Channa Punctatus Research Articles

Fish Distribution Pattern and Management in the Tinau River, Palpa

For study direct observation, survey, questionnaire, interviews and discussion method are used to meet the objectives. The main objectives of the study were fish distribution pattern and fish management. The field work was performed between September 2016 to june 2017 of different five stations in Tinau river. Local fishermen were also used for the collection of fishes from sampling sites. Cast net, hook, Bhureli jal and Nets (Jhal) other locally available devices were used for the collection of fish sample. Altogether 5 orders, 9 families, 14 genera and 25 species were found in the study area. Among them 19 fish species from Station I, 16 fish Species from Station II and station III, 10 fish species from Station IV and 7 species from Station V were collected with the help of local fisherman. Fish species such as Channa punctatus, Puntius conchonius and Glyptothorax pectinopterus were found to be clumped in distribution while the rest of the fishes were uniformly distributed. Cyprinids were found to be the most common and dominant among all the species. The human impacts like construction of dam, bridges, riverbed extraction, bank erosion, illegal fishing and use of poisonous chemicals effects on the fish distribution and management directly of the Tinau river. For the management practices like implementation of strict rules and regulations, made ladder for fish passing, construction of fish barrier, plantation, control water pollution and awareness programmes should be done with the help of local people and other institutions. This study helps the local people to pay more attention towards the knowledge about indigenous or locally found fishes and proper management of the Tinau river.

Correction: Cyto-genotoxic Alterations in Erythrocytes of Fish, Channa Punctatus Exposed to Benzo[a]Pyrene

Correction: Cyto-genotoxic Alterations in Erythrocytes of Fish, Channa Punctatus Exposed to Benzo[a]Pyrene

Histochemical Analysis of DNA and RNA Identified by Methyl Green - Pyronin ‘Y’ Method and Feulgen’s Reaction Staining in Liver of Channa Punctatus

The light microscopy was to identify cells, storage products, tissue deposits, and microbial pathogens. The Assessment of surrounding tissue with special stains may reveal aspects of interest for the tissue. We illustrate the expected staining characteristics of control Channa punctatus liver tissue with Methyl Green -Pyronin ‘Y’ and Feulgen’s Reaction stains. The aim of this study was to characterize the normal structure of the liver of Channa punctatus, a carnivorous freshwater fish found in Hasanparthy Lake, using gross anatomy, histology and histochemistry. Anatomically, the liver presents C-shaped and only two lobes smaller right and bigger left. The gallbladder is located in right lobe and shows elongated shaped. Histological analysis demonstrated that the hepatic parenchyma is made of two hepatocytes plates surrounded by sinusoids. The fish moreover pancreatic tissue was observed in visceral portion of liver, formed by exocrine pancreatic tissue and islet organ, constituting an extrahepatic pancreas. The nucleic acids content in different tissues in the freshwater fish of Channa punctatus. The fish were scarified and the tissues such as liver and Pancreas removed and processed for determination of nucleic acids. The results obtained in the present study may provide a contribution to the knowledge of the characteristics of nucleic acid as parameters of estimation of DNA and RNA levels in Liver of the fish.

“Copper-loaded microplastics unleash endoplasmic reticulum stress-driven liver apoptosis in fish Channa punctatus”

