Amounts Of Mycosporine-like Amino Acids Research Articles

Mycosporine-like Amino Acids from Red Alga Dulse (Devaleraea inkyuleei): Monthly Variation and Improvement in Extraction

Mycosporine-like amino acids (MAAs) are natural UV-absorbing compounds found in microalgae and macroalgae. The content of MAAs in algae varies with the seasons and environmental factors. Red alga dulse in Usujiri (Hokkaido, Japan) is an underutilized resource. Therefore, we investigated the amount of MAAs in Usujiri dulse in 2022 to clarify the suitable months for MAA extraction. In addition, we also evaluated the extraction method focusing on the extraction volume. MAAs were prepared via the 20 volumes of 25% ethanol extraction method and detected via HPLC. The results showed that the amount of MAAs on 25 March 2022 showed the highest value (40.4 μmol/g DW) among the samples from 24 January to 13 May. The tendency of suitable samples for MAA preparation corresponded to the term from mid-February to early April, which was the same as the previous three years. Although the surveys from 2019–2021 were performed by using the successive water–methanol method, it was found that the improved method also reflected the monthly variation in MAAs. The extraction of MAAs was performed via 20 or 40 volumes of 25% ethanol at 4 °C for 24 h. The amount of MAAs with 40 volumes of 25% ethanol extraction increased 1.3-fold compared to that with 20 volumes of 25% ethanol extraction. These data are useful information for valuable compound extraction from Usujiri dulse.

Photoprotection properties of marine photosynthetic organisms grown in high ultraviolet exposure areas: Cosmeceutical applications

Seaweeds have been identified as promising sources of bioactive substances for the cosmeceutical industry, especially by their photoprotection capacity. Accordingly, this study aimed to evaluate the photoprotective properties of extracts from macroalgae and one marine lichen. Samples of 22 species of macroalgae and one marine lichen, were collected along the southern Iberian Peninsula. Hydroethanolic extracts were prepared from algal and marine lichen lyophilized biomass. Ultraviolet (UV) and visible absorption spectra, polyphenol content, antioxidant activity, mycosporine-like amino acid content and composition were analyzed. In order to quantify the photoprotection capacity of the extracts against different biological effects, two new indices were used, i.e., effective solar absorption radiation (%ESAR) and extract photoprotection index (EPI), considering the radiation absorbed and transmitted by the extract, respectively. In the ultraviolet spectrum, Porphyra umbilicalis and Pyropia elongata presented the highest absorbance values at 330 nm, while Ulva lactuca showed a prominent peak at 290 nm. In the visible spectrum, a fucoxanthin peak (450 nm) was strongly evident in extracts from the brown algal species, while green algal extracts presented characteristic chlorophyll a and b peaks at 447, 620 and 664 nm. Polyphenol content and antioxidant activity were much higher in Sargassum vulgare, Carpodesmia tamariscifolia, P. umbilicalis and Lichina pygmaea in comparison to the other species. P. umbilicalis and Bangia atropurpurea showed the highest amount of mycosporine-like amino acids. S. vulgare and P. umbilicalis extracts presented the highest values of potential photoprotection against all analyzed biological response according to the different action spectra. S. vulgare and P. umbilicalis showed an increase in %ESAR values associated with an increase in the concentration of their extracts. Considering the analyzed species, our results suggest that S. vulgare and P. umbilicalis could be potential sources of photoprotective extracts. The potential use of these species in cosmeceutical products is discussed.

Geographic Variation of UV Stress Tolerance in Red Seaweeds Does Not Scale with Latitude Along the SE Pacific Coast.

