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Pharmaceuticals and personal care products (PPCPs) are known to interact with microplastics (MPs) in aquatic environments, with substances such as the antimicrobial triclosan (TCS) and the synthetic hormone 17α-ethinylestradiol (EE2) being prevalent. These persistent contaminants are linked to toxic effects in aquatic organisms. This study aimed to investigate histological and morphometric changes in the gills of Ucides cordatus exposed to microplastics alone and microplastics contaminated with PPCPs. The experimental design included four treatment groups: 1) control (C), 2) virgin microplastics (MP), 3) microplastics fortified with triclosan (MPT), and 4) microplastics fortified with 17α-ethinylestradiol (MPE), with exposure durations of 3 or 7 days. Significant differences were observed in the histopathological indices for treatments with PPCP-fortified microplastics at 3 days (MPT and MPE) and 7 days (MPT). Notable pathologies included necrosis, fibrosis, and circulatory disorders. Exposure duration was significantly associated with morphometric changes, including secondary lamellar width in MPT and secondary lamellar length in MPE. These findings indicate that exposure to microplastics contaminated with PPCPs may impair the osmoregulatory and respiratory functions of Ucides cordatus., Competing Interests: Declaration of competing interest We affirm that all authors have revised and approved the manuscript. This study has not been published previously, nor is it under consideration for publication elsewhere. The funding sources had no involvement on the study design on the collection, analysis, and interpretation of the data, on the writing of the report, or on the decision to submit the paper for publication. The study was conducted in accordance with national and institutional guidelines for the protection of animal welfare., (Copyright © 2024. Published by Elsevier B.V.)

Ocean acidification (OA) and other environmental factors can collectively affect marine organisms. Deltamethrin (DM), a type II pyrethroid insecticide, has been widely detected in coastal and estuarine areas, while little attention has been given to the combined effects of DM and OA. In this study, Haliotis discus hannai was exposed to three pH levels (8.1, 7.7 and 7.4) and three DM nominal concentrations (0 μg/L, 0.6 μg/L and 6 μg/L) for 14 and 28 days. The results indicated that experimental acidification and/or DM exposure led to impaired immune function and pathological damage. Additionally, acidified conditions and DM exposure induced oxidative stress, and gills are more sensitive than digestive glands. With increasing pCO 2 and DM nominal concentrations, superoxide dismutase (SOD) activity decreased, whereas catalase (CAT) and glutathione S-transferase (GST) activities increased in the gills. Moreover, the expression levels of Toll-like receptor (TLR) pathway-related genes were upregulated after exposure. Integrated biomarker response (IBR) analysis proved that acidified conditions and/or DM detrimentally affected the overall fitness of H. discus hannai, and co-exposure to experimental acidification and DM was the most stressful condition. This study emphasizes the necessity of incorporating OA in future pollutant environmental assessments to better elucidate the risks of environmental disturbance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Azoxystrobin, a widely used fungicide, can contaminate water bodies through surface run-off, posing a risk to aquatic organisms. This study aimed to assess the genotoxic effects of azoxystrobin on the fish Pethia conchonius. The 96 h lethal concentration (LC 50 ) of azoxystrobin was determined to be 0.514 mg/L. Based on LC 50, three sub-lethal concentrations (SLCs) of 0.025 mg/L, 0.0514 mg/L, and 0.103 mg/L were used to expose fish for 96 h. The blood and gill samples were collected at 24 h intervals for analysis. The Micronucleus (MN) and Comet assays were used to evaluate nuclear abnormalities and DNA damage, respectively. The results showed that the frequency of nuclear abnormalities and DNA damage in the exposed groups was significantly higher than the control, with increasing concentrations and duration of exposure. The highest levels of micronuclei, notched and blebbed nuclei, and DNA damage parameters were observed in the group exposed to SLC III for 96 h. These findings indicate that azoxystrobin is highly genotoxic to fish causing severe DNA damage., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Heavy metal pollution, particularly lead (Pb), poses a significant threat to aquatic ecosystems and their inhabitants, threatening their delicate balance and long-term viability. This study highlights the urgent need to mitigate heavy metal pollution in aquatic ecosystems., Objective: This study investigates Pb(NO 3 ) 2 exposure effects on tissue accumulation, behavioral abnormalities, and hemato-biochemical parameters in common carp (Cyprinus carpio), a widely distributed freshwater fish species., Methodology: Fish (115 ± 5.23 g) were exposed to various Pb(NO 3 ) 2 concentrations for 10 and 20 days, representing control (0 %), 25 %, 50 %, and 75 % of the LC 50 equivalent to 19.33, 38.66, and 58.0 mg/l, respectively. The standard manual procedure was used for blood sampling. The lead concentration in fish tissue was determined using an atomic absorption spectrophotometer., Results: Results revealed that fish gills showed significant (P < 0.05) increase in Pb(NO 3 ) 2 after 10 days, further rising after 20 days. Liver concentrations also rose significantly (P < 0.05) with prolonged exposure and increasing Pb levels. Muscle had lower concentrations. Hematological parameters (RBC, WBC, HB, HCT) decreased with higher Pb(NO 3 ) 2 levels. Behavioral and morphological changes were significantly more pronounced in the exposure groups when compared to the control group. Hepatic enzyme activities (AST, ALT), glucose, and lipid levels increased, while total protein decreased., Conclusions: The study highlights Pb(NO 3 ) 2 harmful effects on common carp, impacting tissue accumulation, hematological parameters, and biochemical disruptions. It emphasizes the need to monitor and mitigate heavy metal pollution in aquatic environments to safeguard freshwater organisms and ecosystems, and to further increase our understanding of Pb toxicity in freshwater ecosystems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Competing Interests The authors declare that they have no competing interests., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

To probe the mechanisms of gill remodeling in blunt snout bream under hypoxic conditions, we selected gill tissue for primary cell culture to establish and characterize the first blunt snout bream gill cell line, named MAG. The gill cells were efficiently passaged in M199 medium supplemented with 8% antibiotics and 15% fetal bovine serum at 28 °C, exhibiting primarily an epithelial-fibroblast mixed type. Additionally, the MAG cells (17th generation) were subjected to four experimental conditions-normoxia, hypoxia 12 h, hypoxia 24 h, and reoxygenation 24 h (R24h)-to evaluate the effects of hypoxia and reoxygenation on MAG cells during gill remodeling. We found that the MAG cell morphology underwent shrinkage and mitochondrial potential gradually lost, even leading to gradual apoptosis with increasing hypoxia duration and increased reactive oxygen species (ROS) activity. Upon reoxygenation, MAG cells gradually regain cellular homeostasis, accompanied by a decrease in ROS activity. Analysis of superoxide dismutase (SOD), glutathione (GSH), lactate dehydrogenase (LDH), catalase (CAT), anti-superoxide anion, and other enzyme activities revealed enhanced antioxidant enzyme activity in MAG cells during hypoxia, aiding in adapting to hypoxic stress and preserving cell morphology. After reoxygenation, the cells gradually returned to normoxic levels. Our findings underscore the MAG cells can be used to study hypoxic cell apoptosis during gill remodeling. Therefore, the MAG cell line will serve as a vital in vitro model for exploring gill remodeling in blunt snout bream under hypoxia., Competing Interests: Declarations Ethical approval This study was supported by the Ethics Committee of Shanghai Ocean University on the Use and Care of Animals All experiments were carried out in accordance with the Human Care Guide for Experimental Animals in Scientific Research, Ministry of Science and Technology, Beijing, China. Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

This study was conducted to examine the pathogenesis of gill degeneration in the Korean rockfish Sebastes schlegelii, infested with the monogenean ectoparasite, Microcotyle sebastis. We collected 30 Korean rockfish from a fish farm in Tongyeong-si, Gyeongsangnam-do, and examined them with light microscopy, scanning electron microscopy (SEM), and histopathology, in March 2018. The monogenean trematode, M. sebastis, was detected in 27 Korean rockfish (90%), with the intensity of infection being 31.7 per fish. The characteristic surface ultrastructures such as tegument with transverse striations, genital atrium, genital pore, and opisthaptor with numerous clamps were observed. The worms were firmly attached to the gill lamellae using clamps from the opisthaptor, causing gill damage and degeneration. The distal part of the lamellae was ruptured by the sclerites of the clamps. The histopathological examination revealed epithelial hypertrophy, hyperplasia, and occasionally fusion of the lamellae. These ultrastructural and histopathological findings provide some understanding of the pathogenesis of gill degeneration in the Korean rockfish infested with M. sebastis.

