Kuwano Kazuyoshi, Abe Naoko, Nishi Yukari, Seno Hiromi, Nishihara Gregory N, Iima Masafumi, Zachleder Vilém
Graduate School of Science and Technology, Nagasaki University, Bunkyo-machi, Nagasaki, 852-8521, Japan.
Faculty of Fisheries, Nagasaki University, Bunkyo-machi, Nagasaki, 852-8521, Japan.
J Phycol. 2014 Aug;50(4):744-52. doi: 10.1111/jpy.12207. Epub 2014 Jul 3.
The cell-cycle progression of Ulva compressa is diurnally gated at the G1 phase in accordance with light-dark cycles. The present study was designed to examine the spectral sensitivity of the G1 gating system. When blue, red, and green light-emitting diodes (LEDs) were used for illumination either alone or in combination, the cells divided under all illumination conditions, suggesting that all colors of light were able to open the G1 gate. Although blue light was most effective to open the G1 gate, red light alone or green light alone was also able to open the G1 gate even at irradiance levels lower than the light compensation point of each color. Occurrence of a period of no cell division in the course of a day suggested that the G1 gating system normally functioned as under ordinary illumination by cool-white fluorescent lamps. The rise of the proportion of blue light to green light resulted in increased growth rate. On the other hand, the growth rates did not vary regardless of the proportion of blue light to red light. These results indicate that the difference in growth rate due to light color resulted from the difference in photosynthetic efficiency of the colors of light. However, the growth rates significantly decreased under conditions without blue light. This result suggests that blue light mediates cell elongation and because the spectral sensitivity of the cell elongation regulating system was different from that of the G1 gating system, distinct photoreceptors are likely to mediate the two systems.
石莼的细胞周期进程在G1期根据昼夜明暗周期进行昼夜调控。本研究旨在检测G1调控系统的光谱敏感性。当单独或组合使用蓝色、红色和绿色发光二极管（LED）进行照明时，细胞在所有照明条件下均能分裂，这表明所有颜色的光都能够打开G1门控。尽管蓝光打开G1门控的效果最为显著，但即使在低于每种颜色光补偿点的辐照度水平下，单独的红光或绿光也能够打开G1门控。一天中出现的无细胞分裂期表明，G1门控系统在普通冷白色荧光灯照明下通常能正常发挥作用。蓝光与绿光比例的增加导致生长速率提高。另一方面，无论蓝光与红光的比例如何，生长速率均无变化。这些结果表明，光颜色导致的生长速率差异是由光颜色的光合效率差异引起的。然而，在没有蓝光的条件下，生长速率显著下降。这一结果表明蓝光介导细胞伸长，并且由于细胞伸长调节系统的光谱敏感性与G1门控系统不同，可能有不同的光感受器介导这两个系统。
