An ultrastructural study of the seminal vesicle of the hermaphrodite duct of the land snail Limicolaria flammea (Müller) (Pulmonata: Achatinidae)

Genotoxic, Histopathological and Oxidative Stress Responses in Catfish, Clarias gariepinus, Exposed to Two Antifouling Paints

BACKGROUND

Antifouling paints are enriched with biocides and employed in the maritime industry to protect moving and fixed surfaces from fouling activities of sea dwelling invertebrates. There is limited information on their effect on the non-target African catfish, Clarias gariepinus, a commonly consumed fish in Lagos.

OBJECTIVES

This study investigated the effects of two commonly used antifouling paints (Berger TBT-free (A/F783 (H)), reddish brown color and Silka Marine lead based paint, pale orange color) on a non-target catfish species, Clarias gariepinus.

METHODS

The study involved an initial 96-hour acute toxicity assay followed by chronic toxicity evaluation (using 1/10th and 1/100th 96-hour median lethal concentration (LC₅₀) values) for 28 days to determine the ability of the paints to induce micronucleus and red blood cell abnormalities, and histopathological as well as oxidative stress effects in the catfish.Examined anti-oxidative stress enzyme activities include superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and glutathione-s-transferase (GST).

RESULTS

Acute toxicity evaluation results indicated that the Berger paint was 16.1-times more toxic than Silka paint with 96-hour LC₅₀ values of 0.71 mg/L and 11.49 mg/L, respectively. Results from the biochemical assay indicated significantly higher (P<0.05) levels of a lipid peroxidation product, malondialdehyde, in Silka-exposed catfish compared to the control. All enzymes showed significantly higher activities in Berger paint-exposed catfish compared to the control. There was evidence of micronucleated and binucleated cells in the red blood cells of fish exposed to both paints. Histopathological assessment indicated that the exposed fish gills showed evidence of abnormalities such as curved lamellae epithelial necrosis, epithelial lifting and hyperplasia. The liver samples of the catfish showed evidence of portal inflammation as well as mild to severe steatosis, while the gonads showed varying percentages of follicle degeneration.

CONCLUSIONS

The present study combined an array of biomarkers to determine the negative health impacts of two commonly used antifouling paints on non-target catfish inhabiting Lagos Lagoon. Further in situ studies are recommended to determine the current status of the lagoon fish.

ETHICS APPROVAL

Ethical approval was obtained from the Department of Zoology, University of Lagos, Post-Graduate Committee. Note that this work commenced before the establishment of the University of Lagos Ethical Committee for the use of animals and humans in scientific studies. The committee does not give retroactive approval but stands by existing approvals before its establishment. However, this study followed the World Medical Association principles on the treatment of animals used in research (https://www.wma.net/policies-post/wma-statement-on-animal-use-in-biomedical-research/), and also American Fisheries Society Guidelines for the Use of Fishes in Research (https://fisheries.org/policy-media/science-guidelines/guidelines-for-the-use-of-fishes-in-research/).

Oxidative stress, heats shock protein and histopathological effects in the gills of African catfish, Clarias gariepinus induced by bridge runoffs

This study assessed the level of oxidative stress and heat shock proteins (Hsp) induced in gills and liver as well as the histopathological effects in the gills of African catfish, Clarias gariepinus, exposed to runoff water from the Third Mainland Bridge, the busiest bridge in the City of Lagos, Nigeria. The runoff was sampled off the bridge drainage, and the assessment of its physicochemical characteristics in both dry and rainy season indicated a high level of chemical and biological oxygen demand, oil and grease as well as manganese. After a preliminary acute toxicity evaluation, the juveniles of C. gariepinus were exposed to 5, 10, 15, 25, 50 and 100% runoff samples for 30 days. The level of the lipid peroxidation product, malondialdehyde, was significantly different from the control and increased serially with higher concentrations of effluent exposure. There was also an inhibition in the activities of enzymes, superoxide dismutase and catalase as well as significantly lower levels of reduced glutathione after 30 days. Heat shock proteins induced in the catfishes over this period included proteases, sHsps, Hsp 40s, Hsp 60s (for all the fishes-control and exposed) and Hsp 70s (in the exposed fishes only). Histopathological assessments of the gills indicated that the major effects of the runoff exposures were mild to severe thickening and fusion of the gill lamellae, stunting of lamellae, erosion of outer epithelium, epithelial lifting, hyperplasia, oedema and aneurism. The implications of the findings in the Lagos lagoon fishes were discussed.