The extensive use of plastics has led to significant microplastic pollution, posing threats to environmental and human health. Concerns are growing about the toxicity of microplastics (MPs) and their ability to adsorb contaminants like Copper (Cu2+). Therefore, this study investigated the effects of environmentally realistic concentrations of Polyvinyl Chloride (PVC)-MPs and Copper, both individually and together, with a particular focus on triggering Endoplasmic reticulum (ER) stress-driven apoptosis in the liver of Channa punctatus. Well-habituated fish were organized into four groups: Group I (Control), Group II (0.5 mg/L PVC-MPs), Group III (0.85 mg/L Copper), and Group IV (0.5 mg/L PVC-MPs + 0.85 mg/L Copper). The treatment period was 15, 30, 45 and 60 days. Various liver parameters were assessed according to standard protocols to understand the repercussions of intoxication. A significant (p < 0.05) increment in Reactive Oxygen Species (ROS) pointed to a substantial rise in oxidative stress. Enzymatic antioxidants like superoxide dismutase (SOD) and catalase (CAT) showed significantly (p < 0.05) elevated extents while reduced glutathione (GSH) levels significantly (p < 0.05) dropped in a duration-dependent pattern. Additionally, lipid peroxidation (LPO) activities surged significantly (p < 0.05), and notable hepato-structural disruptions were observed. The evidence of liver damage was further verified by a significant (p < 0.05) rise in concentrations of hepatic biomarkers viz. Serum Glutamic Oxaloacetic Transaminase (SGOT), Serum Glutamic Pyruvic Transaminase (SGPT), and Alkaline phosphatase (ALP). Moreover, ER-stress was validated through the increased intracellular calcium levels along with the heightened expression of grp78, chop, atf4, perk, eIF2α, and gadd34 in exposed groups. This intricate cascade subsequently elicited the activation of bax, caspase-3, caspase-9, and apaf-1, while modulation of bcl-2, thereby driving hepatocyte-apoptosis via ER-stress response in C. punctatus, a widely consumed food-fish. Our findings underscore the toxic threats of Copper-laden PVC-MPs to aquatic life and potentially the broader ecosystem.

Effects of Arnebia benthamii Extract on Growth Performance, Immunological Parameters and Disease Resistance against Flexibacter columnare in Spotted Snakehead Channa punctata (Bloch)

Herbal immunostimulants are known to improve disease resistance in fish by enhancing specific and non-specific defensive mechanisms. The present study was conducted to evaluate the effects of Arnebia benthamii extract (AE) on growth rate, immune status, and disease resistance towards Flexibacter columnare in spotted snakehead Channa punctata. Each experimental group of healthy C. punctata was fed on one of the four experimental diets viz. basal diet (without any AE supplementation), AE10 (supplemented with 10 mg AE/kg basal diet), AE20 (supplemented with 20 mg AE/kg basal diet) and AE40 (supplemented with 40 mg AE/kg basal diet) for 42 days. When the concentration of Arnebia benthamii was raised from 0 to 40 mg/kg, the weight gain (WG) and specific growth rate (SGR) were considerably enhanced. The lysozyme activity, C3, C4, and serum globulin levels were also significantly increased in all Arnebia benthamii supplemented groups. IgM concentration in fish fed on AE40 diet was significantly higher than in fish fed on basal diet. All A. benthamii treatment groups exhibited significantly higher survival rates after being challenged with F. columnare. These findings showed that supplementing diet of C. punctata with A. benthamii improved growth, immunological response, and disease resistance against F. columnare, with the greatest benefits in fish fed on AE40 diet for 42 days.

Organophosphate, carbamate and synthetic pyrethroid pesticide residues in muscle tissues of fish from Loktak Lake, a Ramsar Site in Manipur, India

The muscle tissues of Channa punctatus and Anabas testudineus collected from the Loktak Lake (a Ramsar site) and its three major feeder rivers in Manipur, Northeastern India, were analyzed using high-performance liquid chromatography for the presence of residues of organophosphorus, carbamate, and synthetic pyrethroid pesticides. Pesticide residues of all the three types were detected in the fish tissues. Pesticide residues in Channa punctatus ranged from 0.002 – 0.043 µg g-1, and from 0.008 –0.027 µg g-1in Anabas testudineus from Loktak lake in pre-monsoon and post-monsoon seasons. Pesticide residues were detected only in Anabas testudineus (0.002 – 0.078 µg g-1) in Nambul river, while these were detected only in Channa puctatus (0.001 – 0.032 µg g-1) in Moirang river. In Nambol river, pesticide concentrations ranged from 0.002 – 0.026 µg g-1 in Channa punctatus, and from 0.004 – 0.005 µg g-1 in Anabas testudineus. Among the five pesticides detected, concentrations of dichlorvos residues detected in the present study (0.027 and 0.032 µg g-1 wet weight) exceeded the Codex Alimentarius maximum residue limit (MRL) of 0.01 mg kg-1 for animal tissues. The rest of the compounds were within the MRL. None of the pesticide residues was detected in the two fish species collected from the control or reference site. The present study indicates that pesticide contamination is emerging as a threat to the water quality and aquatic biodiversity of Loktak Lake, which calls for more detailed studies on the extent and magnitude of these threats.