Geographic variation of phenotypic traits affects the capacity of species to withstand and adapt to environmental stress. Here, we examined how geographic origin influences UV stress tolerance of the red seaweeds Chondracanthus chamissoi and Gelidium lingulatum distributed along the South-East Pacific coast between 20° S and 42° S. Seaweeds from six (C. chamissoi) and five (G. lingulatum) populations were grown under common-garden conditions and then exposed to consecutive UV stress events and essential biological traits (e.g., growth, photosynthetic responses, antioxidant capacity, and UV-absorbing compounds) were analyzed. In C. chamissoi, a strong UV sensitivity occurred in populations from mid-latitudes (27° S and 29° S) where the lowest recovery of maximum quantum yield (Fv /Fm ; between 32.3% and 66.8% of control) and growth rate were observed. Likewise, the lowest amount of mycosporine-like amino acids (MAAs) and a significant decrease in phycobilins were registered in these populations. In G. lingulatum, recovery of Fv /Fm ranged from 82.0% to 97.7% of control, and antioxidant activity, carotenoid, and MAA contents were positively influenced by UV exposure. The multivariate analysis indicated a significant influence of PAR, cloud cover, and UV index on physiological traits, depending on species. The ecotypic differentiation index (EDI) indicated a higher phenotypic variation in C. chamissoi (EDI=0.10) than G. lingulatum (EDI=0.03). This study shows that the spatial distribution of UV stress tolerance in the studied seaweeds does not follow linear latitudinal or central-edge gradients. Instead, among-site variability of solar intensities driven by specific climatic conditions seems to act as driver of phenotypic variation.

Effect of ultra-violet exposure on production of mycosporine-like amino acids and lipids by Lyngbya purpurem

Cyanobacteria can have high lipid content, are amenable to metabolic engineering, and contain valuable materials, such as ultraviolet (UV) protectants and antioxidants. Maximizing the production and harvesting of several valuable products at the same time is an important objective. UV exposure was evaluated as a strategy to induce synthesis of UV protectants, higher lipid productivity, and a high lipid-saturation index in the cyanobacterium Lyngbya purpurem UTEX LB 2716. While UVA stimulated the highest production of lipids and the largest amount of mycosporine-like amino acids (MAAs), UVB lead to greater generation of MAAs, which correlated to higher antioxidant activity. UVB also showed a shift towards saturated fatty acids, such as C16:0 and C18:0, over unsaturated fatty acids, whereas UVA showed a shift towards the unsaturated fatty acids. In summary, UVB induced the highest MAAs production, anti-oxidant activity, and lipid saturation, and its yield of crude lipids and extracted FAME was only slightly lower than with UVA.

Light and Dehydration but Not Temperature Drive Photosynthetic Adaptations of Basal Streptophytes (Hormidiella, Streptosarcina and Streptofilum) Living in Terrestrial Habitats

Streptophyte algae are the ancestors of land plants, and several classes contain taxa that are adapted to an aero-terrestrial lifestyle. In this study, four basal terrestrial streptophytes from the class Klebsormidiophyceae, including Hormidiella parvula; two species of the newly described genus Streptosarcina (S. costaricana and S. arenaria); and the newly described Streptofilum capillatum were investigated for their responses to radiation, desiccation and temperature stress conditions. All the strains showed low-light adaptation (Ik < 70 μmol photons m−2 s−1) but differed in photoprotective capacities (such as non-photochemical quenching). Acclimation to enhanced photon fluence rates (160 μmol photons m−2 s−1) increased photosynthetic performance in H. parvula and S. costaricana but not in S. arenaria, showing that low-light adaptation is a constitutive trait for S. arenaria. This lower-light adaptation of S. arenaria was coupled with a higher desiccation tolerance, providing further evidence that dehydration is a selective force shaping species occurrence in low light. For protection against ultraviolet radiation, all species synthesised and accumulated different amounts of mycosporine-like amino acids (MAAs). Biochemically, MAAs synthesised by Hormidiella and Streptosarcina were similar to MAAs from closely related Klebsormidium spp. but differed in retention time and spectral characteristics in S. capillatum. Unlike the different radiation and dehydration tolerances, Hormidiella, Streptosarcina and Streptofilum displayed preferences for similar thermal conditions. These species showed a temperature dependence of photosynthesis similar to respiration, contrasting with Klebsormidium spp. and highlighting an interspecific diversity in thermal requirements, which could regulate species distributions under temperature changes.

