The Depuration Effect on Heavy Metals and Total Hydrocarbons Contamination Levels in Donax trunculus and Its Influence on The Expression of Oxidative Stress-Related Genes

Fadiaو Heiba ,Essra El-Rashedy,Mohammed Nassef ,Mahy M Mona

doi:10.21608/eajbsz.2021.153758

Abstract

This study aims to investigate Donax trunculus (D. trunculus) as a biomarker for heavy metals and total hydrocarbon contamination. To achieve this goal, we investigated the effect of 3 day-depuration on the accumulation levels of heavy metals and total hydrocarbons as well as the transcriptional variations in expressions of oxidative stress-related genes of Donax trunculus collected from El-Gameel region, Port Said, Egypt. After 3 day-depuration, all the accumulated tested heavy metals levels showed a considerable decrease (levels after depuration divide by levels before depuration) in D. trunculus tissues by 23%, 20%,72%,98%, 89%, 66% for Pb, Cd, Cu, Fe, Mn and Zn respectively. Additionally, the concentrations of total hydrocarbons in clam’s D. trunculus tissues were reduced to 95%. After 3 days of treatment, the results revealed that the Cat activity decreased to approximately 36% and expression of CYP gene had been up-regulated by about 38%, The Gst gene had been down-regulated by about 2-fold in D. trunculus. Additionally, Mt gene had been up-regulated to approximately 70% and SOD gene had been down-regulated to 50%. To conclude, accumulated heavy metals and total hydrocarbons measured before depuration in the soft parts of D. trunculus was higher than the standard worldwide acceptable limits leading to the hypothesis that D. trunculus in the investigated study area may not be safe for human consumption. Therefore, as a potential public health threat from the seafood diet, more research on the chronic toxic effects of heavy metals and total hydrocarbons in marine species are needed.

Highlights

Owing to their increased potency to move in and gather in the food chain, heavy metals and complete hydrocarbons are among the marine environment's most toxic pollutants. (Tam and Wong, 2000; Erdoğrul and Erbilir, 2007)
After 3 days of treatment, the results revealed that the Cat activity decreased to approximately 36% and expression of CYP gene had been up-regulated by about 38%, The Gst gene had been down-regulated by about 2-fold in D. trunculus
The initial concentration of Mn was the highest value with a mean of 556.03 μg/g reduced after depuration to 89% (495 μg/g) compared to its initial value, while the initial concentration of Cd was the lowest (0.1 μg/g) reduced to less than 20% (0.02 μg/g) of its initial value

Summary

Introduction

Owing to their increased potency to move in and gather in the food chain, heavy metals and complete hydrocarbons are among the marine environment's most toxic pollutants. (Tam and Wong, 2000; Erdoğrul and Erbilir, 2007). Under specific environmental conditions in aquatic systems, heavy metals and hydrocarbons may accumulate to reach a toxic concentration resulting in ecological impairments (Jefferies and Firestone, 1984; Freedman, 1989). The best strategy that has been established for bivalve risk controlling is to use their ability to eliminate pathogenic microorganisms and toxic substances when bivalves are kept in clean uninfected seawater tanks (Wong et al, 1997; Sobsey and Jaykus, 1999; El-Shenawy, 2004). Shellfish managed self-cleaning (depuration) is a common practice used to minimize microorganism loads. It is performed in managed seawater, which is permanently tracked by temperature, salinity, oxygenation and flow rate. The efficacy of the depuration cycle often depends on shellfish abundance and physiology, along with water and system features. (Schneider et al, 2009)

Objectives

Methods

Results

Conclusion