cultures: I. Relationship between Cell Density and Enzymic Activities 下载免费PDF全文
In the growing chloronema cell suspension cultures of the moss Funaria hygrometrica Hedw., activities of several enzymes have been found to be cell-density-dependent. Cyclic nucleotide phosphodiesterase (cNPDE), nitrate reductase (NR), and protein kinase showed highest activity at a low cell density (1 to 2 milligrams per milliliter) while indoleacetic acid (IAA) oxidase and peroxidase were highest at a high cell density (>10 milligrams per milliliter). 3′-Nucleotidase and the glycolytic enzymes (aldolase, hexokinase, phosphofructokinase, phosphoglucoisomerase, pyruvate kinase, and triose phosphate isomerase) showed no significant dependence on the cell density. Alternatively, if the NR and peroxidase activities were determined as a function of time in batch cultures, their levels were maximal 60 to 70 and 320 hours after subculture, respectively, the corresponding cell densities being 1 to 2 and 23 milligrams per milliliter. The relationship between cell density and NR and peroxidase activities is the same, whether these enzymes are measured in batch cultures during a growth cycle or in the cells cultured at different initial inoculum densities for a constant time. Conventionally enzymic changes have been correlated with growth phases; however, it is felt that the pattern of enzymic activities can also be interpreted as cell-density-dependent. 相似文献
7.
8.
Copper and zinc resistant cells of Nicotiana plumbaginifoliawere selected using unmutagenized cell suspensions in mediumcontaining normally lethal concentrations of CuSO4 or ZnSO4.Both resistances were retained for thirty cell doublings withoutselection pressure. The Cu resistant cells were 10-times andthe Zn resistant cells were 6-times as resistant as the wildtype cells. The Zn resistant cells were also somewhat resistantto AlCl3 in comparison with the wild type cells, while the Curesistant cells were also somewhat resistant to ZnSO4 and AlCl3.The uptake of Cu by the Cu resistant cells and Zn by the Znresistant cells was higher than that of the wild type cells. (Received April 21, 1986; Accepted June 30, 1986) 相似文献
9.
Nicotine Biosynthetic Enzyme Activities in Nicotiana tabacum L. Genotypes with Different Alkaloid Levels 总被引:3,自引:1,他引:3 下载免费PDF全文
Young plants of five Nicotiana tabacum L. genotypes were examined for activity of nicotine biosynthetic enzymes. Genotypes near isogenic except at two loci each with two alleles controlling nicotine level were used in a comparison of the four homozygous allelic combinations producing high, high intermediate, low intermediate, and low nicotine levels in a “Burley 21” background. Putrescine N-methyltransferase (EC 2.1.1.53) and quinolinic acid phosphoribosyltransferase (EC 2.4.2.19) activities in root tissue of these four genotypes were proportional to leaf nicotine level, whereas N-methylputrescine oxidase activity in root tissue differed in proportion and ranking. Quinolinic acid phosphoribosyltransferase activities in leaf tissue were lower than in roots, but no differences were found among the four genotypes. The homozygous recessive alleles at either locus affect levels of all three enzyme activities examined in roots. Each locus seems to be involved in regulation of nicotine metabolism, but whether directly as a regulatory locus or indirectly through the metabolic product of a structural locus is not known. 相似文献
10.
Tyrosine and Phenylalanine Ammonia Lyase Activities during Shoot Initiation in Tobacco Callus Cultures 总被引:3,自引:0,他引:3 下载免费PDF全文
Both phenylalanine ammonia lyase and tyrosine ammonia lyase were detected in tobacco (Nicotiana tabacum L. Wisconsin 38) callus. The enzymes were separated from each other by Sephadex G-200 column chromatography. Increased activity of tyrosine ammonia lyase was observed during culture of tobacco callus under shoot-forming conditions, while activity of phenylalanine ammonia lyase increased during culture under non-organ-forming conditions. Confirmation of these findings was obtained by examining the incorporation of [14C]tyrosine and [14C]phenylalanine into p-coumarate and trans-cinnamate, respectively. 相似文献
11.
