Liver Of Catfish Research Articles

, , ,

Heavy metal pollution is a serious environmental problem in freshwaters, potentially impacting public health, water quality and ecosystem integrity worldwide. However, the potential public health risks associated with heavy metal accumulation in water, sediment and commercial fish samples remain unclear. Here we assessed the concentrations and distribution of five heavy metal of public health importance (Iron, Copper, Zinc, Lead and Copper) in water, sediment, and edible organs (muscles, liver, gills, and intestines) of the African sharptooth catfish, Clarias gariepinus obtained from aquaculture ponds. Water, sediment, and fish samples were randomly collected from commercial fishponds across different five locations in Ondo. Metal concentrations in water, sediment and fish samples were analyzed using Atomic Absorption Spectrophotometry (AAS, Model AA-680/ Shimadzu). Mean metal levels observed in water, sediment and fish samples were compared with recommended regulatory guidelines for human consumption. Our results showed mean concentrations for all metals in water exceeded recommended permissible limits in freshwater bodies and aquatic biota, presumably suggesting potential risks for human consumers. Heavy metal levels in sediment samples indicated Fe was maximally accumulated, followed by Zn, Cu, Pb, and Cd. The highest and least accumulations for all the metals were recorded in the gills, and in the liver respectively. Higher concentrations of metals observed in gills corroborate the fact that the gill is a major route for heavy metal accumulation in fish whereas the reduced concentration of metals observed in the liver may be associated with enhanced detoxification mechanism in the liver. These results suggest that fish obtained from these aquaculture ponds may be unsafe for human consumption. Hence, we recommend a periodic assessment of heavy metal levels in commercial fish samples as a major regulatory priority.

Impact of hexaconazole on histo-architecture of liver and intestine of freshwater African catfish, Clarias gariepinus (Burchell, 1822

Impact of hexaconazole on histo-architecture of liver and intestine of freshwater African catfish, Clarias gariepinus (Burchell, 1822

A fish-parasite sentinel system in an assessment of the spatial distribution of polychlorinated biphenyls

The spatial distribution of polychlorinated biphenyls (PCBs), in the Zemplínska Šírava water reservoir and adjacent tributaries in the Bodrog River Basin were investigated using a fish-parasite sentinel system. PCB concentrations were detected in various fish matrices (dorsal and abdominal muscles, liver and intestine) of the Wels catfish (Silurus glanis) and its intestinal cestode Glanitaenia osculata. PCB concentrations in the fish from the water reservoir, located closest to the chemical plant, the primary source of the PCB pollution, were the highest. The analysis of these contaminants in catfish matrices showed the highest concentrations in the abdominal muscle, followed by the dorsal muscle, liver and intestine. Concentrations of ∑PCBs exceeding the limits for food set by European regulations were measured in the muscle tissue of catfish at all sites, even in the Bodrog River, 60 km away from the primary source of contamination, posing a significant risk to humans in the Zemplín region. For the first time, the ability of cestode G. osculata to accumulate higher amounts of PCBs compared to fish matrices has been demonstrated. Due to the enormous ability of the parasites to accumulate PCBs, we recommend this approach for alternative biomonitoring of PCBs in contaminated aquatic environments.

Artemisinin alters disposition regularities of enrofloxacin and its metabolite ciprofloxacin in channel catfish (Ictalurus punetaus) following combined oral administration

The aim of this investigation was to explore the effect of artemisinin (ART) on pharmacokinetic (PK) and tissue distribution characteristics of enrofloxacin (ENR) and ciprofloxacin (CIP) in channel catfish following combined and single medicine. The channel catfish in ENR group were treated with ENR, and the fish in ENR-ART group were orally co-administrated with ENR and ART. ENR and CIP concentrations in channel catfish were determined using ultra performance liquid chromatography, and PK parameters for ENR and CIP were calculated by WinNonlin software. Moreover, the multi-drug resistance 1 (MDR1) gene expression and cytochrome P-450 3A (CYP 3A) enzyme activities in channel catfish liver were measured. The results showed that lower ENR and CIP levels were observed in ENR-ART group than that in ENR group, and similar regularities in PK parameters were also found that Cmax, AUC and MRT values in ENR group were all greater than those in ENR-ART group. Furthermore, higher MDR1 gene expression and CYP 3A enzyme activities in channel catfish liver were observed in ENR-ART group than those in ENR group. The present investigation indicates that ART can reduce the ENR concentrations, accelerate the excretion of ENR and decrease the antibacterial efficacy of ENR in channel catfish.

