Fayez A. Bakry

Bio: Fayez A. Bakry is an academic researcher from Theodor Bilharz Research Institute. The author has contributed to research in topics: Biomphalaria alexandrina & Snail. The author has an hindex of 11, co-authored 26 publications receiving 310 citations.

Ecotoxicological Effect of Sublethal Exposure to Zinc Oxide Nanoparticles on Freshwater Snail Biomphalaria alexandrina

Abstract: Freshwater snails are used as sensitive biomarkers of aquatic ecosystem pollution. The potential impacts of zinc oxide nanoparticles (ZnONPs) on aquatic ecosystems have attracted special attention due to their unique properties. The present investigation was designed to evaluate the possible mechanisms of ecotoxicological effects of ZnONPs on freshwater snail Biomphalaria alexandrina. ZnONPs showed molluscicidal activity against B. alexandrina snails, and the LC50 was 145 μg/ml. Two tested concentrations of ZnONPs were selected: The first concentration was equivalent to LC10 (7 μg/ml), and the second was equivalent to LC25 (35 μg/ml). Exposure to ZnONPs (7 and 35 μg/ml) for three consecutive weeks significantly induced malondialdehyde and nitric oxide with concomitant decreases in glutathione and glutathione-S-transferase levels in hemolymph and soft tissues of treated snails. Moreover, ZnONPs elicited a significant decrease in total protein and albumin contents coinciding with enhancement of total lipids and cholesterol levels as well as activities of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase in hemolymph and soft tissues of treated snails. This study highlights the potential ecological implications of ZnONP release in aquatic environments and may serve to encourage regulatory agencies in Egypt to more carefully monitor and regulate the industrial use and disposal of ZnONPs.

Use of some plant extracts to control Biomphalaria alexandrina snails with emphasis on some biological effects.

Abstract: The present work was carried out to evaluate, the molluscicidal activity of cold water, boiled water, methanol, ethanol, acetone and chloroform extracts of some plant species against Biomphalaria alexandrina snails. Preliminary screening tests on 10 plant species showed that the highest molluscicidal potency was recorded for Euphorbia splendens, Atriplex stylosa and Guayacum officinalis. Exposure of B. alexandrina snails to plant’s methanol extracts led to a significant reduction in their survival and growth rates. In addition, newly hatched snails were susceptible to plant’s methanol extracts than elder ones. LC25 of methanol extract from these plants caused a considerable reduction in the infectivity of Schistosoma mansoni miracidia to the snails. It caused a reduction in number of cercariae per snail during the patent period and in the period of cercarial shedding. The results, also, revealed that the glucose concentration in treated snails was increased in haemolymph, while soft tissue glycogen decreased. The activities of glycogen phosphorylase, succinate dehydrogenase (SDH), glucose-6-phosphatase and acetylcholinesterase (AchE) in homogenate of snail’s tissues were reduced (P < 0.001) in response to treatment with plants methanol extract, while glucose-6-phosphate dehydrogenase (G-6-PD) activity increased (P < 0.001). It was concluded that the application of LC25 of methanol extracts of E. splendens, A. stylosa and G. officinalis may be helpful in snail control as it interferes with the snails’ biology and physiology.

The Impact of Three Herbicides on Biological and Histological Aspects of Biomphalaria alexandrina, Intermediate Host of Schistosoma mansoni

Abstract: Schistosomiasis remains a public health problem in the developing world. Biomphalaria alexandrina is the intermediate host of Schistosoma mansoni, with a widespread distribution in Egypt. In Egypt molluscicides have been important, but otherwise molluscicides have been of minor significance. They may, however, become important now that WHO talks about eradicating schistosomiasis in some countries and that WHO has finally accepted that snail control is important.The present study investigated the different effects of three commercial herbicidical compounds, Butralin (as Amex 48% EC), glyphosate isopropylammonium (Herphosate 48% SL) and Pendimethalin (Stomp 50% EC) on B. alexandrina. All three compounds were found to have a molluscicidal effect, with Pendimethalin the most toxic over the examined range of concentrations. In addition, at sublethal concentrations, these compounds reduced growth rates and reproductive output (numbers of eggs laid) in exposed B. alexandrina, and it reduced viability of...

