共查询到20条相似文献,搜索用时 15 毫秒
1.
The effects of kinetin on starch and sugar levels and on 14CO2 and 32P-orthophosphate labeling patterns of floated Chinese cabbage (Brassica pekinensis) leaf discs were investigated. Kinetin caused gross starch degradation. Neutral sugars were depressed by 30 to 40% in leaf tissue treated with kinetin for 24 hours. 14CO2 labeling of leaf discs pretreated with kinetin for 24 hours showed increased radioactivity in chloroform-soluble material and most sugar phosphates, and a 35 to 40% decrease in radioactivity in the neutral sugars, glucose, sucrose, and fructose. Incorporation into ATP was increased by 40% by kinetin. 32P-Orthophosphate uptake was inhibited 30% by kinetin. When corrected for uptake, kinetin stimulated incorporation into chloroform-soluble material but had little effect on other cell fractions. These results indicate that kinetin mobilizes starch reserves and increases the flow of sugars required for the synthesis of lipids and structural materials in floated discs. 相似文献
2.
A detailed evaluation of the possible contribution of bacteria to radioactive precursor incorporation into nucleic acids of plant tissues 总被引:12,自引:9,他引:3
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An investigation of the possible contribution of bacteria to the labeling patterns of soybean seedling nucleic acid was made. The results using sucrose gradient, MAK column, and acrylamide gel electrophoretic fractionation together with base composition analyses of nucleic acid preparations show that contaminating bacteria do not contribute to the incorporation of 32P-orthophosphate into the RNA of excised hypocotyl or soybean root tip. Sterile, non-sterile, and CM-treated soybean hypocotyl synthesize D-RNA to the same extent. The contaminating bacteria do not synthesize an AMP-rich RNA. The G-C rich 32P-DNA component of the soybean tissues used in these studied results, at least primarily, from the incorporation by contaminating bacteria. CM can be used successfully to eliminate the contribution of bacteria to the labeling of nucleic acids by etiolated plant tissues. Bacterial counts, although valuable, are not sufficient to determine if contaminating bacteria will significantly contribute to nucleic acid labeling in plants. 相似文献
3.
Changes in phosphate metabolism were explored in discs from tobacco (Nicotiana tabacum) leaves of three contrasting types: green leaves which were fully expanded and attached to the plant, leaves which had yellowed following excision and dark starvation, and leaves which had yellowed while attached to the plant. 2,4-Dinitrophenol at 10−5m stimulated the respiration rate of discs from green and yellow-detached leaves only slightly, but markedly stimulated that of discs from yellow-attached leaves. Following a 10-minute uptake period the incorporation of 32P-orthophosphate into phosphate esters and lipids of discs from yellow-detached leaves was resistant to 2,4-dinitrophenol, whereas in discs from green and yellow-attached leaves it was inhibited by 2,4-dinitrophenol. Incorporation into a salt-soluble fraction containing unidentified nucleotide material showed converse behavior in that it was stimulated by 2,4-dinitrophenol in discs from green and yellow-attached leaves; in discs from yellow-detached leaves it was resistant to 2,4-dinitrophenol. In discs from yellow-detached and yellow-attached leaves there was a shift in the labeling pattern of phosphate esters toward increased label in hexose phosphates at the expense of adenine nucleotides, 3-phosphoglycerate, and phosphoenolpyruvate. It is concluded that incorporation into phosphate esters in discs from yellow-detached leaves is by substrate level phosphorylation coupled to enhanced aerobic glycolysis. In discs from yellow-attached leaves, on the other hand, incorporation depends on oxidation phosphorylation, and it is suggested that the shift in labeling pattern is caused by senescence-induced changes in activity of glycolytic enzymes. 相似文献
4.
Induction of deoxyribonucleic Acid synthesis in potato tuber tissue by cutting 总被引:6,自引:5,他引:1
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Incorporation of 32P-orthophosphate was found in the DNA fraction of aerobically incubated potato discs when examined by methylated albumin kieselguhr column chromatography. The estimation of DNA content of the discs was by a method developed for starchy tissues and showed that the incorporation of 32P was due to net synthesis of DNA. The DNA content of a disc rapidly increased after a lag period of about 12 hours. The increase continued during the entire test period although at a lower rate during the later period of aging. DNA synthesis was further examined by measuring the rate of incorporation of 3H-thymidine. The striking similarity which was found between changes in the rate of DNA accumulation and in the rate of 3H-thymidine incorporation indicates that the incorporation of 3H-thymidine actually represents the net synthesis of DNA. Although the experiments with microautoradiography revealed that DNA synthesis occurred exclusively in nuclei, no signs of cell division were detected by microscopic observation. DNA synthesis in potato discs was further examined by using inhibitors of protein and RNA synthesis and was sensitive to those inhibitors. The significance of the present results is discussed in relation to the role of wounding in the induction of DNA synthesis. 相似文献
5.
