scholarly journals Isolation of chloroplasts in the Karwinskia species and determination of their photochemical activity under in vitro conditions

2011 ◽  
Vol 50 (No. 4) ◽  
pp. 149-156 ◽  
Author(s):  
M. Henselová ◽  
M. Regecová ◽  
A. Sováková
Keyword(s):  
Chlorophyll A ◽  
Photochemical Activity ◽  
Hill Reaction ◽  
Reaction Conditions ◽  
Significant Difference ◽  
The Hill ◽  
Isolated Chloroplasts ◽  
Photochemical Activity Of Chloroplasts

Reaction conditions for evaluation of the photochemical activity of isolated chloroplasts in the Hill reaction of Karwinskia humboldtiana (Roem &amp; Schut) Zucc. and Karwinskia parvifolia Rose species were determined. Hill&rsquo;s reaction activity was measured spectrophotometrically at 630 nm as the amount of DCPIP reduction by the chloroplast suspension at an irradiance of 400 &micro;mol/m<sup>2</sup>/sPAR. A significant difference was observed between the activity of chloroplasts isolated at 2&deg;C and 25&deg;C amounting to 27% in Karwinskia humboldtiana and 18.5% in K. parvifolia. After 24 hours of storage of chloroplasts at a suspension of 2&deg;C, a significant decrease of chloroplasts activity was noted in both species, e.g. 38% in Karwinskia humboldtiana and 45% in K. parvifolia. The photochemical activity of chloroplasts increased also with the length of irradiation of the reaction mixture and the content of chlorophyll (a + b) in chloroplast suspension. The activity of chloroplasts was found to be significantly higher in the species K. humboldtiana than in K. parvifolia and it proved higher in both when these were grown under field conditions rather than in a greenhouse.

scholarly journals Polymorphisms in Brucella Carbonic anhydrase II mediate CO2 dependence and fitness in vivo

2019 ◽  
Author(s):  
JM García-Lobo ◽  
Y Ortiz ◽  
C González-Riancho ◽  
A Seoane ◽  
B Arellano-Reynoso ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Primary Cultures ◽  
Low Frequency ◽  
Carbonic Anhydrase Ii ◽  
Carbonic Anhydrases ◽  
Significant Difference ◽  
Dependent Strain

AbstractSome Brucella isolates are known to require an increased concentration of CO2 for growth, especially in the case of primary cultures obtained directly from infected animals. Moreover, the different Brucella species and biovars show a characteristic pattern of CO2 requirement, and this trait has been included among the routine typing tests used for species and biovar differentiation. By comparing the differences in gene content among different CO2-dependent and CO2-independent Brucella strains we have confirmed that carbonic anhydrase II (CA II), is the enzyme responsible for this phenotype in all the Brucella strains tested. Brucella species contain two carbonic anhydrases of the β family, CA I and CA II; genetic polymorphisms exist for both of them in different isolates, but only those putatively affecting the activity of CA II correlate with the CO2 requirement of the corresponding isolate. Analysis of these polymorphisms does not allow the determination of CA I functionality, while the polymorphisms in CA II consist of small deletions that cause a frameshift that changes the C-terminus of the protein, probably affecting its dimerization status, essential for the activity.CO2-independent mutants arise easily in vitro, although with a low frequency ranging from 10−6 to 10−10 depending on the strain. These mutants carry compensatory mutations that produce a full length CA II. At the same time, no change was observed in the sequence coding for CA I. A competitive index assay designed to evaluate the fitness of a CO2-dependent strain compared to its corresponding CO2-independent strain revealed that while there is no significant difference when the bacteria are grown in culture plates, growth in vivo in a mouse model of infection provides a significant advantage to the CO2-dependent strain. This could explain why some Brucella isolates are CO2-dependent in primary isolation. The polymorphism described here also allows the in silico determination of the CO2 requirement status of any Brucella strain.

Inhibition of the hill reaction of isolated chloroplasts by herbicidal phenylureas

1978 ◽  
Vol 9 (1) ◽  
pp. 59-62 ◽  
Author(s):  
John W. Dicks
Keyword(s):  
Hill Reaction ◽  
The Hill ◽  
Isolated Chloroplasts

Spectrofluorimetric Determination of Some Water-Soluble Vitamins

2011 ◽  
Vol 94 (6) ◽  
pp. 1758-1769 ◽  
Author(s):  
Abdel-Maaboud I Mohamed ◽  
Horria A Mohamed ◽  
Niveen M Abdel-Latif ◽  
Marwa R Mohamed
Keyword(s):  
Water Soluble ◽  
Good Precision ◽  
Linear Calibration ◽  
Reaction Conditions ◽  
Pharmaceutical Dosage Forms ◽  
Accuracy And Precision ◽  
Significant Difference ◽  
Spectrofluorimetric Determination ◽  
Comparison Of The Results

