High Mycosporine-like Amino Acids Research Articles

Seasonal changes in stress metabolites of native and introduced red algae in New Zealand

Intertidal algae have to cope with diurnally and seasonally fluctuating environmental factors such as salinity, temperature, dehydration, and light. In New Zealand, solar radiation, including the ultraviolet wavelengths, is also an important stress factor for such algae. Therefore, two native (Bostrychia arbuscula W.H.Harvey [Ceramiales], Champia novae-zelandiae (J.D.Hooker & Harvey) Harvey [Rhodymeniales]) and one introduced red algal taxon (Schizymenia spp. J. Agardh [Nemastomatales]) were investigated over 12 months in terms of stress metabolites which contribute to ultraviolet radiation (UVR) and salinity tolerance. Mycosporine-like amino acids (MAAs), which act as sunscreens, and organic osmolytes were qualitatively and quantitatively analyzed. Porphyra-334, shinorine, and palythine were the most dominant MAAs yet distributed differently among the species. B. arbuscula showed a correlation between photosynthetically active radiation (PAR)/UVR and slightly higher MAA concentrations in summer. In contrast, C. novae-zelandiae displayed the lowest level of MAAs in summer, and no correlation was found between MAA values and solar radiation. In Schizymenia spp., the highest MAA amounts were found in summer, and for most months, a correlation with PAR/UV radiation was visible. While digeneaside and sorbitol were the dominant organic osmolytes in B. arbuscula, floridoside occurred in C. novae-zelandiae and Schizymenia spp. Only B. arbuscula exhibited higher organic osmolyte concentrations in summer. In contrast, floridoside contents in C. novae-zelandiae and Schizymenia spp. were low and highly variable over the course of the seasons. Our data indicate that both native red algal species are well acclimated to the intertidal zone. For the introduced Schizymenia spp., a more narrow salinity tolerance can be assumed, while the high MAA values may explain its establishment in New Zealand.

Mycosporine-Like Amino Acids (MAAs) in Zooplankton.

Organisms have different adaptations to avoid damage from ultraviolet radiation and one such adaptation is the accumulation of mycosporine-like amino acids (MAAs). These compounds are common in aquatic taxa but a comprehensive review is lacking on their distribution and function in zooplankton. This paper shows that zooplankton MAA concentrations range from non-detectable to ~13 µg mgDW−1. Copepods, rotifers, and krill display a large range of concentrations, whereas cladocerans generally do not contain MAAs. The proposed mechanisms to gain MAAs are via ingestion of MAA-rich food or via symbiotic bacteria providing zooplankton with MAAs. Exposure to UV-radiation increases the concentrations in zooplankton both via increasing MAA concentrations in the phytoplankton food and due to active accumulation. Concentrations are generally low during winter and higher in summer and females seem to deposit MAAs in their eggs. The concentrations of MAAs in zooplankton tend to increase with altitude but only up to a certain altitude suggesting some limitation for the uptake. Shallow and UV-transparent systems tend to have copepods with higher concentrations of MAAs but this has only been shown in a few species. A high MAA concentration has also been shown to lead to lower UV-induced mortality and an overall increased fitness. While there is a lot of information on MAAs in zooplankton we still lack understanding of the potential costs and constraints for accumulation. There is also scarce information in some taxa such as rotifers as well as from systems in tropical, sub(polar) areas as well as in marine systems in general.

Short communication: Mycosporine-like amino acids protect natamycin against photodegradation in milk exposed to fluorescent or light-emitting diode light

Natamycin has been used as a natural antimicrobial in dairy products, but the poor light stability of natamycin can limit usefulness in food products. Mycosporine-like amino acids are strong UV absorbers and might be useful as an additive to decrease light-induced degradations. Therefore, the objective of this study was to evaluate the photoprotective effect of mycosporine-like amino acids (MAA) in cow milk stored under 2 lighting conditions in retail commercial display cabinets with fluorescent and high intensity light-emitting diode illumination. When milk was exposed to both fluorescent and light-emitting diode light, natamycin degradation was very fast, and only 17.1 ± 0.9% of its original concentration was observed after 8 d at 4.0°C. On the other hand, by adding MAA into milk, natamycin was retained at 82.2 ± 0.9% and 92.2 ± 0.9% when low and high MAA levels were used, respectively. However, high MAA levels resulted in color changes. Therefore, MAA at low levels had a photoprotective effect for natamycin stability in cow milk exposed to light in refrigerated glass containers.

