The quantitative filter technique for measuring phytoplankton absorption: Interference by MAAs in the UV waveband

Laurion, Isabelle; Blouin, Frédérick; Roy, Sylvie

doi:10.4319/lom.2011.1.1

Cited by 27 publications

(21 citation statements)

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“…Diatoms generally contain low concentrations of MAAs, with some species even reported to produce no MAAs at all (Jeffrey et al 1999, Riegger and Robinson 1997, Laurion et al 2003. However, in agreement with previous reports from Antarctic diatoms (Riegger andRobinson 1997, Hernando et al 2002), Thalassiosira sp.…”

Section: Discussionsupporting

confidence: 78%

Effect of vertical mixing on short-term mycosporine-like amino acid synthesis in the Antarctic diatom, <i>Thalasiossira</i> sp.

Hernando¹,

Carreto²,

Carignan³

et al. 2011

Sci. Mar.

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SUMMARY: One of the adaptations whereby phytoplankton can alleviate damage induced by ultraviolet radiation (280-400 nm) is the synthesis of mycosporine-like amino acids (MAAs). The synthesis of MAAs was studied after exposure of the Antarctic diatom Thalassiosira sp. isolated from Potter Cove (South Shetland Is., Antarctica) to 2 treatments with a solar simulator: surface (Sfix) and vertical mixing (Mix) irradiance conditions. Light exposure was simulated in daily cycles with maximum irradiance at noon. Only 2 MAAs, Porphyra-334 (82-85%) and Shinorine (15-18%), were identified. The concentration of the two compounds increased during experimental light exposure (50-55%) and declined in the dark (10-15%). During the light period the synthesis rate of MAAs per unit of chlorophyll a was higher in the Sfix treatment (µ=0.17 h -1 ) than in the Mix treatment (µ=0.05 h -1 ). In spite of the higher MAA levels, low cell numbers were observed in the Sfix treatment, suggesting that the algae synthesized photoprotective compounds at the expense of growth. Our results document overlapping effects of both daily light cycles and vertical mixing affecting the synthesis of MAAs. This, and the high thermal dissipation of the ultraviolet B radiation energy (280-320 nm) absorbed by these substances, suggest a rapid photoadaptive response of Thalasiossira sp. upon exposure to elevated irradiance in a stratified water column, as well as the complementary role of vertical mixing in photo-protection.Keywords: mycosporine-like amino acids, vertical mixing, Antarctic diatom, photoadaptive response, UV. RESUMEN: Efectos de la mezcla vertical sobre la síntesis a corto plazo de micosporinas (MAAs) en la diatomea antártica Thalasiossira sp. -La síntesis de micosporinas (MAAs) es una de las adaptaciones por las cuales el fitoplancton puede reducir los daños inducidos por la radiación ultravioleta (UVR, 280-400 nm). La síntesis de MAAs fue estudiada después de la exposición de la diatomea antártica Thalasiossira sp., aislada en Caleta Potter (Islas Shetland, Antár-tica), a dos tratamientos: condiciones simuladas de irradiancia en superficie (Sfix) y mezcla vertical (Mix). La luz fue simulada utilizando un simulador solar con ciclos diarios con irradiancia máxima al mediodía. Sólo se identificaron dos MAAs, Porphyra-334 (82-85%) y Shinorina (15-18%). La concentración de ambos compuestos aumentó durante la exposición a la luz (50-55%) y declinó en oscuridad (10-15%). Durante el período de luz, la tasa de síntesis de MAAs (calculada para cada tiempo dividiendo cada valor por el valor correspondiente de clorofila a) fue mayor en el tratamiento Sfix (µ=0.17 h -1 ) comparada con el tratamiento Mix (µ=0.05 h -1 ). A pesar de la alta concentración de MAAs, se observó un bajo número de células en el tratamiento Sfix, sugiriendo que las algas sintetizan los compuestos fotoprotectores a expensas del crecimiento. Nuestros resultados documentan una superposición de los efectos de la luz y la mezcla vertical, afectando la composición de ambas familias de MA...

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Section: Discussionsupporting

confidence: 78%

Effect of vertical mixing on short-term mycosporine-like amino acid synthesis in the Antarctic diatom, <i>Thalasiossira</i> sp.

Hernando¹,

Carreto²,

Carignan³

et al. 2011

Sci. Mar.

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“…5). Although diatom species generally contain low concentrations of MAAs, some species are reported to lack MAAs (Riegger & Robinson, 1997;Jeffrey et al, 1999;Laurion et al, 2003). In coincidence with previous reports (Riegger & Robinson, 1997;Hernando et al, 2002) Thalassiosira sp.…”

Section: Resultssupporting

confidence: 83%

Non enzymatic antioxidant photoprotection against potential UVBR induced damage in an Antarctic diatom (Thalassiosira sp.)

