BLUE LIGHT AND UV‐A RADIATION CONTROL THE SYNTHESIS OF MYCOSPORINE‐LIKE AMINO ACIDS IN CHONDRUS CRISPUS (FLORIDEOPHYCEAE)

Abstract

The induction of UV-absorbing compounds known as mycosporine-like amino acids (MAAs) by red, green, blue, and white light (43% ambient radiation greater than 390 nm) was examined in sublittoral Chondrus crispus Stackh. Fresh collections or long-term cultures of sublittoral thalli, collected from Helgoland, North Sea, Germany, and containing no measurable amounts of MAAs, were exposed to filtered natural radiation for up to 40 days. The MAA palythine ( max 320 nm) was synthesized in thalli in blue light to the same extent observed in control samples in white light. In contrast, thalli in green or red light contained only trace amounts of MAAs. After the growth and synthesis period, the photosynthetic performance of thalli in each treatment, measured as pulse amplitude modulated chlorophyll fluorescence, was assessed after a defined UV dose in the laboratory. Thalli with MAAs were more resistant to UV than those without, and exposure to UV-A ؉ B was more damaging than UV-A in that optimal ( F v / F m ) and effective ( II ) quantum yields were lower and a greater proportion of the primary electron acceptor of PSII, Q, became reduced at saturating irradiance. However, blue light-grown thalli were generally more sensitive than white light control samples to UV-A despite having similar amounts of MAAs. The most sensitive thalli were those grown in red light, which had significantly greater reductions in F v / F m and II and greater Q reduction. Growth under UV radiation alone had been shown previously to lead to the synthesis of the MAA shinorine ( max 334 nm) rather than palythine. In further experiments, we found that preexposure to blue light followed by growth in natural UV-A led to a 7-fold increase in the synthesis of shinorine, compared with growth in UV-A or UV-A ؉ B without blue light pretreatment. We hypothesize that there are two photoreceptors for MAA syn-thesis in C. crispus , one for blue light and one for UV-A, which can act synergistically. This system would predispose C. crispus to efficiently synthesize UV protective compounds when radiation levels are rising, for example, on a seasonal basis. However, because the UV-B increase associated with artificial ozone reduction will not be accompanied by an increase in blue light, this triggering mechanism will have little additional adaptive value in the face of global change unless a global UV-B increase positively affects water column clarity. Abbreviations: Fo , chlorophyll fluorescence of open PSII centers; F m , F v , maximum and variable chlorophyll fluorescence after dark incubation, respectively; F v / F m , optimal quantum yield; F s , F m , steady state and maximum chlorophyll fluorescence in the light, respectively; F o , minimum chlorophyll fluorescence in darkness immediately after a saturating flash; II , effective quantum yield in the light; MAA, mycosporine-like amino acid; PUR, photosynthetically usable radiation; Q, primary electron acceptor of PSII; q P , photochemical quenching of fluorescence; UVR, ultraviolet radiation 1

Variation in sunscreen compounds (mycosporine‐like amino acids) for marine species along a gradient of ultraviolet radiation transmission within doubtful sound, New Zealand

“…This includes correlating algal depth and ambient UV-R intensities with MAA concentration (Bischof et al 2000;Hoyer 2001), correlating geographic variation in ambient UV-R and MAA concentrations (Huovinen 2004), or correlating temporal changes in MAA concentration and ambient UV-R Apprill & Lesser 2003). In vitro experiments and manipulation of ambient UV-R have confirmed these observations, noting that the production and accumulation of MAAs can be induced by exposure to UV-R and blue wavelengths Krabs et al 2001;Apprill & Lesser 2003).…”

“…Previous research has often found a correlation between ambient UV-R and MAA concentration (Banaszak et al 1998;Franklin et al 2001;Hoyer et al 2001;Krabs et al 2002;Apprill & Lesser 2003;Huovinen et al 2004). This includes correlating algal depth and ambient UV-R intensities with MAA concentration (Bischof et al 2000;Hoyer 2001), correlating geographic variation in ambient UV-R and MAA concentrations (Huovinen 2004), or correlating temporal changes in MAA concentration and ambient UV-R Apprill & Lesser 2003).…”

Short-term ecophysiological and biochemical responses of Cystoseira tamariscifolia and Ellisolandia elongata to environmental changes

“…However, the content of MAAs (UV-screening substance) of algae collected at 0.5 m depth depended on the interaction between irradiance and nutrients, as reported by Korbee-Peinado et al (2004). Karsten et al (1998) and Franklin et al (2001) have shown that accumulation of MAAs depend on both quality and quantity of radiation, with higher accumulation of MAAs with high daily PAR doses and UV exposure. Korbee-Peinado et al (2004) found that high ammonium concentrations significantly in creased the content of MAAs in Pyropia columbina (as Porphyra columbina).…”

Effects of light quality on reproduction, growth and pigment content of <em>Gracilaria birdiae</em> (Rhodophyta: Gracilariales)

“…An increase in phycobiliprotein and chlorophyll a (Chl a) content was observed in Chondrus crispus cultivated under blue, red, and green light in comparison with white light controls (Franklin et al 2001). Halymenia floresii optimized its growth rates under green light, inducing Chl a and lutein synthesis, whereas blue and red light stimulated the accumulation of phycobiliproteins (Godínez-Ortega et al 2008).…”