TiO 2 nanoparticles are photocatalytic, generate reactive oxygen, and can be harmful to aquatic biota. We have studied the toxic effects of nTiO 2 combined with high CO 2 levels in water. We exposed goldfish to environmentally relevant concentrations of nTiO 2 and CO 2 levels. Comet assay results showed that DNA breaks increased at high CO 2 concentration, but no effect of nTiO 2 concentrations was seen. Micronucleus assays showed no significant micronucleus formation. Histopathological alterations were seen in the gills but not in the liver., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Nano-zinc oxide (ZnO NPs), as widely used nanomaterials, are inevitably released into aquatic environments, posing potential threats to aquatic organisms. Mytilus galloprovincialis is a bivalve species sensitive to changes in marine ecological environments, but there has been limited research on its toxicity response to ZnO NPs. Therefore, we selected M. galloprovincialis as the research subject and exposed them to 50 µg/L ZnO NPs for 96 h and 30 days to determine the dissolution of ZnO NPs in seawater and their distribution in M. galloprovincialis. The toxicity of ZnO NPs in M. galloprovincialis was then evaluated through gene expression, tissue pathology, and cellular immune response. The results showed that ZnO NPs could enrich Zn in various tissues of the mussel, in the order of gills > hepatopancreas > adductor muscle > mantle. Seven immune-related genes including four heat shock protein genes (HSPA12A, sHSP24.1, sHSP22, TCTP) and three apoptotic genes (Ras, p63 and Bcl-2) were altered to varying degrees. There was a downward trend in lysosomal membrane stability of M. galloprovincialis after exposure to ZnO NPs for 96 h and 30 days, while ROS and apoptosis rates increased significantly. Furthermore, the seven genes, apoptosis, LMS, and ROS were dependent on exposure time, treatment, and their interaction. Histopathological damage included disorganisation of hepatopancreas epithelial cells, gill filament swelling, and contraction of blood sinuses. These results indicated that ZnO NPs exerted toxicity in M. galloprovincialis, affecting the immune system, resulting in changes in the expression of immune-related genes and ultimately leading to histopathological changes. Our research findings could contribute to systematically understand the impact of ZnO NPs on bivalves in aquatic environments and provide a theoretical basis for marine pollution assessment., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Xiaoli Liu reports financial support was provided by Ludong University. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Since the identification of Vibrio mediterranei as a causative agent in mass mortalities of pen shells across the Mediterranean, elucidating its pathogenicity, virulence, and interactions with other bivalves has gained importance. While the cellular and immune responses of bivalves to various Vibrio species have been extensively studied, the infectious characteristics of this Vibrio species, particularly in the context of pen shell outbreaks, remain unclear for other bivalves. Therefore, to evaluate its pathogenicity, we investigated the histological and oxidative effects on the Mediterranean mussel (Mytilus galloprovincialis), a key species in aquaculture. Two distinct infection setups were established: one involving the inoculation of seawater with the bacterial isolate and another involving direct injection of the bacteria into the mussels. After a 24-h exposure period, histological evaluations were conducted on the mantle, gill, and digestive gland tissues of the mussels. Additionally, measurements of superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation levels were performed in the gill and digestive gland tissues. Oxidative responses were significantly elevated in both infection setups compared to the control group, with the directly injected samples exhibiting the highest oxidative responses (p < 0.05). Histological findings indicated that tissue-specific responses to host-pathogen interactions were consistent under both infection conditions. Notable observations included intense hemocytic infiltration in tissues, epithelial hyperplasia, and vacuolization in the gills, as well as focal necrotic areas in the digestive gland. The findings of this study indicate that V. mediterranei, a relatively novel pathogen, can provoke significant acute immune responses and tissue-level reactions in M. galloprovincialis, a species that is both widely distributed and vital to the food chain. These insights into the potential susceptibility of mussels underscore the need for further comprehensive research and inform the development of effective management strategies., Competing Interests: Declaration of competing interest The authors have no relevant financial or non-financial interests to disclose., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Proliferative gill disease (PGD), caused by the myxozoan Henneguya ictaluri , has been the most notorious parasitic gill disease in the US catfish aquaculture industry. In 2019, an unusual gill disease caused by massive burdens of another myxozoan, Henneguya exilis , was described in channel ( Ictalurus punctatus ) × blue ( Ictalurus furcatus ) hybrid catfish. Targeted metagenomic sequencing and in situ hybridization (ISH) were used to differentiate these conditions by comparing myxozoan communities involved in lesion development and disease pathogenesis between massive H. exilis infections and PGD cases. Thirty ethanol-fixed gill holobranchs from 7 cases of massive H. exilis infection in hybrid catfish were subjected to targeted amplicon sequencing of the 18S rRNA gene and compared to a targeted metagenomic data set previously generated from clinical PGD case submissions. Furthermore, serial sections of 14 formalin-fixed gill holobranchs (2 per case) were analyzed by RNAscope duplex chromogenic ISH assays targeting 8 different myxozoan species. Targeted metagenomic and ISH data were concordant, indicating myxozoan community compositions significantly differ between PGD and massive branchial henneguyosis. Although PGD cases often consist of mixed species infections, massive branchial henneguyosis consisted of nearly pure H. exilis infections. Still, H. ictaluri was identified by ISH in association with infrequent PGD lesions, suggesting coinfections occur, and some cases of massive branchial henneguyosis may contain concurrent PGD lesions contributing to morbidity. These findings establish a case definition for a putative emerging, myxozoan-induced gill disease of farm-raised catfish with a proposed condition name of massive branchial henneguyosis of catfish (MBHC)., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Psychotria carthagenensis is a shrubby plant, often consumed by traditional populations in religious rituals. Previous studies have shown that this plant's infusion can inhibit the activity of Acetylcholinesterase (AChE) in rats. Despite the therapeutic potential, there is a lack of research regarding its possible toxicological and genotoxic effects. Hence, this study aimed to analyze the chemical profile of the ethanol extract from P. carthagenensis leaves by LC-DAD-MS and assess its possible toxicity and genotoxicity in zebrafish ( Danio rerio ). Adult zebrafish (N = 9/group) were exposed at different concentrations and the LC 50 was calculated. Frequencies of micronucleus (MN) and nuclear abnormalities (NA) were estimated for genotoxic effects, and degree of tissue changes (DTC) was used to assess the liver and gill histopathology. From the LC-DAD-MS analyses, the identified compounds included N -fructosyl valine, ethyl hexoside, 5- O-E -caffeoylquinic acid, N- feruloylagmatime, roseoside, di-O-deoxyhexoyl-hexosyl quercetin, loiolide, and oleamide. The calculated values of LC 50 did not vary significantly during the time of exposure. At the concentrations of 1.25, 2.5, 3.75, 5, 7.5, 10 and 15 mg/L, there was no genotoxicity, and only low to moderate toxicity for the tissues was observed, despite mortality of 100% at doses of 20-100 mg/L of P. carthagenensis ethanolic leaf extract. There were changes in cytoplasm of hepatocytes at 1.25 mg/L, and karyorrhexis, karyolysis and megalocytosis at 10 mg/L. In the gills, the alterations were primary lamellar hyperplasia in all concentrations, and at 10 mg/L, secondary lamellar edema and vascular hyperemia were common. Additionally, the chemical composition of P. carthagenensis was expanded.

