The molecular biology of Euglena gracilis. XV. Recovery from centrifugation-induced stratification.
The contents of Euglena gracilis cells can be separated in vivo by ultracentrifugation. Within the unbroken cell, each set of components forms a distinct layer according to their respective densities. The degree of segregation increases with both the g-force and the time of centrifugation, up to a maximum at 100,000 x g for 1 h, when six distinct strata can be observed. When returned to normal growth conditions, essentially all the cells return to the normal state and growth pattern. Greater g-forces or longer exposures do not alter the observable strata, but the ability of the cells to recover is diminished. Smaller g-forces result in less separation of cellular contents and all cells recover, even after 18 h of exposure. Euglena cells stratified at 100,000 x g for 1 h were returned to normal growth conditions; recovery was followed microscopically and by the rate of utilization of oxygen as well as that of the single carbon source. The cells recovered their normal state within 1 to 2 h, which is only a tenth of the normal doubling time. The mechanism for this recovery involves a natural process of change in cell shape caused by contraction and relaxation of the pellicle, a cell surface structure.
National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. kempnere@exchange.nih.gov
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Kempner
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Miller
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D048429:Cell Size; D005056:Euglena gracilis / Q000166:cytology* / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism; D014461:Ultracentrifugation
D018698:Glutamic Acid