Can Mycosporine‐Like Amino Acids Act as Multifunctional Compounds in Gymnodinium catenatum (Dinophyceae)?

Abstract

MAAs originating from Gymnodinium catenatum were subjected to H O oxidation, light and heat. Shinorine and porphyra-334 were the more resistant to all treatments, mycosporine-glycine (MYGL) was the least resistant to oxidation and heat, whereas palythene and M-370 were the least resistant to light. MYGL and M-311 were similarly resistant to photodegradation and oxidation in the dark and low temperature, but M-311 was more resistant to oxidation under light or heat. The ratio M-370/M-365 changed from 29:1 to 6:1 ratio after 240 h of exposure to fluorescent light, indicating that M-365 could represent the M-370 cis-isomer. The role of MAAs as antioxidants and/or osmolytes was evaluated by studying effects of abrupt salinity reduction. Both increases or decreases in concentrations were observed and were dependent on the MAA initial concentration and its chemical structure. The relative increase in MAAs with a known antioxidant capacity (MYGL, palythene) followed an exponential decay trend related to initial concentration. The relative decrease in highly polar MAAs (shinorine, porphyra-334, M-332) with a suspected osmolyte role followed a rise to a maximum with the increase in initial concentration. Whether or not MAAs play a significant role in osmoregulation, their loss can occur upon hypoosmotic shock.

Resistance to Hydrogen Peroxide Highlights Gymnodinium catenatum (Dinophyceae) Sensitivity to Geomagnetic Activity

“…Results on MAAs were in line with previous studies carried out in vitro with this strain. Total MAAs normally increase during the light phase, independently of the existence or not of mechanical stress (repeated vigorous shaking) (43). But this increase is normally less than two-fold, as observed here also (Fig.…”

“…MAA levels obtained here for the halogen light source were lower than those observed before . This recent MAA data were obtained in summer 2016, when solar cycle 24 was more advanced in its declining phase.…”

“…MAAs which have an antioxidant capability (M311, mycosporine-glycine, M370, palythene) can be stimulated to increase upon exposure to high-light conditions (38). However, these can also be easily oxidized (43). In the present experiments, total MAAs with antioxidant capability decreased following addition of hydrogen peroxide (Fig.…”

Influence of solar and geomagnetic activity in Gymnodinium catenatum (Dinophyceae) cultures

“…Cellular concentration of MAAs was determined by HPLC with DAD detection as described in Vale (2016).…”

“…The aim of this research was to find in vitro evidence for possible effects from S-GMA in this microalga in order to better understand its natural blooms and their relation with the solar cycle. The experimental design emerged from the continuation of a previous set of experiments targeted at understanding the role of MAAs in osmoregulation (Vale 2016). It involved the introduction of a hypo-osmotic shock to G. catenatum in culture.…”