Alterations in energy metabolism, total protein, uric and nucleic acids in African sharptooth catfish (Clarias gariepinus Burchell) exposed to crude oil and fractions

Water contamination by crude oil is a growing challenge and little is known about the probabilistic and non-probabilistic ecosystem and species consequences. Therefore, research aimed at understanding species survival strategy in crude oil-contaminated environments with focus on cellular metabolic alterations and dynamics is vital. This study assessed the alterations in lactate dehydrogenase (LDH), glucose (GLU), glucose-6-phosphate dehydrogenase (G-6-PDH), total protein (TP), uric and nucleic acids (UA, RNA, and DNA) in the liver, heart, kidney, blood supernatants, and muscle homogenates of African sharptooth catfish ([ASC] Clarias gariepinus) exposed to varying bonny-light crude oil concentrations to understand the underlying cause of their delayed development as well as potential health and wellbeing. Three concentrations (20, 50, and 100 mg/L) of diluted whole bonny-light crude oil (DWC), water-soluble (WSF), and water-insoluble (WIF) fractions of bonny-light crude oil were used to grow ASC for 9 weeks at room temperature. Biochemical assessments revealed significant (at p < 0.05) elevations in heart LDH (48.57 ± 4.67 to 3011.34 ± 4.67 U/L) and blood G-6-PDH activities (54.86 ± 0.00 to 128 ± 18.29 mU/mL), GLU (0.22 ± 0.01 to 0.77 ± 0.01 mg/dL), TP (5.15 ± 0.14 to 22.33 ± 0.21 g/L), UA (0.29 ± 0.05 to 10.05 ± 0.27 mg/dL), as well as liver DNA (0.38 ± 0.02 to 2.33 ± 0.09 μg/mL) and RNA (12.52 ± 0.05 to 30.44 ± 0.02 μg/mL) levels for laboratory-grown ASC in DWC, WSF, WIF, and oil-impacted Ubeji river collected ASC relative to the control. Due to greater levels of cellular metabolic alterations in oil-impacted Ubeji River collected ASC, it is evident that bonny-light contamination levels in the river is greater than 100 mg/L. In conclusion, bonny-light crude oil is toxic to ASC and induces stress response. The ecological changes caused by bonny-light crude oil contamination may ultimately affect niche functioning and the development of organs in ASC.

CRISPR/Cas9-mediated precision integration of fat-1 and fat-2 from Caenorhabditis elegans at long repeated sequence in channel catfish (Ictalurus punctatus) and the impact on n-3 fatty acid level