Microplastics (MPs) and glyphosate-based herbicides (GBH) are among the most common contaminants in aquatic environments. In Brazilian rivers, both contaminants were found in elevated levels, leading to a high probability of their association, which can alter their individual effects and potentially intensify their toxicity. This study evaluated the isolated and combined effects of polyethylene microplastics (PE-MPs) and GBH on Oreochromis niloticus using multi-biomarkers of toxicity. The fish were subjected to a 96-h exposure period, with concentrations set based either isolated, PE-MPs group (5 mg L -1 ), GBH group (5 mg L -1 ), or in a group of associated contaminants (GAC), PE-MP + GBH (5 mg L -1  + 5 mg L -1 ). Toxicity effects were evaluated using biochemical, cytogenetic, hematological, and histopathological biomarkers. We observed change in erythrocyte parameters leading to macrocytic normochromic anemia in GAC. Leukocyte parameters indicate a nonspecific immunosuppression caused by the exposure of associated contaminants, besides the attempts to repair damage caused by PE-MPs. Histopathological markers indicate damage to tissues exposed to contaminants. Besides, there were morphophysiological adjustments on gills, with proliferation and hypertrophy of mitochondria-rich cells on GBH and GAC, besides epithelium ruptures, which were mostly present in the exposed groups. Therefore, this study indicates that PE-MPs and GBHs present toxic effects in O. niloticus with the used concentrations, intensified by the association of contaminants. Thus, multi-biomarkers were useful key to verify toxicity, providing data to the investigation of high levels of contaminant's mixture toxicity present in aquatic environments., (© 2024 Wiley Periodicals LLC.)

Aquatic biota are exposed to toxic substances resulting from human activities, reducing environmental quality and can compromise the health of the organisms. This study aimed to employ Danio rerio as an environmental bioindicator, analyzing the effects of water from distinct urban aquatic environments. An active biomonitoring system was set up to compare the temporal dynamics of histological biomarkers for gill and liver and the patterns of non-protein thiols (NPSH) in muscle in specimens exposed for 3, 6, and 12 days. Three large urban basins in the city of Campo Grande (Midwest of Brazil) were selected. Two sites are in a very populous area (i.e Lagoa and Bandeira) and another on in an area with agricultural activities (i.e Anhanduí). All the streams displayed distinct qualitative characteristics. The presence of metals, including Mn, Zn, Fe, and Al, as well as pH, temperature, and dissolved oxygen, accounted for 38% of the variability (PC1), while total solids, conductivity, ammonia, nitrite, and explained 24 % (PC2). Degree tissue changes index (DTC) in gill and the concentration of NPSH increased in all streams during 3, 6 and 12 days of exposure. DTC in liver increases in all exposure times in most populous stream (i.e Lagoa and Bandeira). Histopathological evidence in the gill, including proliferation, desquamation, and necrosis of the primary lamellar epithelium; fusion and aneurysms in the secondary lamellar epithelium were observed after three days of exposure. Degenerative nuclear figures were noted in the liver after three days of exposure, followed by hepatocellular hypertrophy, lipidosis, and necrosis at twelve days. Our findings showing time-dependent effects of urban aquatic environments in histopathological (i.e DTC) and biochemical biomarkers in zebrafish. The biomonitoring model enabled a comparison of the temporal dynamics of various health markers, using zebrafish as bioindicator. Future studies might use this experimental model and biomarkers for environmental biomonitoring program., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Carlos Eurico dos Santos Fernandes reports financial support and equipment, drugs, or supplies were provided by Federal University of Mato Grosso do Sul. Carlos Eurico dos Santos Fernandes reports a relationship with Foundation for Support and Development of Education Science and Technology of Mato Grosso do Sul State that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The effect of water acidification in combination with normoxia or hypoxia on the antioxidant capacity and oxidative stress markers in gills and hemolymph of the Mediterranean mussel (Mytilus galloprovincialis), as well as on gill microstructure, has been evaluated through an in vivo experiment. Mussels were exposed to a low pH (7.3) under normal dissolved oxygen (DO) conditions (8 mg/L), and hypoxia (2 mg/L) for 8 days, and samples were collected on days 1, 3, 6, and 8 to evaluate dynamic changes of physiological responses. Cytoplasmic concentrations of reactive oxygen species (ROS) and levels of DNA damage were measured in hemocytes, while the activity of catalase (CAT) and superoxide dismutase (SOD) and histopathological changes were assessed in gills. The results revealed that while water acidification did not significantly affect the activity of SOD and CAT in gills under normoxic and hypoxic conditions, there was a trend towards suppression of CAT activity at the end of the experimental period (day 8). Similarly, we did not observe increased formation of ROS in hemocytes or changes in the levels of DNA damage during the experimental period. These results strongly suggest that the oxidative stress response system in mussels is relatively stable to experimental conditions of acidification and hypoxia. Experimental acidification under normoxia and hypoxia caused changes to the structure of the gills, leading to various histopathological alterations, including dilation, hemocyte infiltration into the hemal sinuses, intercellular edema, vacuolization of epithelial cells in gill filaments, lipofuscin accumulation, changes in the shape and adjacent gill filaments, hyperplasia, exfoliation of the epithelial layer, necrosis, swelling, and destruction of chitinous layers (chitinous rods). Most of these alterations were reversible, non-specific changes that represent a general inflammatory response and changes in the morphology of the gill filaments. The dynamics of histopathological alterations suggests an active adaptive response of gills to environmental stresses. Taken together, our data indicate that Mediterranean mussels have a relative tolerance to water acidification and hypoxia at tissue and cellular levels., Competing Interests: Declaration of competing interest Aleksandra Andreyeva reports financial support was provided by Russian scientific foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In the past decade, the increasing distribution of pollutants in the aquatic environment has been observed, causing integrative effects on fish. Likewise, due to anthropogenic activities, the southern gulf of Lake Tana is an impacted region, and the production of Nile tilapia fish is reduced. For this reason, the aim of this study was to conduct a histopathological-based study of 48 Nile tilapia fishes' health status at the southern gulf of Lake Tana and aquaculture using a cross-sectional study from February 2023 to May 2023. The study evaluated the histopathology of the gill, liver, gonads, and spleen organs using descriptive statistics accompanied by a 2 × 2 contingency table and t-test analysis. During the study, different histological alterations were detected, and the numbers of fish affected by a specific histological alteration were presented as percentage prevalence; hence, from the total fish examined, hyperplasia (54.15%), followed by pigment deposits (52%), hemorrhage (50%), and immune cell infiltration (50%), respectively, were the most frequently detected alterations. However, Nile tilapias from the southern gulf of Lake Tana were 1.4 (odds ratio) times more likely to show histopathological alterations than those from aquaculture, although statistically, was not significant (p > 0.05). In addition, the study found the mean value of the fish index (95.3) and regressive indices of the gill (13.6), liver (14.8), and gonad (12.3); moreover, the inflammatory indices of the spleen organ (11.3) and mean severity grade value of the gill (2.35) and gonad (1.7) organs, respectively, were obtained from the southern gulf of Lake Tana, and all those values were significantly higher (p < 0.05) from this site as compared to the aquaculture. In general, it has been found that tilapias from the southern gulf of Lake Tana showed higher pathological severity as compared with aquaculture. Among the four target organs evaluated, liver organs were observed to be the most damaged, while gonads were the least impacted organs. Therefore, it has been concluded that tilapia fish are living in abnormal conditions, so to ensure a sustainable fishery, water pollutant sources from Bahirdar city must receive proper attention, and future studies should consider age differences, seasonal variation, and the detection of specific pollutants., (© 2024. The Author(s).)

