科研之友
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摘要
The cell-cycle progression of Ulva compressa is diurnally gated at the G(1) phase in accordance with light-dark cycles. The present study was designed to examine the spectral sensitivity of the G(1) 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 G(1) gate. Although blue light was most effective to open the G(1) gate, red light alone or green light alone was also able to open the G(1) 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 G(1) 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 G(1) gating system, distinct photoreceptors are likely to mediate the two systems.
- 出版日期2014-8
