Ribonucleic acid degrading activity associated with ribosomes from spinach leaf chloroplasts

1972 ◽  
Vol 50 (4) ◽  
pp. 691-695 ◽  
Author(s):  
Richard C. Howe ◽  
Donald J. Ursino
Keyword(s):  
Ribonucleic Acid ◽  
Component Part ◽  
Free Ribosome ◽  
Spinach Leaf ◽  
Dissociated State ◽  
Spinach Leaves

Ribosomes isolated from the chloroplasts of spinach leaves show the presence of RNA-degrading activity. The activity is optimal at pH 6.0 and at temperatures between 37 and 40 °C. The activity is cation-independent, exhibits exonuclease properties, and is considerably more pronounced under conditions in which the ribosome particles are in the dissociated state. The results are interpreted as showing that the RNA-degrading activity is a component part of the free ribosome population in the chloroplast.

Chloroplast division in spinach leaves examined by scanning electron microscopy and freeze-etching

1980 ◽  
Vol 46 (1) ◽  
pp. 87-96
Author(s):  
N. Chaly ◽  
J.V. Possingham ◽  
W.W. Thomson
Keyword(s):  
Electron Microscopy ◽  
Green Light ◽  
Cell Area ◽  
Low Intensity ◽  
Spinach Leaf ◽  
Freeze Etching ◽  
Leaf Disks ◽  
Scanning Electron ◽  
Spinach Leaves

Spinach leaf disks were cultured for 5 days in low-intensity green light and then were transferred to high-intensity white light. Harvests over the next 16 h established that cell area increased by about 80% and chloroplast number per cell increased by about 65%, while the percentage of dumbbell-shaped chloroplasts per cell decreased by 65%. Freeze-etch replicas of fixed and unfixed leaf disks, as well as scanning electron-microscope preparations of fixed material, contained dumbbell-shaped chloroplasts constricted to various degrees. Freeze-etch replicas of unfixed cells from young leaf bases, in which the number of chloroplasts per cell is known to be rapidly increasing, also contained many constricted chloroplasts. It is concluded that dumbbell-shaped chloroplasts occur in vivo and represent a stage in the division of chloroplasts.

Carbonic anhydrase: Its content in spinach leaves and its taxonomic diversity studied with anti-spinach leaf carbonic anhydrase antibody

1984 ◽  
Vol 33 (2) ◽  
pp. 145-153 ◽  
Author(s):  
Keiichiro Okabe ◽  
Shi-Yuan Yang ◽  
Mikio Tsuzuki ◽  
Shigetoh Miyachi
Keyword(s):  
Carbonic Anhydrase ◽  
Taxonomic Diversity ◽  
Spinach Leaf ◽  
Spinach Leaves

scholarly journals Plant ribulosamine/erythrulosamine 3-kinase, a putative protein-repair enzyme

2005 ◽  
Vol 388 (3) ◽  
pp. 795-802 ◽  
Author(s):  
Juliette FORTPIED ◽  
Rita GEMAYEL ◽  
Vincent STROOBANT ◽  
Emile van SCHAFTINGEN
Keyword(s):  
Kinase Activity ◽  
Specific Activity ◽  
Calvin Cycle ◽  
Pentose Phosphate ◽  
Leaf Extracts ◽  
Protein Repair ◽  
Spinach Leaf ◽  
Mammalian Enzyme ◽  
Spontaneous Reaction ◽  
Spinach Leaves

