Effects of solar UV and visible radiations on the spiral structure and orientation of Arthrospira (Spirulina) platensis (Cyanophyta)
Li, Ping（Shantou Univ, Inst Marine Biol, Shantou 515063, Guangdong, Peoples R China）
- 海洋环境－已发表论文 
Morphological characteristics of Artlrroshira spp. are important for product quality and harvesting efficiency. Solar ultraviolet radiation (UVR) has been previously shown to break their spirals. To further explore the relationship of morphology and UVR, we examined the spiral length, helix diameter, helical pitch and orientation of A. platensis while exposing the cells to solar radiation with or without UVR. Although solar exposures initially led to breakage of the spirals, no significant difference was found among the treatments with or without UVR. During the long-term exposures to solar radiation, the spirals became more compressed in the outdoor strain (grown under sunlight for decades) but more loosened in the indoor strain [grown under artificial photosynthetically active radiation (PAR) for decades]. Spiral orientation was altered from the right- to left-handed only in the outdoor strain, with a frequency of less than 1%. Presence of UVR enhanced such an orientation change, and regrowing under indoor low PAR (UVR-free condition) reversed the orientation to right-handed. Structure of some membrane molecules was suggested to be altered by high solar PAR and UVR.