The changes in the amount, rale of synthesis and the nucleotide composition of different RNA fractions in excised barley leaves floated on water or kinetin (10 mg/l) in the dark were examined. In excised leaves floated on water all nucleic acid components declined and these declines were retarded by kinetin. Barley leaves floated on water showed a stimulation of 32P incorporation into various RNA fractions within 48 hours followed by a decline after 96–144 hours. The leaves floated on kinetin, however, showed an even higher incorporation of 32P into UNA by 48 hours which remained at a comparatively higher level throughout the experiment. In spite of the above changes in RNA synthesis significant differences in the 32P sucrose gradient profiles or in the 32P nucleotide composition of UNA from water and kinetin floated leaves were not noted. The results of this study show that important changes in nucleic acid metabolism occur during the early stages of leaf senescence and that alterations in nucleic acid metabolism during senescence and during kinetin treatment may involve quantitative and only subtle qualitative changes. 相似文献
6.
Effects of Growth Regulators on Ribonucleic Acid Metabolism of Barley Leaf Segments 总被引:2,自引:2,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Illumination or gibberellic acid treatment of etiolated barley leaf segments stimulates unrolling and results in an increased level of RNA. In contrast, segments treated with abscisic acid do not unroll and have a lower content of RNA. Gibberellic acid treatment enhanced the capacity of segments to incorporate radioactivity from 32P-orthophosphate into all the RNA components detected by gel electrophoresis; abscisic acid greatly restricted the incorporation of precursors into all the RNA fractions. In conjunction with a changed capacity for RNA synthesis it was observed that abscisic acid-treated segments had a lowered soluble DNA-dependent RNA polymerase level in comparison to gibberellic acid-treated or illuminated segments. However, the influence of growth regulators on RNA polymerase content of the segments was associated with general effects on protein level rather than a specific effect on the synthesis of polymerase enzyme. 相似文献
7.
Effect of second-leaf removal or kinetin treatment on the nucleic acid metabolism of senescing first seedling leaf of barley 总被引:3,自引:1,他引:2
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1. Changes in nucleic acid metabolism in first seedling leaves of barley plants during aging (from 7 to 27 days) were followed, and the effect of continual removal of the second leaf and basal meristem or of treating the first leaf with 20p.p.m. kinetin on these changes was examined. During aging of the first seedling leaves the ribosomal RNA, DNA and soluble RNA declined, with ribosomal RNA showing the most rapid fall. This was, however, accompanied by increased incorporation of 32P into RNA, which reached its peak on the fifteenth day. 2. Second-leaf removal partially suppressed first-leaf senescence as judged by retarded chlorophyll and nucleic acid decline and by a decreased extent of RNA labelling. Treatment with kinetin, however, did not prove effective. 3. No significant differences in the sucrose-gradient pattern of 32P-labelled nucleic acids or in the 32P-labelled nucleotide composition of RNA fractions during aging or during the two treatments were noted, except for a decrease in CMP content of soluble RNA during aging. 4. The results demonstrate that important changes in RNA metabolism are associated with leaf senescence. 相似文献
8.
When 1, 10-phenanthroline at 10?4 mole/kg was administered intraperitoneally to C3H mice, a significant decrease of (32P) Na2HPO4 incorporation into splenic DNA and RNA was noted within 15 min. The same dose or higher was required to significantly inhibit the incorporation of (5-3H) uridine and (methyl-3H) thymidine into splenic nucleic acid. 1, 10-phenanthroline also decrease the incorporation of the 32P into DNA and RNA in 6C3HED ascites tumor. 1, 7-phenanthroline, a non-chelating analogue at 10?4 mole/kg, less effectively altered the rate of the 32P incorporation into splenic nucleic acid within 15 min, but significantly inhibited the incorporation within 1 hr. 相似文献
9.
