Linking Oxidative Stress and Magnitude of Compensatory Responses with Life-Stage Specific Differences in Sensitivity of White Sturgeon (Acipenser transmontanus) to Copper or Cadmium

Abstract

Sensitivity of white sturgeon (Acipenser transmontanus) to copper (Cu) or cadmium (Cd) has been shown to significantly differ as a function of life-stage. This study investigated oxidative stress, metal homeostasis, and associated compensatory responses as potential mechanisms of this sensitivity pattern in three early life-stages. Sturgeon were most sensitive to Cu at 15 days post hatch (dph), which was accompanied by a significant increase in lipid peroxidation (LPO). Genes involved with amelioration of oxidative stress were significantly less inducible at this stage than in older, less sensitive fry. At 48 dph, acute lethality of sturgeon exposed to Cd was greatest and body LPO was significantly induced by 3.5-fold at 5 μg Cd/L. Moreover, there was a small but significant increase in antioxidative responses. At 139 dph, sturgeon were most tolerant to Cu and Cd and accumulation of these metals was least. Also, expression of metallothionein (MT) and apoptotic genes were greatest while expression of metal transporters was reduced and concentration of LPO was not different from controls. Our results suggest that life-stage specific sensitivity of white sturgeon to metals is complex, encompassing differences in the ability to mount compensatory responses important for metal homeostasis and combating oxidative stress and concomitant damages.

Copper Concentrations in the Upper Columbia River as a Limiting Factor in White Sturgeon Recruitment and Recovery

“…These effects have been documented in fish collected from metal‐contaminated sites and following exposure to Cu in the laboratory. For example, Tang et al (2016) documented elevated lipid peroxidation products in 15 dph white sturgeon exposed to 10 µg/L Cu in background water similar in composition to the Columbia River water. Similarly, elevated lipid peroxidation (oxidative stress), metallothionein increase, and tissue lesions were associated with trace metals in resident trout collected from a mining site with increased concentrations of Cu, Cd, Pb, and Zn (Farag et al 1995).…”

Morphological and Molecular Alterations Induced by Lead in Embryos and Larvae of Danio rerio

“…Exposure to heavy metals triggers several adaptive responses, among which the induction of metal-binding proteins (MTs) involved in both transport and detoxification of metals. Stage-specific differences in the implementation of compensatory responses have been discussed several times in fish exposed to heavy metals [59]. Osman and colleagues [67] showed no significant differences in MTs' expression after exposure to high lead concentrations in embryonic tissues of African catfish (Clarias gariepinus), suggesting that high sensitivity during early stages may be due to the failure of homeostatic mechanisms.…”

“…On the contrary, the significant increase in mtf observed here clearly indicates zebrafish embryos and larvae's ability to mount an adaptive response to lead injuries. According to Tang et al [59], the differential activation of homeostatic mechanisms, including MT induction, may be responsible for species-specific and stage-specific differences in metal sensitivity observed in fishes. Besides, several studies reported that MTs significantly contribute to protecting the organism from oxidative stress acting as scavenging against free oxygen radicals [60][61][62].…”

“…Since the mechanisms through which lead may exert its toxicity may be different and stage-specific, we evaluated the expression of several proteins known as valuable biomarkers of metal exposure in adult fish. To protect themselves against heavy metals, living organisms, including fish and mammals, activate several defense systems, including the metallothionein (MTs) modulation; these are low molecular weight proteins effective for detoxifying non-essential metals, and protecting cells from oxidative stress [35,[56][57][58][59][60][61][62].…”

Analysis of Heavy Metal Pollutant in Wangi River Pasuruan and Its Impact on Gambusia affinis

“…The nature of oxygen (O2) is essentially an electron acceptor so that it will receive free electrons even when it reaches stability, thus forming superoxide (O2.-) these free radicals which bind with oxygen are called Reactive Oxygen Species (ROS), X + + Y-X. + Y: (The process of occurring oxygen species) [37], [40].…”