Insights into biological, immunological, biochemical and ultra-histopathological perturbations as biomarkers to Fluroxypyr-1-methylheptyl ester pollution in freshwater snail, Biomphalaria alexandrina.

Abstract

Biomphalaria alexandrina snails are good invertebrate models for evaluating the chemical toxicity in freshwater habitats. Fluroxypyr-1-methylheptylester (FPMH) is a broad-spectrum herbicide that can find its way to watercourses through effluent. The present work aims to use B. alexandrina as a bio-model to evaluate the toxic effects of FPMH. The present results showed that FPMH has LC₅₀ of 20.7 mg/L after 24 h of semi-static exposure against B. alexandrina snails. After exposure to the sublethal concentrations of FPMH (LC₁₀ and LC₂₅), there were significant (P ≤ 0.05) decreases in survival, reproductive rates and fecundity of adult B. alexandrina snails. Also, there were immunotoxic effects reflected in a significant decrease (P ≤ 0.05) in the total hemocyte count, an increase in the phagocytic index, the percentage of phagocytic hemocytes by flow cytometry and some morphological alterations in the hemocytes. Where hyalinocytes showed abnormalities to in their outer membrane, other cells had degraded or shrunk nuclei according to nucleus/cytoplasm (N/C) ratio. Granulocytes formed pseudopodia and the number of granules increased. These concentrations resulted in significant decreases (P ≤ 0.05; 0.01) in SOD, CAT, Alkaline phosphatase, protein and GSH levels, while increasing GST levels, IL-2 and caspase-3 activity compared to the control group. Also, digestive gland ultrastructural damage occurred after exposure of B. alexandrina snail. Therefore, the study revealed significant adverse effects of FPMH on B. alexandrina snails, highlighted the potential ecological risks of FPMH pollution in freshwater habitats, and demonstrated the use of B. alexandrina as a bioindicator of FPMH pollution in the aquatic ecosystem.