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Seasonal Changes in Mycosporine-Like Amino Acid Production Rate with Respect to Natural Phytoplankton Species Composition.

Ha SY, Lee Y, Kim MS, Kumar KS, Shin KH - Mar Drugs (2015)

Bottom Line: The dominance of diatoms indicated that they had a long-term response to UVR.Our results demonstrate that both the net production rate as well as the concentration of MAAs related to photoinduction depended on the phytoplankton community structure.In addition, seasonal changes in UVR also influenced the quantity and production of MAAs in phytoplanktons (especially Cyanophyceae).

View Article: PubMed Central - PubMed

Affiliation: Division of Polar Ocean Environment, Korea Polar Research Institute (KOPRI), 26 Songdomirae-ro, Yeonsu-gu, Incheon 406-840, Korea. syha@kopri.re.kr.

ABSTRACT
After in situ incubation at the site for a year, phytoplanktons in surface water were exposed to natural light in temperate lakes (every month); thereafter, the net production rate of photoprotective compounds (mycosporine-like amino acids, MAAs) was calculated using (13)C labeled tracer. This is the first report describing seasonal variation in the net production rate of individual MAAs in temperate lakes using a compound-specific stable isotope method. In the mid-latitude region of the Korean Peninsula, UV radiation (UVR) usually peaks from July to August. In Lake Paldang and Lake Cheongpyeong, diatoms dominated among the phytoplankton throughout the year. The relative abundance of Cyanophyceae (Anabaena spiroides) reached over 80% during July in Lake Cheongpyeong. Changes in phytoplankton abundance indicate that the phytoplankton community structure is influenced by seasonal changes in the net production rate and concentration of MAAs. Notably, particulate organic matter (POM) showed a remarkable change based on the UV intensity occurring during that period; this was because of the fact that cyanobacteria that are highly sensitive to UV irradiance dominated the community. POM cultured in Lake Paldang had the greatest shinorine (SH) production rate during October, i.e., 83.83 ± 10.47 fgC·L(-1)·h(-1). The dominance of diatoms indicated that they had a long-term response to UVR. Evaluation of POM cultured in Lake Cheongpyeong revealed that there was an increase in the net MAA production in July (when UVR reached the maximum); a substantial amount of SH, i.e., 17.62 ± 18.34 fgC·L(-1)·h(-1), was recorded during this period. Our results demonstrate that both the net production rate as well as the concentration of MAAs related to photoinduction depended on the phytoplankton community structure. In addition, seasonal changes in UVR also influenced the quantity and production of MAAs in phytoplanktons (especially Cyanophyceae).

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A typical HPLC-DAD chromatogram and absorption spectrum of individual MAAs in the present study; 1: shinorine (λmax = 334); 2: palythine (λmax = 320); 3: mycosporine-glycine (λmax = 310).
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marinedrugs-13-06740-f005: A typical HPLC-DAD chromatogram and absorption spectrum of individual MAAs in the present study; 1: shinorine (λmax = 334); 2: palythine (λmax = 320); 3: mycosporine-glycine (λmax = 310).

Mentions: MAAs in the POM were analysed by lyophilizing (lyophilizer; FD Series, IlshinBioBase, Gyeonggi-do, South Korea) the filtered samples; thereafter, 3 mL of 100% methanol (MeOH) was added to the dried samples. These samples were homogenized using an ultrasonicator (30 s, 50 W; Ulsso Hi-tech ULH-700s, Chongwon-gun, Chungcheongbuk-Do, South Korea), after which they were kept at 4 °C (overnight means 12 h;) for the extraction of MAAs. These samples were then filtered using a syringe filter (PTFE 0.20 μm Hydrophobic, Darmstadt, Germany) into a 2 mL microtube. The supernatants were evaporated to dryness at 45 °C in a centrifugal evaporator (EYELA, CVE-200D, Tokyo, Japan) and the extracts were re-dissolved in distilled water (500 μL). Thereafter, chloroform (100 μL) was added to this solution, followed by centrifugation (10,000 rpm, 10 min); then, 400 μL of the aqueous phase was carefully transferred to a new Eppendorf tube. Further analysis of the extracted MAAs was carried out using a High-Performance Liquid Chromatography (HPLC) system (Agilent Technologies 1200 series; column: Waters 120DS-AP (5 μm) 150 mm × 4.6 ID; Santa Clara, CA, USA). The detector was an Agilent DAD (G1315D; Santa Clara, CA, USA) at 313 nm (250–750 nm scan). The separated MAAs (e.g., shinroine (SH), palythine (PA), and mycosporine-glycine (MG)) were collected using a fraction collector (Agilent analyte (G1364C) FC). The samples (100 μL) were injected into the HPLC column by an autosampler (Agilent). The mobile phase, comprising 0.1% acetic acid in double distilled water, was used at a constant flow rate of 0.8 mL·min−1. Shinorine and porphyra-334 were used as standard references for identification and quantification of MAAs (Figure 5).


