Effect of Cytokinins on the Expansion and Metabolism of Excised Cucumber Cotyledons

1980 ◽  
Vol 7 (3) ◽  
pp. 227
Author(s):  
C Tsui ◽  
Tao Guo-qing ◽  
Chen Hui-ying ◽  
Son Yan-ru ◽  
Lian Han-ping ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Acid Synthesis ◽  
Cell Number ◽  
Cucumis Sativus L ◽  
Biochemical Processes ◽  
Dna And Rna ◽  
Lag Period ◽  
Hydrolysis Of

Expansion of excised cucumber (Cucumis sativus L.) cotyledons was stimulated by treatment with cytokinin, and commenced after a lag period of about 4 h. Expansion induced by benzyladenine (BA) was due mainly to increase of fresh weight, but cell number increased slightly. Hydrolysis of protein and lipid was stimulated by BA, and soluble sugars increased simultaneously. However, there was no significant change in the dry weight of cotyledons during the period of expansion. It is assumed that the transformation of lipid to sugar in the cotyledon is stimulated by BA. The respiration of cotyledons was evidently stimulated by BA and was entirely inhibited by respiratory inhibitors, e.g. NaN,, malonate and dinitrophenol. Inhibitors of protein and nucleic acid synthesis, such as chloramphenicol and actinomycin D, inhibited only the BA-induced expansion. They had no effect on the expansion of controls. These results suggest that different biochemical processes are involved in the expansion of cotyledons induced by BA and in controls. The former is related not only to respiration but also to the synthesis of protein and nucleic acid. BA increased DNA and RNA content per cotyledon. The increase of total RNA is due mainly to the increase of 25 S and 18 S rRNA.

Protein and Nucleic Acid Syntheses in Dark-dormant Common Purslane(Portulaca oleracea)Seed

Weed Science ◽  
1978 ◽  
Vol 26 (6) ◽  
pp. 669-672 ◽  
Author(s):  
Bonnie J. Reger ◽  
Ida E. Yates
Keyword(s):  
Protein Synthesis ◽  
Nucleic Acid ◽  
Rna Synthesis ◽  
Acid Synthesis ◽  
Portulaca Oleracea ◽  
Dark Incubation ◽  
Radicle Protrusion ◽  
Lag Period ◽  
Common Purslane ◽  
H Protein

Dark-incubated common purslane(Portulaca oleraceaL.) seed synthesize very little protein and essentially no nucleic acids. Dark-incubated seed incorporate only 14 × 10−3nmoles14C-leucine/mg protein/12-h dark. In contrast, seed exposed to 12-h light following 24-h dark incubation incorporate 365 × 10−3-nmoles14C-leucine/mg protein/12-h light. Once dormancy is broken by exposure of seed to light, initiation of radicle protrusion occurs at 12 h. Protein synthesis gradually increases with time in the light and precedes nucleic acid synthesis which is associated with radicle protrusion. During the 12-h lag period preceding radicle protrusion protein synthesis increases significantly by 3 to 9 h in light, RNA synthesis by 9 h in light, and DNA synthesis by 12 h in light. After 12 h in light,32P can be detected in all nucleic acid fractions, DNA and RNAs.

Inhibition of nucleic acid synthesis in L1210 cells by nucleoside analogs

1984 ◽  
Vol 49 (11) ◽  
pp. 2551-2556 ◽  
Author(s):  
Jiří Beránek ◽  
Edward M. Acton
Keyword(s):  
Nucleic Acid ◽  
Rna Synthesis ◽  
Nucleoside Analogs ◽  
Acid Synthesis ◽  
Pyrimidine Nucleoside ◽  
Dna And Rna ◽  
L1210 Cells ◽  
Structure Activity ◽  
Dna And Rna Synthesis ◽  
Chloro Derivatives

Series of pyrimidine nucleoside analogs were tested for inhibition of DNA and/or RNA synthesis at L1210 cells. The structure-activity relationship was studied at the analogs of cancerostatic agents 5-fluorouracil and arabinosylcytosine. Out of them the 5'-chloro derivatives give some promise. The inhibitory activity of cyclocytidine vs DNA and RNA synthesis approaches the activity of cancerostatic antibotics.