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are essential for the development and health of human and animals. However, n-3 PUFAs in human diets, aquaculture and livestock feed are mainly from oily marine fishes. To improve n-3 fatty acid levels in channel catfish (Ictalurus punctatus), we generated transgenic channel catfish carrying codon optimized Caenorhabditis elegans fat-1 gene encoding an n-3 fatty acid desaturase and fat-2 gene encoding the delta12 fatty acid desaturase using CRISPR/Cas9 technology. We used a special cocktail design of donor plasmid, utilized mixed HDR, MMEJ and NHEJ repair pathways, and targeted long repeated DNA target sequence (LRS) to improve knock-in (KI) efficiency. Our results showed that two donor DNAs precisely inserted into at least four genomic sites. Detectable on-target KI efficiency of fat-1 was 9.1% (55/605), three times higher than that of fat-2, which might due to the smaller size of the donor fat-1. Sanger sequencing results suggested that HDR was the dominant repair pathway using this method, leading to the highest proportion of on-target KI events. Reverse transcription PCR (RT-PCR) and quantitative real-time PCR (qRT-PCR) demonstrated that the fat-1 and fat-2 transgenes had strong expression, and also greatly improved fads6, elovl2 and elovl5 gene expression in liver and muscle tissues of transgenic channel catfish. Fatty acid analysis showed the fat-1-only transgenic channel catfish had the lower levels of 14:0, 16:0, 18:2n-6, total n-6, and the higher levels of DHA, total n-3 and n-3/n-6 ratio than other genotypes including the fat-2-only, co-integration of fat-1 and fat-2, and wild-type control. In particular, DHA, total n-3 and n-3/n-6 ratio were significantly increased by 37%, 19.8% and 25.2%, respectively, in the fat-1-only transgenic fish than that in the wild-type control (P < 0.05). Our fat-1 and fat-2 KI channel catfish hold promise for improving fish nutritional value, reducing fish oil requirement in aquaculture feed, and serving as an alternative source of n-3 PUFAs.

Effects of cadmium (Cd) on histopathological lesions in the liver of a freshwater catfish, Heteropneustes fossilis

Effects of cadmium (Cd) on histopathological lesions in the liver of a freshwater catfish, Heteropneustes fossilis

Lead biosorption and histological changes in gills and liver of juvenile african catfish (Clarias gariepinus) treated with neem (Azadirachta indica) and mango leaves (Mangifera indica)

Lead (Pb) is non-biodegradable in nature, thus accumulate in the environment especially the aquaculture. This study was aimed at investigating lead biosorption and histological changes in gills and liver of juvenile African catfish (Clarias gariepinus) treated with neem (Azadirachta indica) and mango leaves (Mangifera indica). A total of 180 healthy juveniles of Clarias gariepinus were used for the period of six (6) weeks of this experiment. They were divided into two groups of pulverized neem and mango leaves with ninety (90) in each. They were further divided into three groups of thirty (30) with each comprising of two experimental groups of 10mg/L and 15mg/L of Pb and control. Experiment of biosorption was conducted in muscle, gills and liver while the histology was conducted in the gills and liver only. The results of pulverized neem showed a significant difference (P&lt;0.0001) of biosorption of 15mg/L Pb in muscle, gills and liver with higher value (0.0017) in muscle while in pulverized mango, both 10mg/L and 15mg/L appeared statistically significant (P&lt;0.0001) with liver (0.003) and gills (0.003) respectively had higher statistical values. There was irreversible histological damages of the gills in PNL and 15mg/L of Pb and PNL and 10mg/L Pb and a reversible histological damage in PML and 15mg/L Pb and PML and 10mg/L Pb groups. The histology of the liver appeared irreversibly damage in groups PNL and 15mg/L of Pb and PML and 15mg/L and reversibly damage in PNL and 10mg/L Pb and PML and 10mg/L Shows fatty degenerated parenchyma with focal necrosis with slight sinusoidal distortion. In conclusion, biosorption of lead is more effective with PML since the damage to the tissues are minimal and reversible.

Metallothionein levels on the gill and liver of Mystus nigriceps (Valenciennes, 1840) in Welang River, Pasuruan City, East Java

This research was conducted in October 2021 using a survey method. Sampling was carried out three times with a span of every 2 weeks at 3 stations along the lower reaches of the Welang River Pasuruan Regency. Parameters observed included cadmium metal content in fish gills and liver, metallothionein levels in gills, and liver of M. nigriceps. Fish and the relationship between cadmium metal and metallothionein levels in the gills and liver of M. nigriceps in the Welang River. The average yield of cadmium metal content in the gills of M. nigriceps is 5.943-8.103 mg/l. Meanwhile, the average result of heavy metal content in the liver of M. nigriceps is 6.397-9.997 mg/l. Measurement of metallothionein levels showed that the average level of metallothionein in the gills of M. nigriceps was 5.860-8.688 ng/mL. Meanwhile, the average level of metallothionein in the liver of M. nigriceps is 7.110-8.334 ng/mL. And the results of the linear regression test showed that the average content of cadmium in the gills and liver with the average metallothionein levels in the gills and liver of catfish was significantly correlated.