Cyanobacteria growing on tree barks possess high amount of sunscreen compound mycosporine-like amino acids (MAAs)

The present study describes cyanobacterial species composition and their dominance in biological crusts from barks of different trees, roof top of building and soil of agricultural field. An attempt was also made to explore the presence of photoprotective compounds such as mycosporine-like amino acids (MAAs) in the crust samples. Microscopic examination and growth studies revealed the presence of Oscillatoria species in all the crust samples excluding the crust of roof top of a building. Study on the abundance of dominant genera showed marked differences among various crust samples but Hapalosiphon, Lyngbya, Oscillatoria and Scytonema sp. were the most dominant genera, Oscillatoria being dominant in three crust samples. Screening for the presence of photoprotective compounds showed the presence of major peaks in the range of 308–334 nm thereby pointing to the presence of MAAs in all the crust samples. The highest amount of MAAs was found in the crust of Borassus flabellifer (15,729 nmol g dry wt−1 of bark) followed by crust of roof top (14,543 nmol g dry wt−1 of crust). MAAs were separated and partially purified employing HPLC, the most common MAA present in all the crusts was identified as mycosporine-glycine. Presence of mycosporine-glycine (M-Gly) was further confirmed by FTIR and NMR. Test of in vitro colonization on the bark of Mangifera indica and Azadirachta indica by three isolates namely Hapalosiphon, Oscillatoria and Scytonema sp. showed sign of active colonization. It is felt that identification of all the MAAs other than M-Gly may prove useful in future studies especially for assessing their significance in the protection mechanism of cyanobacteria/algae against various types of abiotic stresses.

Trophic relationships and UV-absorbing compounds in a Mediterranean medio-littoral rocky shore community

Organisms inhabiting shallow coastal ecosystems are potentially exposed to damaging levels of solar UV radiation. UV-sunscreen compounds such as mycosporine like amino-acids (MAAs) are a widespread biochemical strategy among many marine organisms to counteract UV stress. These molecules are produced through a metabolic pathway restricted to cyanobacteria, various algal groups and fungi. This study was designed to search for UV sunscreen compounds in benthic invertebrates of the Catalan medio-littoral rocky shore of the north-western Mediterranean Sea. The relationship between food sources and consumers was investigated using the stable isotope approach in order to elucidate the potential pathways of MAA transfer. The food web associated with the littoral Catalan rocky shore is characterized by a high level of functional complexity. The variability of δ13C and δ15N among and between trophic guilds provides evidence of the diversity of coexisting trophic levels and trophic pathways in a single habitat type. MAAs were present in all sampled metazoan species. We observed a higher MAA diversity in animals than in food sources. This may be explained by the incorporation of MAAs from several trophic resources, by the conversion of the MAAs acquired from the food or by translocation from a symbiont. The amount of MAAs in sea urchins was fairly low compared to other trophic groups. This cannot be explained by depletion of MAAs in their diets, and hence other UV-protective strategies may be more important. Complementary experimental studies should be performed to determine the ability of primary and secondary consumers to assimilate MAAs and convert these compounds.

Effects of N supply on the accumulation of photosynthetic pigments and photoprotectors in Gracilaria tenuistipitata (Rhodophyta) cultured under UV radiation

We have studied the effects of nitrate supply under photosynthetic active radiation (PAR) plus ultraviolet radiation (UVR) exposure on photosynthetic pigments (chlorophyll a and carotenoids), photoprotective UV screen mycosporine-like amino acids (MAAs), and photosynthetic parameters, including the maximum quantum yield (F v/F m) and electron transport rate (ETR) on the red agarophyte Gracilaria tenuistipitata. Apical tips of G. tenuistipitata were cultivated under ten different concentrations of NO 3 − for 7 days. It has been shown that G. tenuistipitata cultured under laboratory conditions has the ability to accumulate high amounts of MAAs following a nitrate concentration-dependent manner under PAR + UVR. Two MAAs were identified, shinorine and porphyra-334. The relative concentration of the first increased under high concentrations of nitrate, while the second one decreased. The presence of antheraxanthin is reported for the first time in this macroalgae, which also contains zeaxanthin, lutein, and β-carotene. The accumulation of pigments, photoprotective compounds, and photosynthetic parameters of G. tenuistipitata is directly related to N availability. All variables decreased under low N supplies and reached constant maximum values with supplements higher than 0.5 mM NO 3 − . Our results suggest a high potential to acclimation and photoprotection against stress factors (including high PAR and UVR) directly related to N availability for G. tenuistipitata.