Nucleic acid synthesis in microsporocytes of Lilium cv. cinnabar: events in the nucleus

1982 ◽  
Vol 57 (1) ◽  
pp. 229-246
Author(s):  
E.K. Porter ◽  
J.M. Bird ◽  
H.G. Dickinson
Keyword(s):  
Nucleic Acid ◽  
Chromosome Pairing ◽  
Rna Synthesis ◽  
Dna Amplification ◽  
Acid Synthesis ◽  
Autoradiographic Study ◽  
Crossing Over ◽  
Electron Microscopic ◽  
Dna And Rna ◽  
Dna And Rna Synthesis

In an electron microscopic autoradiographic study of DNA and RNA synthesis during meiosis isolated Lilium microsporocytes were supplied with [3H]thymidine and [3H]uridine. DNA synthesis occurred in the nucleus during the zygotene and pachytene intervals of meiotic prophase. Most of the activity was associated with the chromatin, but some synthesis early in zygotene was located at the nucleolus. RNA synthesis occurred throughout prophase until diplotene, when all activity ceased until after division. The newly synthesized RNA was found mostly in association with the chromosomal peripheries or in the space between chromosomes. There was also a peak of [3H]uridine incorporation at the nucleolus, which followed shortly after the synthesis of DNA at that site. The localization of DNA and RNA synthesis at the various stages of meiosis is discussed in relation to current concepts of chromosome pairing, crossing-over, ribosomal DNA amplification and cycles of RNA metabolism.

scholarly journals SYNTHETIC CAPACITIES OF CHROMOSOME FRAGMENTS CORRELATED WITH THEIR ABILITY TO MAINTAIN NUCLEOLAR MATERIAL

1962 ◽  
Vol 15 (1) ◽  
pp. 121-130 ◽  
Author(s):  
Nirmal K. Das
Keyword(s):  
Nucleic Acid ◽  
Rna Synthesis ◽  
Acid Synthesis ◽  
Root Tip ◽  
Dna And Rna ◽  
Nucleolar Material ◽  
Dna And Rna Synthesis ◽  
Chromosome Fragments ◽  
Cellular Control ◽  
Mitotic Chromosome Condensation

Onion (Allium cepa) and bean (Vicia faba) root tip cells containing many micronuclei, derived from x-ray-induced chromosome fragments, were exposed to H3-thymidine and H3-cytidine to determine the ability of such fragments to undergo DNA and RNA synthesis. Only a few micronuclei in onion and many in bean roots synthesize nucleic acid simultaneously with their main nuclei. A few micronuclei labeled with H3-thymidine undergo mitotic chromosome condensation along with the main nuclei, while the unlabeled ones never do so. The onset of nucleic acid synthesis as well as mitosis in micronuclei appears to be under generalized cellular control. Although all chromosomes and chromosome fragments at telophase give a positive reaction for a silver stainable nucleolar fraction, in the subsequent interphase only some micronuclei, derived from such chromosome fragments, are found to maintain nucleoli; others lose them with time. Those micronuclei which maintain nucleoli, perhaps due to the presence of specific chromosomal regions, are also active in DNA and RNA synthesis. These results are compatible with the concept that nucleoli and associated chromosome regions play an important role in the primary biosynthetic processes of the cell.

scholarly journals Abnormal Nucleic Acid Metabolism of Lymphocytes in Plasma Cell Myeloma and Macroglobulinemia

Blood ◽  
1969 ◽  
Vol 33 (2) ◽  
pp. 300-312 ◽  
Author(s):  
SYDNEY E. SALMON ◽  
H. HUGH FUDENBERG
Keyword(s):  
Nucleic Acid ◽  
Dna Synthesis ◽  
Past History ◽  
Acid Synthesis ◽  
Nucleic Acid Metabolism ◽  
Lymphocyte Function ◽  
Dna And Rna ◽  
Lymphocyte Dna Synthesis