A suspension culture from potato spindle tuber viroid (PSTV)-infected cells of the wild type potato (Solanum demissum) has been established, which is a suitable model system for studying PSTV replicationin vivo. The conditions for rapid growth of these cells and for permanent extensive viroid biosynthesis within them are described. Biosynthesis of PSTV in the potato cells was demonstrated by32P-incorporation into nucleic acids and their subsequent electrophoretic analysis on polyacrylamide gels. Under optimum culture conditions the amount of32P-orthophosphate incorporation into PSTV reached 10% of that incorporated into the 2 M LiCl-soluble cellular RNA. (+)PSTV and its complementary form, i.e. (?)PSTV were identified after their electrophoretic separation on polyacrylamide and agarose gels by molecular hybridization. This analysis revealed the presence of six high molecular weight(?)PSTV species, which are possibly multimers of the unit length(+)PSTV molecule consisting of 359 nucleotides. 相似文献
10.
Rapid indexing of the sunblotch disease of avocados using a complementary DNA probe to avocado sunblotch viroid 总被引:1,自引:0,他引:1
PETER PALUKAITIS ‡ REW G. RAKOWSKI DONALD McE. ALEXANDER† ROBERT H. SYMONS 《The Annals of applied biology》1981,98(3):439-449
A routine procedure has been established for the sensitive and specific detection of avocado sunblotch viroid in partially purified nucleic acid extracts of avocado leaves by hybridisation analysis with 32P-complementary DNA prepared against the purified viroid. Avocado sunblotch viroid was shown to be present in 12 avocado trees that had indexed positive in a biological test for sunblotch disease but was absent from 10 trees that indexed negative. The complete correlation between sunblotch disease and the presence of viroid indicates that the complementary DNA hybridisation assay procedure can be used for the indexing of sunblotch disease. The overall procedure of leaf extraction and hybridisation analysis can be completed in 5 days and is to be compared with up to 2 yr required for indexing by biological methods. The level of avocado sunblotch viroid in partially purified nucleic acid extracts of a number of different sources of sunblotch infected avocado leaves was found to vary 10 000-fold from 0.2% to 2 × 10-5% by weight. The lower limit of detectability of the viroid by the hybridisation assay is considered to be about 10-5% by weight; this is at least 103 times more sensitive than the detection of the viroid by polyacrylamide gel electrophoresis of the leaf nucleic acid extracts followed by staining. 相似文献
11.
Noriharu Umetsu Takeharu Muramatsu Hiroshi Honda Kinjiro Tamari 《Bioscience, biotechnology, and biochemistry》2013,77(4):791-799
The biological and biochemical studies of the effect of tenuazonic acid on plant cells and seedlings were carried out. Tenuazonic acid exhibited a conspicuous stunting effect on the seedling-growth of rice plant, mung bean, radish and turnip, and on the growth of suspension cultured cells of soybean and rice plants. Tenuazonic acid exhibited no effect on the O2-uptake and the activity of SH-enzyme of the plant, but inhibited the incorporation of 14C-Ieucine into the protein fraction and that of 14C-adenine into nucleic acid fraction of suspension cultured soybean cells as well as these uptake into the cells. And then it has been proved that these incorporation-inhibitions were not merely due to the inhibition of 14C-leucine and 14C-adenine uptake into the cells but based on the intrinsic inhibition of protein and nucleic acid syntheses, respectively. 相似文献
12.
Rainer Niemeyer 《Archives of microbiology》1976,108(3):243-247
The occurrence of linear condensed polyphosphates and cyclic condensed metaphosphates was studied by means of pulse-labeling with 32P-orthophosphate (3–5 h) in a number of Phaeophyceae species: Pylaiella litoralis, Ilea fascia, Ectocarpus siliculosus and also Rhodophyceae species: Ceramium deslongchampsii, C. rubrum, Rhodomela confervoides, Porphyridium purpureum and P. aerugineum. Twodimensional cellulose thin layer chromatography revealed that in all species studied 32P-radioactivity was generally present in all oligopolyphosphates containing 2 to 7 phosphate residues, in cyclic metaphosphates (tri-, tetra-, penta- and hexametaphosphates) and in high-molecular-weight condensed phosphates which remained at the starting point. Among the low-molecular-weight condensed inorganic phosphates the trimetaphosphate had a significantly higher specific activity than the other oligophosphates which were separated on the chromatography plates as measured by the direct scanning with a Geiger-Muller counter.The phosphate uptake strongly depends on the internal pool of reserve phosphates of the algae cells. The 32P-orthophosphate incorporation of the cells is low and sluggish when growning in a synthetic medium or in sea water. Accordingly 32P appeared preferentially in the low-molecular-weight fractions of condensed phosphates since the storage phosphates were not yet used. After previous incubation in a P-free culture medium of the algae the 32P was rather rapidly incorporated and was found mostly in the highmolecular-weight condensed phosphates.During MAK-chromatography the high-molecular-weight fractions were eluted together with the nucleic acids (tRNA and DNA) while most of the low-molecular-weight fractions left the column immediately on elution. 相似文献
13.
