scholarly journals Stress Metabolism II. Changes in Proline Concentration in Excised Plant Tissues

1973 ◽  
Vol 26 (1) ◽  
pp. 57 ◽  
Author(s):  
TN Singh ◽  
D Aspinall ◽  
LG Paleg ◽  
SF Boggess

Shoot apices and excised root systems and sections of the lamina and leaf sheath of the first leaf of to-day barley (cv. Prior) plants were incubated on aerated polyethylene glycol solution (osmotic potential -20 bars) or distilled water. The imino acid proline accumulated rapidly in the leaf lamina sections subjected to osmotic stress and less rapidly, after a delay of 16 hr, in those floated on water.

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
M. Tajdidzadeh ◽  
A. B. Zakaria ◽  
Z. Abidin Talib ◽  
A. S. Gene ◽  
S. Shirzadi

In the present study, gold nanoparticles were synthesized in various polymer solutions by means of employing laser ablation technique at the same ablation time. Specifically, gold nanoparticles were synthesized in polyethylene glycol and chitosan solutions, in order to compare the effects of the liquid media which served as stabilizers for particle size and volume fraction of nanoparticles. In addition, this experiment was repeated in distilled water for reference purposes. As the findings indicated, the particle size which was obtained in polyethylene glycol was about 7.49 nm, that is, smaller than those of chitosan solution and distilled water, respectively. In contrast, it was observed that the volume fraction of gold nanoparticles increased in polyethylene glycol in comparison with the other media which indicated an effect on the formation of NPs. On the other hand,Z-scan technique was employed to measure the nonlinear refractive index and nonlinear absorption coefficient of nanofluids containing gold nanoparticles. Consequently, the nonlinear properties of nanofluids pointed to a significant contribution with the number of nanoparticles observed in fluids and both optical nonlinear parameters were observed to increase by means of a prior increase in the volume fraction of Au-NPs in polyethylene glycol solution.


Author(s):  
Xudong Zhang ◽  
Bastian L. Franzisky ◽  
Lars Eigner ◽  
Christoph‐Martin Geilfus ◽  
Christian Zörb

AbstractChloride (Cl−) is required for photosynthesis and regulates osmotic balance. However, excess Cl− application negatively interacts with nitrate ($${\mathrm{NO}}_{3}^{-}$$ NO 3 - ) uptake, although its effect on $${\mathrm{NO}}_{3}^{-}$$ NO 3 - metabolism remains unclear. The aim was to test whether Cl− stress disturbs nitrate reductase activity (NRA). A maize variety (Zea mays L. cv. LG 30215) was hydroponically cultured in a greenhouse under the following conditions: control (2 mM CaCl2), moderate Cl− (10 mM CaCl2), high Cl− (60 mM CaCl2). To substantiate the effect of Cl− stress further, an osmotic stress with lower intensity was induced by 60 g polyethylene glycol (PEG) 6000 L−1 + 2 mM CaCl2), which was 57% of the osmotic pressure being produced by 60 mM CaCl2. Results show that high Cl− and PEG-induced osmotic stress significantly reduced shoot biomass, stomatal conductance and transpiration rate, but NRA was only decreased by high Cl− stress. The interference of NRA in chloride-stressed maize is supposed to be primarily caused by the antagonistic uptake of Cl− and $${\mathrm{NO}}_{3}^{-}$$ NO 3 - .


Author(s):  
Randi Johnson ◽  
Samantha Wigglesworth ◽  
Rachel Moyle ◽  
Alex Lynch

2000 ◽  
Vol 29 (4) ◽  
pp. 849-854 ◽  
Author(s):  
Ronaldo Reis Jr. ◽  
Lima ◽  
Evaldo F. Vilela ◽  
Raimundo S. Barros

To accomplish systematic studies with coffee leafminer, it is necessary to establish a mass rearing system under artificial conditions. It is possible to rear this species, from egg to adult, under laboratory conditions, without using coffee seedlings but detached leaves maintained in vitro. Synthetic cytokinins are routinely used for maintenance of plant cell and plant tissues in vitro. Two plant growth regulators, benzyladenin and kinetin, in concentrations 10-6 and 10-7 M were used to mantain the leaves. Green leaves collected in the field were maintained in the solution to be tested. Distilled water served as control. The experiment lasted 30 days, a period longer than the necessary for the complete development of the insect. Both artificial cytokinines indeed increased the lifetime of the coffee leaves, maintaining them green and healthy. Leaves placed in the cages for oviposition were attractive to the insect, with significant number of eggs per leaf. In most cases, eggs resulted in individuals that completed the whole developmental cycle. Tests with regulator in different concentrations with healthy leaves showed efficiency. However, we believe that hormone concentrations to be used with mined leaves should be larger, because these when maintained at 10-7 M leaves did not present a satisfactory lifetime. Therefore, tests with mined leaves with different hormone concentrations should be made to find out the ideal concentration for leaf survival. In our laboratory we are successfully using 10-6 M benzyladenin for the maintenance of mined leaves.


2012 ◽  
Vol 49 (2) ◽  
pp. 162-168 ◽  
Author(s):  
Manoel Carlos Vieira ◽  
Claudio Lyoiti Hashimoto ◽  
Flair José Carrilho

CONTEXT: Colonoscopy is currently the gold standard method to examine the colon, the rectum and the terminal ileum. In order to perform the colonoscopy, it is necessary to clean the bowel and use medications that are generally poorly tolerated by the patients. OBJECTIVE: Compare the tolerability, acceptability, safety and efficacy of two solutions used for intestinal preparation for a colonoscopy. METHODS: One hundred patients matched for sex and age were prospective randomized into two groups. Polyethylene glycol group received bisacodyl 10 mg plus 1 L of polyethylene glycol the night before and 1 L on the day of the exam. Mannitol group received bisacodyl 20 mg the day before and 1 L of a 10% mannitol solution on the day of the exam. The diet was the same for both groups. Tolerability and acceptability were measured using previously validated questionnaires. In terms of safety, variations in vital signs before and after the preparation were recorded, in addition to any complications. The quality of the preparation was graded based on the Boston and Ottawa scales. RESULTS: Ninety-six percent (96%) completed the study. As for tolerability, the mannitol preparation group exhibited a significantly higher frequency of nausea, vomiting, abdominal pain, and abdominal distension than polyethylene glycol group (P < 0.05). Acceptability was significantly better in polyethylene glycol group. The polyethylene glycol solution has also previously been shown to be safer than mannitol. No difference was observed in the quality of the preparation between the two preparation methods. CONCLUSIONS: The following conclusions can be made: polyethylene glycol solution had higher tolerability, acceptability, and safety than the mannitol and should be used instead of mannitol. Both preparation solutions have similar efficacy.


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