구멍갈파래 엽상체의 a 형광유도과정의 특성과 수은의 영향 = Characteristics of Fluorescence Induction Kinetics from Ulva pertusa Kjellman and Effects of Mercury

다국어 초록 (Multilingual Abstract)

The effects of mercury on the photosynthetic machinery of Ulva pertusa Kjellman were examined by measuring oxygen evolution, pigment contents, and fluorescence induction process. By increasing the concentration of added HgCl₂upto 0.6 ppm, oxygen evolution rate and pigment contents were decreased gradually. Chlorophyll α/b ratio was also decreased, suggesting that chlorophyll α was decreased (probable degraded) more rapidly than chlorophyll b by the treatment of mercury. Overall pattern of the fluorescence induction curve was very similar to that measured from terrestrial plant leaves. However, several characteristic differences observed: (1) fluorescence intensity decreased very rapidly after P(peak), (2) D(dip)-P increase was significantly reduced when measured 30 sec after a saturation pulse, and (3) Fmax was decreased when measured again 30 sec after a first measurement by using a saturation pulse. Due to the second and third characteristics, at least 30 min dark interval was required before starting an additional measurement using a sample. When the mercury concentration was increased, Fp (fluorescence intensity at P) was decreased gradually, but Fi(the intensity at inflection) did not increased. The decrease in Fp could be explained by the inhibition of mercury at a site near oxygen evolving complex. By the addition of 0.2 ppm HgCl₂, Fp was increased slightly without significant changes in ID pattern. This result suggests that the inhibition site of mercury at the electron transport chain on the reducing side of PSⅡ is not the Q_B or DCMU binding site. When the mercury concentration was increased, Fo was decreased slightly, but Fmax, (Fv)m/Fmax, qQ and qN was decreased significantly. By the addition of mercury more than 0.6 ppm, photosynthetic activities was almost completely blocked but pigment contents was stayed the same.