Auxin-induced ethylene production as related to auxin metabolism in leaf discs of tobacco and sugar beet 总被引:2,自引:2,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Exogenously supplied indole-3-acetic acid (IAA) stimulated ethylene production in tobacco (Nicotiana glauca) leaf discs but not in those of sugar beet (Beta vulgaris L.). The stimulatory effect of IAA in tobacco was relatively small during the first 24 hours of incubation but became greater during the next 24 hours. It was found that leaf discs of these two species metabolized [1-14C]IAA quite differently. The rate of decarboxylation in sugar beet discs was much higher than in tobacco. The latter contained much less free IAA but a markedly higher level of IAA conjugates. The major conjugate in the sugar beet extracts was indole-3-acetylaspartic acid, whereas tobacco extracts contained mainly three polar IAA conjugates which were not found in the sugar beet extracts. The accumulation of the unidentified conjugates corresponded with the rise of ethylene production in the tobacco leaf discs. Reapplication of all the extracted IAA conjugates resulted in a great stimulation of ethylene production by tobacco leaf discs which was accompanied by decarboxylation of the IAA conjugates. The results suggest that in tobacco IAA-treated leaf discs the IAA conjugates could stimulate ethylene production by a slow release of free IAA. The inability of the exogenously supplied IAA to stimulate ethylene production in the sugar beet leaf discs was not due to a deficiency of free IAA within the tissue but rather to the lack of responsiveness of this tissue to IAA, probably because of an autoinhibitory mechanism existing in the sugar beet leaf discs. 相似文献
14.
Stimulation by abscisic acid of RNA synthesis in discs from healthy and tobacco mosaic virus-infected tobacco leaves 总被引:2,自引:0,他引:2
Uptake of abscisic acid from the culture medium by discs of healthy and tobacco mosaic virus-infected tobacco leaves was measured. Small (two to five-fold) increases in abscisic acid concentration in discs caused increases in rates of [3H]uridine and [3H]adenine incorporation into total nucleic acid, virus RNA and host ribosomal RNA. Net accumulation of virus RNA was also enhanced by abscisic acid. This evidence for stimulation of RNA synthesis is compared with previous reports showing inhibition of RNA synthesis in other tissues. It is suggested that the increase in endogenous abscisic acid caused by tobacco mosaic virus infection may be at least partly responsible for observed increases in rates of RNA synthesis after infection.Abbreviations ABA
abscisic acid
- TMV
tobacco mosaic virus 相似文献
15.
Summary Discs from senescing radish leaves were floated either on water or on a solution of kinetin and incubated in the dark. The kinetin-treated discs were fed with orotic acid-5-T and the control discs with orotic acid-6-C14. The two lots of discs were combined and the RNA extracted by the phenol method. The H3:C14 ratio of the RNA after fractionation on sucrose density gradient was compared with the H3:C14 ratio of RNA extracted from two lots of control discs, one fed with orotic acid-5-T and the other with orotic acid-6-C14 and then extracted together. In this way it was found that 21 hours treatment with kinetin causes a small but consistent stimulation of labelled precursor incorporation into all classes of RNA investigated. 相似文献
16.
Dick S Funchal C Pelaez Pde L Loureiro SO Vivian L Pessutto FD Almeida LM Wannmacher CM Pessoa-Pureur R 《Neurochemical research》2002,27(12):1569-1576
In this work we tested human mononuclear cells as a peripheral marker to study neurotoxicity of phenylalanine (Phe). Slices of cerebral cortex of rats or human mononuclear cells were incubated with different concentrations of Phe and/or Ala in the presence of 32P-orthophosphate, the cytoskeletal fraction was extracted, and the radioactivity incorporated into intermediate filament proteins was measured. Our results show that 2 mM Phe as well as 1 mM Ala are effective in increasing the 32P in vitro incorporation into IFs in both tissues. When cerebral cortex slices or mononuclear cells were incubated with different concentrations of Phe and/or Ala, the effects on the 32P in vitro incorporation into IF proteins was compatible with an antagonistic mechanism of action of the two amino acids on the enzymes of the phosphorylating system. In addition, these blood cells may be a possible peripheral marker to study neurotoxicity of Phe in patients with PKU. 相似文献
17.