FN3K (fructosamine 3-kinase) is a mammalian enzyme that catalyses the phosphorylation of fructosamines, which thereby becomes unstable and detaches from proteins. The homologous mammalian enzyme, FN3K-RP (FN3K-related protein), does not phosphorylate fructosamines but ribulosamines, which are probably formed through a spontaneous reaction of amines with ribose 5-phosphate, an intermediate of the pentose–phosphate pathway and the Calvin cycle. We show in the present study that spinach leaf extracts display a substantial ribulosamine kinase activity (approx. 700 times higher than the specific activity of FN3K in erythrocytes). The ribulosamine kinase was purified approx. 400 times and shown to phosphorylate ribulose-ε-lysine, protein-bound ribulosamines and also, with higher affinity, erythrulose-ε-lysine and protein-bound erythrulosamines. Evidence is presented for the fact that the third carbon of the sugar portion is phosphorylated by this enzyme and that this leads to the formation of unstable compounds decomposing with half-lives of approx. 30 min at 37 °C (ribulosamine 3-phosphates) and 5 min at 30 °C (erythrulosamine 3-phosphates). This decomposition results in the formation of a 2-oxo-3-deoxyaldose and inorganic phosphate, with regeneration of the free amino group. The Arabidopsis thaliana homologue of FN3K/FN3K-RP was overexpressed in Escherichia coli and shown to have properties similar to those of the enzyme purified from spinach leaves. These results indicate that the plant FN3K/FN3K-RP homologue, which appears to be targeted to the chloroplast in many species, is a ribulosamine/erythrulosamine 3-kinase. This enzyme may participate in a protein deglycation process removing Amadori products derived from ribose 5-phosphate and erythrose 4-phosphate, two Calvin cycle intermediates that are potent glycating agents.

The role of malate in nitrate reduction in spinach leaves

1980 ◽  
Vol 58 (5) ◽  
pp. 517-521 ◽  
Author(s):  
K. C. Woo ◽  
D. T. Canvin
Keyword(s):  
Nitrate Reduction ◽  
Nitrite Accumulation ◽  
Antimycin A ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Leaf Discs ◽  
Spinach Leaf ◽  
Spinach Leaves

In spinach leaf discs the accumulation of nitrite from nitrate reduction under anaerobic conditions in the light in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) was inhibited by air. The inhibition of nitrate reduction by air was reversed by antimycin A but not by rotenone or amytal. The nitrate-reducing system of DCMU-inhibited leaf discs in the light appeared similar to noninhibited leaf discs in the dark. In aerobic conditions, the addition of malate stimulated nitrite accumulation. This stimulation was unaffected by malonate. Under anaerobic conditions, malate reversed the inhibition of nitrate reduction caused by either iodoacetate or arsenite to rates similar to those observed in the dark and in the light with DCMU. Malate can apparently provide a direct source of cytosolic NADH for nitrate reduction.

scholarly journals Site of inhibition by 2-amino-1,1,3-tricyanopropene of photosynthetic oxygen evolution by spinach leaf chloroplasts (Short Communication)

1973 ◽  
Vol 134 (2) ◽  
pp. 663-665
Author(s):  
E. Margaret Burden ◽  
Alan A. Horton
Keyword(s):  
Steady State ◽  
Short Communication ◽  
O2 Evolution ◽  
Photosynthetic Oxygen Evolution ◽  
Photo Oxidation ◽  
Steady State Fluorescence ◽  
Spinach Leaf ◽  
Photosynthetic O2 Evolution ◽  
Photosynthetic Oxygen ◽  
Spinach Leaves

2-Amino-1,1,3-tricyanopropene inhibits photosynthetic O2 evolution, but, unlike 3-(3,4-dichlorophenyl)-1,1-dimethylurea, has little effect on the steady-state fluorescence of chlorophyll. In chloroplasts prepared from spinach leaves and inhibited by 2-amino-1,1,3-tricyanopropene, a 3-(3,4-dichlorophenyl)-1,1-dimethylurea-sensitive photoreduction of ferricyanide may be restored by addition of semicarbazide. It is concluded that 2-amino-1,1,3-tricyanopropene acts at a point close to the photo-oxidation of water.

scholarly journals Detection of Latent Peronospora effusa Infections in Spinach

Plant Disease ◽  
2018 ◽  
Vol 102 (9) ◽  
pp. 1766-1771 ◽  
Author(s):  
Chaitra S. Subbarao ◽  
Amy Anchieta ◽  
Lorena Ochoa ◽  
Nikhilesh Dhar ◽  
Sridhara G. Kunjeti ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Production Systems ◽  
Conventional Polymerase Chain Reaction ◽  
Organic Production ◽  
Latent Infections ◽  
Conventional Production ◽  
Spinach Leaf ◽  
Pathogen Dna ◽  
Field Plots ◽  
Spinach Leaves

