Influence of salinity on population growth, oxidative stress and antioxidant defense system in the marine monogonont rotifer Brachionus plicatilis

Abstract

Salinity stress influences energy balance, induction of stress proteins, and reproductive success, which are important to life parameters of aquatic organisms. However, physiological and molecular responses of salinity stress have not been studied in the rotifer. To understand the effects of salinity changes on the rotifer, we examined the marine monogonont rotifer Brachionus plicatilis (B. plicatilis) for salinity stress-induced changes in population growth, reactive oxygen species (ROS) levels, and antioxidant enzymatic activities (e.g., glutathione S-transferase [GST], superoxide dismutase [SOD] and catalase [CAT]). In addition, antioxidant-related transcripts (GSTs [GSTs-1-1 and GSTs-1-2], MnSOD1 and CAT2) were investigated in different salinity-exposed rotifers. A significant decrease (P < 0.05) in population growth was observed in response to high salinity (35 psu) in B. plicatilis. Moreover, the rotifers exposed to high salinity (35 psu) exhibited increased ROS levels with enhanced SOD and CAT enzymatic activities, compared to those in controls (15 psu). Additionally, significant change (P < 0.05) of antioxidant-related genes (GSTs [GSTs-1-1 and GSTs-1-2], MnSOD1 and CAT2) was observed in response to different salinities. Overall, these findings indicate that high salinity induce ROS-mediated oxidative stress, leading to growth retardation and modulation of the antioxidant defense system in B. plicatilis. These findings provide a better understanding on the adverse effects of salinity changes on lifecycle parameters and oxidative stress defense mechanism in rotifers.