Photoprotective compounds in weakly and strongly pigmented copepods and co‐occurring cladocerans

Summary1. The prevalence of mycosporine‐like amino acids (MAAs) – a group of potential ultraviolet (UV)‐photoprotective compounds – was surveyed across 11 species of freshwater copepods from 20 lakes of varying ultraviolet radiation (UVR) transparency in North America, New Zealand and Argentina. Co‐occurring cladocerans were also analysed (seven species from 12 lakes). Many of the calanoid copepod populations were red with carotenoid pigmentation, allowing comparison of MAA and carotenoid accumulation as photoprotective strategies.2. In two Pennsylvania (U.S.A.) lakes, MAA and carotenoid contents were followed during the early spring to mid‐summer period of lake warming. A pronounced seasonal pattern of higher carotenoid/low MAA content in spring, shifting to low carotenoid/higher MAA content in summer, was observed in calanoids from the more UV transparent lake.3. All copepod samples contained MAAs. Visibly red calanoids, especially southern Hemisphere Boeckella, often had moderate to high concentrations (2.5–11 μg MAA mg−1 dw), but low concentrations (0.04–1 μg MAA mg−1 dw) in some N. American red calanoids show that high carotenoid pigmentation (e.g. 5–10 μg carotenoid mg−1 dw) does not necessarily imply high MAA content.4. No cladoceran sample had more than trace amounts of MAAs (&lt;0.05 μg mg−1 dw). Therefore, MAA accumulation does not seem to be a photoprotective strategy utilized by Daphnia (five species from nine lakes) or other cladocerans.5. Seven identifiable MAAs were widely distributed among both calanoids and cyclopoids. Shinorine was ubiquitous and was usually the most abundant MAA in N. American samples. In contrast, porphyra‐334 was the predominant MAA in the southern Hemisphere Boeckella.6. Copepods from higher UVR lakes tended to have a higher MAA content, but this relationship was statistically weak overall and taxon‐specific when found.

The occurrence of mycosporine-like amino acids in the gametophytic and sporophytic stages of Bangia (Bangiales, Rhodophyta)

C. Boedeker and U. Karsten. 2005. The occurrence of mycosporine-like amino acids in the gametophytic and sporophytic stages of Bangia (Bangiales, Rhodophyta). Phycologia 44: 403–408.Ultraviolet-absorbing mycosporine-like amino acids (MAAs) were identified and quantified in both the gametophytic and sporophytic life stages of the cosmopolitan intertidal genus Bangia. Field samples were compared with culture material originating from different biogeographic regions, including freshwater populations. All cultures were kept for a long time under low-irradiance conditions prior to MAA analysis. Within all isolates investigated, four distinct compounds were found which were identified as shinorine, porphyra-334, asterina-330 and palythine. Gametophytic filaments always exhibited high concentrations of MAAs, with porphyra-334 being the dominant compound. Field and culture material did not differ in the amount of MAAs, indicating that Bangia does not adjust the amount of sunscreens to environmental conditions. Freshwater isolates contained lower amounts of MAAs compared to marine strains. However, a biogeographical trend in MAA contents reflecting the origin of the samples from habitats with different climate and insolation was not observed. Even the shell-boring sporophytic conchocelis stage contained significant amounts of MAAs, but in lower concentrations than the gametophytes, raising the possibility of MAAs fulfiling different functions in the two life stages.

