Oxidative Damage in Response to Natural Levels of UV‐B Radiation in Larvae of the Tropical Sea Urchin Tripneustes gratilla

Abstract

To assess the effects of UV radiation (280-400nm) on development, oxidative damage and antioxidant defence in larvae of the tropical sea urchin Tripneustes gratilla, a field experiment was conducted at two depths in Aitutaki, Cook Islands (18.85°S, 159.75°E) in May 2008. Compared with field controls (larvae shielded from UV-R but exposed to VIS-radiation), UV-B exposure resulted in developmental abnormality and increases in oxidative damage to proteins (but not lipids) in embryos of T. gratilla held at 1m depth. Results also indicated that larvae had the capacity to increase the activities of protective antioxidant enzymes when exposed to UV-B. The same trends in oxidative damage and antioxidant defence were observed for embryos held at 4m, although the differences were smaller and more variable. In contrast to UV-B exposure, larvae exposed to UV-A only showed no significant increases in abnormality or oxidative damage to lipids and proteins compared with field controls. This was true at both experimental depths. Furthermore, exposure to UV-A did not cause a significant increase in the activities of antioxidants. This study indicates that oxidative stress is an important response of tropical sea urchin larvae to exposure to UV radiation.

Diatom-derived oxylipins induce cell death in sea urchin embryos activating caspase-8 and caspase 3/7

“…The transparent embryo enables easy observation of malformation, making it possible to detect sub-lethal effects of pollutants on multicellular body formation at an early stage in development. To date, the stressors that have been examined using the sea urchin as a model include physico-chemical changes in the water, such as acidic pH (Dupont et al, 2010), hypoxia (Kodama et al, 2010), UV Schröder et al, 2005;Bonaventura et al, 2005Bonaventura et al, , 2006Lister et al, 2010aLister et al, , 2010bRusso et al, 2010), X-rays Bonaventura et al, 2011), and chemicals such as antifouling agents/pesticides (Garaventa et al, 2010;Aluigi et al, 2010), endocrine disruptors (Sugni et al, 2010;Horiguchi et al, 2010) and metals (Pinsino et al, 2014;Kiyomoto et al, 2010). Natural toxins represent a major source of stress for marine organisms.…”

Overview of the molecular defense systems used by sea urchin embryos to cope with UV radiation

“…Embryos of this Antarctic species, as many animals adapted to low temperatures, show moderate to high levels of both SOD and CAT enzymes when compared with other marine larvae (Lister et al, 2010a). Similar field experiments on the tropical T. gratilla embryos exposed to UVB, at the depth of 1 and 4 m in the water column, showed that these embryos had increased enzymatic activities of SOD, glutathione peroxidase (GPx) and glutathione reductase (GR), when compared with embryos protected from UVB and used as controls (Lister et al, 2010b). The proteomic analyses on early S. purpuratus embryos showed that UVB induced changes in a large number of proteins that are biomarkers of oxidative stress, i.e.…”

“…Lipids oxidative damage occurred in T. gratilla embryos exposed to solar radiation at depths of 1 and 4 m in field experiments (Lister et al, 2010b). In parallel, the activities of antioxidant enzymes significantly increased (see Section 3.2.1), indicating that embryos upregulate their antioxidant defenses to provide protection to oxidative damages of proteins as well as lipids (Lister et al, 2010b).…”

“…The abnormal morphologies of the survivor embryos indicate that UVR strongly affects development, in particular at the expenses of the skeleton, probably reflecting the energetic costs of the molecular mechanisms activated to prevent and repair damages. This relocation of the energetic resources from development to defense mechanisms might significantly influence larval fitness and⁄ or survivability as suggested by Lister et al (2010b).…”

“…A common form of damage in response to stress is the lipid peroxidation occurring at the plasma membrane that generates H 2 O 2 , an upstream intermediate signal that can activate multiple signaling pathways (Kültz, 2005). Lipids oxidative damage occurred in T. gratilla embryos exposed to solar radiation at depths of 1 and 4 m in field experiments (Lister et al, 2010b). In parallel, the activities of antioxidant enzymes significantly increased (see Section 3.2.1), indicating that embryos upregulate their antioxidant defenses to provide protection to oxidative damages of proteins as well as lipids (Lister et al, 2010b).…”