Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America

Marine microalgae exposed to ultraviolet radiation (UV) have complex adaptive responses provided by a series of protection and repair mechanisms. Interspecific differences in UV sensibility could result in differential selection of the more tolerant species, having consequences for the structure of...

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Autores principales: MONTECINO,VIVIAN, MOLINA,XIMENA, MARTÏNEZ,GINGER, OLMEDO,M. ISABEL, RETAMAL,LEIRA, HANNACH,GABRIELA, ORELLANA,MÓNICA V.
Lenguaje:English
Publicado: Sociedad de Biología de Chile 2001
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Acceso en línea:http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000200007
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spelling oai:scielo:S0716-078X20010002000072001-11-08Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South AmericaMONTECINO,VIVIANMOLINA,XIMENAMARTÏNEZ,GINGEROLMEDO,M. ISABELRETAMAL,LEIRAHANNACH,GABRIELAORELLANA,MÓNICA V. photosynthesis absorbance photoreactivation growth UV response Marine microalgae exposed to ultraviolet radiation (UV) have complex adaptive responses provided by a series of protection and repair mechanisms. Interspecific differences in UV sensibility could result in differential selection of the more tolerant species, having consequences for the structure of phytoplankton assemblages. The relative importance of protection and photorepair mechanisms of microalgal cells exposed to potential UV-B stress was studied in monocultures with different taxonomic, ecological and size characteristics obtained from the Chilean coast. Differences in photosynthesis and growth rates were predicted, since the ability to effectively acclimate to UV is not universal between microalgal species. The dinoflagellate Alexandrium catenella Whedon et Kofoid Balech, the diatom Phaeodactylum tricornutum Bohlin, the chrysophyte Aureococcus sp. and the cyanobacterium Spirulina subsalsa Oersted were acclimated during exponential cell growth under PAR + UV-A radiation (365 nm, 140-240 kJ m-2 d-1) and thereafter exposed 2 h d-1 to high and low UV-B radiation (312 nm, maximum 3.1 kJ m-2 d-1) at the center of the 16 h light period. Measured parameters were growth rates (µ), in vivo spectral absorption, cellular fluorescence capacity, pigment concentration, photosynthesis and photoreactivation during three cycles in controls and treatment samples. Growth rates diminished less than 35 % in Phaeodactylum and Aureococcus compared to 80-100 % decrease in Alexandrium and Spirulina. In these two last species, a significant increase in UV absorbing substances was observed, probably related to the presence of mycosporine-like aminoacids (MAAs) and scytonemin, respectively, and also lower photoreactivation efficiency compared to Phaeodactylum and Aureococcus. The analysis of photosynthetic performance under different PAR/UV-A ratios for Alexandrium and Phaeodactylum, could also explain the differences in µ. These results suggest that in time, species with high rates of photorepair might be more tolerant to UV-B than those species, which depend on the synthesis of UV absorbing compounds as their principal protection mechanisminfo:eu-repo/semantics/openAccessSociedad de Biología de ChileRevista chilena de historia natural v.74 n.2 20012001-06-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000200007en10.4067/S0716-078X2001000200007
institution Scielo Chile
collection Scielo Chile
language English
topic photosynthesis
absorbance
photoreactivation
growth
UV response
spellingShingle photosynthesis
absorbance
photoreactivation
growth
UV response
MONTECINO,VIVIAN
MOLINA,XIMENA
MARTÏNEZ,GINGER
OLMEDO,M. ISABEL
RETAMAL,LEIRA
HANNACH,GABRIELA
ORELLANA,MÓNICA V.
Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America
description Marine microalgae exposed to ultraviolet radiation (UV) have complex adaptive responses provided by a series of protection and repair mechanisms. Interspecific differences in UV sensibility could result in differential selection of the more tolerant species, having consequences for the structure of phytoplankton assemblages. The relative importance of protection and photorepair mechanisms of microalgal cells exposed to potential UV-B stress was studied in monocultures with different taxonomic, ecological and size characteristics obtained from the Chilean coast. Differences in photosynthesis and growth rates were predicted, since the ability to effectively acclimate to UV is not universal between microalgal species. The dinoflagellate Alexandrium catenella Whedon et Kofoid Balech, the diatom Phaeodactylum tricornutum Bohlin, the chrysophyte Aureococcus sp. and the cyanobacterium Spirulina subsalsa Oersted were acclimated during exponential cell growth under PAR + UV-A radiation (365 nm, 140-240 kJ m-2 d-1) and thereafter exposed 2 h d-1 to high and low UV-B radiation (312 nm, maximum 3.1 kJ m-2 d-1) at the center of the 16 h light period. Measured parameters were growth rates (µ), in vivo spectral absorption, cellular fluorescence capacity, pigment concentration, photosynthesis and photoreactivation during three cycles in controls and treatment samples. Growth rates diminished less than 35 % in Phaeodactylum and Aureococcus compared to 80-100 % decrease in Alexandrium and Spirulina. In these two last species, a significant increase in UV absorbing substances was observed, probably related to the presence of mycosporine-like aminoacids (MAAs) and scytonemin, respectively, and also lower photoreactivation efficiency compared to Phaeodactylum and Aureococcus. The analysis of photosynthetic performance under different PAR/UV-A ratios for Alexandrium and Phaeodactylum, could also explain the differences in µ. These results suggest that in time, species with high rates of photorepair might be more tolerant to UV-B than those species, which depend on the synthesis of UV absorbing compounds as their principal protection mechanism
author MONTECINO,VIVIAN
MOLINA,XIMENA
MARTÏNEZ,GINGER
OLMEDO,M. ISABEL
RETAMAL,LEIRA
HANNACH,GABRIELA
ORELLANA,MÓNICA V.
author_facet MONTECINO,VIVIAN
MOLINA,XIMENA
MARTÏNEZ,GINGER
OLMEDO,M. ISABEL
RETAMAL,LEIRA
HANNACH,GABRIELA
ORELLANA,MÓNICA V.
author_sort MONTECINO,VIVIAN
title Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America
title_short Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America
title_full Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America
title_fullStr Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America
title_full_unstemmed Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America
title_sort ecophysiological strategies in response to uv-b radiation stress in cultures of temperate microalgae isolated from the pacific coast of south america
publisher Sociedad de Biología de Chile
publishDate 2001
url http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000200007
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