NanoE-Tox: New and in-depth database concerning ecotoxicity of nanomaterials

Abstract: The increasing production and use of engineered nanomaterials (ENMs) inevitably results in their higher concentrations in the environment. This may lead to undesirable environmental effects and thus warrants risk assessment. The ecotoxicity testing of a wide variety of ENMs rapidly evolving in the market is costly but also ethically questionable when bioassays with vertebrates are conducted. Therefore, alternative methods, e.g., models for predicting toxicity mechanisms of ENMs based on their physico-chemical properties (e.g., quantitative (nano)structure-activity relationships, QSARs/QNARs), should be developed. While the development of such models relies on good-quality experimental toxicity data, most of the available data in the literature even for the same test species are highly variable. In order to map and analyse the state of the art of the existing nanoecotoxicological information suitable for QNARs, we created a database NanoE-Tox that is available as Supporting Information File 1. The database is based on existing literature on ecotoxicology of eight ENMs with different chemical composition: carbon nanotubes (CNTs), fullerenes, silver (Ag), titanium dioxide (TiO2), zinc oxide (ZnO), cerium dioxide (CeO2), copper oxide (CuO), and iron oxide (FeO x ; Fe2O3, Fe3O4). Altogether, NanoE-Tox database consolidates data from 224 articles and lists altogether 1,518 toxicity values (EC50/LC50/NOEC) with corresponding test conditions and physico-chemical parameters of the ENMs as well as reported toxicity mechanisms and uptake of ENMs in the organisms. 35% of the data in NanoE-Tox concerns ecotoxicity of Ag NPs, followed by TiO2 (22%), CeO2 (13%), and ZnO (10%). Most of the data originates from studies with crustaceans (26%), bacteria (17%), fish (13%), and algae (11%). Based on the median toxicity values of the most sensitive organism (data derived from three or more articles) the toxicity order was as follows: Ag > ZnO > CuO > CeO2 > CNTs > TiO2 > FeO x . We believe NanoE-Tox database contains valuable information for ENM environmental hazard estimation and development of models for predicting toxic potential of ENMs.

Molecular identification and expression study of differentially regulated genes in the Pacific oyster Crassostrea gigas in response to pesticide exposure

Abstract: The effects of pesticide contamination on the metabolism of marine molluscs are poorly documented We investigated the response of a marine bivalve, the Pacific oyster, Crassostrea gigas, using a suppression subtractive hybridization method to identify up- and down-regulated genes after a 30-day exposure period to herbicides (a cocktail of atrazine, diuron and isoproturon, and to the single herbicide glyphosate) A total of 137 unique differentially expressed gene sequences was identified, as well as their associated physiological process The expression of 18 of these genes was analyzed by RT-PCR under laboratory experimental conditions The metabolic functions they are associated with include xenobiotic detoxification, energy production, immune system response and transcription This study provides a preliminary basis for studying the response of marine bivalves to long-term herbicide exposure in terms of regulated gene expression and characterizes new potential genetic markers of herbicide contamination

Effects of pollution on freshwater aquatic organisms.

Abstract: This paper presents the reviews of scientific papers published in 2018 issues on the effects of anthropogenic pollution on the aquatic organisms dwelling in freshwater ecosystem at global scale. The first part of the study provides the summary of relevant literature reviews followed by field and survey based studies. The second part is based on categories of different classes/sources of pollutants which affect freshwater organism. This is composed of several sections including metals and metalloids, wastewater and effluents, sediments, nutrients, pharmaceuticals, polycyclic aromatic hydrocarbons, flame retardants, persistent organic pollutants, pharmaceuticals and illicit drugs, emerging contaminants, pesticides, herbicides, and endocrine disruptors. The final part of the study highlights the reviews of published research work on new pollutants such as microplastics and engineered nanoparticles which affect the freshwater organisms. PRACTITIONER POINTS: Heavy metals concentrations should be assessed at nano-scale in aquatic environment. Air pollutants could have long-term effects on freshwater ecosystem. Future studies should focus on bioremediations of freshwater pollution.