Heavy metal bioaccumulation and oxidative stress in Austroaeschna inermis (Dragon fly) of the Lagos Urban ecosystem

Abstract

Urban ecosystems are often characterized by the receipt of pollutants, especially heavy metals from diverse anthropogenic activities. To better understand the distribution of heavy metals (Cd, Cu, Pb, Mn and Zn), Austroaeschna inermis from five different sites (Unilag, Mile 12, Olushosun Dump site, Imoshe and Badagry) in Lagos, sediments from the respective sites were assessed. This was followed by assessment of lipid peroxidation product; Malondialdehyde (MDA) and antioxidative stress enzymes; superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and reduced glutathione (GSH) in A. inermis. The results indicate widespread heavy metal distribution with Mn and Zn having the highest concentrations of 13.369±0.800 mg/kg and 21.473±2.001 mg/kg in sediment samples from Mile 12 and Olushosun Dump site respectively. Only Cd was bioaccumulated at two sites (Unilag and Badagry) with biota to soil accumulation factor (BSAF) of approximately 2. The oxidative stress biomarkers assessment in the insects did not indicate any trend to link heavy metal concentrations with respective sites. However there was strong (r ≥ 0.5 < 0.7) to very strong (r ≥ 0.7) positive correlation between Pb concentrations in A. inermis and most biomarkers. All enzymes and MDA showed negative correlation with the other heavy metals with values mostly between strong (r ≥-0. 5<-0.7) to very strong (r ≥-0.7) negative. The findings from this study reaffirms the ubiquity of heavy metals in the City of Lagos and the relevance of the insects as pollution indicators were discussed.

The integration between insect biomonitoring study and GIS study to assess the pollution impacts as oxidative stress parameters within Abu-Zaabal industrial area

“…Research conducted in this study suggests that significant differences of environmental stress marker levels in c. erythrea are not a direct result of the site of insect collection but depend on differences in contamination and pollutants concentration in environment among studied sites. Similar results and finding were observed by Ihechiluru et al, (2015), who found insignificant difference between oxidative stress markers and the sites of collections, however there were strong positive or negative overall correlations between heavy metal concentrations in insects and respective oxidative stress markers.…”

“…ROS are known to convert amino groups of proteins and thereby, change protein structure and function. The oxidative stress increased the number of modified carbonyl groups correlates with protein damage (Hermes-Lima, 2004). Also, ROS can cause fragmentation of the peptide chain, alteration of electrical charge of proteins, cross-linking of proteins, and oxidation of specific amino acids and therefore lead to increase susceptibility to proteolysis by degradation of specific proteases (Kelly and Mudway, 2003;Abdelfattah et al, 2021).…”

“…5-7). It was suggested that the depletion of the antioxidant enzyme activity in male insect may be due to accumulation of heavy metals in male more than female, which lead to inactivate enzyme activity as result of structural changes of the antioxidant enzyme (Iszard ,1995;Wilczek et al 2003;Yan et al, 2007). Also, Zhang et al (2011) referred the depletion of antioxidant enzyme activity occurred due to decrease in protein synthesis which depend on aging (developmental stage).…”

“…Environmental stress primarily increases the production of reactive oxygen species (ROS) in organisms. In aerobic cells, ROS are produced from molecular oxygen as result of normal cellular metabolism (Hermes-Lima, 2004;Sena and Chandel, 2012). Exogenous sources, such as fertilizer industries one of the main exogenous sources that can directly or indirectly influence the level of ROS in cells of different organisms (Amado et al, 2006;Dos Anjos et al, 2011).…”

A Role for Zinc in Plant Defense Against Pathogens and Herbivores

“…Herbivores have also elaborated protective mechanisms against the presence of toxic Zn concentrations in plant tissues. The ingestion of toxic metal concentrations induces ROS causing oxidative stress in herbivores (Ihechiluru et al, 2015). In order to survive, herbivores activate an effective antioxidant defense system (enzymes and non-enzyme compounds) that inhibits the metal-induced oxidative damage (Barata et al, 2005).…”