TY  - JOUR
A1  - Hu, Chenlin
A1  - Ludsin, Stuart A.
A1  - Martin, Jay F.
A1  - Dittmann, Elke
A1  - Lee, Jiyoung
T1  - Mycosporine-like amino acids (MAAs)-producing Microcystis in Lake Erie
BT  - Development of a qPCR assay and insight into its ecology
JF  - Harmful algae
N2  - Mycosporine-like amino acids (MAAs) are UV-absorbing metabolites found in cyanobacteria. While their protective role from UV in Microcystis has been studied in a laboratory setting, a full understanding of the ecology of MAA-producing versus non-MAA-producing Microcystis in natural environments is lacking. This study presents a new tool for quantifying MAA-producing Microcystis and applies it to obtain insight into the dynamics of MAA-producing and non-MAA-producing Microcystis in Lake Erie. This study first developed a sensitive, specific TaqMan real-time PCR assay that targets MAA synthetase gene C (mysC) of Microcystis (quantitative range: 1.7 × 101 to 1.7 × 107 copies/assay). Using this assay, Microcystis was quantified with a MAA-producing genotype (mysC+) in water samples (n = 96) collected during March-November 2013 from 21 Lake Erie sites (undetectable − 8.4 × 106 copies/ml). The mysC+ genotype comprised 0.3–37.8% of the Microcystis population in Lake Erie during the study period. The proportion of the mysC+ genotype during high solar UV irradiation periods (mean = 18.8%) was significantly higher than that during lower UV periods (mean = 9.7%). Among the MAAs, shinorine (major) and porphyra (minor) were detected with HPLC-PDA-MS/MS from the Microcystis isolates and water samples. However, no significant difference in the MAA concentrations existed between higher and lower solar UV periods when the MAA concentrations were normalized with Microcystis mysC abundance. Collectively, this study’s findings suggest that the MAA-producing Microcystis are present in Lake Erie, and they may be ecologically advantageous under high UV conditions, but not to the point that they exclusively predominate over the non-MAA-producers.
KW  - Shinorine
KW  - Porphyra
KW  - UV irradiation
KW  - Sunscreen
KW  - Eutrophication
KW  - Harmful algal bloom
Y1  - 2018
U6  - https://doi.org/10.1016/j.hal.2018.05.010
SN  - 1568-9883
SN  - 1878-1470
VL  - 77
SP  - 1
EP  - 10
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Hu, Chenlin
A1  - Völler, Ginka
A1  - Sussmuth, Roderich
A1  - Dittmann-Thünemann, Elke
A1  - Kehr, Jan-Christoph
T1  - Functional assessment of mycosporine-like amino acids in Microcystis aeruginosa strain PCC 7806
JF  - Environmental microbiology
N2  - The biological role of the widespread mycosporine-like amino acids (MAAs) in cyanobacteria is under debate. Here, we have constructed and characterized two mutants impaired in MAA biosynthesis in the bloom-forming cyanobacterium Microcystis aeruginosaPCC 7806. We could identify shinorine as the sole MAA type of the strain, which is exclusively located in the extracellular matrix. Bioinformatic studies as wells as polymerase chain reaction screening revealed that the ability to produce MAAs is sporadically distributed within the genus. Growth experiments and reactive oxygen species quantification with wild-type and mutant strains did not support a role of shinorine in protection against UV or other stress conditions in M.aeruginosaPCC 7806. The shinorine content per dry weight of cells as well as transcription of the mys gene cluster was not significantly elevated in response to UV-A, UV-B or any other stress condition tested. Remarkably, both mutants exhibited pronounced morphological changes compared with the wild type. We observed an increased accumulation and an enhanced hydrophobicity of the extracellular matrix. Our study suggests that MAAs in Microcystis play a negligible role in protection against UV radiation but might be a strain-specific trait involved in extracellular matrix formation and cell-cell interaction.
Y1  - 2015
U6  - https://doi.org/10.1111/1462-2920.12577
SN  - 1462-2912
SN  - 1462-2920
VL  - 17
IS  - 5
SP  - 1548
EP  - 1559
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -