Combined effects of temperature and metal exposure on the fatty acid composition of cell membranes, antioxidant enzyme activities and lipid peroxidation in yellow perch ( Perca flavescens )

Abstract

The aim of this study was to investigate the combined effects of temperature and metal contamination (cadmium and nickel) on phospholipid fatty acid composition, antioxidant enzyme activities and lipid peroxidation in fish. Yellow perch were acclimated to two different temperatures (9°C and 28°C) and exposed either to Cd or Ni (respectively 4μg/L and 600μg/L) for seven weeks. Superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase activities and glutathione concentration were measured as indicators of antioxidant capacities, while malondialdehyde concentration was used as an indicator of lipid peroxidation. Poikilotherms including fish counteract the effects of temperature on phospholipid fatty acid ordering by remodelling their composition to maintain optimal fluidity. Accordingly, in our study, the fatty acid composition of yellow perch muscle at 9°C was enhanced in monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) compared to fish maintained at 28°C, in agreement with the theory of homeoviscous adaptation. Using ratios of various fatty acids as surrogates for desaturase and elongase activities, our data suggests that modification of the activity of these enzymes is responsible for the thermal acclimation of phospholipid fatty acid profiles. However, this response was altered under Ni and Cd exposure: PUFA decreased (specifically n-6 PUFA) while the proportion of saturated fatty acids increased at 9°C, whereas at 28°C, PUFA increased to proportions exceeding those observed at 9°C. Lipid peroxidation could be observed under all experimental conditions. Both enzymatic and non-enzymatic antioxidant defense systems acted cooperatively to cope with oxidative stress leading to lipid peroxidation, which was not affected by temperature acclimation as indicated by malondialdehyde concentration, in spite of a higher polyinsaturation in cold-acclimated fish which would be predicted to increase their vulnerability to peroxidation. However, in warm-acclimated, Ni-exposed fish, in which the highest proportion of PUFA was observed, lower concentrations of malondialdehyde were measured, suggesting an overcompensation of antioxidant mechanisms in these fish which could represent a substantial metabolic cost and explain their lower condition.

Cadmium transcriptionally regulates Scd1 expression in silver pomfret

“…However, 8 weeks of Cd exposure did not change the mRNA level of scd1 in the brain and muscle of fathead minnow . In addition, Scd1 activity was not affected by 7 weeks of Cd exposure in the muscle of yellow perch . It seems that Cd exposure modified the transcription levels of scd1 in a time‐, tissue‐ and species‐specific manner .…”

“…As an environmental stressor, Cd exposure also induces scd1 expression in common carp . However, recent studies in fathead minnow and yellow perch indicated that Scd1 transcription or activity was not affected by Cd exposure . It seems that upregulation in the activity of Scd1 to recompense the fatty acid profile is species specific during Cd exposure …”

Inhibitory effects of glutaraldehyde on Geotrichum citri‐aurantii and its possible mechanism

“…It was recently reported that membrane disruption by some antimicrobial compounds correlates with lipid peroxidation (Chowhan et al ; Pasquariello et al ). MDA, an important marker of membrane stress, is the main product of membrane lipid peroxidation (Fadhlaoui and Couture ; Zhang et al ). In our study, the extracellular and total MDA contents of GA treatments were significantly higher than those of the control group, which indicated that the membrane permeability had changed, and membrane lipid peroxidation had occurred (Fig.…”

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“…A positive correlation does exist with the desaturase index and membrane saturation states, as previously established in two fish species, milk fish and the grass carp when subjected to cold acclimation from 25 °C to 15 °C over 21 days (Hsieh & Kuo 2005). Similarly higher desaturase index for SCD was observed in yellow perch (Perca flavescens) acclimated at 9 °C than at 28°C (Fadhlaoui & Couture 2016).…”

“…In the present study the desaturase index (DSI) (C16:1c9/C16:0) and (C18:1c9/C18:0) were shown to correlate with the saturation states of the membrane and DSI has been used as a surrogate for the measurement of stearoyl-CoA desaturase (SCD) enzyme activity in membrane remodelling in response to temperature (Fadhlaoui & Couture 2016). The enzyme SCD plays a key role in unsaturation of SFA by catalysing the synthesis of MUFA, primarily by the introduction of the first double bond between the C9 and C10 position of the fatty acid which results in increased membrane disorder and enhanced fluidity (Paton & Ntambi 2009).…”