Evaluation of the Physiological Relationship Between Oxidative Stress and Metabolic Characters: Insights From Hybridization Between Anarhichas minor × A. lupus

Abstract

Physiological indicators such as lipid peroxidation and enzymes involved in aerobic/anaerobic energy metabolism were measured in pure and hybrid lines of wolffish juveniles (Anarhichas minor, ♀ A. minor ⨯ ♀ A. lupus). Interspecific hybridization was introduced as a powerful tool to promote augmentation of phenotypic variability and consequently improve our capacity for the detection of clear physiological relationships amongst oxidative stress and metabolic characters. Mitochondrial sequence genes analysis between the Atlantic (A. lupus) and spotted wolffish (A. minor) were later performed to further assess the extent of divergence between A. lupus and A. minor mitochondrial haplotypes. The observed divergences (2.0% and the number of nonsynonymous substitution n=23) do not seem to be sufficient to generate detectable differences in ETS complexes catalytic capacities. Total LDH activity was however higher in hybrids than in the pure strands and tightly correlated to TBARS levels which suggest that LDH actively participates to the regulation of cellular redox status. Our results are discussed in comparison with a similar study on a charr hybrid (Salvelinus alpinus × S. fontinalis).

Does chronic exposure to moderate hypoxia affect growth, physiological and oxidative stress biomarkers in adult spotted wolffish (Anarhichas minor) and the hybrid A. minor × A. lupus?

“…It was suggested that specific enzyme activity such as LDH and PK may predict the growth rate of the Atlantic wolffish (Lamarre et al., 2004) and of the Atlantic cod (Pelletier et al., 1993), but the result of this study corroborates this statement for PK activity only. The LDH activity relationship with growth was evaluated in juveniles A. minor × A. lupus (Gaudreau et al., 2013), where one family of newly hatched hybrids showed a higher LDH activity compared to newly hatched spotted wolffish. It was suggested that the difference observed was a result of size difference, as the hybrids were smaller.…”

“…The concentration of TBARS was quantified using an assay kit (Zeptometrix No. 0801192, Antylia Scientific) and expressed in MDA nmol ml and carried out as described by Gaudreau et al (2013).…”

“…(2) their growth rate was never examined at this size range and (3) hybridization can cause disruption of co-adaptations of the mitochondrial and nuclear genomes, which in turn can alter aerobic metabolism and increase oxidative stress (functional incompatibilities) and potentially result in (3) decreased fitness (hybrid breakdown phenomenon) (Blier et al, 2006;Du et al, 2017;Gaudreau et al, 2013;Mathers et al, 2014) 2) the measurement of the activity level of aconitase (ACO). We suspect that sublethal DO levels will induce metabolic and oxidative stress and therefore correlate negatively with growth, fish condition and affect metabolic enzyme activity levels in both fish groups.…”

“…Additionally, aquaculture of wolffish (spotted wolffish, Atlantic wolffish and/or their hybrids) is set to take place in Canada (Le François, Fairchild, et al., 2021) and the foreseen rearing technology, land‐based recirculated aquaculture systems (RAS) using low‐level raceways, can potentially generate chronic and acute DO variations due to limited water renewal, volumes involved and elevated fish densities (Foss et al., 2004; Le François et al., 2013; Tremblay‐Bourgeois et al., 2010: 200–300 kg/m 3 ); underlining the importance of evaluating potential long‐term effect of prolonged hypoxia exposure such as growth reduction, reduced appetite, alteration of metabolic pathways, re‐allocation of energy resources, poor feed conversion efficiency and prolonged digestion (Shen et al., 2023; Wang et al., 2009). Hybrids were included in the study because (1) they are of potential interest for aquaculture (Le François et al., 2010); (2) their growth rate was never examined at this size range and (3) hybridization can cause disruption of co‐adaptations of the mitochondrial and nuclear genomes, which in turn can alter aerobic metabolism and increase oxidative stress (functional incompatibilities) and potentially result in (3) decreased fitness (hybrid breakdown phenomenon) (Blier et al., 2006; Du et al., 2017; Gaudreau et al., 2013; Mathers et al., 2014) or (4) improved fitness‐related traits ‘hybrid vigour’ resulting in greater hypoxia tolerance.…”

“…A. lupus being the more coastal species (Barsukov, 1972;Scott & Scott, 1988), it is believed to be adapted to a wider range of environmental conditions, whereas A. minor is considered more stenothermal and inhabits deeper ocean areas (Foss et al, 2001;Le François et al, 2004). Wolffish species can hybridize in nature (Templeman, 1986), and studies on the early development of hybrid wolffish revealed that they were viable despite the detection of slight mitochondrial functional incompatibilities (Gaudreau et al, 2009(Gaudreau et al, , 2013. The 2009 study by Gaudreau et al observed similar growth rates during the first 300 days post-hatch period compared to the pure strains.…”