Herbicide paraquat dichloride augments the expression of the c-abl-noxa-apoptotic pathway, instigating ovarian atresia in edible fish, Channa punctatus.

Ovarian cells of animals undergo atresia to regulate egg numbers and their release. However, unrestrained atretic activity decreases the chances of oocyte maturity and further process, ultimately resulting in a reduced population. Edible fishes are a critical source of nutrition and it is required to regulate their population. The application of herbicides at fish production sites is a threat to their population by altering female reproductive activity. In concern to this, here, this 60-day study investigates herbicide paraquat dichloride (PD)-induced atresia in ovarian cells of Channa punctatus (C. punctatus). Further, 96-h LC50 of PD for C. punctatus was calculated as 58.40mg/L. At the end of each exposure period, an increase in intracellular ROS in blood cells and activities of SOD and CAT in ovary tissue were observed in PD-treated fish with increasing concentration. The frequency of micronuclei in blood cells subsequently increased with the highest PD concentration. A significant (p < 0.05) increase in the relative expression of target genes was observed at the 30th and 60th day of the sampling periods in the fish treated with the highest concentration of PD. The histological study confirmed the occurrence of atretic ovary cells in PD-exposed fish. From the results it can be concluded that PD enhances the uncontrolled death of ovarian cells and has consequences of impairing the ovary health and reproductive potential of fish, hence reducing the fish population.

Insights into molecular characterization of NOD1-RIPK interaction and transcriptional modulation in response to LPS in spotted snakehead, Channa punctata (Bloch, 1793)

NOD1, plays a pivotal role in immune responses against bacterial as well as viral invasions. While the downstream signaling pathway of NOD1 is well understood in mammals, its characterization in lower vertebrates remains elusive. In present study, an effort was made to identify and characterize downstream signaling cascade of NOD1 in response to LPS, a potential ligand of NOD1 in teleosts, in spotted snakehead. In addition, the temporal effect of LPS on transcriptional modulation of NOD1 and its downstream signaling molecule RIPK2 was investigated. Docking studies revealed well conserved leucine rich domains of NOD1 that could bind with LPS. Further, NACHT-ATP interactions revealed differences in ATP binding motifs within the NACHT domain in spotted snakehead compared to those reported in other fish species and mammals pointing towards species-specific nature of ATP interactions within the NACHT domain. Further, it was revealed that the ssNOD1-CARD domain interacts with the CARD domain of downstream signaling molecule ssRIPK. Interestingly, LPS treatment modulated the expression of both, ssNOD1 and ssRIPK2 in a time-dependent manner.

Morphological and molecular identification of Euclinostomum heterostomum (Trematoda: Clinostomidae) from spotted snakehead Channa punctata in Bangladesh.

Parasites belonging to the trematode family Clinostomidae have a global distribution. Freshwater fish in Bangladesh frequently serve as hosts for different clinostomid species. During the metacercaria stage, the digenetic trematode Euclinostomum heterostomum exhibits a specific preference for Channidae species, where it undergoes encystment within the liver, kidneys, and muscles of these hosts. The study aimed to identify E. heterostomum in Channa punctata through combined morphological and molecular analysis. Light and scanning electron microscopy were conducted to investigate the morphological characteristics of the species. The histological examination of the infected liver tissue revealed the presence of encysted flukes, inflammatory leukocyte infiltrates, and degeneration and loosening of hepatic tissue. In molecular analysis, the generated internal transcribed spacer 1 (ITS1), 5.8S ribosomal DNA and ITS2 regions sequence (GenBank accession no: OR591452) of 830 bp showed 100% identity with Euclinostomum heterostomum identified in India (MT785786). The phylogenetic reconstruction provided substantial evidence of genetic similarities (0-1% genetic distance) among different isolates of the genus Euclinostomum, suggesting that there is a shared heritage.