The Use of Cinnamon Essential Oils in Aquaculture: Antibacterial, Anesthetic, Growth-Promoting, and Antioxidant Effects

Cinnamon essential oils (EOs) are widely known for their pharmaceutical properties; however, studies investigating the use of these EOs in aquaculture are scarce. The aims of this study were to evaluate the anesthetic effect of bathing silver catfish (Rhamdia quelen) with Cinnamomum cassia EO (CCEO) and its nanoemulsion (NCCEO); the growth-promoting and antioxidant effects of dietary supplementation with CCEO in silver catfish; and the in vitro antibacterial effect of CCEO, NCCEO, and Cinnamomum zeylanicum EO (CZEO) against bacteria isolated from diseased silver catfish. The two cinnamon EOs showed promising antibacterial activity, which was potentiated by the nanoemulsion. CCEO showed satisfactory anesthetic activity in silver catfish, and its nanoemulsion intensified the sedative activity. Supplementation of 1.0 mL CCEO per kg of diet for 60 days increased weight, length, and weight gain when compared to the control group, evidencing the growth-promoting activity of this EO. Dietary supplementation of CCEO for 30 and 60 days also showed an antioxidant effect, as it decreased levels of thiobarbituric acid reactive species and increased the superoxide dismutase activity in the liver of silver catfish. Therefore, cinnamon EOs have a promising use in aquaculture.

Insights into the mechanisms of tris(2-chloroethyl) phosphate-induced growth inhibition in juvenile yellow catfish Pelteobagrus fulvidraco.

With the gradual elimination of brominated flame retardants (BFRs), the production and application of tris (2-chloroethyl) phosphate (TCEP), as a substitute of BFRs, has increased greatly. The objective of the present study was to comprehensively explore the potential adverse effects of TCEP on fish growth and the possible underlying mechanisms. To this end, juvenile yellow catfish (Pelteobagrus fulvidraco) were exposed to environmentally relevant concentrations of TCEP (0, 1, 10 and 100 µg/L) for 30 days. The results showed that exposure to high concentrations of TCEP (10 and 100 µg/L) significantly decreased body weight, body length and specific growth rate (SGR). Plasma IGF-I levels and hepatic mRNA levels of igf1 and igf1r were all reduced, while the transcriptional levels of IGFBPs (igfbp2, igfbp3, igfbp5) were significantly up-regulated in the liver of yellow catfish under exposure to 10 and 100 µg/L TCEP. TCEP-induced growth inhibition might be related to somatostatin (SS) signaling system, as evidenced by elevated mRNA transcriptions of ss in brain and its receptors (sstr2, sstr3, sstr5) in liver. In addition, fish exposed to high concentrations of TCEP displayed multiple histological alterations in liver. Taken together, these findings suggested that TCEP (>10 µg/L) might exert its inhibitory effect on fish growth through interfering with the GH/IGF axis and SS signaling system, and by impairing hepatic structures.

Glutamine synthetase (GS) deficiency can affect ammonia tolerance of yellow catfish Pelteobagrus fulvidraco

Glutamine synthetase (GS) plays a crucial role in the regulation of glutamine synthesis in fish which is a very effective ammonia detoxification strategy. In this study, the full-length GS was cloned from the liver of yellow catfish. The full-length cDNA sequence of GS was 1928 bp in length and encoded 371 amino acids. The amino acid sequence of GS showed high homology (99%) with that of channel catfish. The highest mRNA expression of GS was found in the brain of yellow catfish. Acute ammonia stress (96 h LC50) significantly increased ammonia levels in plasma, liver, and brain, and GS gene expression was significantly up-regulated in the liver and brain. RNA interference inhibited the GS mRNA expression level in primary cultured hepatocytes after acute ammonia stress and reduced hepatocyte survival rate. It is suggested that GS plays a key role in ammonia detoxification in yellow catfish by regulating glutamine synthesis.