The histological changes in the liver, kidney, spleen, and gills of Syacium papillosum from the continental shelf of the Yucatan Peninsula, Gulf of Mexico, and their statistical associations with environmental conditions and pollutants were assessed in 2010, 2011, and 2012. We evaluated the extension and severity of the lesions through a degree of tissue change (DTC), and, with the sum of the number of lesion types within each of their DTC stages, we determined the histological alteration index (HAI). The liver and kidney were the most affected organs, with HAI values > 100. Fish with the most severe damage were observed on the Campeche Bank and the Caribbean Sea, contrasting with those collected from the northern Yucatan continental shelf. The presence of foci cellular alteration and abundant melanomacrophage centers indicated that these flatfishes were chronically exposed to environmental stress factors. Redundancy analyses showed strong associations between HAI values and hydrocarbon and heavy metal concentrations in muscle. Our results provide evidence for the first time of a differential health condition of the Yucatan shelf through the histopathology shown in S. papillosum, establishing the baseline for future monitoring programs in the region., (© 2024. The Author(s).)

Pesticides are commonly used in agriculture and aquaculture. Triazophos, an organophosphate-based pesticide, is widely used in agriculture to control many insect pests. Due to its high photochemical stability and mode of action, Triazophos could persist in the aquatic ecosystem and cause toxic effects on non-target organisms. We have studied the potential toxic effects of Triazophos on L. rohita. Primarily, we determined the median lethal concentration (LC 50 ) of Triazophos for 24 and 96 h. Next, we studied acute (96 h, LC 50-96 h ) toxicity. Then, we studied chronic (35 days, 1/10 th LC 50-24 h Treatment I: 0.609 mg/L, 1/5 th LC 50-96 h Treatment II: 1.044 mg/L) toxicity. We analyzed blood biomarkers such as hematology (Hb, Hct, RBC, WBC, MCV, MCH and MCHC), prolactin, cortisol, glucose and protein levels. Concurrently, we analyzed tissue biomarkers such as glycogen, GOT, GPT, LDH and histopathology. IBRv2 index assessment method was also to evaluate the Triazophos toxicity. Studied hematological, hormonal, biochemical and enzymological biomarkers were affected in Triazophos treated groups when compare to the control group. The changes in these biomarkers were statistically significant at the 0.05 alpha level. Triazophos exposed fish shown a severe degenerated primary and secondary lamellae, lamellar fusion, hypertrophy and telangiectasia in the gills. In the hepatic tissue, it caused moderate necrosis, blood congestion, distended sinusoids with minor vacuolation, prominent pyknotic nuclei, hypertrophy, cloudy swelling of cells, lipid accumulation and fibrotic lesions. In the renal tissue, Triazophos caused thickening of Bowman's capsule, hyaline droplets degeneration, irregular renal corpuscle, congestion, cellular swelling, degeneration of tubular epithelium, necrosis, shrunken glomerulus, vacuolated glomerulus, hypertrophy, exudate and edema. IBRv2 analysis suggested that tissue biomarkers are highly sensitive to Triazophos toxicity and prolonged exposure could cause serious health effects like acute toxicity in fish. Triazophos could cause multiorgan toxicity at studied concentrations., Competing Interests: Declaration of competing interest none., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Pesticides are widely used to control weeds and pests in agricultural settings but harm non-target aquatic organisms. In this study, our objective was to evaluate the effect of short-term exposure (one week) to environmentally relevant concentrations of pesticides mixture (low concentration: 0.4 μg/l atrazine, 0.5 μg/l Roundup®, and 0.5 μg/l 2,4-D; high concentration: 0.8 μg/l atrazine, 1 μg/l Roundup®, and 1 μg/l 2,4-D) on tissue architecture, body fluid conditions, and 3-nitrotyrosine protein (NTP) and Na + /K + -ATPase, expressions in tissues of American oyster (Crassostrea virginica) under controlled laboratory conditions. Histological analysis demonstrated the atrophy in the gills and digestive glands of oysters exposed to pesticides mixture. Periodic acid-Schiff (PAS) staining showed the number of hemocytes in connective tissue increased in low- and high-concentration pesticides exposure groups. However, pesticides treatment significantly (P < 0.05) decreased the amount of mucous secretion in the gills and digestive glands of oysters. The extrapallial fluid (i.e., body fluid) protein concentrations and glucose levels were dropped significantly (P < 0.05) in oysters exposed to high-concentration pesticides exposure groups. Moreover, immunohistochemical analysis showed significant upregulations of NTP and Na + /K + -ATPase expressions in the gills and digestive glands in pesticides exposure groups. Our results suggest that exposure to environmentally relevant pesticides mixture causes morphological changes in tissues and alters body fluid conditions and NTP and Na + /K + -ATPase expressions in tissues, which may lead to impaired physiological functions in oysters., Competing Interests: Declaration of competing interest There are no competing interests in this research work., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Cyanobacterial blooms are worldwide distributed and threaten aquatic ecosystems and public health. The current studies mainly focus on the adverse impacts of planktonic cyanobacteria or pure cyanotoxins, while the benthic cyanobacteria-induced ecotoxic effects are relatively lacking. The cyanobacterial cell-induced toxic effects on aquatic organisms might be more serious and complex than the pure cyanotoxins and crude extracts of cyanobacteria. This study explored the chronic effects of toxin-producing planktonic Microcystis aeruginosa (producing microcystin) and benthic Oscillatoria sp. (producing cylindrospermopsin) on the behaviors, tissue structures, oxidative stress, apoptosis, and inflammation of the Asian clams (Corbicula fluminea) under 28-d exposure. The data showed that both M. aeruginosa and Oscillatoria sp. can decrease the behaviors associated with the feeding activity and induce tissue damage (i.e. gill and digestive gland) in clams. Furthermore, two kinds of cyanobacteria can alter the antioxidant enzyme activities and increase antioxidant, lipid oxidation product, and neurotransmitter degrading enzyme levels in clams. Moreover, two kinds of cyanobacteria can activate apoptosis-related enzyme activities and enhance the proinflammatory cytokine levels of clams. In addition, two kinds of cyanobacteria can disturb the transcript levels of genes linked with oxidative stress, apoptosis, and inflammation. These results suggested harmful cyanobacteria can threaten the survival and health of clams, while the benthic cyanobacteria-induced adverse effects deserve more attention. Our finding also indicated that it is necessary to focus on the entire algal cell-induced ecotoxicity when concerning the ecological impacts of cyanobacterial blooms., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

