ISSN:
1432-2048
Keywords:
Amino acid
;
Sucrose concentration
;
Spinacia (leaf)
;
Metabolite compartmentation
;
Subcellular volumes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Cellular and subcellular volumes in mature leaves of spinach (Spinacia oleracea L. US Hybrid 424) were determined stereologically from light and electron micrographs. Forty-nine-day-old leaves of spinach with a total leaf volume of 1177 μL per mg chlorophyll (Chl) were found to be composed of 3% epidermis, 58% mesophyll, 1% vascular tissue, 5% apoplasm and 32% gas space. In the epidermal cells 89% of the volume was occupied by the vacuole. The mesophyll cells consisted, expressed in mg·Chl−1, of 546 μL (79%) vacuole, 66 μL (9.5%) chloroplast stroma, 24 μL (34%) cytosol, 3.7 μL (0.5%) mitochondria and 2.1 μL (0.3%) nucleus. From previous measurements of the subcellular levels of sucrose, of phosphorylated intermediates of carbohydrate metabolism, of malate, oxoglutarate and various amino acids in illuminated leaves, and the above subcellular volumes, the corresponding subcellular metabolite concentrations have been determined. Of the substances measured, only with malate was the concentration higher in the vacuole than in the cytosol. The concentration of sucrose in the cytosol was 5 times, and that of amino acids even 30 times higher than in the vacuole.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02411558
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