Negative impacts of chemicals are documented in the environment, but a shortage exists in bioremediation studies for residues of such chemicals in aquatic systems. This study focused on the effects of Ethidium Bromide (EtBr) on fry of Oreochromis niloticus and the role of Spirulina platensis (SP) as a bioremediation agent. Five groups of fish were divided into (1) control, and four treatment groups: (2)10 µg L ^− 1 EtBr, (3)10 µg L ^− 1 EtBr with 200 mg L ^− 1 SP, (4)100 µg L ^− 1 EtBr, and (5)100 µg L ^− 1 EtBr with 200 mg L ^− 1 SP for 15 days. Antioxidant biomarkers–total antioxidant capacity; TAC, Superoxide dismutase; SOD, and catalase; CAT–were assessed. Exposure to EtBr led to a decrease in TAC after exposure to 100 µg L ^− 1 EtBr and 100 µg L ^− 1 EtBr +200 mg L ^− 1 SP. No significant change in SOD and CAT activity was observed compared with control fish, except for fish treated with 100 µg L ^− 1 EtBr. This treatment induces an increase in activity of SOD and CAT. DNA fragmentation increased significantly after exposure to EtBr alone and this increase was counteracted by combined exposure to SP. Exposure to EtBr induced alteration in antioxidant capacity and DNA damage. SP protects against these negative impacts.

Despite extensive research on the toxic effects of microplastics (MPs), there is no obtainable data on the use of phytobioremediation against MPs toxicity in fish. This study aimed to investigate the protective role of lycopene, citric acid, and chlorella against the toxic effects of MPs in African catfish (Clarias gariepinus) using hematology, biochemical, antioxidants, erythron profiles (poikilocytosis and nuclear abnormalities) and the accumulation of MPs in tissues as biomarkers. Five groups of fish received: normal diet (control); 500 mg/kg diet MPs (Group 2); MPs (500 mg/kg diet) + lycopene (500 mg/kg diet) (Group 3); MPs (500 mg/kg diet) + citric acid (30 g/kg diet) (Group 4); and MPs (500 mg/kg diet) + chlorella (50 g/kg diet) (Group 5) for 15 days. Group 2 had significantly higher amounts of MPs in the stomach, gills, and feces, electrolyte imbalances (HCO3, Fe, Na⁺, K⁺, Ca⁺², Cl⁻, and anion gap, hematobiochemical alterations, and decreases in the activities of superoxide dismutase, catalase, total antioxidant capacity, and glutathione S-transferases compared to the control. Additionally, Group 2 had significant increase in the percentage of poikilocytosis, and nuclear abnormalities in RBC's compared to the control group. The co-treatment of MPs-exposed fish with lycopene, citric acid, and chlorella-supplemented diets ameliorated the hematological, biochemical, and erythron profile alterations, but only slightly enhanced the antioxidant activity. Overall, lycopene, citric acid, and chlorella can be recommended as a feed supplement to improve hematobiochemical alterations and oxidative damage induced by MPs toxicity in the African catfish (C. gariepinus).

The present study was aimed to examine the effectsof microplastics on erythrocytes using eryptosis (apoptosis) andan erythron profile (poikilocytosis and nuclear abnormalities)as novel biomarkers in Nile tilapia.Four groups of fishes were used; the first group was the control group, the second group was exposed to (1mg/L of MPs), the third group was exposed to (10mg/L of MPs), and the fourth group was exposed to (100mg/L of MPs) for 15 days and 15 days of recovery. The fish treated with microplasticsexperienced a significant rise in the percentage of eryptosis, poikilocytosis and nuclear abnormalities of red blood cells(RBCs) compared with the control group in a concentration-dependent manner. Poikilocytosis of microplastics exposed- groups included sickle cell, schistocyte,elliptocyte,acanthocyte, and other shapes.Nuclear abnormalities of microplastics exposed- groups included micronuclei,binucleated erythrocytes, notched, lobed, blebbed, and hemolyzed nuclei.
After the recovery period, a greaterpercentage of eryptosis, poikilocytotic cells and nuclear abnormalities in RBCs werestillevident in microplastics-exposed groups compared with the control group.The results reinforceconcerns regarding the toxicity ofmicroplastics in tilapia.

This study examines the potential defending effects of the diatom, Amphora coffeaeformis, as a feed additive versus the deleterious effects (mainly on gonads) caused by microplastics (MPs) in Nile tilapia, Oreochromes niloticus. Groups of male tilapia were pre-fed diets with four different supplementation levels of A. coffeaeformis (0%, 2.5%, 5%, and 7.5%) for 70 days, then exposed to 10 mg/L MPs for 15 days. Thereafter, samples were taken from the four experimental groups and the control fish group, for evaluating blood picture, erythrocytes alterations, biochemical parameters, catalase (CAT), superoxide dismutase (SDO), and total antioxidant capacity (TAC). In addition, male reproductive performance was assessed by quantifying the follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T), also testicular sections and GSI% were also assessed. The results showed that the number of erythrocytes were significantly (p < 0.05) higher, but the number of red blood cells (RBCs), the level of Hemoglobin (Hb), the percentage of Hematocrit (Ht), the number of platelets, and the eosinophil percentages were significantly decreased (p < 0.05) when fish exposed to MPs. Biochemical parameters (ALP, glucose, uric acid, albumin, and A/G ratio) were significantly increased after MP exposure compared with the control group. Furthermore, MPs induced a significant decline in both serum LH and T levels. Testicular, histological, degenerative changes and testis-ova were found in the MP-exposed fish. Thus, A. coffeaeformis supplementation displayed ameliorative properties that detoxified the negative effects of MPs. This study provides a better understanding of the reproductive injuries caused by MPs exposure and evidence for the use of A. coffeaeformis as a natural remedy in freshwater tilapia.

The methanol-to-dimethyl ether (MTD) process has been considered one of the potential methods for manufacturing environmentally friendly fuel, i.e., dimethyl ether (DME). The process requires an efficient, stable, and sustainable catalyst. Herein, metal-organic frameworks (MOF-5, zinc-terephthalate framework) and ZIF-8 (zeolitic imidazolate framework, zinc-imidazolate) were used as sacrificial precursors for the fabrication of MOF-derived ZnO-doped carbon (ZnO@C) via a single carbonization step. The materials were characterized using X-ray diffraction (XRD), thermal analysis (thermogravimetric analysis (TGA) and differential thermal analysis (DTA)), X-ray photoelectron spectroscopy (XPS), Fourier transforms infrared (FT-IR), and nitrogen adsorption-desorption isotherms. The material's acidity was evaluated using isopropyl alcohol dehydration, chemisorption, and pyridine-temperature programming desorption (TPD) analysis. Data analysis reveals that the acidity of ZnO@C is due to Brønsted acidic sites of weak and intermediate strength. ZnO@C catalysts showed an excellent catalytic conversion (100%) towards DME via methanol dehydration with a selectivity of 100%. They displayed a high conversion and selectivity, increasing the percentage of methanol in the reacting stream and gas hourly space velocity (GHSV). They can be recycled several times with high catalytic activity and long-term stability for 160 h.