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Latin american journal of aquatic research

versión On-line ISSN 0718-560X

Resumen

HERNANDO, Marcelo; MALANGA, Gabriela; PUNTARULO, Susana  y  FERREYRA, Gustavo. Fotoprotección antioxidante no-enzimática contra el potencial daño inducido por UVBR en una diatomea antártica (Thalassiosira sp.). Lat. Am. J. Aquat. Res. [online]. 2011, vol.39, n.3, pp.397-408. ISSN 0718-560X.

In January 1999, unialgal cultures of the diatom Thalassiosira sp., solate from natural phyto-plankton assemblages from Potter Cove, Antarctica, were exposed to solar ultraviolet radiation (UVR, 280400 nm) in order to study the long-term acclimation of this species. Ultraviolet radiation B (UVBR, 280-315 nm) inhibited the growth rate during the first and second days of exposure. No UVBR inhibition was observed on the third day. The initial content of α-tocopherol (13 pmol (104 cell)-1) showed a marked decrease during the exponential growth phase (4 pmol (104 cell-1) by day 3). The initial content of β-carotene (3 pmol (104 cell)-1) did not show significant differences over time in cells exposed to UVBR. Two mycosporine-like amino acids (MAAs) were identified: porphyra-334 and shinorine. Cellular concentrations of MAAs increased significantly on days 2 and 3, and exposure of the algae to UVBR significantly enhanced this value. The relative importance of MAAs concentration was significant (P < 0.05) in relation to the α-tocopherol content. A positive correlation was shown between cellular MAAs concentration and growth rate. Our results suggest that photoprotection against UV-induced damage is characterized by short-term consumption of α-tocopherol and longer-term synthesis of MAAs. The UVBR damage/repair ratio during long-term exposure involves the combined action of several endogenous factors within the cell, with MAAs synthesis being the most effective factor related to photoprotection.

Palabras clave : β-carotene; α-tocopherol; growth rate; diatoms; MAAs; photoprotection; Antarctica.

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