Abstract Two simple and sensitive spectrofluorimetric methods were developed for determination of three water-soluble vitamins (B1, B2, and B6) in mixtures in the presence of cyanocobalamin. The first one was for thiamine determination, which depends on the oxidation of thiamine HCl to thiochrome by iodine in an alkaline medium. The method was applied accurately to determine thiamine in binary, ternary, and quaternary mixtures with pyridoxine HCl, riboflavin, and cyanocobalamin without interference. In the second method, riboflavin and pyridoxine HCl were determined fluorimetrically in acetate buffer, pH 6. The three water-soluble vitamins (B1, B2, and B6) were determined spectrofluorimetrically in binary, ternary, and quaternary mixtures in the presence of cyanocobalamin. All variables were studied in order to optimize the reaction conditions. Linear relationship was obeyed for all studied vitamins by the proposed methods at their corresponding λexc or λem. The linear calibration curves were obtained from 10 to 500 ng/mL; the correlation ranged from 0.9991 to 0.9999. The suggested procedures were applied to the analysis of the investigated vitamins in their laboratory-prepared mixtures and pharmaceutical dosage forms from different manufacturers. The RSD range was 0.46–1.02%, which indicates good precision. No interference was observed from common pharmaceutical additives. Good recoveries (97.6 ± 0.7–101.2 ± 0.8%) were obtained. Statistical comparison of the results with reported methods shows excellent agreement and indicates no significant difference in accuracy and precision.

The Hill Reaction of Photosynthesis in Isolated Chloroplasts A Quantitative Approach

1996 ◽  
Vol 58 (5) ◽  
pp. 303-306 ◽  
Author(s):  
Rob L. Dean
Keyword(s):  
Quantitative Approach ◽  
Hill Reaction ◽  
The Hill ◽  
Isolated Chloroplasts

INTERPRETATIONS OF THE CARBON DIOXIDE DEPENDENCE OF THE HILL REACTION

1965 ◽  
Vol 43 (1) ◽  
pp. 119-127 ◽  
Author(s):  
Norman E. Good
Keyword(s):  
Carbon Dioxide ◽  
Quantum Theory ◽  
Hill Reaction ◽  
Oxygen Production ◽  
Quantum Mechanism ◽  
Photosynthetic Oxygen ◽  
The One ◽  
A Site ◽  
The Hill ◽  
Isolated Chloroplasts

Heretofore Warburg's one-quantum theory of photosynthesis has seemed inconsistent with the existence of the Hill reaction. The one-quantum theory states that massive oxygen uptake and CO2 release are preconditions of photosynthetic oxygen production, yet isolated chloroplasts produce oxygen at high rates apparently without consuming any oxygen or producing any CO2. Warburg has attempted to resolve the dilemma by pointing out a CO2 dependence of the Hill reaction. On the basis of this observation he proposed a reinterpretation of the Hill reaction which is consistent with the one-quantum theory. The effect of CO2 on isolated chloroplasts has been confirmed and some of the conditions which are necessary for the demonstration of the effect have been defined. It is not clear if CO2 is actually metabolized as Warburg claims. Contrary to Warburg's model, its participation seems to be at a site remote from the photochemical act. A number of other reasons for doubting the reality of the one-quantum mechanism are presented.

THE CARBOXYLASES OF LEAVES AND THEIR ROLE IN PHOTOSYNTHESIS

1952 ◽  
Vol 30 (4) ◽  
pp. 395-409 ◽  
Author(s):  
K. A. Clendenning ◽  
E. R. Waygood ◽  
P. Weinberger
Keyword(s):  
Sugar Beet ◽  
Hydrogen Cyanide ◽  
Malic Enzyme ◽  
Hill Reaction ◽  
Leaf Extracts ◽  
Root Extracts ◽  
Phosphoglyceric Acid ◽  
Reaction Capacity ◽  
The Hill

