Studies on halimeda. V. effect of temperature on chloroplast migration in this Siphonous green alga&* |
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Authors: | Edward A Drew Kay M Abel |
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Institution: | Australian Institute of Marine Science , PMB No 3, MC, Townsville, Q 4810, Australia |
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Abstract: | Abstract The effect of temperatures between 15 and 30°C on the daily cycle of chloroplast migration in Halimeda distorta and H tuna was determined from changes in segment pigmentation recorded by time‐lapse videography throughout the experiments. An un‐named opuntioid species was also tested between 20 and 35°C. Both the daily pattern and the amplitude of change in surface pigmentation, which were sustained for at least 5 days at 25°C, were unchanged at the higher temperatures. At 20°C the amplitude was considerably reduced but cyclical changes in surface pigmentation continued to occur throughout the 3‐day low temperature period. However, at 15°C even greater reduction in amplitude was observed together with a reduced rate of paling at the onset of darkness and absence of pre‐dawn re‐greening. Furthermore, at 15°C all daily changes in surface pigmentation had ceased by the second day in H tuna and by the third day in H distorta. These effects of lower temperatures were reversed when the plants were returned to 25°C, although after the 15°C treatment of H tuna the amplitude of the change in surface pigmentation in two of the three replicate plants was small on the first night back at 25°C whilst the third plant lost pigmentation progressively and was completely white, and apparently dead, two days later. |
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Keywords: | Halimeda coenocytic green alga chloroplast movement elevated temperature reduced temperature cytoskeleton |
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