Salt relations of Dunaliella. Transitional changes in glycerol content and oxygen exchange reactions on water stress |
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Authors: | D. S. Kessly A. D. Brown |
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Affiliation: | (1) School of Microbiology, University of New South Wales, 2033 Kensington;(2) Department of Biology, University of Wollongong, 2500 Wollongong, N.S.W., Australia;(3) Present address: Southern Cross Laboratories, 2518 Dural, N.S.W., Australia;(4) Department of Biology, University of Wollongong, 2500 Wollongong, N.S.W., Australia |
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Abstract: | Changes in glycerol content are reported for Dunaliella tertiolecta over an 8 h period after a salt stress or dilution stress. Under the experimental conditions, the new glycerol level was reached in about 30 min in light or dark but there was evidence of oscillations after that, particularly on dilution stress. Glycerol disappearance on dilution stress is caused predominantly by dissimilation. A salt stress immediately inhibited photosynthetic oxygen evolution and caused net oxygen uptake for a period of about 36 h after the stress. Oxygen evolution was reestablished after that and the process of recovery to the point of resumption of net evolution was not affected by conditions designed to inhibit protein synthesis. Dilution stress of comparable magnitude diminished but did not eliminate photosynthetic oxygen evolution and recovery to a pre-stress level took about 18 h. Effects of HCO3-concentration suggested that photorespiration was not the sole determinant of oxygen uptake induced by salt stress but it was not possible to apportion with confidence the contribution of mitochondrial and other types of respiration. There was no evidence that modification by stress of energy-induced proton fluxes across the plasma membrane constituted an osmoregulatory signal in either species. |
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Keywords: | Compatible solute Dunaliella Glycerol Osmoregulation Osmotic shock Photosynthesis Respiration Salt stress Salt tolerance |
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