Downy mildew disease of spinach, caused by Peronospora effusa, is managed in conventional fields by a combination of host resistance and scheduled fungicide applications. Fungicides are currently applied to prevent downy mildew epidemics regardless of the infection status of spinach crops. A more streamlined approach would be to develop methods to target either latent infections for fungicide application in conventional production systems or to hasten harvest in organic production. In this study, conventional polymerase chain reaction (PCR) was applied to detect P. effusa DNA in symptomless spinach leaves in three spatially and temporally separated field plots, each containing four 2-m beds, 35 m in length. Spinach leaves were sampled weekly at 3-m intervals at 48 locations throughout each plot. Initial samples were asymptomatic and yet PCR enabled detection of P. effusa DNA extracted from sampled spinach leaves. Detection of latent downy mildew infection in spinach leaves was confirmed by PCR as early as 7 days prior to symptom development. The limit of pathogen DNA detection in spinach leaves was calculated at 10 pg using the conventional PCR approach. Quantitative PCR with TaqMan methodology revealed the presence of inhibitors from spinach leaf DNA extracts and affected amplification efficiencies, but not when diluted, enabling detection of P. effusa DNA at a concentration of <0.1 pg. In conclusion, detection of latent infections may enable management decisions for earlier-than-normal harvest of infected, symptomless organic crops, and for timing fungicide applications on symptomless plants in conventional production.

Kinetics and Regulation of the NAD(P)H-Dependent Glyoxylate-Specific Reductase from Spinach Leaves

1995 ◽  
Vol 50 (1-2) ◽  
pp. 21-28 ◽  
Author(s):  
Leszek A. Kleczkowski
Keyword(s):  
Potent Inhibitor ◽  
Kinetic Mechanism ◽  
Plant Tissues ◽  
Ping Pong ◽  
Spinach Leaf ◽  
Sequential Addition ◽  
Glyoxylate Reductase ◽  
Spinach Leaves

Abstract Kinetic mechanism of purified spinach leaf NAD(P)H glyoxylate reductase (GR-1) was studied using either NADPH and NADH as alternative substrates with glyoxylate. The mech­anism was elucidated from substrate kinetic patterns using NADH as a cofactor rather than NADPH. With NADPH varied versus glyoxylate, and with NADPH and glyoxylate varied at a constant ratio, the patterns obtained on double reciprocal plots appeared to be consistent with a ping-pong mechanism; however, kinetic patterns with NADH conclusively ruled out the ping-pong reaction in favour of the sequential addition of the reactants. Product inhi­bition studies with glycolate and NADP have suggested either that NADPH binds to the enzyme before glyoxylate or that the addition of substrates is a random one. Studies with active group modifiers suggested an involvement of histidine, serine and cysteine residues in GR-1 activity. Salts had little or no effect on the activity of the enzyme, with the exception of cyanide, which had an apparent Ki of ca. 2 mᴍ. Studies with several metabolites used as possible effectors of GR-1 activity have suggested that the enzyme is modulated only by substrate availability in vivo. The apparent insensitivity of GR-1 to metabolic effectors is consistent with the proposed role of the enzyme in detoxifying glyoxylate which may act as a potent inhibitor of photosynthetic processes in plant tissues.

scholarly journals Siklus hidup Spodoptera frugiperda J.E. Smith dengan pakan daun bayam cabut hijau dan daun bayam duri hijau di laboratorium

2021 ◽  
Vol 10 (2) ◽  
pp. 201-216
Author(s):  
Ichsan Luqmana Indra Putra ◽  
Aulia Wulanda
Keyword(s):  
Life Cycle ◽  
Spodoptera Frugiperda ◽  
Host Plants ◽  
Homogeneity Test ◽  
Larval Weight ◽  
Alternative Feed ◽  
Normality Test ◽  
Spinach Leaf ◽  
Number Of Males ◽  
Spinach Leaves

