MEPS 561:99-107 (2016)  -  DOI: https://doi.org/10.3354/meps11946

ABSTRACT: To understand the effects of UV radiation on the Antarctic copepod Tigriopus kingsejongensis and the temperate copepod Tigriopus japonicus, the 96 h half lethal dose (LD50-96h) was calculated and compared with the levels of intracellular reactive oxygen species (ROS), antioxidant enzymatic activities, and gene expression profiles of the defensome in response to UV radiation over time (control, 1, 3, 6 h) in these copepods. ‘Defensome’ refers to the integrated system of defense mechanisms—such as detoxification, antioxidation, apoptosis, and cell proliferation—that were altered by UV exposure. The LD50-96h and no observed effect level (NOEL) at 96 h after UV exposure were determined as 23.16 kJ m^-2 and 12 kJ m^-2, respectively, in T. kingsejongensis and 26.42 kJ m^-2 and 12 kJ m^-2, respectively, in T. japonicus. ROS levels in response to 12 kJ m^-2  UV increased slightly (p < 0.05) in T. kingsejongensis over time, and were also higher (p < 0.05) in T. japonicus. Transcript levels of antioxidant-related genes were mostly down-regulated in response to 12 kJ m^-2 UV radiation, except for glutathione-S transferase delta epsilon (GST-Delta-E), manganese-superoxide dismutase (Mn-SOD), glutathione reductase (GR), and glutathione peroxidase (GPx) genes in T. kingsejongensis. T. japonicus heat shock protein (hsp) genes were mostly up-regulated, but only small hsp genes (hsp10 and hsp20) showed up-regulation in T. kingsejongensis. This finding provides a better understanding of how UV radiation affects in vivo endpoints and the relevant molecular response in 2 different copepod species from contrasting environments.

KEY WORDS: Ultraviolet radiation · Antarctic copepod · Temperate copepod · Tigriopus kingsejongensis · Tigriopus japonicus · Reactive oxygen species