Vol.3 No.3 – 3: The Antioxidant defense Responses of Sea cucumber Holothuriapolii Against Rickettsia-like organism (RLOs) Infection and Heavy Metal Pollution in Alexandria coast

By : Mohamed M. Elghazaly and Aml Z. Ghoneim

Abstract

Holothuriapolii, the common black sea cucumber (Echinodermata, Holothuroidea), is abundant in Mediterranean Sea alongAlexandria coast. This species was given the great valued commercially and for human consumption.The present study was objective to assess the biological effect of marine pollution on the sea cucumber,Holothuriapolii collected from two locations in Alexandria coast; Abo-Qir station as an industrial area compared with Miami station as a reference area, using the oxidative stress biomarkers approach, heavy metals bio-accumulation, and Rickettsia-like organism (RLOs) infection. Sea cucumber samples were collected from bothstations in Alexandria, during two seasons; winter (January) and summer (July) 2016. Atomic absorption spectrophotometer was used to detect Zn, Mn, pb, Cu and Cd in the body wall of the animal as wellas in water samples.
The resultsshowed a significant decrease in the antioxidant parameters; catalase (CAT), superoxide dismutase (SOD), Glutathione reductase (GSH), and Glutathione transferase(GST) activities, while theMalondialdehyde (MDA) level was significantly increased in the body wall tissue of sea cucumber collected from Abo-Qir station as compared with Miami station.The concentrations of heavy metals (Zn, Mn, Pb, Cu and Cd) in body wall of sea cucumber and sea water samples at the two stations differed significantly, showed increasing in the industrial area (Abo-Qir station) compared with Miami station. As parasites areubiquitous in the marine pollutant environment, so thepresent study proved that the sea cucumber samples collected from Abo-Qir station were infected by Rickettsia-like organism (RLOs), found inthe digestive tract and the respiratory tree of this marine animal. The present results of pollutant biomarkers indicated that, the degree of pollution increased in summer as compared with winter season in the two locations.

This study alsosuggestedthat the sea cucumberwas anideal bioindicator animal for marine pollution. The suppression of antioxidant biomarkers inthe tissue of sea cucumber compared with high values of MDA confirmed the presence of anthropogenic contaminants in Abo-Qir station, which essentially due to the industrial rejections. Also,Rickettsia-like organism (RLOs) infection and the bio-accumulation of theheavy metalsin the tissues of sea cucumber obstructed the antioxidant defense responses in the animal.

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