为了解橄榄(Canarium album)果实质地差异形成的原因,以鲜食型橄榄‘清榄1号’和加工型橄榄‘长营’为材料,对果实发育过程中细胞壁物质含量和相关酶活性进行了测定。结果表明,随着橄榄果实的成熟,‘清榄1号’较‘长营’维持较高的果胶甲酯酶(PME)活性,促进了果胶的水解,离子型果胶(ISP)含量较高而共价型果胶(CSP)含量较低。2个橄榄品种纤维素含量均较高,‘清榄1号’果实的半纤维素含量低于‘长营’。‘清榄1号’木质素含量低于‘长营’,较高的苯丙氨酸解氨酶(PAL)和过氧化物酶(POD)活性促进了木质素含量的增加。因此,ISP、CSP、半纤维素和木质素含量的不同可能是2个橄榄品种果实质地差异形成的原因。 相似文献
12.
d-Tryptophan was converted to l-tryptophan in tissue cultures of tobacco, in whole cells treated with dimethylsulfoxide, and in cell-free extracts treated by Sephadex G-25 filtration. Evidence was obtained that tryptophanase, tryptophan pyrrolase, and transaminase activities were not involved. The data were best explained by the presence of a tryptophan racemase as the enzyme catalyzing the reaction. The possible role of d-tryptophan in the biosynthesis of indoleacetic acid is discussed. 相似文献
13.
目的:观察2'-羟基二氢黄酮诱导白血病细胞HL-60凋亡过程中胞内抗氧化酶活性的变化,并探讨其抗肿瘤作用机制.方法:采用CASY-TT亚流式细胞术测定2′-羟基二氢黄酮对HL-60细胞存活率的影响;Annexin V/PI双染流式细胞仪检测分析细胞凋亡变化;化学比色法测定2′-羟基二氢黄酮作用后,HL-60细胞胞内抗氧化酶SOD、CAT、GSH-Px的活性变化.结果:2′-羟基二氢黄酮显著降低HL-60细胞存活率,其作用呈剂量和时间依赖性;凋亡分析结果显示,20 μM的2′-羟基二氢黄酮作用HL-60细胞后,细胞凋亡率逐渐升高,并在12 h后显著高于作用前水平;酶活性检测表明,20 μM 2′-羟基二氢黄酮作用后,HL-60细胞胞内抗氧化酶SOD、CAT、GSH-Px活性均显著降低.脂质过氧化产物MDA含量显著升高.结论:2′-羟基二氢黄酮显著降低白血病HL-60细胞存活率并诱导细胞凋亡,其中伴随着胞内抗氧化酶活性的显著降低. 相似文献
14.
Proteins and Plant Cell Walls. Proline to Hydroxyproline in Tobacco Suspension Cultures 总被引:5,自引:0,他引:5 下载免费PDF全文
Alfred C. Olson 《Plant physiology》1964,39(4):543-550
15.
Activities of glucose 6-phosphate and 6-phosphogluconate dehydrogenases,transketolase and transaldolase in twigs of Populus gelricawere measured throughout a year. In the living bark, activitiesof the four enzymes of the pentose phosphate cycle changed atabout the same time in the life cycle of the plant. In the differentiatingxylem cells there also occurred a simultaneous change in thefour enzyme activities. After differentiation of cambium toxylem, the high levels of the four enzyme activities fell graduallyand reached minimum levels by early September. In early September,the former two dehydrogenase activities began to rise again,while the latter two transferase activities continued to decrease.The elevated levels of the two dehydrogenases in the differentiatedxylem remained unchanged in the non-growing period of the lifecycle of the plant. Such a changing pattern of enzyme activitiesin the life cycle suggested that the pentose phosphate cyclein the differentiated xylem is interrupted in part at the stepof transketolase reaction, which results in an increased supplyof pentoses and NADPH. Moreover, these characteristic changesin the enzyme activities in the xylem are correlated with thechanges in the fine structures of the cells.
1 Contribution No. 2272 from the Institute of Low TemperatureScience, Hokkaido University, Sapporo, Japan (Received June 26, 1981; Accepted September 28, 1981) 相似文献
16.
甘蔗和烟草叶原生质体分离期间的膜损伤及有关酶活性变化何若天,覃伟,李任强(广西农业大学实验中心,南宁530005)关键词:原生质体,超氧阴离子自由基(O_2~-),膜损伤,甘蔗,烟草植物原生质体分离期间,所用细胞壁降解酶和高渗介质等对细胞生理有深刻影响... 相似文献
17.