Feed Restriction Alleviates Chronic Thermal Stress-Induced Liver Oxidation and Damages via Reducing Lipid Accumulation in Channel Catfish (Ictalurus punctatus).

Caloric restriction is known to suppress oxidative stress in organ systems. However, whether caloric/feed restriction alleviates chronic thermal stress in aquatic animals remains unknown. Here, we set up three feeding rations: 3% BW (3% body weight/day), 2.5% BW (restricted feeding, 2.5% body weight/day) and 2% BW (high restricted feeding, 2% body weight/day), to investigate the effects and mechanism of feed restriction on improving chronic heat-induced (27 to 31 °C) liver peroxidation and damages in channel catfish (Ictalurus punctatus). The results showed that, compared to 3% BW, both 2.5% BW and 2% BW significantly reduced the liver expressions of hsc70, hsp70 and hsp90, but only 2.5% BW did not reduce the growth performance of channel catfish. The 2.5% BW and 2% BW also reduced the lipid deposition (TG) and improved the antioxidant capacity (CAT, SOD, GSH and T-AOC) in the liver of channel catfish. The heat-induced stress response (plasma glucose, cortisol and NO) and peroxidation (ROS and MDA) were also suppressed by either 2.5% BW or 2% BW. Moreover, 2.5% BW or 2% BW overtly alleviated liver inflammation and damages by reducing endoplasmic reticulum (ER) stress (BIP and Calnexin) and cell apoptosis (BAX, Caspase 3 and Caspase 9) in the liver of channel catfish. In conclusion, 2.5% body weight/day is recommended to improve the antioxidant capacity and liver health of channel catfish during the summer season, as it alleviates liver peroxidation and damages via suppressing lipid accumulation under chronic thermal stress.

Identifying miRNAs in the modulation of gene regulation associated with ammonia toxicity in catfish, Clarias magur (Linnaeus, 1758).

The small non-coding microRNAs play a vital role in post-transcriptional gene regulation associated with different physiological events such as metabolism, stress, etc. The freshwater catfish, Clarias magur, can grow within hyper ammonia containing stagnant water bodies and/or muddy substratum. We intended to identify organ-specific miRNAs associated with ammonia stress management. The miRNA-libraries were generated from QC passed total RNA extracted from liver, muscle, and kidney of ammonia-treated (exposed to 25mM NH4Cl for 14days) and untreated catfish. The libraries were validated using High sensitivity D1000 Screen tape. The trimmed quality-filtered reads for control and treated samples of kidney were 19,406,210; 14,904,423; for liver 15,467,727; 18,582,072; and for muscle 25,081,345; 19,782,182 respectively. Total 120 known and 150 novel differentially expressed miRNAs were identified, out of which miR-200, miR-217, miR-122, miR-133, miR-145, miR-221, miR-19, miR-138, miR-34, and miR-184 were predicted to be involved in the metabolism of nitrogen. The key miRNAs targeted several genes associated with urea synthesis like Glutaminase 2, Argininosuccinate lyase, Glutamate dehydrogenase 1, Alanine aminotransferase 2-like, Aspartate aminotransferase, cytoplasmic-like, Glutamate ionotropic receptor NMDA type subunit 2A, etc. CONCLUSIONS: This is the first report of miRNAs, which serve as a vital resource for regulating nitrogen metabolism in freshwater catfish, C. magur. The data will be resourceful for further evaluating the regulatory role of miRNAs in fishes, which grow and reproduce very well in hazardous ammonia-contaminated water bodies.