Windows in Arctic sea ice: Light transmission and ice algae in a refrozen lead

AbstractThe Arctic Ocean is rapidly changing from thicker multiyear to thinner first‐year ice cover, with significant consequences for radiative transfer through the ice pack and light availability for algal growth. A thinner, more dynamic ice cover will possibly result in more frequent leads, covered by newly formed ice with little snow cover. We studied a refrozen lead (≤0.27 m ice) in drifting pack ice north of Svalbard (80.5–81.8°N) in May–June 2015 during the Norwegian young sea ICE expedition (N‐ICE2015). We measured downwelling incident and ice‐transmitted spectral irradiance, and colored dissolved organic matter (CDOM), particle absorption, ultraviolet (UV)‐protecting mycosporine‐like amino acids (MAAs), and chlorophyll a (Chl a) in melted sea ice samples. We found occasionally very high MAA concentrations (up to 39 mg m−3, mean 4.5 ± 7.8 mg m−3) and MAA to Chl a ratios (up to 6.3, mean 1.2 ± 1.3). Disagreement in modeled and observed transmittance in the UV range let us conclude that MAA signatures in CDOM absorption spectra may be artifacts due to osmotic shock during ice melting. Although observed PAR (photosynthetically active radiation) transmittance through the thin ice was significantly higher than that of the adjacent thicker ice with deep snow cover, ice algal standing stocks were low (≤2.31 mg Chl a m−2) and similar to the adjacent ice. Ice algal accumulation in the lead was possibly delayed by the low inoculum and the time needed for photoacclimation to the high‐light environment. However, leads are important for phytoplankton growth by acting like windows into the water column.

Mild Acid Hydrolysis-related Release of Water-soluble Sunscreen Pigments from the Exopolysaccharide Matrix of Edible Terrestrial Cyanobacteria

Terrestrial cyanobacteria, Nostoc flagelliforme and Nostoc commune, are important natural resource for producing ultraviolet-absorbing mycosporine-like amino acids (MAAs), in addition to their edible value. MAAs can be used as sun-screening cosmetics, antioxidants and pharmaceuticals. Usually, water-soluble MAAs are extracted by pure or aqueous methanol after sample grinding. Development of new extraction technique without specific morphological destroyment will contribute to adequately exploit the commercial values of both edible cyanobacteria. The N-acetylcysteine solution has been preliminarily mentioned to cause the release of MAAs from N. flagelliforme via mere incubation with the sample. In this study, we explored the potential mechanism underlying this influence and further applied it to extract MAAs from various samples. It was revealed that N-acetylcysteine solutions primarily played a mild acid hydrolysis role in causing the dissociation and release of MAAs from the exopolysaccharide matrix of samples. N-acetylcysteine solutions also exerted similar physiological or morphological effects on the samples as other acidic solutions, and the morphological integrity of the treated samples was not destroyed. Finally, we found that those samples with good vitality could achieve high MAA harvests. In general, means of incubation with acidic solution serves as a simple and relatively nondestructive technique for MAA extraction from the edible terrestrial cyanobacteria.

Contrasting patterns of MAAs accumulation in two populations of the copepod Boeckella gracilipes