The continuity and intensity of ultraviolet irradiation affect the kinetics of biosynthesis, accumulation, and conversion of mycosporine‐like amino acids (MAAs) in the coral Stylophora pistillata

Colonies of Stylophora pistillata unexposed to ultraviolet radiation (UVR) in laboratory aquaria contained minimal amounts of mycosporine‐like amino acids (MAAs). The concentration of MAAs increased rapidly during exposure to broadband UVR, then stabilized between 14 and 28 d of exposure. The four MAAs known to be produced by diverse zooxanthellae (Symbiodinium spp.) in culture were the first to increase in coral colonies, followed by six additional MAAs. Decreases in these four primary MAAs between days 14 and 28 were balanced by stoichiometric increases in the six secondary MAAs, suggesting a precursor‐product relationship. Discontinuing UV exposure caused rapid declines in the concentrations of primary MAAs, while secondary MAAs continued to increase, likely a manifestation of different rates of turnover of the putative enzymes involved in the de novo biosynthesis of primary MAAs and their conversion to secondary MAAs. The continued production of certain MAAs after UV exposure ceased indicates that UV is not required catalytically but is a signal that induces the enzymes of the biosynthetic pathway. Biochemically inhibiting the biosynthesis of primary MAAs after a pool of these MAAs had accumulated did not affect their conversion to secondary MAAs. Doubling the UV irradiance increased the rate of accumulation, first, of primary MAAs and, later, of secondary MAAs. Under normal UV irradiance, the eventual decline in the accumulation rate of primary MAAs was quantitatively explained by their conversion to secondary MAAs. Under doubled UV irradiance, where MAA concentrations were higher, the deceleration of accumulation of primary MAAs was twice as great as the acceleration in secondary MAAs, suggesting a regulation of the de novo biosynthesis of MAAs, perhaps by their own progressive, concentration‐dependent attenuation of UVR.

Bioaccumulation and role of UV-absorbing compounds in two marine crustacean species from Patagonia, Argentina.

Experiments were conducted during summer and winter, 2000, and summer 2001 to determine the bioaccumulation and role of UV-absorbing compounds in two crustacean species--the amphipod Amphitoe valida and the isopod Idothea haltica--from the mid-littoral of the Patagonia coast (Argentina). Macroalgae constituting the diet for these species differed in the concentration of UV-absorbing compounds, from high amounts in the rhodophyte Polysiphonia sp. to almost null in chlorophyte species (i.e., Enteromorpha sp. and Codium sp.). Consequently, transferring and bioaccumulation of these compounds, identified as the mycosporine-like amino acids (MAAs) Porphyra-334 and Shinorine, varied in the crustaceans according to their algal diet, being high when feeding on Polysiphonia sp. Survival experiments carried out with crustaceans feeding on poor and rich-MAA diets demonstrated that the role of these compounds in A. valida and I. baltica was different. In A. valida, and based on a significantly higher survival in those individuals feeding on the rhodophyte, MAAs seem to provide an effective protection against UV-B radiation (280-320 nm). In I. baltica, mortality was not significantly different in individuals feeding on rich and poor MAA diets. However, judging from the comparatively high amounts of MAAs in eggs/embryos, these compounds might provide protection to the progeny rather than to adult organisms.

Mycosporine-like amino acids protect the copepod Boeckella titicacae (Harding) against high levels of solar UVR

Studies were conducted in Lake Titicaca, Bolivia (16°S, 69°W, 3810 m a.s.l.) to determine the effects of solar ultraviolet radiation (UVR; 280‐400 nm) and the protective role of mycosporinelike amino acids (MAAs) in the calanoid copepod Boeckella titicacae (Harding). Zooplankton samples were taken from two different radiation environments: Lake Titicaca and a tank with running lake water, which was covered with layers of neutral-density screen for over a year, receiving ~10% of incident radiation. Samples collected from the lake had significantly higher amounts of MAAs compared with those from the tank. During short-term experiments (6‐8 h incubations; six radiation treatments using sharp cut-off Schott filters), significantly higher mortality was observed in B. titicacae from the tank than from the lake. The higher sensitivity of B. titicacae containing low amounts of MAAs (compared with specimens collected from the lake) was assessed through the determination of biological weighting functions (BWFs). A 3-day-long experiment performed with specimens collected from the lake indicated an increase in mortality as a function of UVR exposure, reaching values as high as 70% at the end of day 3 for those individuals that received full radiation compared with <10% for those that received only photosynthetically active radiation (PAR; 400‐700 nm). Concomitantly, a reduction in the concentration of UV-absorbing compounds as a function of UVR dose and decreasing wavelength was determined. The relatively high UVR dose threshold for mortality (~300 kJ m ‐2 ), as well as a comparison with related species, demonstrated the high resistance of B. titicacae to UVR. Our results indicate that this resistance is provided by the presence of protec

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

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 (λmax 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 (Fv/Fm) and effective (φII) 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 Fv/Fm and φII and greater Q reduction. Growth under UV radiation alone had been shown previously to lead to the synthesis of the MAA shinorine (λmax 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 synthesis 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.

