Organs Of Fish Research Articles

Influence of age on the concentrations of perfluoroalkyl acids (PFAA) in the tissues of perch (Percafluviatilis)

Globally, perfluoroalkyl acids (PFAA) are ubiquitous due to their almost unlimited applications in industry and households and are detected in a wide variety of matrices.Aquatic ecosystems are of particular importance due to the spread of PFAA via water fluxes. The majority of published studies describe PFAA concentrations in fish or aquatic mammals, but not the dependence of PFAA concentrations in tissues and organs in fish of different ages. Since this is very important for understanding the accumulation behavior of these substances our study systematically investigates the influence of age on the PFAA concentration in the tissues of 74 perches (Perca fluviatilis), a very popular edible fish. Fish are particularly suitable as indicators of PFAA contamination of water because of their uptake via water (gills and skin) and food (predominantly piscivorous diet). The mean total PFAA concentrations (as the sum of the individual concentrations of 11 compounds) were: 114 μg/kg (kidney), 112 μg/kg (heart), 79.9 μg/kg (liver), 78.4 μg/kg (spleen), 64.6 μg/kg (gills) and 21.7 μg/kg (muscle), with longer-chain compounds accounting for 90% of the substances. Perfluorooctanesulfoic acid (PFOS) accounted for the largest percentage of the total PFAA concentration in all tissues at 43–63%. With the exception of the heart and spleen, a significant increase in total concentrations was observed with increasing age of the perch. The strongest correlation was observed for the kidney, followed by the liver and gills. With regard to their consumption as human nutrition the tolerable weekly PFAA intake of 4.4 ng/kg bodyweight and week for the sum of the 4 EFSA PFAA in adults and children was exceeded many times over (860% and 1600% respectively) with an average fish consumption per week. The maximum PFAA levels set in the E.U. since January 2023 were exceeded five times.

Sonic hedgehog (shh) gene from Pseudopleuronectes yokohamae (Teleostei: Pleuronectidae): Molecular cloning, characterization, and expression profile during early embryonic, juvenile, and adult stages.

The hedgehog signaling pathway plays an important role in early development and growth of most vertebrates. Sonic hedgehog (shh) gene is a critical regulator of embryonic development in many species, including humans. However, it is not clear what roles shh can play in the development of fish. In this paper, shh gene was cloned from Pseudopleuronectes yokohamae. The full-length complementary DNA (cDNA) of P. yokohamae sonic hedgehog gene (Pyshh) comprises 3194 bp, with a 1317-bp open reading frame (ORF) that encodes a polypeptide of 438 amino acids with a typical HH-signal domain and Hint-N domain. The conserved sequences of the protein among species were predicted by using multiple sequence comparison. The phylogenetic tree construction showed that PySHH is clustered in a branch of Pleuronectidae. To explore the expression of Pyshh gene in various tissues of P. yokohamae, we used real-time fluorescence quantitative PCR technology to detect it. The results showed that Pyshh gene is widely distributed in various tissues of P. yokohamae juveniles, different tissues of adult males and females, and is particularly expressed in immune organs. The Pyshh gene expression was higher in the muscle and brain of juvenile fish, and higher in bone, gill, and skin of male fish than that of female fish, suggesting that Pyshh might be involved in the formation of immune organs of P. yokohamae. The expression of Pyshh gene significantly upregulated from the gastrula stage to the hatching stage. Western blotting of the expression levels of PySHH during different embryonic development stages revealed that PySHH levels increased gradually during development stages from oosperm stage to hatching stage. These results indicate that Pyshh is highly conserved among species and plays a critical role in the complex process of embryonic development. Its precise regulation is essential for the proper formation of many organs and tissues in the body, and disruptions in its function may have serious consequences for the formation of immune organs in fish.