Impact of Sodium Arsenate on Histological Changes in Liver and Kidney of Fresh Water Catfish, Clarias batrachus

Background: In new age, Arsenic is a major environmental pollutant and exposure occurs through agricultural, environmental, medicinal and occupational sources. The toxicity of sodium arsenate has been shown in catfish, Clarias batrachus and the histology report suggested that the sodium arsenate may adversely effect on the catfish, Clarias batrachus. Methods: The histological analysis carried out during the period of 2018-19 for sodium arsenate with Clarias batrachus as test animal for 96 hour as per ideal method and determine the lethal concentration (LC50). The liver and kidney tissues were collected from the fishes exposed to sodium arsenate and standard histology procedure were followed to investigate the histological alterations. Result: Exposure of sodium arsenate causes severe histological changes in liver like nucleus blabbing, infiltration, necrosis of hepatocytes, disruption of normal architecture, shrunkeri hepatocytes, lytic hepatocytes etc. In kidney sodium arsenate exposure causes hemorrhage, inflammation and tubular atrophy in renal tubules, disruption of tubular linings, dense chronic inflammation, hemorrhage and vacoulation in Bowman’s capsule etc. The present investigation suggests that the inorganic forms of arsenic showing the highest toxicity level.

HSF1-SELENOS pathway mediated dietary inorganic Se-induced lipogenesis via the up-regulation of PPARγ expression in yellow catfish

At present, studies involved in the effects of dietary Se sources on lipid metabolism were very scarce and the underlying mechanism remains unknown. Previous studies reported that dietary Se sources differentially affected selenoprotein S (SELENOS) expression and SELENOS affected lipid metabolism via the inositol-requiring enzyme 1α (IRE1α)- spliced X-box binding protein 1 (XBP1s) pathway. Thus, we used yellow catfish as an experimental model to explore whether dietary selenium sources affected the hepatic lipid metabolism, and further determined the role of SELENOS-IRE1α-XBP1s pathway in dietary selenium sources affecting hepatic lipid metabolism. Compared with the selenomethionine (S-M) group, sodium selenite (SS) group possessed higher liver triglycerides (TGs) (34.7%), lipogenic enzyme activities (57.9–70.6%), and lower antioxidant enzyme activities (23.3–35.5%), increased protein levels of heat shock transcription factor 1 (HSF1) and SELENOS (1.17-fold and 47.4%, respectively), and XBP1s- peroxisome proliferators-activated receptor γ (PPARγ) pathway. Blocking SELENOS and PPARγ by RNA interference demonstrated that the SELENOS/XBP1s/PPARγ axis was critical for S-S-induced lipid accumulation. Moreover, S-S-induced upregulation of SELENOS was via the increased DNA binding capacity of HSF1 to SELENOS promoter, which activated the XBP1s/PPARγ pathway and promoted lipogenesis and lipid accumulation. XBP1s is required for S-S-induced upregulation of PPARγ expression. Our finding elucidated the mechanism of dietary Se sources affecting the lipid metabolism in the liver of yellow catfish and demonstrated novel function of SELENOS in metabolic regulation. Our study also suggested that seleno-methionine was a better Se source than selenite against abnormal lipid deposition in the liver of yellow catfish.

Detection, diagnosis, Koch’s postulate, hepatorenal and antioxidant indicators for some systemic pathogenic fungi invading the liver and kidneys of African catfish ( Clarias gariepinus ) in Egypt with a histopathological approach

Recently, systemic fungal infections have emerged as significant causes of fish morbidity and mortality. Hence, the current study investigates the occurrence of some pathogenic systemic fungi inducing severe lesions in the liver and kidneys of African catfish. Two hundred diseased African catfish were collected from private fish farms in Egypt, and only 120 fish were infected with 212 different fungal isolates at a rate of 60%. The seasonal survey revealed isolation of 72 isolates of yeast (Candida albicans) and 140 isolates of moulds including non-pigmented moulds, Aspergillus ochraceous and Aspergillus flavus, as well as pigmented mould (Cladosporium herbarum). The isolated fungi induced characteristic post-mortem lesions. To date, this is the first report for isolation of C. herbarum and C. parapsilosis from Nile catfish liver and kidneys. Various techniques were performed to identify the fungi including gross observation, microscopic examination of tissue squashes, in vitro culture and histopathology. Koch's postulate was fulfilled to confirm the fungal pathogenicity. The challenged fungi altered the hepatorenal indicators (ALP, AST, ALT, urea and creatinine) and oxidative stress biomarkers (MDA, CAT and SOD). The results indicate the virulence of the isolated fungi, and future studies are needed for treatment trials.

