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

Abstract

Laboratory cultures of the paralytic shellfish poisoning producing microalga Gymnodinium catenatum were subjected to a hypo-osmotic shock and changes in cell concentration were observed in two separate experiments of 8 and 24 hours duration, respectively. The increase in geomagnetic activity (GMA), radio and X-ray fluxes and solar X-ray flares were negatively correlated with cell numbers. Cell losses were observed in the short experiment, but not in the longest one. GMA action was related to the course of the experimental period, while electromagnetic radiation (EMR) was only significantly related when the previous hours before the experiments were considered. The differential action windows might be indicative of two differential disruptive mechanisms: EMR might act on DNA synthesis and mitosis phases of the cell cycle (taking place in the dark period) and GMA might be more disruptive at the end of mytosis or cytokinesis phases taking place in the light period. Formation of long chains (> 4 cells/chain) was reduced with salinity and with temperatures above 27ºC but increased with EMR and GMA, particularly when grown at the highest temperatures recorded during the study period (≥28ºC).

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

“…In halogen‐acclimated cells, basal concentration of the major MAAs with a putative osmolyte role (shinorine and porphyra‐334) was low in comparison with previous studies . These cells, collected in June 2016, were preceded by a decade of days with an X‐ray flux equal or below 1.0 B‐level units, lower than the minimal of 2.0 B‐level units found in previous studies.…”

“…a), probably reflecting their in vivo oxidation. This group of MAAs was previously observed to decrease along with the increase in solar X‐ray flux or geomagnetic activity . ROS generation is well known for extremely high‐frequency radiation such as X‐rays .…”

“…Chain formation is a useful morphological stress indicator in G . catenatum and has been previously related with salinity and temperature stress , as well as solar X‐ray flux, X‐ray flares, radio flux and geomagnetic activity .…”

“…For the S‐GMA experiment, X‐ray flux varied between 1.1 and 5.2 B‐level units, daily X‐ray flare number between 0 and 8, and radio flux between 79 and 117 F 10.7 units. By contrast, in early 2015, X‐ray flux varied between 1.9 and 9.0 B‐level units, daily X‐ray flare number between 0 and 23, and radio flux between 94 and 163 F 10.7 units . Based on the negative findings on G .…”

“…This Index is calculated with data measured at two antipodal magnetic observatories. The an Geomagnetic Index was used before , but it was not available at the time data analysis was performed (due to technical problems with the ISGI servers).…”