"Malic" enzyme isolated from the cytoplasm of parsley and sugar beet leaves was linked with illuminated spinach chloroplast fragments to effect photosynthesis in vitro. The model photosynthesis system containing excess "malic" enzyme was not inhibited by 5 × 10−4 M hydrogen cyanide. The "malic" enzyme system was inhibited by cyanide, however, at very low enzyme concentrations. The richest source of "malic" enzyme found in this study was the mature parsley leaf. Expressed on the same basis, the enzymatic capacities of parsley leaf "malic" enzyme and the Hill reaction capacity of isolated spinach chloroplasts are of similar magnitude. Higher "malic" enzyme and oxalacetic carboxylase activities were found in purified extracts of parsley leaves than in the corresponding root extracts. Oxalacetic, oxalsuccinic, α-ketoglutaric, and pyruvic carboxylases were not inhibited by 10−3 M hydrogen cyanide. The α-ketoglutaric and pyruvic carboxylases were much less abundant in leaves than in other plant organs; formic dehydrogenase was not detected in leaves although it is abundant in seeds. Glutamic carboxylase was found in the cytoplasm of wheat and sugar beet leaves, and with the aid of C14O2 was shown to be only weakly reversible. No evidence was obtained for the presence in leaf extracts of an enzyme, or mixture of enzymes, capable of decarboxylating phosphoglyceric acid in vitro.

Interference of Herbicides with the Hill Reaction of Isolated Chloroplasts

Weeds ◽  
1962 ◽  
Vol 10 (3) ◽  
pp. 229 ◽  
Author(s):  
D. E. Moreland ◽  
K. L. Hill
Keyword(s):  
Hill Reaction ◽  
The Hill ◽  
Isolated Chloroplasts

scholarly journals Determination of in Vitro Antioxidant Enzyme Capacity and Oxidative Stress Levels in Mazı Meşesi (Quercus infectoria)

2021 ◽  
Vol 9 (4) ◽  
pp. 814-817
Author(s):  
İlter Demirhan ◽  
Büşra Çitil ◽  
Mehmet Özyurt ◽  
Meltem Güngör ◽  
Erkan Öner ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Superoxide Dismutase ◽  
Antioxidant Capacity ◽  
Antioxidant Enzyme ◽  
Antioxidant Enzyme Activities ◽  
Spectrophotometric Methods ◽  
Significant Difference ◽  
Quercus Infectoria

South East Anatolia Region has a large genetic plant diversity due to its physical and different climatic charesteristics. These plants are potential sources of antioxidants that prevent oxidative stress caused by oxygen and photons. In recent years, it has become important to study the antioxidant capacity of many molecules found naturally in foods and biological systems. The reason for this is that it is believed that when the consumption of food rich in antioxidants is increased, the risk of developing different degenerative diseases will be reduced. In this study, it was aimed to measure the antoxidant capacity of Quercus infectoria, G.olivier gal seeds grown in Southeastern Anatolia. Q. infectoria gal seeds from Sanlıurfa province were used in our study. Q. infectoria gal seeds were extracted with water, ethanol and methanol and then antioxidant enzyme activities (catalase and superoxide dismutase) and malondialdehyde levels, which are indicators of oxidative stress were determined by spectrophotometric methods. It was found that the antioxidant capacity (catalase and superoxide dismutase activities) of extracts obtained from ethanol and methanol were higher and their malondialdehyde levels were statistically lower than those obtained from water. However, it was determined that there was no statistically significant difference between the antioxidant capacity and malondialdehyde levels of the extracts obtained from methanol compared to the extracts obtained from ethanol. It has been concluded that Q. infectoria gal seed has a effective antioxidant effect. In addition, it was observed that extracts obtained from ethanol and methanol have higher antioxidant capacity than extracts obtained from water.

Light Saturation of Growth and Photosynthesis of the Shade Plant Marchantia Polymorpha

1973 ◽  
Vol 12 (2) ◽  
pp. 391-401
Author(s):  
R. MACHE ◽  
S. LOISEAUX
Keyword(s):  
Growth Rate ◽  
Photosystem Ii ◽  
Light Intensity ◽  
Marchantia Polymorpha ◽  
Hill Reaction ◽  
Light Saturation ◽  
Shade Plant ◽  
Low Illumination ◽  
The Hill ◽  
Isolated Chloroplasts

The growth rate of the shade plant Marchantia was at its maximum for a low illumination, 2-3 x 103 lx, and was inhibited by an excess of light. Photosynthesis by intact thalli and by isolated chloroplasts of Marchantia was saturated by a light intensity of 2-3 x 103 lx. These isolated chloroplasts were able to carry on satisfactory rates of photosynthesis, up to 35 µM CO2/h/mg chlorophyll. The Hill reaction and photosystem II were also saturated by the same light intensities, demonstrating that the factor limiting the light saturation of photosynthesis is located in the chloroplast. The structure of chloroplasts was strongly modified by an excess of light, small grana and fret membranes being replaced by continuous grana.

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