Mycosporine-like amino acids (MAAs) protect against UV-B-induced damage in Gyrodinium dorsum Kofoid

The protective effect of mycosporine-like amino acids (MAAs) against ultraviolet-B (UV-B; 280-315 nm) radiation has been studied in the marine dinoflagellate Gyrodinium dorsum. Cultures were irradiated with artificial (simulated) solar radiation with 320-nm (UV-A + PAR) and 395-nm (PAR only) cut-off filters for a period of up to 48 h in order to stimulate the synthesis of MAAs in the cells. A pronounced rise in the amount of MAAs was detected in the cells that were exposed to UV-A + PAR, while cells that were exposed to PAR induced only a marginal increase in their MAAs content. HPLC analyses of the samples revealed the presence of five MAAs, i.e., shinorine (λmax 334 nm), porphyra-334 (λmax 334 nm), palythine (λmax 320 nm), and two unidentified MAAs having λmax at 310 and 331 nm. Both cultures (one having high MAAs and another having low MAAs content) were subjected to high UV-B (8 W m−2) irradiation from a transilluminator, and motility and velocity were analyzed at regular time intervals. Cells with low MAAs content suffered a complete loss of motility within 3 h, while the cells with high MAAs content survived at least 2 times longer. The results provide further evidence that MAAs function as a UV-B absorbing/screening compound in G. dorsum and help them survive in high UV-B radiation regimes.

Comparative studies on mycosporine-like amino acids, paralytic shellfish toxins and pigment profiles of the toxic dinoflagellates Alexandrium tamarense, A. catenella and A. minutum

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 223:49-60 (2001) - doi:10.3354/meps223049 Comparative studies on mycosporine-like amino acids, paralytic shellfish toxins and pigment profiles of the toxic dinoflagellates Alexandrium tamarense, A. catenella and A. minutum Jose I. Carreto*, Mario O. Carignan, Nora G. Montoya Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Paseo Victoria Ocampo 1, PO Box 175, 7600 Mar del Plata, Argentina *E-mail: jcarreto@inidep.edu.ar ABSTRACT: Surface bloom-forming species, predominantly of the Dinophyceae, have the capacity to accumulate high amounts of mycosporine-like amino acids (MAAs). The 3 dinoflagellate species (Gonyaulacales, Dinophyceae), Alexandrium tamarense (Lebour) Balech, A. catenella (Weedon et Kofoid) Balech, and A. minutum Halim, are bloom-forming toxic isolates. They are usually found forming blooms near the surface, hence, they are exposed to high light conditions. Using an improved HPLC methodology, 9 MAAs were separated and identified. Several forms of atypical MAAs, not previously reported in the literature, were also revealed. The chromatographic behaviour of these new compounds, UV spectra, chemical properties and mass spectra indicate that they contain 2 or more common MAAs linked among themselves. These atypical MAAs were present in the 3 Alexandrium species. At the same time, the chromatographic profile of A. minutum, A. tamarense and A. catenella, showed great differences. The biochemical composition of the cells is highly variable with growth conditions. Hence, we also reported, for the sake of a comparative discussion, the toxin and pigment composition of these Alexandrium isolates. The 3 species showed the same pigment pattern characteristic of peridinin-containing dinoflagellates. On the contrary, as reported previously, great variation of the toxin profiles was observed among the Alexandrium species. We conclude that although MAAs are common among phytoplankton, the occurrence of different types of novel MAAs in the 3 Alexandrium species studied here would indicate some degree of biogeographic or ecotypic diversification. KEY WORDS: Ultraviolet radiation · Mycosporine-like amino acids · Toxins · Photosynthetic pigments · Bloom-forming species · Alexandrium Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 223. Online publication date: November 28, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Photoprotective substances in Antarctic macroalgae and their variation with respect to depth distribution, different tissues and developmental stages