Radiological characterisation of freshwater fish species from strategic locations in Bangladesh

A radiological assessment of inland freshwater fishes of wetland haor zones, near a uranium mine and Rooppur Nuclear Power Plant (RNPP) areas, was performed. Gamma spectrometric analysis showed the accumulation of 226Ra, 228Ra, and 40K in all studied fishes, with varying degree levels of concentrations. The average radioactivity levels of 226Ra, 228Ra and 40K in haor fish samples ranged from 2.76 ± 1.51 to 22.02 ± 3.81 Bq kg−1, 1.78 ± 0.69 to 21.53 ± 1.40 Bq kg−1 and 405.51 ± 22.04 to 749.80 ± 42.65 Bq kg−1, respectively. Conversely, the respective values for Bata fish samples of Rooppur Nuclear power plant sites varied from 2.66 ± 0.80 to 6.62 ± 0.81 Bq kg−1, 2.31 ± 0.62 to 5.18 ± 49.81 Bq kg−1 and 342.00 ± 4.98 to 461.45 ± 18.00 Bq kg−1, respectively. Activity levels of Taki fish (Channa punctatus) from haors zones were almost 3–4 times higher than the Meni fish (Nundus nundus) of the same locations and Bata fish (Labeo bata) of the RNPP site. The general public may attain doses of 244.54 µSv from the consumption of haor fish and 84.02 µSv from the fish of the RNPP sites yearly. The chance of an increase in cancer risk from intake of haor fish was higher than the ICRP values of 2.9 × 10−4. Univariate statistics showed that 226Ra and 228Ra radionuclides do not normally distribute, whereas 40K is normally distributed in the studied fish species. Multivariate statistical analysis demonstrated that the radioactivity and estimated radiological parameters are strongly positively correlated with 226Ra and 228Ra, and also positively correlated with 40K. Hence, it indicated that the contents in the freshwater fish species are usually controlled and influenced by similar geogenic sources and occur together. It is presumed that the radiological risk is mostly associated with and dominated by the uranium and thorium series and non-series 40K radionuclides in the freshwater fish species.

A study on membrane enzyme Na+-K+-ATPase in lindane exposed fish, Channa punctatus

Na+-K+-ATPase is a membrane bound enzyme responsible for the transport of ions through the membrane and immediate release of energy. This enzyme is known to be an early target for oxygen radical induced damage to intact cell. Exposure of C. punctatus to subacute concentrations of lindane for 96 h caused significant reduction in the activities of Na+-K+-ATPase in all the tissues of the fish tested; brain being maximally affected and the heart being least affected organ at the highest concentration of lindane (0.1 mg/L). The effect of pesticide was concentration dependent. The percent decrease in the activity of Na+-K+-ATPase in brain, gills, heart, kidney, liver and muscle was found to be 36.7, 23.4, 19.2, 29, 22.9 and 29.7, respectively. The order of level of enzyme activity recorded was as following: liver &gt; gills &gt; kidney &gt; brain &gt; muscle &gt; heart in the control.

Novel ACE inhibitory peptides from enzymatic hydrolysate of Channa punctata protein: In vitro and In silico assay of structure-activity relationship

Channa punctata flesh meat is well known for its ethnomedicinal values. The objective of this study was to isolate and identify peptides having Angiotensin-Converting Enzyme (ACE) inhibitory potential from the Channa punctata fish protein hydrolysates (FPH) and to investigate the inhibitory mechanism by docking study. ACE inhibitory potential of the ultrafiltrate of C. punctata 240 min protein hydrolysates was analysed. The PrAHyd240 (<3 kDa) had the strongest ACE inhibitory potential as it has the lowest IC50 value i.e., 66.08 μg/ml. To identify the ACE inhibitory peptides, PrAHyd240 (<3 kDa) was evaluated by LC ESI mass spectrometer. The amino acid residues of 3 peptides within the intensity count 100–250 were determined by de novo sequencing.The docking analysis reveals that the peptides were deeply buried in the active site of ACE. Thr 5 of ISISTSGGSFR, Val 3 of SLVNLGGSK, and Val 6, Ala 7 of SISISVAR form highly stable metal coordination bonds with the Zn cofactor present in the binding site of ACE. Similar to captopril, the peptide SISISVAR interacted with the amino acids His 353 and His 513 of the binding sites of ACE via H-bond interactions. The MD simulation study reveals that the peptides ISISTSGGSFR, SLVNLGGSK, and SISISVAR interacted with the Zn+ ion via H-bond with 100% occupancy respectively. The above study reveals that Channa punctata protein hydrolysate is a rich source of ACE inhibitory peptides and the isolated peptides ISISTSGGSFR, SLVNLGGSK, and SISISVAR are potential ingredients in the preparation of functional foods.

