| Autor: |
Wood, J. G., Cruickshank, D. H., Kuchel, R. H. |
| Zdroj: |
Australian Journal of Experimental Biology & Medical Science; Mar1943, Vol. 21 Issue 1, p37-53, 17p, 1 Diagram, 1 Chart, 12 Graphs |
| Abstrakt: |
Details are given of eight experiments in which leaves of Sudan Grass (Andropogen sudanensis, L. and B.) and Kikuyu Grass (Pennisetum clandestinum, Hockst.) were placed under starvation conditions both in air and in nitrogen. Observations which are essentially new include the following: During starvation in air chloroplast protein is broken down into soluble products. In Sudan Grass chloroplast-protein breaks down more rapidly than cytoplasmic protein, but in Kikuyu both chloroplast and cytoplasmic proteins break down al approximately equal rates. Decrease in amount of protein with time is approximately linear until a point is reached, coincident with cessation of yellowing, when there is little further decrease in protein. Decrease in amounts of chlorophyll, ascorbic acid and dehydroascorbic acid is associated with decrease in chloroplast protein. Cessation of protein hydrolysis in the leaves is associated with disintegration of the chloroplast structure. In air onset of protein breakdown is determined by the initial sucrose content; and residual amino acids, glutamine, asparagine and ammonia successively attain maximum contents, but their formation commences with commencement of protein breakdown. The maximum asparagine content coincides with cessation of protein loss. In nitrogen amount of protein degradation is very small compared with that in air and amino acids only, but not amides and ammonia, accumulate in the leaves. On transferring the leaves to air proteins decrease in amount and production of amides and ammonia takes place. In air respiration rate initially decreases with falling sucrose content, but this is followed by a climacteric rise which occurs between the times of maximum residual amino-acid content and maximum asparagine content. The onset of the climacteric appears to be determined by the initial carbohydrate content and its form by the sucrose and amino acid contents. In nitrogen no climacteric rise in respiration rate... [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Plný text