Study of Microplastic Contamination in the Digestive Organs of Parrotfish (Scarus rivulatus) Caught in Ekas Bay

Microplastics have become a major concern in global environmental research due to their significant impact on marine ecosystems. Microplastic pollution has been detected in almost all aquatic environments, including oceans, rivers and lakes. This study aims to evaluate the level of microplastic contamination in the digestive organs of old parrot fish caught in Ekas Bay. Focusing on the digestive organs is important because ingested microplastics can have detrimental effects on fish health, including digestive disorders and bioaccumulation of harmful chemicals. The research method used was descriptive with a sample size of six parrot fish. Based on research conducted on the digestive organs of parrot fish, it was found that the types of microplastics found were in the form of fragments, films, pellets and fibers. The total abundance of microplastics in the intestinal organs ranges from 290 par/gr to 410 par/gr, while in the stomach organs it is 272 par/gr to 310 par/gr. The highest percentage of microplastics in the intestinal organs was pellets at 47% and in the stomach organs it was fragments at 54%.

Effect of Enterococcus faecalis infection on some immune parameters, immune genes expression and tissue pathology of Argyrosomus regius

Enterococcus faecalis is a newly emerged fish pathogen affecting many cultured fish species. The present work aimed to determine the cause of mortalities affecting the cultured Meagre farm and study the infectious agent virulence, disease pathology. Also, to determine the influence of infection on complement 3, cyclooxygenase, and lysozyme gene expression and concentrations in fish serum. The internal organs of diseased fish were severely congested with the presence of petechial haemorrhages on the liver, gonads, and all over the elementary tract. Thirty-one bacterial isolates were recovered from naturally infected fish; seventeen were identified biochemically as E. faecalis. Random E. faecalis isolate was verified for pathogenicity in meager fingerlings and was indeed pathogenic with lethal dose-fifty (LD50) estimated by 4.6 × 106 colony forming unit (CFU) fish−1. The posterior kidney and hepatopancreas of experimentally infected fish showed severe inflammation, necrosis, degeneration, and haemorrhage. Detachment of mucosa lining the stomach and intestine (intestinal villi and gastric glands) was prominent. The examined gastric tissues exhibited inflammation, leucocytic infiltration, and congestion. The expression of C3, Cox2, and Lyz was upregulated 24-h post-infection and then decreased near the baseline at 96 h. Serum C 3 and Lyz concentrations peaked at 24 h and 48 h after that decreased. IgM level gradually increased with time and peaked at 96 h. In conclusion, E. faecalis is assumed pathogenic for cultured meager, experimental infection stimulated immune systems and upregulated the expression of some immune-related genes.

Trematode Diplostomum pseudospathaceum inducing differential immune gene expression in sexual and gynogenetic gibel carp (Carassius gibelio): parasites facilitating the coexistence of two reproductive forms of the invasive species.

Parasite-mediated selection is considered one of the potential mechanisms contributing to the coexistence of asexual-sexual complexes. Gibel carp (Carassius gibelio), an invasive fish species in Europe, often forms populations composed of gynogenetic and sexual specimens. The experimental infection was induced in gynogenetic and sexual gibel carp using eye-fluke Diplostomum pseudospathaceum (Trematoda), and the transcriptome profile of the spleen as a major immune organ in fish was analyzed to reveal the differentially expressed immunity-associated genes related to D. pseudospathaceum infection differing between gynogenetic and sexual gibel carp. High parasite infection was found in gynogenetic fish when compared to genetically diverse sexuals. Although metacercariae of D. pseudospathaceum are situated in an immune-privileged organ, our results show that eye trematodes may induce a host immune response. We found differential gene expression induced by eye-fluke infection, with various impacts on gynogenetic and sexual hosts, documenting for the majority of DEGs upregulation in sexuals, and downregulation in asexuals. Differences in gene regulation between gynogenetic and sexual gibel carp were evidenced in many immunity-associated genes. GO analyses revealed the importance of genes assigned to the GO terms: immune function, the Notch signaling pathway, MAP kinase tyrosine/threonine/phosphatase activity, and chemokine receptor activity. KEGG analyses revealed the importance of the genes involved in 12 immunity-associated pathways - specifically, FoxO signaling, adipocytokine signaling, TGF-beta signaling, apoptosis, Notch signaling, C-type lectin receptor signaling, efferocytosis, intestinal immune network for IgA production, insulin signaling, virion - human immunodeficiency virus, Toll-like receptor signaling, and phosphatidylinositol signaling system. Our study indicates the limited potential of asexual fish to cope with higher parasite infection (likely a loss of capacity to induce an effective immune response) and highlights the important role of molecular mechanisms associated with immunity for the coexistence of gynogenetic and sexual gibel carp, potentially contributing to its invasiveness.

