Abstract
One mechanism of pollution resistance in marine populations is through transgenerational plasticity, whereby offspring capacity to resist pollution reflects parental exposure history. Our study aimed to establish correlations between oxidative stress biomarkers and key reproductive fitness parameters in the temperate sea urchin Evechinus chloroticus following exposure to dietary polycyclic aromatic hydrocarbons (PAHs). PAH-exposed adults exhibited total gonad tissue concentrations of PAHs in excess of 4 and 5 times baseline levels, for females and males respectively. Antioxidant enzymes were upregulated and oxidative lipid and protein damage to gonad tissues occurred. In addition, early stage offspring reflected maternal antioxidant status, with progeny derived from exposed females demonstrating significantly higher baselines than those derived from control females. Maternal exposure history enhanced the capacity of embryos to minimise oxidative damage to lipids and proteins following exposure to additional PAHs, but provided less of an advantage in protection against oxidative DNA damage. Abnormal embryonic development was largely independent of oxidative damage, remaining high in all embryo populations regardless of parental PAH-history. Overall, results document evidence for maternal transfer of antioxidant potential in E. chloroticus, but imply that a short-term inherited resilience against oxidative stress may not necessarily translate to a fitness or survival gain.
Highlights
The phenotype of an animal is influenced by its genotype and the physical environment in which it lives, and by interactions with other organisms[1]
Research investigating the link between reproduction and oxidative stress has so far been limited to a small number of vertebrate studies, as reviewed by ref. 12, and the impacts of reactive oxygen species (ROS) on life-history evolution across a greater range of taxa remains to be explored
Our study aimed to establish correlations between a range of oxidative damage and defence biomarkers and key reproductive fitness parameters in the temperate sea urchin Evechinus chloroticus, an important keystone species endemic to coastal New Zealand[28]. This was carried out using experimental induction of oxidative stress via dietary administration of polycyclic aromatic hydrocarbons (PAHs), a group of widespread and highly toxic contaminants found in the marine environment[29]
Summary
The phenotype of an animal is influenced by its genotype and the physical environment in which it lives, and by interactions with other organisms[1]. Given that development potentially imposes high levels of ROS it has been hypothesized that animals should have evolved comprehensive mechanisms to counteract oxidative stress during this period[23] Despite their widespread use as model organisms, studies employing oxidative stress biomarkers in echinoderms are few[15, 18, 19, 24,25,26] and our knowledge regarding the stage(s) of development at which marine invertebrate embryos start to generate their own antioxidant systems rather than relying on those that are maternally derived is limited. The following questions were asked: 1. Do short-term (21 day) dietary exposures to PAHs during the peak reproductive period cause changes in oxidative stress biomarkers in adult male and female E. chloroticus gonad tissue and released gametes?
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