Seasonal Changes in Mycosporine-Like Amino Acid Production Rate with Respect to Natural Phytoplankton Species Composition.

Ha SY, Lee Y, Kim MS, Kumar KS, Shin KH - Mar Drugs (2015)

A typical HPLC-DAD chromatogram and absorption spectrum of individual MAAs in the present study; 1: shinorine (λmax = 334); 2: palythine (λmax = 320); 3: mycosporine-glycine (λmax = 310).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663551&req=5

marinedrugs-13-06740-f005: A typical HPLC-DAD chromatogram and absorption spectrum of individual MAAs in the present study; 1: shinorine (λmax = 334); 2: palythine (λmax = 320); 3: mycosporine-glycine (λmax = 310).
Mentions: MAAs in the POM were analysed by lyophilizing (lyophilizer; FD Series, IlshinBioBase, Gyeonggi-do, South Korea) the filtered samples; thereafter, 3 mL of 100% methanol (MeOH) was added to the dried samples. These samples were homogenized using an ultrasonicator (30 s, 50 W; Ulsso Hi-tech ULH-700s, Chongwon-gun, Chungcheongbuk-Do, South Korea), after which they were kept at 4 °C (overnight means 12 h;) for the extraction of MAAs. These samples were then filtered using a syringe filter (PTFE 0.20 μm Hydrophobic, Darmstadt, Germany) into a 2 mL microtube. The supernatants were evaporated to dryness at 45 °C in a centrifugal evaporator (EYELA, CVE-200D, Tokyo, Japan) and the extracts were re-dissolved in distilled water (500 μL). Thereafter, chloroform (100 μL) was added to this solution, followed by centrifugation (10,000 rpm, 10 min); then, 400 μL of the aqueous phase was carefully transferred to a new Eppendorf tube. Further analysis of the extracted MAAs was carried out using a High-Performance Liquid Chromatography (HPLC) system (Agilent Technologies 1200 series; column: Waters 120DS-AP (5 μm) 150 mm × 4.6 ID; Santa Clara, CA, USA). The detector was an Agilent DAD (G1315D; Santa Clara, CA, USA) at 313 nm (250–750 nm scan). The separated MAAs (e.g., shinroine (SH), palythine (PA), and mycosporine-glycine (MG)) were collected using a fraction collector (Agilent analyte (G1364C) FC). The samples (100 μL) were injected into the HPLC column by an autosampler (Agilent). The mobile phase, comprising 0.1% acetic acid in double distilled water, was used at a constant flow rate of 0.8 mL·min−1. Shinorine and porphyra-334 were used as standard references for identification and quantification of MAAs (Figure 5).

Bottom Line: The dominance of diatoms indicated that they had a long-term response to UVR.Our results demonstrate that both the net production rate as well as the concentration of MAAs related to photoinduction depended on the phytoplankton community structure.In addition, seasonal changes in UVR also influenced the quantity and production of MAAs in phytoplanktons (especially Cyanophyceae).

View Article: PubMed Central - PubMed

Affiliation: Division of Polar Ocean Environment, Korea Polar Research Institute (KOPRI), 26 Songdomirae-ro, Yeonsu-gu, Incheon 406-840, Korea. syha@kopri.re.kr.

ABSTRACT
After in situ incubation at the site for a year, phytoplanktons in surface water were exposed to natural light in temperate lakes (every month); thereafter, the net production rate of photoprotective compounds (mycosporine-like amino acids, MAAs) was calculated using (13)C labeled tracer. This is the first report describing seasonal variation in the net production rate of individual MAAs in temperate lakes using a compound-specific stable isotope method. In the mid-latitude region of the Korean Peninsula, UV radiation (UVR) usually peaks from July to August. In Lake Paldang and Lake Cheongpyeong, diatoms dominated among the phytoplankton throughout the year. The relative abundance of Cyanophyceae (Anabaena spiroides) reached over 80% during July in Lake Cheongpyeong. Changes in phytoplankton abundance indicate that the phytoplankton community structure is influenced by seasonal changes in the net production rate and concentration of MAAs. Notably, particulate organic matter (POM) showed a remarkable change based on the UV intensity occurring during that period; this was because of the fact that cyanobacteria that are highly sensitive to UV irradiance dominated the community. POM cultured in Lake Paldang had the greatest shinorine (SH) production rate during October, i.e., 83.83 ± 10.47 fgC·L(-1)·h(-1). The dominance of diatoms indicated that they had a long-term response to UVR. Evaluation of POM cultured in Lake Cheongpyeong revealed that there was an increase in the net MAA production in July (when UVR reached the maximum); a substantial amount of SH, i.e., 17.62 ± 18.34 fgC·L(-1)·h(-1), was recorded during this period. Our results demonstrate that both the net production rate as well as the concentration of MAAs related to photoinduction depended on the phytoplankton community structure. In addition, seasonal changes in UVR also influenced the quantity and production of MAAs in phytoplanktons (especially Cyanophyceae).

Show MeSH