Analysis Of Mercury (Hg) In Mujair Fish (Oreochromis mosambicus) In Limboto Lake, Gorontalo Province

The occurrence of silting of the lake and sedimentation in Limboto Lake has become a place for the deposition of heavy metals, especially mercury. In recent years it has been known that the water of Lake Limboto has been polluted by mercury based on data from the Agency for the Environment, Research and Technology (Balihristi), Gorontalo Province in 2007.This study aims to analyze the mercury (Hg) content of mujair fish (Oreochromis mossambicus) in Limboto Lake. This research was conducted in November 2018- June 2019. The method used in this research is descriptive method. Sampling of water and fish was carried out by purposive sampling by dividing the research location into 2 stations, namely Station I in the floating net cages and Station II outside the KJA Measurement of mercury content (Hg) was carried out at the Laboratory of Fisheries Product Quality Development and Testing (LPPMHP) Gorontalo City using the Atomic Absorbtin Spectrophotometer (AAS). From the results of the study, it was found that, the Mercury (Hg) Content in Lake Limboto Waters, Stasion I was 0.0014 ppm and Station II was 0.0007 ppm, and for mujair fish organs the highest was in meat, namely outside KJA 0.0037 ppm and in meat, the lowest was in KJA 0.0035 ppm.. Nakoe et al. (2014) examined the risk of exposure to mercury (Hg) in humans who consume Mujair (Oreochromis niloticus) from Lake Limboto using the Limboto approach. Limboto using an environmental health analysis approach with a variable test method of body weight, consumption level and frequency. Concentration mercury levels of tilapia in Lake Limboto are between 0.007 - 0.089 mg/kg while the mercury levels in the lake are between 0.0014 mg/L. lake is around 0.0014 mg/L.

Ultrastructural Biomarkers in Target Organs of Fish from Algeria Coastline to Access Water Quality

Ultrastructural Biomarkers in Target Organs of Fish from Algeria Coastline to Access Water Quality

Heavy Metal Concentration in Fish Species Clarias gariepinus (Catfish) and Oreochromis niloticus (Nile Tilapia) from Anambra River, Nigeria

Studies have emphasized that the presence of heavy metals in freshwater fish represents a global public health issue. Nigeria, being a developing nation with less emphasis on the quality of seafood consumed by the residents, ranks this study very vital. The policy implication of this study is the advancement of a healthy population in contemporary Nigeria. Hence, this study assessed heavy metal concentration in two fish species, Clarias gariepinus (Catfish) and Oreochromis niloticus (Nile Tilapia), in the Anambra River. The sample included twenty fishes, of which eighteen were collected from the three sampling locations (the fish ports of Anambra River), namely Otu-nsugbe, Otuocha, and Ikemivite) while two control samples were collected from a pond about 200 m away from the river. The levels of heavy metals were determined using Varian AA 240 atomic absorption spectrophotometer (AAS). The results showed that the concentrations of heavy metals (cadmium and arsenic) in the sampled fishes from Anambra River exceeded the joint World Health Organization and Food and Agriculture Organization (FAO/WHO) standard for fish and fish product consumption, while the concentration of chromium, mercury, and lead are within the permissible limit. The study also showed the distribution of the heavy metals in the fish organ varies among fish species. Heavy metals occur higher in Clarias garepinus than in Oreochromis niloticus, while tissue preference for heavy metal accumulation is in the order of gill > liver > muscle. It was recorded from this study that the heavy metal concentration in the fish from the pond is generally higher than the fish from the river for some metals. The high level of heavy metals in the sampled fish was attributed to heavy metals contamination of the river as a result of various anthropogenic activities such as mining, burning of fossil fuel and emission from the exhaust of boats/vehicles, overuse of fertilizers and pesticides, discharge of effluent, sewage, and hospital waste. This study concluded that long-term consumption of fish from the river may pose health risks to the consumers due to the possible bioaccumulation of heavy metals, especially cadmium and arsenic. It was recommended that continuous monitoring of heavy metal levels in the fish and water, public awareness, and appropriate legislative provisions should be put in place to ensure that harvested fish and fish products may be safe for human consumption.

Discovery and Genomic Characterization of a Novel Hepadnavirus from Asymptomatic Anadromous Alewife (Alosa pseudoharengus).

