Effects of Various Light Spectra on Physiological Stress and DNA Damage by Thermal Stress in Juvenile Rock Bream (Oplegnathus fasciatus)

: In this study, we investigated the effects of light spectra on physiology stress and DNA damage in juvenile rock bream ( Oplegnathus fasciatus ) using light-emitting diodes (LEDs; green, 520 nm; red, 630 nm) at two intensities (0.25 and 0.5 W/m 2 ) with application of thermal stress (25 and 30 o C). We measured the mRNA expression of heat shock protein 70 ( HSP70 ) and the levels of plasma cortisol, glucose, aspartate aminotransferase (AspAT), and alanine aminotransferase (AlaAT). Additionally, DNA damage was measured using comet assays. Our findings showed that HSP70 mRNA expression and plasma cortisol, glucose, AspAT, and AlaAT levels were significantly higher after exposure to high temperatures and were significantly lower after exposure to green LED light. Thus, although high water temperatures induced stress in juvenile rock bream, green LED light inhibited stress. In particular, green LED light reduced stress and DNA damage to a greater degree than other light sources.