The bio-accumulation of mycosporine-like amino acids (MAAs) is common in planktonic copepods that inhabit environments exposed to high levels of solar radiation. MAAs accumulation in copepods can be affected both by extrinsic (environmental) and intrinsic factors (local adaptation, genotype, etc.). Laboratory experiments were performed to study the bio-accumulation of MAAs in two geographically-isolated populations of Boeckella gracilipes from a mountain and a piedmont lake of North Patagonia. We performed two series of 10-day incubations of B. gracilipes from the different lakes applying two radiation conditions (PAR + UVR and darkness), at five different temperatures (5 to 20 °C) and providing a MAA-free flagellate as food. We assumed that differences in final MAAs concentrations between copepod populations should be exclusively due to environmental factors, and that any difference in the patterns of MAAs accumulation should exclusively arise from differences in MAAs concentration at the time of collection. MAAs concentration was three fold higher in B. gracilipes from Lake Verde than in copepods from the Lake Morenito. The MAAs suite was dominated (∼90%) by a combination of porphyra-334 and mycosporine-glycine in copepods from Lake Verde, and porphyra-334 and MAA-332 in those from Lake Morenito. Two exclusive MAA compounds were identified, mycosporine-glycine in copepods from Lake Verde and shinorine in the copepod population from Lake Morenito. Laboratory experiments showed that: (i) exposure to PAR + UVR stimulated the accumulation of MAAs in both copepod populations; (ii) temperature affected the response of MAAs and, remarkably, low temperatures stimulated MAAs accumulation even in dark incubations, (iii) the response to radiation and temperature in MAAs accumulation was more pronounced in the population with low initial MAAs than in the population with high initial MAAs concentrations. The differences in intrinsic factors between B. gracilipes populations, such as local adaptation to contrasting UV and temperature scenarios, among others, appear to play an important role in determining levels and patterns of MAAs accumulation in B. gracilipes.

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.

Distribution of Mycosporine-Like Amino Acids Along a Surface Water Meridional Transect of the Atlantic

The composition and abundance of mycosporine-like amino acids (MAAs) were investigated in the surface waters along a 13,000-km meridional transect (52° N to 45° S) in the Atlantic Ocean (Atlantic Meridional Transect programme: Cruise AMT 18: 4/10/2008-10/11/2008). MAAs were ubiquitous along the transect, although the composition of the MAAs was variable. Highest concentrations were in the far south (below 40° S; MAA >1 μg L(-1)) and in north subtropical equatorial region (NER: 0-25° N; MAA up to 0.8 μg L(-1)). Highest MAA relative to chlorophyll-a occurred in the NER (MAA/chl-a ratio between 2 and 5). MAA/chl-a significantly correlated with the preceding month's mean daily UV dose and with UV-B/UV-A. In the far south, high MAA concentrations coincided with high phytoplankton biomass, high nutrients and a deep mixed layer associated with the austral spring. Here, the phytoplankton community was dominated by micro- and nano-eukaryotes. At the NER, the high MAA/chl-a coincided with low nutrient concentrations, a shallow mixed layer depth (20-70 m) and to a lesser extent to a shallow nitracline (40-90 m). Here, the phytoplankton consisted primarily of picophytoplankton (0-0.2 μm), dominated by the pico-cyanobacteria Synechococcus sp. and Prochlorococcus sp. and by the nitrogen fixing filamentous cyanobacterium Trichodesmium. The low nitrate concentrations (<0.1 μmol L(-1)) at the NER suggest that nitrogen fixation was required for MAA production. Specific MAAs could not easily be assigned to particular groups of phytoplankton and we could not rule out the possibility that MAAs were associated with symbiotic cyanobacteria contained within heterotrophic dinoflagellates or diatoms.

Effect of vertical mixing on short-term mycosporine-like amino acid synthesis in the Antarctic diatom, &lt;i&gt;Thalasiossira&lt;/i&gt; sp.

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.

Effect of nutrient supply on photosynthesis and pigmentation to short-term stress (UV radiation) in Gracilaria conferta (Rhodophyta)

The effects of increased photosynthetic active radiation (PAR), UV radiation (UVR), and nutrient supply on photosynthetic activity, pigment content, C:N ratio and biomass yield were studied in tank cultivated Gracilaria conferta (Rhodophyta). Electron transport rate (ETR) and biliprotein content were higher under high nutrient supply (HNS), obtained from fishpond effluents, compared to low nutrient supply (LNS), in contrast to mycosporine-like amino acids (MAAs) dynamic. The high MAA content in LNS-algae could be explained by higher UVR penetration in the thallus and by the competition for the use of nutrients with other processes. Effective quantum yield decreased after short-term exposure to high irradiance whereas full recovery in shade was produced only under slightly heat shock. UVA radiation provoked an additional decrease in photosynthesis under high water temperature. UVB radiation reversed UVA’s negative effect mainly with HNS. Results support that nutrient-sufficiency help G. conferta to resist environmental changes as short-term temperature increase.