The alewife (Alosa pseudoharengus) is an anadromous herring that inhabits waters of northeastern North America. This prey species is a critical forage for piscivorous birds, mammals, and fishes in estuarine and oceanic ecosystems. During a discovery project tailored to identify potentially emerging pathogens of this species, we obtained the full genome of a novel hepadnavirus (ApHBV) from clinically normal alewives collected from the Maurice River, Great Egg Harbor River, and Delaware River in New Jersey, USA during 2015-2018. This previously undescribed hepadnavirus contained a circular DNA genome of 3146 nucleotides. Phylogenetic analysis of the polymerase protein placed this virus in the clade of metahepadnaviruses (family: Hepadnaviridae; genus: Metahepadnavirus). There was no evidence of pathology in the internal organs of infected fish and virions were not observed in liver tissues by electron microscopy. We developed a Taqman-based quantitative (qPCR) assay and screened 182 individuals collected between 2015 and 2018 and detected additional qPCR positives (n = 6). An additional complete genome was obtained in 2018 and it has 99.4% genome nucleotide identity to the first virus. Single-nucleotide polymorphisms were observed between the two genomes, including 7/9 and 12/8 synonymous vs nonsynonymous mutations across the polymerase and surface proteins, respectively. While there was no evidence that this virus was associated with disease in this species, alewives are migratory interjurisdictional fishes of management concern. Identification of microbial agents using de novo sequencing and other advanced technologies is a critical aspect of understanding disease ecology for informed population management.

Assessment, distribution, and ecological risk of contaminants of emerging concern in a surface water-sediment-fish system impacted by wastewater

The presence of contaminants of emerging concern in aquatic ecosystems represents an ever-increasing environmental problem. Aquatic biota is exposed to these contaminants, which can be absorbed and distributed to their organs. This study focused on the assessment, distribution, and ecological risk of 32 CECs in a Spanish river impacted by effluents from a wastewater treatment plant, analyzing the organs and plasma of common carp. Environmental concentrations in water and sediment were examined at sites upstream and downstream of the wastewater treatment plant. The two downstream sites showed 15 times higher total concentrations (12.4 μg L−1 and 30.1 μg L−1) than the two upstream sites (2.08 μg L−1 and 1.66 μg L−1). Half of the CECs were detected in fish organs, with amantadine having the highest concentrations in the kidney (158 ng g−1 w.w.) and liver (93 ng g−1 w.w.), followed by terbutryn, diazepam, and bisphenol F in the brain (50.2, 3.82 and 1.18 ng g−1 w.w.). The experimental bioaccumulation factors per organ were compared with the bioconcentration factors predicted by a physiologically based pharmacokinetic model, obtaining differences of one to two logarithmic units for most compounds. Risk quotients indicated a low risk for 38 % of the contaminants. However, caffeine and terbutryn showed an elevated risk for fish. The mixed risk quotient revealed a medium risk for most of the samples in the three environmental compartments: surface water, sediment, and fish.

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.

Protective effects of Moringa oleifera against carbofuran induced toxicity in fish (Labeo rohita): Insight into hematobiochemical, histology, oxidative and antioxidant biomarkers

Carbofuran pesticide is used to control insects in agriculture and acts as a contaminant that pollutes aquatic ecosystems, exerting harmful effects on fish health. The present study was conducted to evaluate the ameliorative effects of moringa leaf powder after fish being exposed to carbofuran on hematobiochemical and histological changes, oxidative and antioxidative mechanisms in the soft tissues of rohu Labeo rohita. Fish were divided into three groups (A, B, and C). Group A treated as control while groups B and C were exposed to two sublethal doses (0.32 and 0.84 mg/L) of carbofuran for 28 days. At day 28, ten fish were removed from the high dose group and transferred to carbofuran-free freshwater (group D) for recovery responses. Results revealed that concentrations of hemoglobin (HGB), red blood cells (RBCs), high-density lipoprotein (HDL), low-density lipoprotein (LDL), albumin, globulin, total proteins, triiodothyronine (T3), thyroxin (T4) and blood urea nitrogen (BUN) significantly decreased. White blood cells (WBCs), triglycerides, cholesterol, very low-density lipoprotein (VLDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood glucose, thyroid stimulating hormone (TSH), urea, and creatinine levels were elevated significantly in carbofuran exposed fish. Results showed a significant rise in oxidative stress content (TBARS and ROS), and a decline in the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione (GSH) in the brain, kidney, liver, and gills of exposed fish. Histological alterations showed deleterious effects on different organs in carbofuran-exposed fish. After the recovery period, all parameters were recovered to some extent. The results of this study indicated that carbofuran is harmful to fish even at low doses. Therefore, extreme care should be taken to prevent the drainage of carbofuran into water bodies.