Effect of Ethrel and Ceratocystis fimbriata on the Synthesis of Fatty Acids and 6-Methoxy Mellein in Carrot Root
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The rate of incorporation of 14C from acetate-1-14C into fatty acids by carrot root discs, 18 hours after inoculation with Ceratocystis fimbriata, was 9-fold greater than that in freshly cut discs. The rate in discs treated with water or Ethrel was 3-fold greater. The rate of incorporation of 14C from glucose-U-13C into fatty acids was 3-fold greater 18 hours after any of the above treatments. The rate of 14C incorporation from malonate-2-14C into fatty acids 24 hours after inoculation with C. fimbriata or treatment with water was 25 and 60%, respectively, of that in freshly cut discs. Linoleic acid was the principal fatty acid in carrot root, but incorporation of 14C from acetate-1-14C into the acid was low until 18 hours after inoculation with C. fimbriata or treatment with Ethrel. Turnover rates of the fatty acids appeared low and were similar for all treatments. 相似文献
18.
Incorporation of C-Leucine into Apple Leaf Protein and Its Inhibition by Protein Synthesis Inhibitors during Growth and Senescence
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Spencer PW 《Plant physiology》1973,52(2):151-155
Of the total 14C-leucine taken up by intact apple (Pyrus malus L., Golden Delicious) leaf discs, 44 to 62% is incorporated into protein from June to early October. Of this amount, an average of 35% is released by mild, room temperature acid hydrolysis. Prior to mid-August when leaf protein begins to decline, 15 to 20% of the 14C-leucine incorporated into protein occurs in water-(buffer) soluble protein, of which only 3% is released by mild acid hydrolysis. After mid-August, 40% of the label in protein occurs in soluble protein. The specific radio-activity of the soluble protein increases by 4- to 5-fold after mid-August, while that of total protein increases by less than 2-fold. In presenescent leaves (before the decline of protein in August) 20 micrograms per milliliter cycloheximide inhibits the incorporation of 14C-leucine into protein by 71%, and 20 micrograms per milliliter chloramphenicol inhibits it by 30%. In senescing leaves, cycloheximide inhibits 14C-leucine by 85% or more, while chloramphenicol inhibits it by less than 15%. Coincident to the initial decline of leaf protein, chloramphenicol greatly loses its ability to inhibit the incorporation of 14C-leucine into apple leaf protein. At all leaf ages, chloramphenicol increases the loss of chlorophyll from apple leaf discs. The effect of cycloheximide on leaf disc senescence changes with leaf age: in early season samples, it increases the loss of chlorophyll; in mid-season samples, it has no effect; and in late season samples, it retards the loss of chlorophyll. 相似文献
19.
J. A. BAILEY 《The Annals of applied biology》1969,64(2):315-324
A sterile culture nitrate of Penicillium expansum was shown to induce pisatin synthesis in pea leaf discs. The amount of pisatin produced by pea leaves was shown to decrease as they underwent senescence. N6-benzyladenine delayed senescence, and at the same time maintained the production of pisatin at a high level. In darkness, leaf discs maintained on either benzyl-adenine solution or distilled water produced greater amounts of pisatin than leaf discs which were not treated in this way. Benzyladenine also increased pisatin production by leaf discs kept in the light. The relevance of these results to disease resistance and possible mechanisms involved are discussed. 相似文献
20.
J. Lakshmanan 《Biochemical and biophysical research communications》1978,82(3):767-775
The addition of nerve growth factor to organ cultures of superior cervical ganglia from immature rats specifically stimulated the incorporation of 32P-orthophosphate into phosphatidylinositol fraction. Equimolar concentrations of other hormones such as insulin, glucagon, thyroxine and growth hormone did not cause any stimulation of the incorporation of 14C-myoinositol into phosphatidylinositol. The stimulation of phosphatidylinositol turnover was observed over a concentration of nerve growth factor ranging from 10?10M to 10?7M. Nerve growth factor specific “inositide effect” was found to be sensitive to nerve growth factor antibody, 2,4-dinitrophenol, a high concentration of bovine growth hormones but not to Actinomycin D. The physiological significance of this finding in relation to nerve growth factor action in this target tissue is discussed. 相似文献