Ultraviolet sunscreens in Gymnodinium sanguineum (dinophyceae): mycosporine-like amino acids protect against inhibition of photosynthesis

摘要: Marine phytoplankton are sensitive to inhibition of photosynthesis by solar ultraviolet (UV) radiation, although sensitivity varies, depending on the growth environment. A mechanism suggested increase resistance UV is accumulation UV-absorbing compounds, such as mycosporine-like amino acids (MAAs) found in many marine organisms. However, effectiveness these compounds direct optical screens microorganisms has remained unclear. The red-tide dinoflagellate Gymnodinium sanguineum Hirasaka accumulates about 14-fold more MAAs (per unit chlorophyll) high (76 W·m−2) than low (15 irradiance. Biological weighting functions were estimated for and showed that high-light-grown cultures have lower radiation at wavelengths strongly absorbed MAAs. time course during exposure was measured using pulsed amplitude modulated (PAM) fluorometry displayed a steady-state level after 15 min exposure, indicating active repair damage photosynthetic apparatus. Repair blocked presence antibiotic streptomycin, yet high-light G. less did low-light cultures. These experiments show act spectrally specific sunscreens phytoplankton.