Transcriptome Analysis Elucidates the Potential Key Genes Involved in Rib Development in bmp6-Deficient Silver Carp (Hypophthalmichthys molitrix).

Bone morphogenetic protein 6 (BMP-6) is a constituent of the TGF-β superfamily, known for its ability to stimulate bone and cartilage formation. The investigation of bmp6's involvement in the formation of intermuscular bones in fish has garnered significant attention in recent years. The rib cage is an important skeletal structure that plays a protective function for internal organs in fish. However, there has been limited research conducted on the effects of the bmp6 gene on rib development. Silver carp is one of four major fish in China, favoured for its affordability and tender muscle. Nevertheless, the presence of numerous intermuscular bones in silver carp significantly hinders the advancement of its palatability and suitability for processing. This study showcases the effective utilisation of CRISPR/Cas9 technology for the purpose of disrupting the bmp6 gene in silver carp, leading to the creation of chimeras in the P0 generation, marking the first instance of such an achievement. The chimeras exhibited complete viability, normal appearance, and partial intermuscular bones loss, with approximately 30% of them displaying rib bifurcation or bending. Subsequently, a transcriptome analysis on ribs of P0 chimeras and wild-type silver carp was conducted, leading to the identification of 934 genes exhibiting differential expression, of which 483 were found to be up-regulated and 451 were found to be down-regulated. The results of the KEGG analysis revealed that the "NF-kappa B signalling pathway", "Hippo signalling pathway", "osteoclast differentiation", and "haematopoietic cell lineage" exhibited enrichment and displayed a significant correlation with bone development. The up-regulated genes such as tnfα, fos, and ctgf in pathways may facilitate the proliferation and differentiation of osteoclasts, whereas the down-regulation of genes such as tgfb2 and tgfbr1 in pathways may hinder the formation and specialisation of osteoblasts, ultimately resulting in rib abnormalities. This study presents novel findings on the impact of bmp6 gene deletion on the rib development of silver carp, while simultaneously investigating the previously unexplored molecular mechanisms underlying rib defects in fish.

Identification of microplastics in milkfish (Chanos chanos) in tradisional ponds in Pedaleman Village, Serang Regency

The entry of microplastic waste into pond waters come from household and fishing activities. This study aims to identify the presence of microplastics in milkfish in the Pedaleman Village pond by considering the type, color, and size of microplastics and to determine the polymers structure found in the digestive tract of milkfish. A total of 24 samples were collected directly from the pond in March to April 2023. The fish were measured for length (cm) and weight (g), and then dissected to remove the organs including digestive tract and muscle. The organs were then destroyed and microplastics were identified using microscope stereo. The fish organs were destroyed using 10% KOH after wet weight was measured. The sample were incubated for 24 hours until the organic matter was destroyed. Then, filtered using Whattman 42 paper and dried in an oven. The types of microplastics found in milkfish were fibers, films, and fragments. Fragment were the most abundant type of microplastics, followed by fiber and film. The fiber had a variety of colors, while the fragments are only found in black. The types of microplastic polymers found in milkfish intestines were polyethylene (PE), polytetrafluoroethylene (PTPE), Polymethyl methacrylate (PMMA), and nylon.

