scholarly journals The Influence of 0.03% Carbon Dioxide on Protein Metabolism of Etiolated Avena sativa Coleoptiles

1974 ◽  
Vol 54 (1) ◽  
pp. 19-22 ◽  
Author(s):  
A. W. Bown ◽  
T. Aung
1972 ◽  
Vol 50 (9) ◽  
pp. 1937-1942
Author(s):  
A. W. Bown ◽  
W. W. Lampman

Various concentrations of carbon dioxide have been used to assess the influence of carbon dioxide on protein metabolism in etiolated coleoptiles of Avena sativa. Increases in carbon dioxide concentration from 0% to 0.03% to 3% result in dramatic increases in both the total level of protein and the incorporation of radioactive leucine into protein. In addition an electrophoretic analysis indicates that as the carbon dioxide concentration is raised from 0% to 0.03% there is both an increased synthesis of most proteins plus a pronounced synthesis of one particular protein fraction. These results indicate that the normal atmospheric concentration of carbon dioxide has a profound influence on protein metabolism in Avena sativa coleoptiles and are discussed in connection with the well-documented phenomenon of carbon dioxide stimulated growth in etiolated plant tissues.


1987 ◽  
Vol 65 (3) ◽  
pp. 488-490 ◽  
Author(s):  
Gordon I. McIntyre

When intact oat coleoptiles (Avena sativa var. Harmon) were submerged in water, saturation of the water with CO2 promoted their elongation but eliminated their phototropic response to blue light. Increasing the pH of the CO2-saturated water prevented the promotion of coleoptile elongation but did not prevent the elimination of the phototropic response. In air, phototropic curvature was significantly reduced by 10% CO2 and was eliminated by 30%, without any reduction in growth. It is postulated that the increase in CO2 concentration may eliminate the phototropic curvature of the coleoptile by preventing the light-induced inhibition of growth on the illuminated side of the organ. Possible mechanisms are briefly discussed.


1971 ◽  
Vol 49 (2) ◽  
pp. 321-326 ◽  
Author(s):  
A. W. Bown ◽  
W. W. Lampman

Phosphopyruvate carboxylase and malic enzyme were detected in etiolated coleoptiles of Avena sativa, and it was concluded that the incorporation of 14C-labeled bicarbonate into aspartate and glutamate involved the activity of the former enzyme. IAA stimulated the fixation of labeled bicarbonate, and the incorporation of labeled leucine into protein was increased in the presence of carbon dioxide. It is suggested that the carbon dioxide stimulated growth of Avena coleoptiles is due to an increased rate of protein synthesis which is dependent on carbon dioxide fixation.


1977 ◽  
Vol 55 (12) ◽  
pp. 1641-1645 ◽  
Author(s):  
I. J. Dymock ◽  
B. Hill ◽  
A. W. Bown

Etiolated Avena sativa L. cv. Victory coleoptiles were used to determine the influence of indoleacetic acid (IAA) or malate on in vivo and in vitro rates of CO2 fixation. In addition, the influence of malate on IAA-stimulated growth was investigated. Concentrations of malate which stimulate growth did not influence the in vivo rate of dark [14C]bicarbonate fixation but did inhibit in vitro phosphoenolpyruvate carboxylase (EC 4.1.1.31) activity. IAA did not influence this enzymic activity or reduce the inhibition of the enzyme by malate, and the rate of [14C]bicarbonate fixation was not measurably influenced by 20 μM IAA within the time period required for IAA stimulation of growth to become apparent. In the absence of atmospheric levels of CO2, 1 mM malate and 20 μM IAA stimulate growth in a weakly synergistic manner. These results are discussed in relationship to a suggestion that IAA-stimulated H+ secretion and growth involves a rapid effect on CO2 fixation.


Author(s):  
K. C. Tsou ◽  
J. Morris ◽  
P. Shawaluk ◽  
B. Stuck ◽  
E. Beatrice

While much is known regarding the effect of lasers on the retina, little study has been done on the effect of lasers on cornea, because of the limitation of the size of the material. Using a combination of electron microscope and several newly developed cytochemical methods, the effect of laser can now be studied on eye for the purpose of correlating functional and morphological damage. The present paper illustrates such study with CO2 laser on Rhesus monkey.


Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.


Author(s):  
B. K. Kirchoff ◽  
L.F. Allard ◽  
W.C. Bigelow

In attempting to use the SEM to investigate the transition from the vegetative to the floral state in oat (Avena sativa L.) it was discovered that the procedures of fixation and critical point drying (CPD), and fresh tissue examination of the specimens gave unsatisfactory results. In most cases, by using these techniques, cells of the tissue were collapsed or otherwise visibly distorted. Figure 1 shows the results of fixation with 4.5% formaldehyde-gluteraldehyde followed by CPD. Almost all cellular detail has been obscured by the resulting shrinkage distortions. The larger cracks seen on the left of the picture may be due to dissection damage, rather than CPD. The results of observation of fresh tissue are seen in Fig. 2. Although there is a substantial improvement over CPD, some cell collapse still occurs.Due to these difficulties, it was decided to experiment with cold stage techniques. The specimens to be observed were dissected out and attached to the sample stub using a carbon based conductive paint in acetone.


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