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UV absorption by mycosporine-like amino acids in Phaeocystis antarctica Karsten induced by photosynthetically available radiation
Moisan, T.A.; Mitchell, B.G. (2001). UV absorption by mycosporine-like amino acids in Phaeocystis antarctica Karsten induced by photosynthetically available radiation. Mar. Biol. (Berl.) 138(1): 217-227. hdl.handle.net/10.1007/s002270000424
In: Marine Biology. Springer: Heidelberg; Berlin. ISSN 0025-3162, more
Peer reviewed article  

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Keyword
    Marine

Authors  Top 
  • Moisan, T.A.
  • Mitchell, B.G.

Abstract
    Mycosporine-like amino acids (MAAs), which occur in diverse taxonomic groups, exhibit in?vivo absorption maxima between 310?nm and 360?nm and may play a photoprotective role against ultraviolet (UV) exposure. Using cultures of colonial Phaeocystis antarctica, we examined the relationship between MAA concentration, in?vivo UV absorption, photoprotective (carotenoid) and photosynthetic pigments, and photosynthetically available radiation (PAR, 350–700?nm). UV absorption was high; chlorophyll-specific absorption, a * ph, at 330?nm ranged from 0.06 to 0.41?m2/mg chlorophyll a. Values of a * ph (330) were 4–13 times greater than a * ph (676). Mycosporine-glycine, shinorine, and mycosporine-glycine valine are responsible for the strong in?vivo UV absorption. The sum of all MAAs increased with irradiance when normalized to chlorophyll a or carbon concentrations, whereas individual MAAs varied independently from each other. Mycosporine-glycine concentrations showed no statistically significant change over the range of light intensities, whereas mycosporine-glycine and shinorine concentrations increased at higher irradiances. The relative fluorescence yield for chlorophyll a was low in the UV region compared to the visible region, implying that absorbed UV radiation (<375?nm) is transferred inefficiently to chlorophyll a in the reaction center. Quantitative estimates of UV screening by MAAs are attributed to elevated MAA concentrations and increased diameter at high light.

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