Impact of freshwater rearing history on Atlantic salmon gill response to viral stimulation post seawater transfer

Land-based recirculating aquaculture systems (RAS) have risen in prevalence in recent years for Atlantic salmon production, enabling intensive production which allows increased growth and environmental control, but also having the potential for reducing water use and eutrophication. The Atlantic salmon has an anadromous life history with juvenile stages in freshwater (FW) and on-growing in seawater (SW), enabled by a transformational process known as smoltification. The timing of smoltification and transfer of smolts from FW to SW is critical under commercial production with high mortalities during this period. The impact of FW rearing system on immune function following seawater transfer (SWT) is not well understood. In this study parr were raised in either RAS or a traditional open-LOCH system until smolting and then transferred to a common marine environment. Two-weeks post-SWT fish were immune stimulated with a viral mimic (poly I:C) for 24 h to assess the ability to mount an antiviral immune response, assessed by whole transcriptome analysis of gill tissue, an important immune organ in fish. We show that unstimulated smolts reared in the LOCH had higher immune gene expression than those reared in RAS as determined by functional analysis. However, following stimulation, smolts reared in the RAS mounted a greater magnitude of response with a suite of immune genes displaying higher fold induction of transcription compared to LOCH reared smolts. We suggest RAS smolts have a lower steady state immune-associated transcriptome likely due to an unvarying environment, in terms of environmental factors and lack of exposure to pathogens, which shows a compensatory mechanism following stimulation allowing immune ‘catch-up’ with those reared in the LOCH. Alternatively, the RAS fish are experiencing an excessive response to the immune stimulation.

Histopathological alterations in the vital organs of Indian major carp Labeo rohita exposed to monosodium glutamate (MSG)

BackgroundMonosodium glutamate (MSG E621) is one of the most popular flavouring agents of modern times and is widely used in many commercially packed food and even in house hold cooking. Previous studies revealed that excessive intake of MSG in diet causes obesity, metabolic defects, nephrotoxicity, neurotoxicity and hepatotoxicity in rats, but no reports are available in the literature about the ecotoxicological assessment of MSG by using fishes as a bioindicators. Since fishes are important consumer in aquatic food chain and directly linked with human health status, the present study was aimed to investigate the impact of MSG in freshwater fish Labeo rohita by using histological biomarkers.ResultsNinety-six h-LC50 of MSG to Labeo rohita was determined (1.5 g/L), and fish exposed to sub-lethal concentration of MSG (1/10th of 96 h-LC50 concentration of MSG (150 mg/L)) showed distinguished behavioural changes like erratic movement, loss of appetite and excessive mucous secretion all over the body as an adaptive syndrome to avoid the direct exposure to MSG in the medium. Histopathological analysis clearly depicts severe damages in the vital organs of fish. In gills, epithelial necrosis, hypertrophy, hyperplasia, primary and secondary gill lamellae degeneration, oedema, fusion of adjacent secondary lamellae and rupture of gill epithelium were observed. The intensity of tissue damage was increased as the exposure period was extended. The liver displayed vein congestion, vacuole formation, degeneration in parenchymal cells and bile stagnation, whereas MSG-treated kidney tissue showed high interstitial inflammation. Among the vital organs gill and liver displayed the highest histopathological alterations.ConclusionsThe present study clearly demonstrated that MSG is toxic to fish and able to cause significant damages in the vital organs as the exposure period was extended. Since the studies on the toxicity of MSG to fish are rare, the present investigation may contribute to the scarce literature on sub-lethal toxicity of MSG to freshwater fishes.

Incidence of microplastics in Indian anchovy Stolephorus indicus from Tuticorin, Southeast coast of India

In the present study, the occurrence of microplastics (MPs) in the gut, gill, and muscle of edible fish Stolephorus indicus sampled from Tuticorin coastal regions of Tamilnadu, India was investigated. We recorded a total of 689 MPs which includes 510 and 179 MPs from males and females respectively. The total abundance of MPs was significantly (P < 0.05) higher in the gut followed by gills and muscle. The sex-wise distribution of average MPs showed high in the females' gut and compared to that in males. Further, the length wise distribution of MPs was higher in the muscle in both male and female fish, followed by other organs. The predominance of MPs in tissues were transparent and blue colour with fibers and fragments in both males and females. Besides, polyethylene terephthalate and nylon were evidenced by the Fourier-transform infrared spectroscopy spectrum in all organs of fishes.

