Toxicity effects of multi-walled carbon nanotubes (MWCNTs) nanomaterial on the common carp (Cyprinus carpio L. 1758) in laboratory conditions

Over the past decade, the usages of carbon nanotubes in various industries have been increased. Multi-walled carbon nanotubes (MWCNTs) are special form of carbon nanotubes which are used as nano-absorbents for various purposes of different industries due to their high surface to volume ratio. In aquatic environments these active nano-agents can easily absorb and accumulate in animal cells and tissues due to their tiny sizes and induce toxicity effects on bio-organisms mainly via pro-oxidants production. The present study assayed MWCNTs toxicity effects on anti-oxidative enzymes activities, serum hormonal and biochemical stress biomarkers, hematology parameters, histopathology and growth performance of the common carp Cyprinus carpio. Experiment was conducted in five treatments including 0 (control), 5, 10, 15, 20 mg/l MWCNTs in triplicate and each of the experimental tanks consisted of a 400-l recirculating system, stocked with, 20 fish (12 ± 2 g) for 28 days. The results indicated that by increasing the concentrations of the MWCNTs weight gain, specific growth rate and survival rate parameters were decreased. The findings showed that cortisol secretion, blood glucose level and anti-oxidative enzymes activities were increased with the increase of MWCNTs concentrations in the treatments. Histopathology results depicted that 15 and 20 mg/l MWCNTs caused hyperplasia, telangiectasia, apoptosis, and necrosis damages in gills and also, apoptosis, sinusoidal spaces, fibrosis, hepatocyte degeneration and necrosis in the liver of C. carpio. Despite these findings, further researches on effects of nanomaterials on aquatic organisms and ecosystems are essential to protect these environments against the newly found nanomaterials hazards.

Hematological, hepatic enzymes' activity and oxidative stress responses of gray mullet (Mugil cephalus) after sub-acute exposure to copper oxide

Given the importance of assessing potential toxicity of heavy metals in valuable species of aquatic animals, the goal of the present research was to assess the sub-acute effects of copper oxide on hematological, enzymological, and oxidative stress responses of gray mullet to measure toxicity of copper oxide pollution in this significant fish. The median lethal concentration (LC₅₀) value of copper oxide to gray mullet was detected at 3.15 ± 0.039 mg/L for 96 h, and 25 and 50% of the 96-h LC₅₀ values were selected as sub-acute concentrations. The fish were exposed to (0.79 and 1.57 mg/L) copper oxide for 21 days. At the end of 21 days, the results showed that hemoglobin (Hb), hematocrit (Hct), red blood cells (RBC) count, MCV, MCH, and MCHC levels were found to be decreased in copper oxide treated fish, whereas white blood cells (WBC) count increased in copper-treated fish. Plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) activity increased in treated groups; however, copper oxide in both groups of sub-acute exposure significantly decreased plasma alkaline phosphatase (ALP) activity compared to the control group. Superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels significantly declined in copper oxide-treated fish. These findings indicated the deleterious effects of copper oxide on gray mullet, even at low concentrations, and offered that hematological and hepatic enzyme activity and antioxidants are suitable tools for evaluating heavy metals toxicity.

Camellia sinensis supplemented diet enhances the innate non-specific responses, haematological parameters and growth performance in Mugil cephalus against Photobacterium damselae

This study evaluated the effect of dietary supplementation of Camellia sinensis leaf-extract on non-specific immune responses and disease resistance of Mugil cephalus fingerling against P. damselae. Fish were fed with 0 (unsupplemented), 50, 100 and 200 mg/kg of green tea extract (GTE) supplemented diets. Results indicated that GTE decreased mortality in M. cephalus in a dose-dependent manner after challenge with P. damselae. Haematological parameters containing RBC, Hct, Hb and WBC and growth performance (weight gain) showed remarkable changes in comparison with control group. In addition, the phagocytic (PA) and respiratory burst activity (RBA) significantly increased in M. cephalus, fed 100 and 50, 100 and 200 mg/kg GTE, respectively. Lysozyme statistically increased in GTE supplemented fish. Overall, our results indicated that incorporation of C. sinensis supplemented diet at 100 and 200 mg/kg doses significantly enhanced the immune responses in M. cephalus and that the mortality percentage could be remarkably reduced after challenging the fish against P. damselae.