Oxidative stress and RNA/DNA ratio following longline capture in the silky shark Carcharhinus falciformis (Müller & Henle, 1839)
ABSTRACT This study used transcriptomics tracers and measurements of oxidative stress to examine the effect of capture by longline on the silky shark Carcharhinus falciformis. From February 2010 to May 2012, C. falciformis individuals captured in the eastern Pacific Ocean were initially examined for sex, degree of maturity, and morphometric data. Samples were then taken from muscle tissue to determine RNA, DNA, and protein concentrations as well as RNA/DNA and protein/DNA ratios. The levels of three oxidative stress indicators [superoxide dismutase (SOD), glutathione (GSH), and malondialdehyde (MDA)] were determined in muscle. The analysis of the 159 specimens (93 juveniles and 66 adults) showed low RNA/DNA ratios at the different stages of maturity. This basal level of transcriptomics capacity may have been caused by the physiological stress resulting from capture. In juveniles, the low RNA/DNA and protein/DNA ratios were associated with low levels of cellular damage related to oxidative stress, whereas in adults the level of cell damage due to oxidative stress was high, especially in older females. This pattern indicated decreased antioxidant response capacity with increasing age in elasmobranchs.