Abstract Twenty-six patients with multiple myeloma and macroglobulinemia of Waldenström were studied clinically and immunologically with characterization of their paraproteins and normal immunoglobulins, as well as by in vitro culture of their peripheral lymphocytes for evaluation of DNA and RNA synthesis after phytohemagglutinin stimulation. The lymphocytes of the patients were found to be significantly deficient in response to PHA as compared to normals and patients with benign hypergammaglobulinemia. Levels of normal immunoglobulins were reduced in almost all of the paraproteinemic patients, but there was not a direct correlation between lymphocyte unresponsiveness and immunoglobulin deficiency. The defect in lymphocyte function appeared to be cellular inasmuch as normal lymphocytes had normal DNA synthesis when cultured in myeloma plasma. The decrease in lymphocyte nucleic acid synthesis appeared to be unrelated to immunoglobulin class, quantitative levels or antigenic characteristics of the patients’ paraproteins. Untreated myeloma patients with a past history of infection had lower levels of lymphocyte DNA synthesis than those patients who lacked such a history, suggesting a relationship between the in vitro lymphocyte response to PHA and the in vivo response to the antigenic challenge of bacterial infection.

Physiological effects of glycinebetaine on gamma-irradiated stressed fenugreek plants

2010 ◽  
Vol 58 (2) ◽  
pp. 103-111
Author(s):  
H. Moussa ◽  
C. Jaleel
Keyword(s):  
Soluble Sugars ◽  
Hydrolytic Enzymes ◽  
Dry Weight ◽  
Protective Role ◽  
Bisphosphate Carboxylase ◽  
Dna And Rna ◽  
Hydrolytic Activities ◽  
Γ Ray ◽  
Pre Treatment ◽  
Gamma Irradiated

Irradiation stress adversely affects plant growth and development. No radioprotective activity of glycinebetaine (GB) has yet been reported in plants. When applied pre-sowing to dry seeds of fenugreek, gamma rays at doses of 0, 25, 50, 100 and 150 Gray (Gy) from a cobalt ( 60 Co) source with a strength of 500 Ci and a dose rate of 0.54 Gy/min significantly reduced the chlorophyll content, total protein, photosynthetic efficiency ( 14 CO 2 fixation), total dry weight, and accumulation of reducing, non-reducing and total soluble sugars in comparison with the un-irradiated control. It also significantly repressed the activities of hydrolytic enzymes (α-amylase and invertase) and the carboxylating enzyme (ribulose-1,5-bisphosphate-carboxylase/oxygenase) in the fenugreek plants. Soaking irradiated seeds with glycinebetaine (50 mM) for 24 hours partially alleviated the depression effects of irradiation in these parameters. Gamma irradiation significantly increased the H 2 O 2 content, while pre-soaking irradiated seeds with GB significantly decreased the H 2 O 2 level. The magnitude of the reversal declined as the irradiation dose increased.Gamma irradiation induced a significant decrease in the level of nucleic acids (DNA and RNA), accompanied by a corresponding induction of the hydrolytic activities of DNase and RNase in comparison with the un-irradiated control. These changes were more significant at higher γ-ray doses. Post-treatment of irradiated seeds with GB partially alleviated the adverse effects of radiation, significantly increasing nucleic acid levels and repressing the activities of DNase and RNase. The protective role played by glycinebetaine was more significant at lower γ-ray doses. Pre-treatment of seeds with GB may play an effective role in the radio-repair mechanism.

High-resolution nucleic acid sequence mapping via in situ hybridization at the Electron Microscope level

1995 ◽  
Vol 53 ◽  
pp. 752-753
Author(s):  
B.A. Hamkalo ◽  
S. Narayanswami ◽  
A.P. Kausch
Keyword(s):  
Nucleic Acid ◽  
Interphase Nucleus ◽  
Genome Mapping ◽  
Precise Location ◽  
Electron Microscope Level ◽  
Rna Sequences ◽  
Fundamental Interest ◽  
Whole Cells ◽  
Dna And Rna

The availability of nonradioactive methods to label nucleic acids an the resultant rapid and greater sensitivity of detection has catapulted the technique of in situ hybridization to become the method of choice to locate of specific DNA and RNA sequences on chromosomes and in whole cells in cytological preparations in many areas of biology. It is being applied to problems of fundamental interest to basic cell and molecular biologists such as the organization of the interphase nucleus in the context of putative functional domains; it is making major contributions to genome mapping efforts; and it is being applied to the analysis of clinical specimens. Although fluorescence detection of nucleic acid hybrids is routinely used, certain questions require greater resolution. For example, very closely linked sequences may not be separable using fluorescence; the precise location of sequences with respect to chromosome structures may be below the resolution of light microscopy(LM); and the relative positions of sequences on very small chromosomes may not be feasible.

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