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Isolated cell envelopes from the leaf mesophyll of Italian ryegrass were examined in a transmission electron microscope equippedwith an energy-dispersive X-ray spectrometer. Silicon was detectedin these walls at an estimated concentration of 12 percent. Samples were also subjected to a range of techniques,for the removal of organic matter, which confirmed the presenceof silica throughout the cell walls. Lolium multiflorum Lam, Italian rye grass, cell walls, silica, electron microscopy, X-ray microanalysis 相似文献
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The Interrelations of Cell Turgor Pressure, Gas-vacuolation, and Buoyancy in a Blue-green Alga 总被引:5,自引:0,他引:5
The increase in pressure required to collapse gas vacuoles onsuspending the cells of the blue-green alga Anabaena flos-aquaein hypertonic sucrose solutions shows the turgor pressure tovary over the range of 265 to 459 KN m2 under differentculture conditions. The cell turgor increased at a rate of upto KN m2 h1 on transferring the alga from lowto high light intensity. This rise appears to be a result ofthe accumulation of photosynthate, as it is dependent on thepresence of carbon dioxide in the gas phase and is inhibitedby DCMU. Experiments using 14CO2 indicate that the increasedrate of photosynthesis during the high light exposure is easilysufficient to account for the observed turgor rise. The rise in turgor can bring about collapse of sufficient ofthe alga's gas vacuoles to destroy its buoyancy. Higher turgorpressures, and consequently a lower degree of gas vacuolationand buoyancy, were maintained when the alga was kept at highlight intensitives for a week and more. The significance ofthis behaviour is discussed in relation to stratification ofplanktonic blue-green algae in natural habitats. 相似文献
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