Amyloodiniosis, caused by the ectoparasite Amyloodinium ocellatum, affects the healthy development of mariculture. This study used a local infection method to identify the pathogenic target organ responsible for the death of infected fish. Comparing the relationship between the abundance of trophonts in gills and skin with the mortality of infected fish using local infection showed that severe gill infections cause the mortality of infected fish. At the 40 % survival rate of infected fish, the parasite abundance in the gill was 14,167 ± 4371. The gill filaments of the infected fish were structurally disordered, with pronounced lesions associated with the presence of trophonts, such as epithelial cell degeneration and massive lymphocytic infiltration. However, the skin showed no obvious pathological changes. The TUNEL assay showed a significant presence of apoptotic cells concentrated in the area of A. ocellatum infection. The trophonts on the gills developed faster than those parasitising the skin and fins. Microbiome analysis revealed that at the phylum level, Proteobacteria, Bacteroidota, and Firmicutes are abundant in the skin, while Verrucomicrobiota, Bacteroidota, and Proteobacteria are abundant in the gills of A. latus. Furthermore, A. ocellatum infection significantly reduced (p < 0.05) the richness and diversity of the gill microbial community of A. latus. Infection by A. ocellatum increased the relative abundance of several putative pathogenic bacteria (Flavobacterium and Nocardia) in the gill and skin of A. latus, possibly increasing the likelihood of disease in the host. In conclusion, these results evidenced that severe gill infections by A. ocellatum cause mortality in infected fish, which clarifies the direction for exploring the pathogenesis of amyloodiniosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Microplastics pollution and salinity intrusion in freshwater ecosystem is one of the worldwide climate change consequences those have negative impacts on the physiology of aquatic organisms. Hence, a 15-day experiment was carried out where Nile tilapia (Oreochromis niloticus) was exposed to different salinity gradients i.e. 0 ‰, 3 ‰, 6 ‰, 9 ‰, and 12 ‰ alone and along with 10 mg/L polyamide microplastics (PA-MP) in order to measure its effects on the hematology, gill, and intestinal morphology. The results exhibited that all the fish treated with PA-MP ingested microplastics and the quantity of accumulation was significantly greater in higher salinity gradients (9 ‰ and 12 ‰). In addition, the PA-MP treated fish showed increased glucose level and at the same time reduced hemoglobin concentration with the increase of salinity. The percentages of abnormalities in erythrocytes both cellular (twin, teardrop and spindle shaped) and nuclear (notched nuclei, nuclear bridge and karyopyknosis) significantly enhanced with PA-MP exposure again in higher salinity treatments (9 ‰ and 12 ‰). The principal component analysis (PCA) exhibited that the addition of 10 mg/L PA-MP negatively affected the hematology of Nile tilapia than that of salinity treatments alone. Besides, the exposure of PA-MP in 9 ‰ and 12 ‰ salinity gradients escalated the severity of histological damages in gills and intestine. Overall, this experiment affirms that the increase of salinity enhanced the microplastics ingestion and toxicity in Nile tilapia, therefore, PA-MP possibly is addressed as additional physiological stressors along with increased salinity gradients in environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Plastic waste has emerged as a major environmental concern in recent years. As plastic waste discharged into the marine environment, it undergoes a breakdown process, eventually accumulating in aquatic organisms in the form of microplastics (MPs). To date, reduced food intake, nutritional absorption, and impaired immune system are known adverse effects of MPs-exposed aquatic organisms. This study aims to investigate whether MP exposure accelerated white spot syndrome virus (WSSV) infection in Pacific white shrimp ( Penaeus vannamei ) via laboratory tests. Briefly, experimental shrimp were divided into four groups; WSSV (group 1); MP (group 2); WSSV + MP (group 3); and Control (group 4). No mortality was observed in group 2, group 4, and even in group 1. However, group 3 showed a cumulative mortality of 50% during the experimental period. The PCR assay results showed no WSSV in the other three groups (groups 1, 2, and 4), but the dead and alive shrimp collected from group 3 were confirmed to be infected with the virus. Histopathological examination revealed normal structures in the hepatopancreas, gill, and muscle tissues of group 4, whereas numerous abnormally shaped nuclei were detected in the gill tissue of group 2. Moreover, group 1 showed minor WSSV-related lesions with few basophilic inclusion bodies in the gills, interestingly, group 3 exhibited severe lesions with numerous basophilic inclusion bodies in the gills. In conclusion, this study confirmed the correlation between the viral disease of shrimp and MPs, which can cause significant economic losses to the shrimp aquaculture industry.

Background: Understanding the relationship between resident microbiota and disease in cultured fish represents an important and emerging area of study. Marine gill disorders in particular are considered an important challenge to Atlantic salmon (Salmo salar) aquaculture, however relatively little is known regarding the role resident gill microbiota might play in providing protection from or potentiating different gill diseases. Here, 16S rRNA sequencing was used to examine the gill microbiome alongside fish health screening in farmed Atlantic salmon. Results were used to explore the relationship between microbial communities and gill disease., Results: Microbial community restructuring was observed throughout the sampling period and linked to varied drivers of change, including environmental conditions and severity of gill pathology. Taxa with significantly greater relative abundance on healthier gills included isolates within genus Shewanella, and taxa within family Procabacteriaceae. In contrast, altered abundance of Candidatus Branchiomonas and Rubritalea spp. were associated with damaged gills. Interestingly, more general changes in community richness and diversity were not associated with altered gill health, and thus not apparently deleterious to fish. Gross and histological gill scoring demonstrated seasonal shifts in gill pathology, with increased severity of gill damage in autumn. Specific infectious causes that contributed to observed pathology within the population included the gill disorder amoebic gill disease (AGD), however due to the uncontrolled nature of this study and likely mixed contribution of various causes of gill disease to observed pathology results do not strongly support an association between the microbial community and specific infectious or non-infectious drivers of gill pathology., Conclusions: Results suggest that the microbial community of farmed Atlantic salmon gills undergo continual restructuring in the marine environment, with mixed influences upon this change including environmental, host, and pathogenic factors. A significant association of specific taxa with different gill health states suggests these taxa might make meaningful indicators of gill health. Further research with more frequent sampling and deliberate manipulation of gills would provide important advancement of knowledge in this area. Overall, although much is still to be learnt regarding what constitutes a healthy or maladapted gill microbial community, the results of this study provide clear advancement of the field, providing new insight into the microbial community structure of gills during an annual production cycle of marine-stage farmed Atlantic salmon., (© 2024. The Author(s).)

The compound Honokiol, derived from the bark of Magnolia officinalis, possesses the ability to induce apoptosis and inhibit cellular damage caused by reactive oxygen species. The objective of this study was to investigate the toxicological and histopathological effects of Honokiol on zebrafish (Danio rerio) through conducting a semistatic acute toxicity test involving immersion in an Honokiol-containing solution. The results showed that the toxic effects of Honokiol on zebrafish were primarily manifested in the liver and gills. When exposed to 0.6 mg/L of Honokiol, it could lead to liver hemorrhage as well as swelling and necrosis of gill tissues, and high concentrations of Honokiol could trigger inflammatory responses. Additionally, research found that Honokiol could induce apoptosis in liver and gill tissues through the P53 pathway and possessed the ability to enhance antioxidation. The present findings significantly contribute to a more profound understanding of the toxic impact of Honokiol and its underlying mechanism, thereby providing a valuable reference for the future safe utilization of Honokiol and related pharmaceutical advancements., (© 2024 Wiley Periodicals LLC.)