Incidence and pathological effects during encysted progenetic Euclinostomum heterostomum metacercariae infection in the freshwater fish spotted snakehead (Channa punctatus)

Aim: To assess the incidence and pathological effects during encysted progenetic Euclinostomum heterostomum metacercariae infestation in the freshwater fish spotted snakehead (Channa punctatus). Methodology: Samples of Channa punctatus were collected from Tilaiya Reservoir, Koderma, Jharkhand, India, during pre-monsoon, monsoon, and post-monsoon seasons. The encysted metacercariae trematodes were isolated from Channa punctatus. Characterization was performed based on the morphology and sequencing analysis of a partial 18S rRNA gene. Further, the kidney and liver samples from infected fish were subjected to histopathological studies. Prevalence, abundance, and Intensity of infection were further determined. Results: Morphological identification suggests that the encysted metacercariae belonged to Digenean trematodes of genera Euclinostomum, and amplification of partial sequence of 18S rRNA, and phylogenetic analysis revealed the isolated metacercariae were Euclinostomum heterostomum. The histopathological study of the kidney showed hepatocyte degeneration, cytoplasmic vacuolation, and nuclear transformations. Liver fibrosis was observed in Channa punctatus. The prevalence during pre-monsoon, monsoon, and post-monsoon season ranged from 66.1% to 81.1%, abundance from 0.74 to 0.92, and intensity ranged from 1 to 1.14 using the Margolis formula. Interpretation: The study highlights the infestation of Euclinostomum heterostomum in Channa punctatus during the pre- monsoon climate appears favorable for the abundance of parasites. Hence, a proper inspection before consumption is necessary. Key words: Euclinostomum heterostomum, Infestation, Metacercariae, Parasites, Progenetic infection

Protein level alteration and micronuclei induction in Channa punctatus fish exposed to chlorpyrifos and their alleviation by Melissa officinalis and Mentha piperita extracts

Aim: To assess alteration in the protein levels of major organs and induction of micronuclei in the freshwater fish, Channa punctatus following exposure to chlorpyrifos, while also investigating the potential mitigating effects of extracts from Melissa officinalis and Mentha piperita on the adverse impacts induced by this pesticide. Methodology: Two weeks of acclimatized healthy fish were divided into four different groups. Group G1 served as the control group, while G2 contained chlorpyrifos (LC50/10, 96 hr). Group G3 was exposed to chlorpyrifos (LC50/10, 96 hr) along with 8 mg l-1 of Melissa officinalis ethanolic extract, and similarly, G4 contained chlorpyrifos (LC50/10, 96 hr) along with 8 mg l-1 ethanolic extract of Mentha piperita. Sampling was conducted over various durations of 7, 14, 21, and 28 days. The ethanolic extracts of Melissa officinalis and Mentha piperita were used as remedial compounds as they are rich in several bioactive compounds, primarily polyphenols. Results: The investigation revealed a notable decrease in the total protein content of kidney, liver, gills and muscles following exposure to chlorpyrifos after each sampling duration. While, upon exposure to remedies containing the ethanolic extracts of Melissa officinalis and Mentha piperita, the protein levels exhibited a significant recovery (p &lt; 0.05) in a duration-dependent manner, compared to the control group. This suggests a promising ameliorative capability of Melissa officinalis and Mentha piperita against chlorpyrifos toxicity. Further, the induction of micronuclei by chlorpyrifos and their subsequent recovery through the application of phytoextracts Melissa officinalis and Mentha piperita displayed a similar pattern, indicating the potential protective effects of these extracts against chlorpyrifos-induced genotoxicity. Interpretation: It is plausible to conclude that standardized doses of Melissa officinalis and Mentha piperita hold the potential to enhance aquaculture practices and safeguard fish production in agriculturally contaminated water bodies. These findings emphasize their valuable contribution in sustaining fish health amidst toxic environments. Key words: Channa punctatus, Chlorpyrifos, Melissa officinalis, Mentha piperita

Effects of Ammonium Chloride on Some Vital Organs of Snakehead Fish, Channa punctatus (Bloch.)

