Assessment of the Impact of Cadmium on the Redox Status and Metabolic Profile of the Sea Urchin Paracentrotus lividus

Summary

This protocol highlights the methods of extraction and characterization of bioactive compounds from the sea urchin Paracentrotus lividus (Echinoderm) as well as determination of oxidative stress parameters after cadmium exposure.

Abstract

Cadmium (Cd) is one of the most harmful heavy metals to aquatic organisms and a widespread pollutant in marine biota. Because of its high bioavailability, persistence, and ability to bioaccumulate, cadmium (Cd), a toxic heavy metal discharged by mining runoff, industrial discharge, and agricultural inputs, is one of the most detrimental pollutants to aquatic organisms and a common pollutant in marine biota. The current study assessed the potentially toxic effects of cadmium on oxidative stress biomarkers and metabolite profiles in Paracentrotuslividus gonads exposed to a range of concentrations (0.0183, 0.183, and 1.83 mg/L) over 96 h. The results showed that Cd induced oxidative stress by increasing malondialdehyde, hydrogen peroxide, and lipid hydroperoxide levels compared to the control group, as well as increasing antioxidant activities (reduced glutathione and catalase). In addition, based on the gas chromatography-mass spectrometry analysis, 74 metabolites were identified in the gonadal extracts of both treated sea urchins and the control. The Partial Least Squares Discriminant Analysis revealed a clear class separation and discriminated nine relevant metabolites through the VIP scores. The performed heatmap analysis highlighted disturbance in the levels of sterols and fatty acid compounds such as Cholest-5-en-3-ol(3.beta.)-, Desmosterol, and (23S)-ethylcholest-5-en-3.beta.-ol and eicosapentaenoic acid (EPA), as well as the antioxidant defenses such as retinoic acid, and steroid regulation such as Pregna-5-en-20-one, 3-hydroxy-,(3β). Overall, our data revealed the high sensitivity of gonads to Cd, even at relatively low concentrations.

Introduction

The marine environment can also be considered an important sink for several toxic chemicals, such as heavy metals. Due to their lipophilicity, these elements have a tendency to bind with suspended particulate matter and progressively build up in marine sediments, where they show decreased mobility and bioavailability. As a result, marine sediments serve as a major heavy metal sink¹. Among these contaminants, Cadmium (Cd) has long been acknowledged as a major global water pollutant that threatens ecosystems and their related biota². One-third of the Cd present in aquatic ecosystems comes from the manufacturing and us....

Protocol

1. Samples and experimental design

1. Collect a total of 40 adult sea urchins P. lividus specimens (20 males and 20 females, mean length: 45 ± 4 mm, mean age: 2.0 ± 0.5 years, mean weight: 22.54 ± 2.50 g) by divers at the depth range of 5-7 m in May 2023 from Bizerte coasts (Mediterranean Sea, Tunisia).
2. Transfer the collected sea urchins P. lividus of mixed sex, estimated age approximately 12-18 months based on size to the lab and keep in aerated natural seawater 16 ± 1 °C with natural salinity of ~38 PSU, pH of 7.8-8.0 and photoperiod of 12:12. Monitor the parameters daily throughout the e....

Results

The validity and efficacy of our methods were ensured by the use of biological and technical replicates, which enabled consistent and reliable measurements. The assays demonstrated low variability, with standard deviations typically less than 10%, indicating high repeatability. To ensure accurate metabolite quantification, GC-MS analyses included calibration curves and internal standards. All techniques used are based on widely accepted protocols that have previously been validated in mar.......

Discussion

This study was planned to evaluate the toxic effect of Cd on the sea urchin P. lividus gonads by analyzing biochemical biomarkers and active metabolites. The exposure of P. lividus to different concentrations of Cd produced an oxidative stress response. These findings are similar to previous reports indicating close correlations between the increased antioxidant levels in the sea urchin grounds and contaminant levels¹³.

Our results revealed a significa.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Freeze dryer	Biobase	BK-FD12PT freeze dryer	Lyophilization
Gas chromatograph	Agilent Technologies	HP 6890 gas chromatograph	Flame Ionization Detector (FID)
GC column	Agilent Technologies	HP-5 (5%-Phenyl)-methylsiloxane column	Nonpolar column that delivers superb performance in a wide range of applications
Mass spectrometer	Agilent Technologies	HP 5973 mass spectrometer	Quadrupole MS