Hernando

Malanga

Puntarulo

et al. 2011

lajar

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ABSTRACT. In January 1999, unialgal cultures of the diatom Thalassiosira sp., solate from natural phytoplankton assemblages from Potter Cove, Antarctica, were exposed to solar ultraviolet radiation (UVR, 280-400 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 (10 4 cell)) showed a marked decrease during the exponential growth phase (4 pmol (10 4 cell -1 ) by day 3). The initial content of β-carotene (3 pmol (10 4 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. Keywords: β-carotene, α-tocopherol, growth rate, diatoms, MAAs, photoprotection, Antarctica.Fotoprotección antioxidante no-enzimática contra el potencial daño inducido por UVBR en una diatomea antártica (Thalassiosira sp.) RESUMEN. Durante enero 1999, cultivos unialgales de una diatomea Thalassiosira sp., aislada de poblaciones fitoplanctónicas naturales de Caleta Carlos Potter, Antártida, fueron expuestos a radiación solar ultravioleta (UVR, 280-400 nm) con el objetivo de estudiar su aclimatación a largo plazo. La radiación ultravioleta B (UVBR, 280-315 nm) inhibió la tasa de crecimiento durante el primer y segundo día de exposición. No se observó inhibición por UVBR durante el tercer día. El contenido inicial de α-tocopherol (13 pmol (10 4 cel) -1 ) mostró una marcada disminución durante la fase de crecimiento exponencial (4 pmol (10 4 cel) -1 al día 3). El contenido inicial de β-caroteno (3 pmol (10 4 cel)) no mostró diferencias significativas entre días en células expuestas a UVBR. Se identificaron dos aminoácidos parecidos a micosporina (MAAs), porfira-334 y shinorina. Las concentraciones celulares de MAAs mostraron aumentos significativos en los días 2 y 3, que resultaron mayores cuando las algas fueron expuestas a UVBR. La importancia relativa de la concentración de MAAs fue significativa (P < 0.05) en relación al contenido de α-tocopherol. Se encontró una relación positiva entre la concentración celular de MAAs y la tasa de crecimiento. Estos resultados sugieren que la fotoprotección contra el daño inducido...

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“…This type of study would provide further insights in its role in phytoplankton photo-protection processes, and is strongly recommended for future research. Finally, the possible release of packaged MAAs during filtration within the matrix of the filter without going into the dissolved fraction cannot be excluded, in particular for samples in which dinoflagellates are dominant (Laurion et al 2003). This fraction of MAAs would still be quantified by HPLC as part of the pMAA fraction, but would lead to higher than expected values in a p in the UV region.…”

Section: Particulate Absorption Coefficient In the Uvmentioning

confidence: 99%

“…The interior of the filter holder connected to the optical fibre facing the detector, was covered with reflective material to ensure that most of the scattered light arising from the filter was collected back into the optical fibre and hence quantified by the detector. The measurements were done onboard on fresh samples and within 5 to 10 min after the end of the filtration to minimise changes in the absorption properties in the UV range, as delays in measurements or freezing of samples have been shown to increase UV absorption (Laurion et al 2003). Triplicate measurements were made on each filter and averaged.…”

Section: Particulate Absorption Coefficient a P (λ)mentioning

confidence: 99%

Production of mycosporine-like amino acids by phytoplankton under ultraviolet radiation exposure in the Sub-Antarctic Zone south of Tasmania

Oubelkheir¹,

Clementson²,

Moore³

et al. 2013

Mar. Ecol. Prog. Ser.

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Phytoplankton production of mycosporine-like amino acids (MAAs) against the damaging effects of ultraviolet (UV) radiation, and the associated changes in absorption properties, were examined across different trophic regions south of Tasmania, from the Polar Frontal Zone (PFZ) to the Sub-Antarctic Zone (SAZ) and in sub-tropical waters. The MAA concentration and particulate absorption coefficient were determined in the 0 to 100 m layer across a latitudinal gradient from 54 to 44 degrees south. These spatial observations were complemented with daily incubation experiments at 3 stations located in the PFZ and in the SAZ southeast and southwest of Tasmania. MAAs were widespread, with a predominance of primary MAAs such as porphyra-334 in the PFZ and secondary MAAs such as palythenic acid in the stratified waters in the north of the SAZ. Under surface irradiance levels during deck incubation experiments, phytoplankton from the PFZ and SAZ produced significant amounts of MAAs under UVB radiations, and a fraction was released into the dissolved fraction (generally < 20% of the total MAAs). MAA production rates in the north of the SAZ ranged from 0.0009 to 0.0436 mg m −3 kJ −1 UVB m −2 southwest and southeast of Tasmania, respectively. Changes in MAA distribution are discussed in relation to environmental factors (UV radiation exposure, mixing, nutrients) and shifts in the phytoplankton assemblage composition. The strong variability in MAA distribution and composition across the study region is driven primarily by UV radiation exposure and vertical mixing and secondarily by speciesspecific responses to UV radiation. KEY WORDS: Phytoplankton · UV · Mycosporine-like amino acids · Absorption coefficientResale or republication not permitted without written consent of the publisher Editorial responsibility: Ronald Kiene,

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The quantitative filter technique for measuring phytoplankton absorption: Interference by MAAs in the UV waveband

Cited by 27 publications

References 0 publications

Effect of vertical mixing on short-term mycosporine-like amino acid synthesis in the Antarctic diatom, <i>Thalasiossira</i> sp.

Effect of vertical mixing on short-term mycosporine-like amino acid synthesis in the Antarctic diatom, <i>Thalasiossira</i> sp.

Non enzymatic antioxidant photoprotection against potential UVBR induced damage in an Antarctic diatom (Thalassiosira sp.)

Production of mycosporine-like amino acids by phytoplankton under ultraviolet radiation exposure in the Sub-Antarctic Zone south of Tasmania

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