Avermectin is a commonly used insect repellent for aquaculture and crops, but it is easy to remain in the aquatic environment, causing organism disorders, inflammation, and even death. This resulted in significant economic losses to the carp aquaculture industry. Silybin has antioxidant, anti-inflammatory, and anti-apoptotic properties. However, it is unclear whether Silybin counteracts gill damage caused by avermectin exposure. Therefore, we modeled avermectin exposure and Silybin intervention by adding 2.404 μg/L avermectin to water and 400 mg/kg of Silybin to feed. Gill tissue was collected and analyzed in depth during a 30-day experimental period. The results showed that avermectin exposure induced structural disorganization of gill filaments and led to increased reactive oxygen species, inhibition of antioxidant functions, induction of inflammatory responses, and endoplasmic reticulum stress in addition to the endogenous apoptotic pathway. In contrast, Silybin effectively alleviated pathological changes and reduced reactive oxygen species levels, thereby attenuating oxidative stress and endogenous apoptosis and inhibiting endoplasmic reticulum stress pathways. In addition, Silybin reduced avermectin-induced gill tissue inflammation in carp, and it is considered that it might modulate the cGAS-STING pathway. In summary, Silybin alleviates avermectin-induced oxidative damage within the carp's respiratory system by modulating the cGAS-STING pathway and endoplasmic reticulum stress. The main goal is to understand how Silybin reduces oxidative damage caused by avermectin in carp gills, offering management strategies. Concurrently, the current study proposes that Silybin can serve as a dietary supplement to reduce the risks brought on by repellent buildup in freshwater aquaculture., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Nanoplastics (NPs) are one of the most hazardous marine litters, having the potential to cause far-reaching impacts on the environment and humankind. The effect of NPs on fish health has been studied, but their impact on the subcellular organelles remains unexplored. The present investigation studied the possible implications of polystyrene-nanoplastics (PS-NPs) on the hematology, tissue organization, and endoplasmic reticulum (ER) stress-related proteins in Nile tilapia (Oreochromis niloticus). Fish were exposed to ∼100 nm PS-NPs at environmentally relevant (0.1 mg/L), and sublethal (1, 10 mg/L) concentrations for 14 days through water exposure. The growth performance and hematological parameters such as erythrocytes, hemoglobin, hematocrit, and leucocytes decreased, while thrombocytes increased with PS-NPs dose-dependently. The gills, liver, kidney, and heart tissues displayed increasing degrees of pathology with increased concentrations of PS-NPs. The gills showed severe epithelial hyperplasia and lamellar fusion. The liver had an abstruse cellular framework, membrane breakage, and vacuolation. While glomerular and tubular atrophy was the most prominent pathology in the kidney tissue, the heart displayed extensive myofibrillar loss and disorderly arranged cardiac cells. The ER-stress-related genes such as bip, atf6, ire1, xbp1, pkr, and apoptotic genes such as casp3a, and bax were over-expressed, while, the anti-apoptotic bcl2 was under-expressed with increasing concentrations of PS-NPs. Immunohistochemistry and blotting results of GRP78, CHOP, EIF2S, and ATF6 in gills, liver, kidney, and heart tissues affirmed the translation to ER stress proteins. The results revealed the sub-lethal adverse effects and the activation of the ER-stress pathway in fish with sub-chronic exposure to PS-NPs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The first author is an Editorial Board Member for Cardiovascular Toxicology and was not involved in the editorial review or the decision to publish this article., (Copyright © 2023. Published by Elsevier Inc.)

Background: Gills monogenean infestation causes significant mortalities in cultured fishes as a result of respiratory manifestation. Medicinal plants are currently being heavily emphasized in aquaculture due to their great nutritional, therapeutic, antimicrobial activities, and financial value., Methods: The current study is designed to assess the effect of garlic (Allium sativum) and onion (Allium cepa) extracts as a water treatment on the hematological profile, innate immunity, and immune cytokines expression besides histopathological features of gills of Nile tilapia (Oreochromis niloticus L.) infected with gills monogenetic trematodes (Dactylogyrus sp.). Firstly, the 96-hour lethal concentration 50 (96 h-LC 50 ) of garlic extract (GE) and onion extract (OE) were estimated to be 0.4 g/ L and 3.54 g/ L for GE and OE, respectively. Moreover, the in-vitro anti-parasitic potential for (GE) was found between 0.02 and 0.18 mg/mL and 0.4 to 1.8 mg/mL for OE. For the therapeutic trial, fish (n = 120; body weight: 40-60 g) were randomly distributed into four groups in triplicates (30 fish/group, 10 fish/replicate) for 3 days. Group1 (G1) was not infected or treated and served as control. G2 was infected with Dactylogyrus spp. and not exposed to any treatment. G3, G4 were infected with Dactylogyrus sp. and treated with 1/ 10 and 1/ 5 of 96 h LC 50 of OE, respectively. G5, G6 were infected with Dactylogyrus sp. and treated with 1/ 10 and 1/ 5 of 96 h LC 50 of GE, respectively., Results: No apparent signs or behaviors were noted in the control group. Dactylogyrus spp. infected group suffered from clinical signs as Pale color and damaged tissue. Dactylogyrus spp. infection induced lowering of the hematological (HB, MCH, MCHC and WBCs), and immunological variables (lysozyme, nitric oxide, serum Anti- protease activities, and complement 3). the expression of cytokine genes IL-ß and TNF-α were modulated and improved by treatment with A. sativum and A. cepa extracts. The obtained histopathological alterations of the gills of fish infected with (Dactylogyrus spp.) were hyperplasia leading to fusion of the gill filament, lifting of epithelial tissue, aneurism and edema. The results indecated that G4 and G5 is more regenarated epithelium in compare with the control group., Conclusion: A. sativum and A. cepa extracts enhance the blood profile and nonspecific immune parameters, and down-regulated the expression level of (IL-1β and TNF-α)., (© 2024. The Author(s).)

Introduction: Vibrio alginolyticus is a Gram-negative, rod-shaped bacterium belonging to the family of Vibrionaceae , a common pathogen in aquaculture animals, However, studies on its impact on Scylla serrata (mud crabs) are limited. In this study, we isolated V. alginolyticus SWS from dead mud crab during a disease outbreak in a Hong Kong aquaculture farm, which caused up to 70% mortality during summer., Methods: Experimental infection and histopathology were used to investigate the pathogenicity of V. alginolyticus SWS in S. serrata and validate Koch's postulates. Comprehensive whole-genome analysis and phylogenetic analysis antimicrobial susceptibility testing, and biochemical characterization were also performed., Results: Our findings showed that V. alginolyticus SWS caused high mortality (75%) in S. serrata with infected individuals exhibiting inactivity, loss of appetite, decolored and darkened hepatopancreas, gills, and opaque muscle in the claw. Histopathological analysis revealed tissue damage and degeneration in the hepatopancreas, gills, and claw muscle suggesting direct and indirect impacts of V. alginolyticus SWS infection., Conclusions: This study provides a comprehensive characterization of V. alginolyticus SWS as an emerging pathogen in S. serrata aquaculture. Our findings underscore the importance of ongoing surveillance, early detection, and the development of targeted disease management strategies to mitigate the economic impact of vibriosis outbreaks in mud crab aquaculture., Competing Interests: Author W-ML was employed by the company AI Farming Company Hong Kong Limited. The authors declare that this study received funding from AI Farming HK Ltd. The funder had the following involvement in the study: provided technical support and revised manuscript. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Kwok, Yu, Hau, Cheung, Ng, Fung, Wong, Yau, Liu, Kong, Siu, Chow and Seto.)