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.

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.

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.

Ultraviolet sunscreen compounds in epiphytic red algae from mangroves

Epiphytic red algae of the order Ceramiales from mangroves and salt marshes (nine species from Bostrychia, three from Stictosiphonia and four from Caloglossa) produce varying levels of the UV-absorbing compounds mycosporine-glycine, shinorine, porphyra-334, palythine, asterina-330 and palythinol, a suite of substances chemically assigned as mycosporine-like amino acids (MAAs). Mean MAA levels varied from 0.02 to 12.8 mg g−1 DW in field-collected and laboratory cultured specimens. While in field samples of Bostrychia montagneiHarvey, Bostrychia radicans (Montagne) Montagne and Caloglossa apomeiotica J.West et G.Zuccarello MAA concentrations were generally higher compared to cultured plants of the same taxa, Bostrychia tenella(Lamouroux) J.Agardh did not show such a difference. Catenella caespitosa (Withering) L.Irvine, Catenella impudica (Montagne) J.Agardh and Catenella nipae Zanardini (Gigartinales, Caulacanthaceae) produce two novel UV-absorbing compounds: MAA-1 (1.4–4.3 mg g −1 DW) and MAA-2 (0.1–1.0 mg g−1 DW), which absorb at 334 nm and 320 nm, respectively. In laboratory culture of Bostrychia moritziana when photosynthetically active radiation (PAR) was increased from 20 to 40 μmol photons m−2 s−1, the total level of palythinol increased by 85% (from 2.0 to 3.7 mg g−1 DW). In a culture of Caloglossa leprieurii when PAR was increased from 40 to 80 μmol m−2 s−1the porphyra-334 content increased by 77% (from 3.1 to 5.5 mg g−1 DW). Extremely high MAA contents of >30 mg g−1 DW were detected in mature tetrasporangial sori prepared from two isolates of laboratory-cultured reproductive Caloglossa apomeiotica compared to vegetative plants (about 10 mg MAAs g−1 DW) indicating tetraspores loaded up with UV-sunscreens. All data demonstrate that mangrove red algae contain high MAA concentrations, particularly the reproductive structures, and hence these compounds may act as biochemical photoprotectants against exposure to UV-radiation.

Evidence Regarding the UV Sunscreen Role of a Mycosporine-Like Compound in the Cyanobacterium Gloeocapsa sp

The UV sunscreen role commonly ascribed to mycosporine-like amino acids (MAAs) was investigated with an isolate of the terrestrial cyanobacterium Gloeocapsa sp. strain C-90-Cal-G.(2), which accumulates intracellularly an MAA with absorbance maximum at 326 nm but produces no extracellular sunscreen compound (i.e., scytonemin). The intracellular concentrations of MAA achieved were directly related to the intensity of the UV radiation (maximum at 320 nm) received by the cells. However, the presence of high concentrations of MAA was not necessary for the physiological acclimation of the cultures to UV radiation. The measured sunscreen factor due to MAA in single cells was 0.3 (the MAA prevented 3 out of 10 photons from hitting potential cytoplasmic targets). High contents of MAA in the cells correlated with increased resistance to UV radiation. However, when resistance was gauged under conditions of desiccation, with inoperative physiological photoprotective and repair mechanisms, cells with high MAA specific contents were only 20 to 25% more resistant. Although UV radiation centered around both 320 and 365 nm resulted in chlorophyll a photobleaching and photoinhibition of photosynthesis, the difference in sensitivity correlated with MAA accumulation occurred only at 320 nm (absorbed by MAA) and not at 365 nm (not absorbed by MAA). This difference represents the maximal protection ascribable to the presence of MAA for single cells, i.e., if one does not consider the enhancing effects of colony formation on protection by sunscreens.