Toxicity of Aqueous Stem-Bark Extract of Albizia chevalieri on the Liver and Kidney of Juvenile African Catfish (Clarias gariepinus)

Toxicity of Aqueous Stem-Bark Extract of Albizia chevalieri on the Liver and Kidney of Juvenile African Catfish (Clarias gariepinus)

Optical coherence tomography as an alternative tool for evaluating the effects of glyphosate on hybrid catfish (Clarias gariepinus × Clarias macrocephalus)

Glyphosate contamination in fresh water is a major problem in agricultural countries. It affects many vital organs in freshwater organisms that are important in the food chain. Hence, the effects of glyphosate on living organism organs are of particular interest. However, several existing techniques for evaluating the effect of glyphosate on aquatic organisms require stained tissue. To study organ tissue with minimal processing, alternative technique is demanded. Here, we investigated the used of optical coherence tomography (OCT) as an alternative tool for ex vivo evaluation of the effect of glyphosate on organ tissues of aquatic organisms, i.e., hybrid catfish (Clarias gariepinus × Clarias macrocephalus). The targeted samples were organ tissues from the brain, gill, and liver of hybrid catfish after glyphosate exposion at concentration of 10 mg L−1 for 24 h. The alteration was then verified by histology, and immunohistochemistry. The study found that all three techniques provide correlated results. We observed that OCT clearly showed damage to the brain and gill tissues of glyphosate-exposed hybrid catfish. However, the alteration in liver tissue was observable but not clear for this low concentration of exposure. The results from histology and immunohistochemistry confirmed the effect of glyphosate on brain, gill, and liver tissues of hybrid catfish. The results suggest that all three techniques could be used to examine the effects of glyphosate exposure in hybrid catfish. However, the choice of a suitable technique depends upon the purpose of the study.

Histological Alterations in Some Organs of African Catfish (Clarias gariepinus) Exposed to Sub-lethal Concentrations of Glyphosate [N-(phosphonomethyl) glycine

This study used a static bioassay to investigate the histological effects of glyphosate on the gill, liver and muscle of African catfish (Clarias gariepinus) fingerlings. This was done with a view of further characterising the effect of glyphosate on C. gariepinus fingerlings and other aquatic life forms. Six-week old C. gariepinus fingerlings with an average weight of 10.02 ± 0.2 g were stocked into three exposure sets (control, 2.75 ppm (25% of the 96 h LC50 value) and 5.50 ppm (50% of the 96 h LC50 value)) in triplicate at 30 fish per tank for 70 days. The 96 h LC50 value was 11.00 mg/L. Histological examination of the C. gariepinus exposed to various sublethal concentrations of glyphosate showed that major histological changes in their organs were concentration dependent such as gill arch vacuolation, excessive mucosal secretions, lifting of epithelial, and epithelium thickening, hyperplasia and telangiectasis in the gills, discolouration, change in form and consistent alterations involving hyperplasia, narrowing of the central nerve, necrosis, pkynosis, blood congestion and vacuolation of the liver, mild hyperplasia and inflammatory responses in the muscle of the fish. The severity of histological alteration was more pronounced in fish organs exposed to 5.50 ppm of glyphosate concentration. This study concluded that the toxicant (glyphosate) is highly toxic to C. gariepinus particularly at a concentration of 5.50 ppm, therefore its use near farm lands or adjacent water bodies should be discouraged.