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Aquatic Toxicology
Elsevier B.V.
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Abstract: |
This study was established to look into the toxicological consequences of chronic exposure to a fungicide (mancozeb;
MAZ) on the immune-antioxidant response, gene expressions, hepato-renal functions, and histological
pictures of Nile tilapia (Oreochromis niloticus). Additionally, the effectiveness of Indian frankincense resin extract
(IFRE) to mitigate their toxicity was taken into account. Fish (n =240; average body weight: 22.45 ± 2.21 g) were
randomized into four groups for eight weeks in six replicates (control, IFRE, MAZ, and IFRE +MAZ), where ten fish
were kept per replicate. The control and IFRE groups received basal diets that included 0.0 and 5 g/kg of IFRE
without MAZ exposure. The MAZ and IFRE+MAZ groups received the same diets and were exposed to 1/10 of the
96-h of LC50 of MAZ (1.15 mg/L). The outcomes displayed that MAZ exposure resulted in a lower survival rate
(56.67 %) and significantly decreased levels of immune-antioxidant variables (antiprotease, complement3,
phagocytic activity, lysozyme, glutathione peroxidase, superoxide dismutase, and total antioxidant capacity)
compared to the control group. The MAZ-exposed fish showed the greatest levels of lipid peroxide (malondialdehyde),
alkaline phosphatase, alanine amino-transferase, and stress indicators (cortisol and glucose). Additionally,
histopathological alterations, including vacuolation, severe necrosis, degeneration, and mononuclear cell infiltrations
in the hepatic, renal, and splenic tissues resulted, besides a reduction in the melanomacrophage center in
the spleen. A down-regulation of immune-antioxidant-associated genes [toll-like receptors (TLR-2 and TLR-7),
nuclear factor kappa beta (NF-κβ), transforming growth factor-beta (TGF-β), phosphoinositide-3-kinase regulatory
subunit 3 gamma b (pik3r3b), interleukins (IL-1β and IL-8), glutathione synthetase (GSS), glutathione peroxidase
(GPx), and superoxide dismutase (SOD)] were the consequences of the MAZ exposure. Remarkably, the dietary
inclusion of IFRE in MAZ-exposed fish augmented the immune-antioxidant parameters, including their associated
genes, decreased stress response, and increased survival rate (85 %) compared with the MAZ-exposed fish. Moreover,
dietary IFRE improved hepato-renal function indices by preserving the histological architecture of the hepatic,
renal, and splenic tissues. The insights of this study advocate the use of an IFRE-dietary addition to protect Nile
tilapia from MAZ toxicity, which provides perspectives for future implementations in enhancing fish health for
sustainable aquaculture.
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