Early cyanobacterial blooms studies observed that exposure to blue-green algae led to fish gills impairment. The objective of this work was to evaluate the toxic mechanisms of exudates of Microcystis aeruginosa (MaE) on fish gills. In this study, the toxic mechanism of MaE (2×10 6 cells/mL) and one of its main components phytosphingosine (PHS) with two concentrations 2.9 ng/mL and 145 ng/mL were conducted by integrating histopathology, biochemical biomarkers, and transcriptomics techniques in Sinocyclocheilus grahami (S. grahami) for 96 h exposure. Damaged gill tissue with epithelial hyperplasia and hypertrophy, remarkable Na + /K + -ATPase (NKA) enzyme activity, disrupted the redox homeostats including lipid peroxidation and inflammatory responses were observed in the fish of MaE exposure group. Compare to MaE exposure, two concentrations of PHS exposure appeared to be a trend of lower degree of tissue damage, NKA activity and oxidative stress, but induced obviously lipid metabolism disorder with higher triglycerides, total cholesterol and total bile acid, which might be responsible for inflammation responses in fish gill. By transcriptome analysis, MaE exposure were primarily enriched in pathways related to gill function and immune response. PHS exposure, with higher number of differentially expressed genes (DEGs), were enriched in Toll-like receptor (TLR), Mitogen-Activated Protein Kinase (MAPK) and NOD-like receptor protein 3 (NLRP3) pathways. We concluded that MaE and PHS were induced the inflammatory responses, with oxidative stress-induced inflammation for MaE exposure but lipid metabolism disorder-induced inflammation for PHS exposure. The present study provided two toxin-induced gill inflammation response pathways under cyanobacterial blooms, which could be a scientific basis for the ecological and health risk assessment in the aquatic environment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Lindane is a broad-spectrum insecticide widely used on fruits, vegetables, crops, livestock and on animal premises to control the insects and pests. The extensive use of pesticides and their residues in the soil and water typically join the food chain and thus accumulate in the body tissues of human and animals causing severe health effects. The study was designed to determine the toxicity effects of sub-lethal concentrations of lindane on hemato-biochemical profile and histo-pathological changes in Rohu (Labeo rohita). A significant increase in the absolute (p<0.05) and relative (p<0.05) weights was observed along with severe histo-pathological alterations in liver, kidneys, gills, heart and brain at 30μg/L and 45μg/L concentration of lindane. A significant (p<0.05) decrease in RBCs count, PCV and Hb concentration while a significant (p<0.05) increased leukocytes were observed by 30μg/L and 45μg/L concentrations of lindane at 45 and 60 days of the experiment. Serum total protein and albumin were significantly (p<0.05) decreased while hepatic and renal enzymes were significantly (p<0.05) increased due to 30μg/L and 45μg/L concentrations of lindane at days-45 and 60 of experiment compared to control group. The observations of thin blood smear indicated significantly increased number of erythrocytes having nuclear abnormalities in the fish exposed at 30μg/L and 45μg/L concentrations of lindane. ROS and TBARS were found to be significantly increased while CAT, SOD, POD and GSH were significantly decreased with an increase in the concentration and exposure time of lindane. The results showed that lindane causes oxidative stress and severe hematological, serum biochemical and histo-pathological alterations in the fish even at sub-lethal concentrations., Competing Interests: The authors declare no conflict of interest., (Copyright: © 2024 Afzal et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Monogenean trematodes, particularly those belonging to the Diplectanidae family, are significant metazoan parasites with substantial implications for aquaculture expansion. This study, investigatied the occurrence, prevalence, and pathological impact of Diplectanum spp. in European seabass (Dicentrarchus labrax) across three distinct Egyptian fish farms. During 2021-2022, we sampled 1800 European seabass (Dicentrarchus labrax) from three Egyptian fish farms (600 fish per farm). Farms 1 and 2 used semi-intensive earthen pond systems, while Farm 3 utilized an intensive floating cage system. Employing Clinical, post-mortem, parasitological, and molecular examination technique. Pathological lesions were identified, including skin and gill discoloration, emaciation, and internal organ abnormalities. Seasonal prevalence exhibited significant variations between farms, with highest rates observed in spring and Farm 3 reached an overall peak prevalence of 84.67 %. Parasitological examination distinguished two Diplectanum species morphologically, while molecular techniques exhibited limited specificity. Histopathology unveiled damage to gill, liver, spleen, kidney, and intestine, attributed to Diplectanum haptors including inflammation and internal bleeding, potentially leading to secondary infections. Molecular identification via PCR targeting ITS and 28SrDNA genes, revealing similar band sizes for the two Diplectanum species, indicating limited intraspecific genetic diversity. The study emphasizes investigating parasitic infections' prevalence and impact in aquaculture, necessitating robust molecular techniques for species differentiation. This study underscores the importance of investigating the prevalence and impact of parasitic infections in aquaculture. It highlights the need for robust molecular techniques to differentiate species. By focusing on Diplectanum spp. infections in D. labrax, the study offers valuable insights into managing parasites in aquaculture effectively., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study was designed to investigate the toxic effects of two frequently used commercial insecticides containing endosulfan and indoxacarb on a freshwater amphipod Gammarus kischineffensis. In this context, the 24, 48, 72 and 96 h LC50 values of these pesticides were determined for G. kischineffensis. Then the histopathological effects of these pesticides on the gill tissues of this species were evaluated. At the end of the study, the 96 h LC50 values of commercial-grade endosulfan and indoxacarb for G. kischineffensis were determined as 1.861 μg L -1 and 20.212 mg L -1 , respectively. Histopathologically, the most common histopathological alterations in individuals exposed to sublethal concentrations of commercial-grade endosulfan and indoxacarb were pillar cell hypertrophy resulting in atrophy of the hemocoelic space and hemocytic infiltration. Considering these results, it can be said that commercial-grade endosulfan is extremely and indoxacarb is slightly toxic to G. kischineffensis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Heavy metals are one of the most important environmental pollutants in marine coastal ecosystems. Cadmium is a heavy metal that enters to marine environments via industrial wastes and oil production activities., Objectives: This study were done to determine the toxicity of cadmium to Litopenaeus vannamei and to evaluate the histological changes in gill tissues after exposure to sublethal concentrations of cadmium at different salinities., Methods: For this reason, toxicity test was done to determine the lethal concentration (LC50) of cadmium for whiteleg shrimp. According to the calculated LC50 amount, sublethal doses of cadmium were used to determine its histological effects in different salinity during 2 weeks exposing period., Results: LC50 of cadmium for 96 h for whiteleg shrimp was 6.56 mg/L. Histological alterations in the gill were observed in L. vannamei after 14 days exposure to different concentrations of cadmium and salinity. Histopathological index was increased in a dose-dependent manner., Conclusion: Our findings showed that doses lower than 2 mg/L have repairable effects on gill structure, but the concentration of 2 mg/L cadmium leaves irreparable and destructive effects on the gill tissue., (© 2024 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Aniline (C 6 H 5 NH 2 ) is one of the hazardous aromatic amine where an amino group -NH 2 ) is connected to phenyl ring (C 6 H 5 ). Based on the evaluation of the 96-hour LC 50 of aniline, two sublethal concentrations (4.19 mg/l and 8.39 mg/l) were selected for acute exposure tests in freshwater fish Channa punctatus. The liver, gills and kidney of fish being the principal sites of xenobiotic material accumulation, respiration, biotransformation, and excretion are the focus of the present study. Throughout the exposure time, the comet assay revealed increased tail length and tail DNA percentage indicating maximum damage to liver, gills and kidney of treated group after 96 h. After acute exposure, there was a significant (p ≤ 0.05) increase in the enzymatic activity of glutathione-S-transferase (GST) and acetylcholinesterase (AChE), whereas decline in superoxide dismutase (SOD) and catalase (CAT) activity was observed. Meanwhile, levels of malondialdehyde (MDA) increased over the exposure period for both concentrations. After 96 h of exposure, degree of tissue change (DTC) was evaluated in liver, gill and kidney of aniline exposed fish. Additionally, light microscopy revealed multiple abnormalities in liver, gills and kidney of all the treated groups. Significant changes were observed in the levels of biochemical markers viz., glucose, triglyceride, cholesterol, aspartate transaminase, alanine transaminase and urea following a 96-hour exposure to aniline. Studies using ATR-FTIR and transmission electron microscopy (TEM) revealed changes in biomolecules and structural abnormalities in several tissues of the aniline-exposed groups in comparison to the control group respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The development and application of functional feed ingredients represents a great opportunity to advance fish growth and health, boost the immune system, and induce physiological benefits beyond those provided by traditional feeds. In the present study, we looked at the feasibility of in vitro methods for screening the qualities of functional feed ingredients using the fish cell line RTgill-W1, which has never been used in fish nutrition, and the culture of Paramoeba perurans. Five functional feed ingredients (arginine, β-glucan, vitamin C, and two phytogenic feed additives) were selected to investigate their effects on cell viability and reactive oxygen species production. Three of the selected ingredients (arginine and two phytogenic feed additives) were additionally tested to assess their potential amoebicidal activity. As these functional ingredients are the core of a commercially available feed (Protec Gill, Skretting AS), their beneficial effects were further assessed in a field trial in fish affected by complex gill disease. Here, the analyzed parameters included the evaluation of macroscopic and histopathological gill conditions, pathogen detections, and analyses of plasma parameters. RTgill-W1 cell line assays were a good tool for screening functional ingredients and provided information about the optimal ingredient concentration ranges, which can be helpful for adjusting the concentrations in future feed diets. Through the culture of P. perurans, the tested ingredients showed a clear amoebicidal activity, suggesting that their inclusions in dietary supplements could be a viable way to prevent microbial infections. A three-week period of feeding Protec Gill slowed the disease progression, by reducing the pathogen load and significantly improving gill tissue conditions, as revealed by histological evaluation. The use of diets containing selected functional ingredients may be a feasible strategy for preventing or mitigating the increasingly common gill diseases, particularly in cases of complex gill disease, as documented in this study., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Vitale et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: In recent years, anthropogenic activities have released heavy metals and polluted the aquatic environment. This study investigated the ability of the silica-stabilized magnetite (Si-M) nanocomposite materials to dispose of lead nitrate (Pb(NO 3 ) 2 ) toxicity in Nile tilapia and African catfish., Results: Preliminary toxicity tests were conducted and determined the median lethal concentration (LC 50 ) of lead nitrate (Pb(NO 3 ) 2 ) to Nile tilapia and African catfish to be 5 mg/l. The sublethal concentration, equivalent to 1/20 of the 96-hour LC 50 Pb(NO 3 ) 2 , was selected for our experiment. Fish of each species were divided into four duplicated groups. The first group served as the control negative group, while the second group (Pb group) was exposed to 0.25 mg/l Pb(NO 3 ) 2 (1/20 of the 96-hour LC 50 ). The third group (Si-MNPs) was exposed to silica-stabilized magnetite nanoparticles at a concentration of 1 mg/l, and the fourth group (Pb + Si-MNPs) was exposed simultaneously to Pb(NO 3 ) 2 and Si-MNPs at the same concentrations as the second and third groups. Throughout the experimental period, no mortalities or abnormal clinical observations were recorded in any of the treated groups, except for melanosis and abnormal nervous behavior observed in some fish in the Pb group. After three weeks of sublethal exposure, we analyzed hepatorenal indices, oxidative stress parameters, and genotoxicity. Values of alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), urea, and creatinine were significantly higher in the Pb-intoxicated groups compared to the control and Pb + Si-MNPs groups in both fish species. Oxidative stress parameters showed a significant decrease in reduced glutathione (GSH) concentration, along with a significant increase in malondialdehyde (MDA) and protein carbonyl content (PCC) concentrations, as well as DNA fragmentation percentage in the Pb group. However, these values were nearly restored to control levels in the Pb + Si-MNPs groups. High lead accumulation was observed in the liver and gills of the Pb group, with the least accumulation in the muscles of tilapia and catfish in the Pb + Si-MNPs group. Histopathological analysis of tissue samples from Pb-exposed groups of tilapia and catfish revealed brain vacuolation, gill fusion, hyperplasia, and marked hepatocellular and renal necrosis, contrasting with Pb + Si-MNP group, which appeared to have an apparently normal tissue structure., Conclusions: Our results demonstrate that Si-MNPs are safe and effective aqueous additives in reducing the toxic effects of Pb (NO 3 ) 2 on fish tissue through the lead-chelating ability of Si-MNPs in water before being absorbed by fish., (© 2024. The Author(s).)