In order to assess resistance to common bean blight, populations of two isolates of Xanthomonas campestris pv. phaseoli were monitored in leaves of two Phaseolus vulgaris breeding lines, BLT87-2 (susceptible) and OAC88-1 (partially resistant) and a resistant tepary bean accession, P. acutifolius P. I. 440795. The breeding line OAC88-1 possesses resistance to common bacterial blight which was incorporated from P. acutifolius by an interspecific cross. In susceptible, leaves, bacterial populations increased to 108 CFU/g leaf at 3 wk after inoculation whereas, in resistant leaves, bacterial populations declined to 101 - 103 CFU/g leaf. In partially resistant leaves the population first declined similar to that in resistant P. acutifolius but later increased, and typical bacterial blight symptoms appeared. Cellulase, protease and amylase activities were monitored in culture and intercellular leaf spaces. Only cellulase activity was, clearly related to bacterial growth in the susceptible host; other enzyme activities were variable in their relationship to host resistance and bacterial growth. Differences between strains in cellulase activity inside partially resistant leaves corresponded to their ability to secrete cellulase in culture. Measuring cellulase activity in intercellular wash fluids may be a simple and sensitive method for determining X. c. phaseoli populations in leaves. 相似文献
18.
Large rod-shaped structures corresponding to paracrystals were seen in the nucleus, cytoplasm, or both of adenovirus type 2 (Ad2)-infected cells by immunofluorescence staining with antibody prepared against purified Ad2. In exception to this, Ad2-induced crystals did not stain with either hexon or fiber antibody. The crystalline structures were first observed in Ad2-infected Vero cells at 28 hr with a maximum number at 70 hr postinoculation. The kinetics of paracrystalline formation closely paralleled the experimental synthesis of infectious progeny virus. Acridine-orange staining revealed the lack of nucleic acids associated with the crystal. Also, the paracrystals stained intensely with phenanthrenequinone, suggesting that they are composed of basic proteins. Interferon induced by Newcastle disease virus from African green monkey kidney cell cultures was used to pretreat Vero cells prior to Ad2 infection. This resulted in inhibiting the formation of viral-induced paracrystals in 97% of the cells and reduced virus yields by 95%. The African green monkey kidney cell culture interferon did not reduce Ad2 yields in HeLa cell cultures or display any virus inhibitory activity in rabbit kidney cell cultures. Staining procedures, fluorescent-antibody tests with whole virus, hexon or fiber antibody, and interferon studies suggested that the paracrystals were viral-directed and composed of basic proteins (possibly core proteins). 相似文献
19.
Pedro Iñarrea Raquel Alarcia María A. Alava José L. Capablo Alvaro Casanova Cristina Iñiguez María Iturralde Pilar Larrodé Jesús Martín Enrique Mostacero José R. Ara 《Molecular neurobiology》2014,49(1):1-9
Blood platelets have been widely proposed as biomarkers in studies of mitochondrial function and aging-related and neurodegenerative diseases. Defects in mitochondrial function were found not only in the substantia nigra of Parkinson’s disease patients but also in their blood platelets. Similarly, it has also been described in the blood platelet mitochondria of Alzheimer’s disease patients. To study mitochondrial aerobic metabolism function and protein expression in platelets of multiple sclerosis (MS) patients and control subjects, mitochondrial aconitase, mitochondrial superoxide dismutases 1 and 2 (SOD1 and SOD2), and respiratory complex enzyme activities in platelets of MS patients and control subjects were determined. Likewise, mitochondrial lipid peroxidation and mitochondrial SOD1 and cytochrome c expressions were investigated. Mitochondrial aconitase activity was higher in MS patients than in controls (P?<?0.05). A significant increase on all respiratory complex activities in MS patients was observed (P?<?0.05). Mitochondrial lipid peroxidation was significantly higher in MS patients than in controls (P?<?0.05). Significant changes of cytochrome c and mitochondrial SOD1 expressions were detected (P?<?0.05), with a decrease of 44?±?5 % and an increase of 46?±?6 %, respectively. Our study reveals that significant changes in mitochondrial aerobic metabolism function and mitochondrial SOD1 and cytochrome c expressions are produced in platelets of MS patients. 相似文献
20.
RNA-dependent RNA polymerase activities were measured in healthyand tobacco mosaic virus (TMV)-infected tomato plants, to investigatethe possibility that altered activity might be involved in theoperation of the Tm-I gene for resistance to TMV. Healthy, susceptibleand resistant plants had similar levels of enzyme activity.Infection with TMV strain 0, which is inhibited by Tm-I, causeda 2-fold increase in activity in susceptible plants but no increasein Tm-I plants. Infection with a number of strain 1 isolates,which overcome Tm-I resistance, led to a 2 to 4-fold increasein enzyme activity in resistant plants. RNA-dependent RNA polymerase, Tm-I resistance gene, tobacco mosaic virus, tomato, Lycopersicon esculentum 相似文献