The present study includes the chronic exposure of sublethal concentrations (20 mg/L) of inorganic fertilizer, ammonium chloride for 30 days to snakehead fish, Channa punctatus caused histopathological alteration in some vital organs. There were very significant histopathological changes were observed in gill, liver, intestine and kidney of treated fish group. The ammonium chloride treated fish group showed lamellar fusion, deterioration of secondary lamellae, hemorrhage and destruction of gill arches in gill. The remarkable changes like hyperemia, vacuolar degeneration, necrosis and mononuclear cells filtration in portal regions were observed in liver of treated fish group. The very distinguish alterations like hydropic degeneration, necrosis, desquamation in epithelium cells at the apex of the villi and mononuclear cell infiltration in the lamina propria were observed in kidney and proximal and distal tubules cellular shrinkage, nuclear pycnosis, and vacuolar degenerative changes in the tubular epithelium were observed in treated fish group. The finding of present investigation clearly analyzed that ammonium chloride caused dysfunction of some vital organs of C. punctatus. The study suggested that contamination of fertilizer, ammonium chloride in fish culture pond water should be avoided to fish production.

Heavy Metal Intake by Fishes of Different River Locations in Bangladesh: A Comparative Statistical Review

Bangladesh a nation with a high population density, gets all of the protein it needs from river fishes. The observation is very alarming that heavy metals polluted the major river water by the growing garment washing, dyeing and textile, fertilizer, cement, tannery, metal, electrochemical and pharmaceutical industries were the main culprits that don’t have proper effective effluent treatment plants (ETP). High-value heavy metals in industrial area river fish as chromium (Cr) 164.73 mg/kg in Heteropneustes fossilis (stinging catfish) at Buriganga River, Hazaribagh, zinc (Zn) 309.47 mg/kg in Mastacembelus armatus (Bain) fish at Bangshi river, Savar, copper (Cu) 26.33 mg/kg in Mastacembelus armatus (Bain) at Bangshi river, Savar, arsenic (As) 5.64 mg/kg in Heteropneustes fossilis (stinging catfish) at Bangshi river, Savar, lead (Pb) 18.16 mg/kg in Channa punctatus (Taki) at Buriganga river, Hazaribagh and cadmium (Cd) 2.03 mg/kg in Heteropneustes fossilis (stinging catfish) at Buriganga river, Hazaribagh were observed. The two rivers are identified as most contaminated by heavy metals one is the Bangshi River, Savar, Gazipur and another one Buriganga River, Hazaribagh. The main reason for the contamination of these two rivers was uncontrolled industrialization around Dhaka and in Hazaribagh, a huge number of tanneries have grown that use a huge quantity of Cr creating a threat to the ecosystem and even a serious health risk for humans. Heavy metals that fish consume are contaminating river water ecosystems. This contamination spreads to human bodies and is the cause of many serious ailments.

Comparative pathology of (Encysted and non-encysted) trematodes in the liver of snake headed fresh water fish Channa punctatus (Bloch, 1793)

Comparative pathology of (Encysted and non-encysted) trematodes in the liver of snake headed fresh water fish Channa punctatus (Bloch, 1793)

Study on the Genotoxic Effect of Copper Sulphate in the Spotted Snakehead Fish Channa Punctatus (Bloch, 1793)

The genotoxic effects of a herbicide containing CuSO4 were assessed using the micronucleus assay in Channa punctatus. The study involved intraperitoneal administration of three different doses (1.0, 3.0, and 5.0 mg/kg body weight) and exposure to varying concentrations of copper sulphate (15, 25, and 35 ppm) in laboratory aquaria. Peripheral blood smears stained with 15 to 20% Giemsa (pH=7.0) were examined. Apart from micronuclei, the herbicide induced other nuclear and cytoplasmic abnormalities. The findings suggest a direct impact of increasing CuSO4 concentration on the biological samples of Channa punctatus. This fish species is commonly found in freshwater habitats like ponds, ditches, wetlands, and rice fields, especially in Odisha, India. India is crucial for maintaining aquatic biodiversity. The study highlights the potential detrimental effects of improper use of CuSO4 containing pesticides in agriculture on Channa punctatus and emphasizes the need for careful management of such chemicals to protect aquatic ecosystems.

