Algae. 2002; 17(4): 259-265.
Rhythmic Phenomena in the Green Alga Ulva pertusa Kjellman
Jeong-Ae Kong, Young-Seok Han, Taejun Han
Division of Biology and Chemistry, University of Incheon
Patterns of chloroplast arrangement, cell division and starch accumulation were studied for the green alga Ulva pertusa Kjellman. When grown under 12:12 h light-dark phases the plant exhibited a rhythmic change in the chloroplast size with the maximal size (140-150 ㎛²) during the day and the minimal size (50-60 ㎛²) at night. Such change was not noted for the thalli kept in continuous darkness. Cell division appeared to take place three times in the thalli incubated in light-dark cycles as reflected from three peaks in the cell size while only two cell size peaks were observed in the continuous dark. Starch accumulation seemed to be under the control of light quality, showing that the relative amount of starch was greater in red than in blue light although a rhythmic change was recognized regardless of the spectral qualities. When transferred from red to blue light the plants showed a significant decrease in the starch amount reaching to the levels found in thalli kept in blue light from the beginning. Transfer of thalli to red light from blue brought about continued starch accumulation. A simple equation of quantifying the cellular starch content was generated using the starch area as measured by an image analyzer after the potassium iodideiodine reaction.
Keywords : chloroplast, spectral qualities, starch, Ulva pertusa