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 211:117-129 (2001) - doi:10.3354/meps211117 Photoprotective substances in Antarctic macroalgae and their variation with respect to depth distribution, different tissues and developmental stages Kirsten Hoyer*, Ulf Karsten**, Thomas Sawall, Christian Wiencke Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany *E-mail: khoyer@awi-bremerhaven.de **Present address: University of Rostock, Institute of Aquatic Ecology, 18051 Rostock, Germany ABSTRACT: In this study the distribution pattern of UV-absorbing mycosporine-like amino acids (MAAs) was identified and quantified in Antarctic macroalgae and correlated with habitat as well as with the radiation climate in air and under water. In addition, specific amounts of MAAs from selected species collected at different depths, from different parts of the thallus and developmental stages were investigated. Seven different MAAs were detected in 17 out of 28 red algal species, whereas in all brown and 2 green algal species only traces of MAAs were found. In the green alga Prasiola crispa ssp. antarctica a high concentration of an unknown UV-absorbing substance with an absorption maximum at 324 nm was detected. MAA content was negatively correlated with water depth. Higher concentrations of UV-absorbing substances were found in the marginal tissues of thalli than in the basal parts. Tetrasporophytes and gametophytes exhibited similar MAA values. After transplantation from deep to shallow water, the MAA content remained unchanged for 8 d after transplantation. The data presented indicate 3 physiologically different groups of algae in terms of MAA values: (1) species with no capability for MAA biosynthesis; (2) species with a basic MAA concentration which is adjusted relative to changes in environmental radiation; (3) species with a constant relatively high MAA composition and concentration irrespective of environmental conditions. KEY WORDS: Antarctica · Macroalgae · Mycosporine-like amino acids · UV-absorbing compounds · UV radiation Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 211. Online publication date: February 14, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Effects of ultraviolet (UV) radiation on larval settlement of the reef coral Pocillopora damicornis

Sedimentation, predation and visible light are cited as causal factors to explain the pref- erential recruitment of coral larvae to shaded habitats in shallow water. Here I examine the effects of ultraviolet radiation (UVR, 280 to 400 nm) on settlement of Pocillopora damicornis (Linnaeus) larvae, and the role of UV-absorbing compounds, mycosporine-like amino acids (MAAs), in 3 field experi- ments. Larvae were obtained from adults of 4 origins: shallow (<0.5 m), deep (2 to 3 m), acclimated under UV-transparent (UVT) filters, and under UV-opaque (UVO) filters. Larvae were then exposed to UVT or UVO conditions in specially designed larval settlement chambers placed on the reef at 0.5 m depth. UVR had a negative effect on total settlement. However, UVR did not significantly increase mortality. High performance liquid chromatography analyses revealed significantly higher concentrations of MAAs in adults incubated in UVT conditions compared to those in UVO, and in shallow larvae compared to deep larvae. Despite the differences in MAA concentrations, larval ori- gin did not significantly affect survival or settlement. Lack of an 'origin' effect suggests that either MAAs may not be important to the larval ecology of this species, or that the deep and UVO larvae had at least the minimum amount of MAAs required for UVR protection. Regardless of MAAs, these experiments indicate that larvae may delay settling to the substrate when UVR levels are high (behavioral response), or that UVR is inhibiting the settlement process in some way (physiological response).

Factors Controlling the Formation of UV-absorbing Mycosporine-like Amino Acids in the Marine Red Alga Palmaria palmata from Spitsbergen (Norway)