Zoonotic human liver flukes, a type 1 biocarcinogen, in freshwater fishes: genetic analysis and confirmation of molluscan vectors and reservoir hosts in Bangladesh

BackgroundOpisthorchiid flukes, particularly Opisthorchis viverrini, Opisthorchis felineus, Clonorchis sinensis, and Metorchis spp. are the most common fish-borne zoonotic human liver flukes (hLFs). Liver fluke infections are more prevalent in resource-deprived and underprivileged areas. We herein estimated the prevalence of the metacercariae (MC) of major hLFs in common large freshwater fishes (lFWF) marketed for human consumption from some selected areas of Bangladesh along with detection of their molluscan vectors and reservoirs.MethodsThe current status of fish-borne zoonotic hLF infections in lFWF was investigated along with their molluscan vectors and mammalian reservoir hosts in Mymensingh and Kishoreganj in Bangladesh from July 2018–June 2022 using conventional and multiple molecular techniques, such as PCR, PCR-restriction fragment length polymorphism (RFLP), sequencing, and bioinformatic analyses. The infection rate of fishes was analyzed using the Z-test and the loads of MC were compared using the chi-squared (χ2) test.ResultsThe MC of C. sinensis, Opisthorchis spp., and Metorchis spp. were detected in 11 species of common and popular lFWF. In lFWF, the estimated prevalence was 18.7% and the mean load was 137.4 ± 149.8 MC per 100 g of fish. The prevalence was the highest (P < 0.05) in spotted snakehead fishes (Channa punctata, 63.6%). The highest rate of infection (P < 0.05) was observed with the MC of C. sinensis (11.8%). Metacercariae were almost equally (P > 0.05) distributed between the head and body of fishes. The infection rate was slightly higher in cultured (19.6%) fishes. The MC of C. sinensis, O. felineus, O. viverrini, and Metorchis orientalis in fishes were confirmed using PCR, PCR-RFLP and bioinformatics. The cercariae of opisthorchiid (Pleurolophocercus cercariae) flukes were only recovered from Bithynia spp. (3.9%, 42 out of 1089). The ova of hLFs from dogs (4.3%, 5 out of 116) and cats (6.0%, 6 out of 100), and adult flukes (M. orientalis) from ducks (41.1% 113 out of 275) were detected.ConclusionsThe MC of hLFs are highly prevalent in fresh water fishes in Bangladesh. Reservoir hosts, such as street dogs, cats, and ducks carried the patent infection, and residents of Bangladesh are at risk.Graphical

Prolonged exposure to mercuric chloride induces oxidative stress-mediated nephrotoxicity in freshwater food fish Channa punctatus.

Mercury (Hg) is regarded as a serious hazard to aquatic life and is particularly prevalent in aquatic ecosystems. However, there is little evidence available regarding the toxicity of mercury chloride (HgCl2) in vital organs of fish. This study was conducted to assess the effects of HgCl2 (0.039mg/L and 0.078mg/L) on oxidative stress-mediated genotoxicity, poikilocytosis, apoptosis, and renal fibrosis after 15, 30, and 45days of the exposure period. According to the findings, HgCl2 intoxication in fish resulted in a significantly (P < 0.05) elevated lipid peroxidation (LPO), protein carbonyls (PC), lactate dehydrogenase (LDH) activity levels in kidney tissues and significantly (P < 0.05) increased reactive oxygen species (ROS), poikilocytosis, DNA tail length, and the frequency of apoptotic cells (AC%) in blood cells. Kidney's ultra-structure and histopathology revealed its fibrosis, which was evident by mRNA expression of targeted genes KIM1, NOX4, TGFβ, and NFϏβ. Different indicators of oxidative stress, apoptosis, and genotoxicity were altered in a dose and time-dependent manner, according to a two-way ANOVA analysis. There was a considerable positive link between oxidative stress and kidney fibrosis in the fish Channa punctatus, and it is evident from regression correlation and PCA data analysis. The kidney's ultra-structure evaluation and histopathology both revealed a noticeable fibrosis state. Additionally, a significant (P < 0.05) downregulation in PPARδ reveals that fish body was unable to combat diseases such as kidney fibrosis induced by HgCl2. This study shed fresh light on the mechanisms underlying nephrotoxicity caused by HgCl2 exposure.