Protective effect of Nannochloropsis Oculata against mercuric-induced histopathological alterations in the kidney of Nile tilapia.

Abstract

The present study was designed to evaluate the toxic effect of sublethal concentration of mercuric chloride (0.3 mg/L HgCl2) on histopathological lesions in the kidney of Nile tilapia (O. niloticus) and the protective effect of microalgae, Nannochloropsis oculata (N. oculata) against the induced tissue alterations for 3 weeks. Design: Randomized controlled study Animals: Nile tilapia Procedures: Fish were randomly assigned to 4 groups, group1: control (basal diet), group 2 (Hg/ exposed to HgCl2 at a dose of 0.3 mg/L (1/4 of LC50), and fed basal diet), group 3: (Hg+N5, similar to group2, but fed diet supplemented with N. oculata 5% and group 4 (Hg+N10, similar to group2, but fed diet supplemented with N. oculata 10 %. Two fish from each aquarium tank (6 fish/group) were sampled at weeks 1, 2, and 3 of the experiment. The posterior kidney was dried out in a graded ethanol series and then embedded in paraffin. Each block of tissue was cut into serial sections (5 μm thick) and stained with hematoxylin and eosin (H&E). Results: Histopathological alterations were induced following mercuric exposure in a time-dependent manner. The kidney showed congestion, hemosiderosis, and hemorrhage with vacuolated tubula r epithelium, hyaline droplet degeneration, and necrosis of the tubular epithelium. Supplementation with N. oculata, particularly at 10 %, succeeded in alleviating the histopathological induced lesions in the kidney. Conclusion and clinical relevance:Our findings demonstrate that HgCl2 has nephrotoxic properties that led to severe histopathological alterations in the kidney of Nile tilapia, while dietary supplementation with N. oculata was able to alleviate the induced kidney alterations.

Therapeutic efficacy and bioaccumulation of albendazole in the treatment of tambaqui ( Colossoma macropomum ) parasitized by acanthocephalan ( Neoechinorhynchus buttnerae )

“…For parasitological analysis and evaluation of total residue bioaccumulation 6 fish from each treatment were sampled (Leonard et al, 2014;Mamdouh et al, 2020). To have a mean total residue ingestion at each time point a randomized collection was conducted.…”