Summary The effects of various filtered natural radiation conditions (solar without UVA+B, solar without UV B, solar) on the contents of UV-absorbing mycosporine-like amino acids (WAS) in the marine red alga Palmaria palmata have been investigated in the Arctic Kongsflord (Spitsbergen, Norway) over the summer 1997. Eight different UV-absorbing mycosporine-like amino acids (MAAs) were detected in this alga, seven of which could be identified, namely mycosporine-glycine, shinorine, porphyra-334, palythine, asterina-330, palythinol and palythene. The remaining substance exhibited an absorption maximum at 357 nm, but could not be identified. The specific amount of MAAs decreased with increasing collecting depth. Transplantation of P. palmata from 3 m depth to near surface water (0.2 m) followed by 1 week exposure to the various radiation treatments stimulated the accumulation of MAAs. All treatments led to a strong increase in total MAAs, but individual compounds showed different responses under the three spectral wavebands. While exposure to natural solar radiation without UVA+B was accompanied with a 6-fold increase in the porphyra-334 concentration, treatment without UV -13 gave similar results plus an accumulation of shinorine. Under the full solar spectrum P. palmata showed the accumulation of three MAAs, porphyra-334 and shinorine, and additionally that of palythine. These data indicate a wavelengthspecific stimulation of the formation of different MAAs, as well as the strongest accumulation of total MAAs under the full solar spectrum. In another experiment P. palmata was collected from 7.5 m depth, transplanted to 1 m and exposed for 9 days to solar radiation without UV A+B, solar radiation without UV -13 and the full solar spectrum to follow the kinetics of MAA accumulation. All radiation treatments led to an accumulation of total MAA contents over time with the full solar spectrum being the most effective. However, in contrast to P. palmata transplanted from 3 m depth, plants from 7.5 m showed a different response in the MAA accumulation pattern. In the latter samples palythine was always the quantitatively dominant MAA and exhibited also the strongest increase after transplantation to shallow waters under all radiation treatments. Finally, a microscale variation in the MAA concentrations along the algal thalli was measured. Older self-shaded basal parts of P. palmata exhibited much lower NM amounts than young apical tips. All data well support the suggested physiological function of MAAs as natural UV-sunscreens.

The effect of ultraviolet radiation on photosynthesis and ultraviolet‐absorbing substances in the endemic Arctic macroalga Devaleraea ramentacea (Rhodophyta)

In field studies conducted at the Kongsfjord (Spitsbergen), the effect of filtered natural radiation conditions (solar without ulraviolet [UV]‐A+UV‐B, solar without UV‐B, solar) on photosynthesis and the metabolism of UV‐absorbing mycosporine‐like amino acids (MAAs) in the marine red alga Devaleraea ramentacea have been studied. While solar treatment without UV‐A+UV‐B did not affect photosynthesis during the course of a day, solar without UV‐B and the full solar spectrum led to a strong inhibition. However, after offset of the various radiation conditions, all algae fully recovered. Isolates collected from different depths were exposed in the laboratory to artificial fluence rates of photosynthetic active radiation (PAR), PAR+UV‐A, and PAR+UV‐A+UV‐B. The photosynthetic capacity was affected in accordance with the original sampling depth, i.e. shallow‐water isolates were more resistant than algae from deeper waters, indicating that D. ramentacea is able to acclimate to changes in irradiance. Seven different UV‐absorbing MAAs were detected in this alga, namely mycosporine‐glycine, shinorine, porphyra‐334, palythine, asterina‐330, palythinol, and palythene. The total amount of MAAs continuously decreased with increasing collecting depth when sampled in mid June, and algae taken in late August from the same depths contained on average 30–45% higher MAA concentrations, indicating a seasonal effect as well. The presence of increasing MAA contents with decreasing depth correlated with a more insensitive photosynthetic capacity under both UV‐A and UV‐B treatments. Populations of D. ramentacea collected from 1 m depth, with one fully exposed to solar radiation and the other growing protected as understorey vegetation underneath the kelp Laminaria saccharina, exhibited quantitatively different MAA compositions in the apices. The exposed seaweeds contained 2.5‐fold higher MAA values compared with the more shaded algae. Moreover, the exposed isolates showed a strong tissue gradient in MAAs, pigments, and proteins. The green apices contained 5‐fold higher MAA contents than the red bases. Transplantation of D. ramentacea from 2 m depth to the surface induced the formation and accumulation of MAAs after 1 week exposure to the full solar spectrum. Control samples which were treated with the solar spectrum without UV‐A+B or with solar without UV‐B showed unchanged MAA contents, indicating a strong UV‐B effect on MAA metabolism. All data well supported the suggested physiological function of MAAs as natural UV sunscreens in macroalgae.