Untitled

Abstract

The dinofl agellates, Gymnodinium catenatum and Alexandrium pacifi cum, have been previously studied regarding daily variations in solar-terrestrial interaction, known as space weather (SPW). To perform in vitro simulation of geomagnetic pulsations, an external extremely low-frequency magnetic fi eld was employed previously for the study of their growth and metabolite production. Here, the same fi eld was "informationally" transferred through a prior 24 h exposure of a culture media aliquot, the so-called "water memory" eff ect. To understand the eff ect of the magnetically treated culture media (MTCM), results had to be interpreted in light of the hormesis dose-response curve regarding natural fl uctuations in SPW. The MTCM reduced growth at the hormesis optimum for selected SPW parameters. In these cells with reduced growth, the ultraviolet -photoprotective pigments mycosporine-like amino acids (MAAs) and the paralytic shellfi sh poisoning toxins (PSTs) increased in concentration. G. catenatum was more aff ected by MTCM than A. pacifi cum, with a generalized reduction trend in growth and MAA concentration. These pigments, besides having a UV-protection role, can also function as osmolites and antioxidants in microalgae. The use of MTCM elicited the same eff ect as direct exposure to an external extremely low-frequency magnetic fi eld.