Spodoptera frugiperda merupakan hama baru di Indonesia yang menyerang tanaman jagung dan memiliki berbagai macam tanaman inang lain. Salah satu tanaman yang dimungkinkan menjadi inang dari hama ini di Indonesia adalah bayam. Tujuan penelitian ini untuk mengetahui lama siklus hidup S. frugiperda yang diberikan pakan daun bayam cabut hijau dan daun bayam duri hijau. Metode penelitian ini yaitu permeliharaan S. furgiperda dengan sumber pakan yang berbeda dan mengamati beberapa parameter. Analisis statistik berupa inferensial, data yang dilakukan dengan uji normalitas Shapiro-Wilk. Apabila data normal dilakukan uji homogenitas dengan dilanjutkan analisis ANNOVA. Hasil penelitian menunjukan bahwa S. frugiperda pada pakan kontrol (daun jagung) memiliki lama siklus hidup 38 hari, daun bayam cabut hijau 40 hari, dan daun bayam duri hijau 42 hari. Panjang larva S. frugiperda paling panjang didapatan pada pakan daun bayam duri hijau, sedangkan diameter kepala tidak terdapat perbedaan antara ketiga pakan. Bobot larva paling berat didapatkan pada pakan daun bayam cabut hijau. Panjang dan berat pupa S. frugiperda paling tinggi didapatkan pada pakan daun bayam duri hijau. Jumlah jantan paling banyak dihasilkan pada pakan daun bayam cabut hijau dan daun bayam duri hijau, sedangkan jumlah betina paling banyak dihasilkan pakan kontrol. Jumlah telur paling banyak dihasilkan pada pakan kontrol dan paling sedikit pada bayam duri hijau. Pakan bayam cabut dan bayam duri daun bayam cabut hijau dan bayam duri hijau dapat digunakan sebagai pakan alternatif bagi S. frugiperda di laboratorium. Kata kunci: pakan alternatif; perkembangan; pertumbuhan; Spodoptera frugiperda ABSTRACTLife cycle of Spodoptera frugiperda J.E. Smith with green spinach and green thorn  spinach leaves in the laboratory. Spodoptera frugiperda is a new pest in Indonesia that attacks maize and has a wide variety of other host plants. One of the plants that is possible to host this pest in Indonesia is spinach. The purpose of this study was to determine the length of the life cycle of S. frugiperda which was fed with green spinach leaves and green thorn spinach leaves. This research method is the maintenance of S. furgiperda with different feed sources and observing several parameters. Statistical analysis in the form of inferential, the data was done by using the Shapiro-Wilk normality test. If the data is normal, the homogeneity test is carried out followed by ANNOVA analysis. The results showed that S. frugiperda in control diets (corn leaves) had a life cycle length of 38 days, green spinach leaves 40 days, and green thorn spinach leaves 42 days. Thelarvae of longestS. frugiperda were found in green thorn spinach leaf feed, while there was no difference in head diameter between the three diets. The heaviest larval weight was found in green pulled spinach feed. Thelength and weight ofpupa were S. frugiperda highestfound in green thorn spinach leaf feed. The highest number of males was produced in green spinach leaf and green spinach leaf feed, while the highest number of females was produced in control feed. The highest number of eggs was produced in the control feed and the least was the green thorn spinach. Spinach feed and spinach spines, green pulled spinach and green spiny spinach can be used as an alternative feed for S. frugiperda in the laboratory.  Keywords: alternative food; development; growth; Spodoptera frugiperda

EARLY EFFECTS OF GLUCOCORTICOIDS ON RIBONUCLEIC ACID AND PROTEIN METABOLISM IN RAT LIVER

1963 ◽  
Vol 44 (4_Suppla) ◽  
pp. S3-S36 ◽  
Author(s):  
Kristian F. Jervell
Keyword(s):  
Rat Liver ◽  
Ribonucleic Acid ◽  
Protein Metabolism ◽  
Early Effects

The Folk Concept of the World as a Component Part of the History of Social Thought

1963 ◽  
Vol 2 (1) ◽  
pp. 3-11
Author(s):  
L. A. Kogan
Keyword(s):  
Social Thought ◽  
Component Part ◽  
Folk Concept ◽  
The World ◽  
History Of
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