Ecotoxicological evaluation of chitosan biopolymer films particles in adult zebrafish (Danio rerio): A comparative study with polystyrene microplastics

To mitigate the environmental impact of microplastics (MPs), the scientific community has innovated sustainable and biodegradable polymers as viable alternatives to traditional plastics. Chitosan, the deacetylated form of chitin, stands as one of the most thoroughly investigated biopolymers and has garnered significant interest due to its versatile applications in both medical and cosmetic fields. Nevertheless, there is still a knowledge gap regarding the impact that chitosan biopolymer films (CBPF) may generate in aquatic organisms. In light of the foregoing, this study aimed to assess and compare the potential effects of CBPF on the gastrointestinal tract, gills, brain, and liver of Danio rerio against those induced by MPs. The findings revealed that both CBPF and MPs induced changes in the levels of oxidative stress biomarkers across all organs. However, it is essential to note that our star plots illustrate a tendency for CBPF to activate antioxidant enzymes and for MPs to produce oxidative damage. Regarding gene expression, our findings indicate that MPs led to an up-regulation in the expression of genes associated with apoptotic response (p53, casp3, cas9, bax, and bcl2) in all fish organs. Meanwhile, CBPF produced the same effect in genes related to antioxidant response (nrf1 and nrf2). Overall, our histological observations substantiated these effects, revealing the presence of plastic particles and tissue alterations in the gills and gastrointestinal tract of fish subjected to MPs. From these results, it can be concluded that CBPF does not represent a risk to fish after long exposure.

Efficacy of fennel (Foeniculum vulgare) and anise (Pimpinella anisum) essential oils as anaesthesics in common carp (Cyprinus carpio L. 1758)

In this study, the anaesthetic effects of fennel and anise essential oils were investigated on common carp. Fish (10 ± 0.45 g) were exposed to nine concentrations of essential oils (5, 10, 20, 50, 100, 200, 300, 400 and 500 mg L−1). Additionally, the histopathological effects on the fish tissues including gill, skin and hepatopancreas and physiological effects on some blood parameters (Na+, K+, Ca+2, Cl−, total plasma protein and glucose) of essential oils were investigated in carp. At the end of the experiment, fennel oil showed an anaesthetic effect at a concentration of 500 mg L−1 in carp (anaesthesia induction and recovery times were 308 and 472 s, respectively). Anise essential oil showed deep anaesthesia at a concentration of 100 mg L−1, but anaesthesia induction time was found to be very long (20 min). In addition, anise oil at concentrations above 100 mg L−1 caused 10% mortality in fish. Blood parameters except glucose level in both essential oils were unchanged during deep anaesthesia in carp. However, plasma glucose levels were found lower in fish anaesthetized with anise oil than control and fennel groups (P < 0.05). At the histopathological examination, no pathological findings were observed in any organ of fish in the fennel group. However, severe hyperemia and inflammatory cell infiltrations in gills, erosive lesions in the skin and slight inflammatory reactions in the skin were observed in the anise group. The present study demonstrated that fennel essential oil at 500 mg L−1 concentration can be used as an effective and safe anaesthetic in common carp, but anise essential oil is not suitable.

Oral feed-based administration of phage cocktail protects rohu fish (Labeo rohita) against Aeromonas hydrophila infection.

Aeromonas hydrophila is one of the major freshwater fish pathogens. In the current study, a cocktail of D6 and CF7 phages was given orally to Labeo rohita to assess phage survival in fish organs as well as to determine the therapeutic efficacy of phage treatment against fish mortality caused by A. hydrophila. In the phage-coated feed, prepared by simple spraying method, phage counts were quite stable for up to 2 months with a decline of ≤ 0.23 log10 and ≤ 1.66 log10 PFU/g feed during 4 oC and room temperature storage. Throughout the experimental period of 7 days, both phages could be detected in the gut of fish fed with phage-coated feed. Besides, both CF7 and D6 phages were also detected in fish kidneys indicating the ability of both the phage to cross the intestinal barrier. During challenge studies with LD50 dose of A. hydrophila, phage cocktail doses of 1 × 106 - 1 × 108 PFU/g feed prevented the mortality in L. rohita with relative percentage survival (RPS) of 8.7-65.2. When challenged with LD90 dose of A. hydrophila, an RPS value of 28.6 was obtained at a phage cocktail dose of 1 × 108 PFU/g feed. The RPS data showed that orally-fed phage cocktail protected the fish against the mortality caused by A. hydrophila in a dose-dependent manner. Simple practical approaches for phage cocktail development, medicated feed preparation and oral administration along with phage survival and protection data make the current study useful for farmer-level application.