This study aimed to isolate and identify pathogenic bacteria in the intestinal tract, skin, and muscles of Sciades herzbergii; detect histopathological changes in the gill and liver; and use these biomarkers for the assessment of potential risks to human health. Fish were sampled during the rainy and dry seasons at two points in São Marcos Bay, Maranhão, Brazil: Ilha dos Caranguejos (IC) and Porto Grande (PG). Isolation and quantification were carried out using COLItest®. Colonies were subjected to identification and phenotypic investigation of antimicrobial resistance using Vitek®. Gill and liver samples were subjected to routine histological examination. The results indicated the presence of Klebsiella pneumoniae and Escherichia coli, the latter of which showed phenotypic resistance to norfloxacin and gentamicin. Fish caught at PG exhibited more extensive gill and liver damage than fish caught at IC. The findings suggest that histological changes in target organs of S. herzbergii may be influenced by infection with pathogenic bacteria., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Nile tilapia (Oreochromis niloticus) is valued in aquaculture because of its quick development and ability to thrive in various environments. Myxosporeans are among the fish parasites that affect fish productivity, as they impact fish growth and reproduction, resulting in large fish deaths in farms and hatcheries. This study has been focused on morpho-molecular identification for the myxosporean parasites infecting Nile tilapia from three governorates in Egypt and assessment of gene expression of different cytokines (Interleukin-1βeta (IL-1β), major histocompatibility complex class II (MHC-II), and clusters of differentiation 4 (CD-4) and 8 (CD-8)) in tissues. Additionally, this work aimed to correlate the developed histopathological alterations and inflammatory reactions in gills with immunohistochemical expression of inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-α). Finally, the infected fish's cortisol levels and blood glucose were assessed. Results of BLAST sequence analysis of the 18S rRNA for the collected protozoans confirmed Myxobolus agolus, M. brachysporus, M. tilapiae, and Henneguya species. The molecular characterization of the immunological status of gills revealed marked upregulation of different inflammatory cytokines in the gills of infected fish. There was a significantly increased serum cortisol and glucose level in infected fish compared with control, non-infected ones. Severe histopathological alterations were observed in the infected fish gills, associated with increased expression of iNOS and TNF-α and related to myxosporean infection. The present study provides new insights into oxidative stress biomarkers in Nile tilapia infected with Myxosporeans and elucidates the gill's immune status changes as a portal of entry for protozoa that contribute to tissue damage., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Ramadan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Hypoxia, a major issue in aquatic ecosystems, in special reference to climate change, and exacerbated by anthropogenic activities. It is causing slow growth, disease outbreaks, and mortality in finfish and shellfish. Therefore, adaptation to lowering oxygen levels through supplementation of herbs or their extracts in diets is imperative. In this study, hypoxia was simulated in controlled conditions with quercetin-enriched diets. Quercetin is a plant pigment (flavonol) possessing anti-oxidant property and is present in vegetables, leaves, seeds, pulses, and fruits. The experiment was conducted on rohu Labeo rohita, which is most widely cultured in India. There were four treatments including T1 (Normoxia: > 5 ppm dissolved oxygen; DO 2 ), T2 (hypoxia: 3-4 ppm DO 2 ), T3 (hypoxia + 50 mg quercetin/kg diet), and T4 (hypoxia + 100 mg quercetin/kg diet). The study was conducted for 30 days, and water quality was measured regularly. The results revealed that the hematological parameters were negatively affected. The tissue micro-architecture illustrated the impairment through degeneration of neurons in the brain, increased pigmentation as melanosis in the kidney, increased thickness of primary lamellae in the gills, and dilatations of sinusoids in the liver in hypoxia groups, while quercetin-enriched diets improved the hematological and histomorphological parameters. The results confirm the utility of hematological and histopathological tools as biomarkers and reflect the possible threats of hypoxia on fish. In conclusion, quercetin in diets appeared to show resistance towards chronic hypoxia by restoring the structure and functions of the vital organs towards normalcy and could be recommended as a potential ameliorative agent., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The advancement of nanotechnology and the widespread use of nanoparticles (NPs) in various industries have highlighted the importance of studying the potential harmful effects of nanomaterials on organisms. This study aimed to evaluate the lethal toxicity thresholds of Copper Oxide Nanoparticles (CuO-NPs). The investigation focused on examining the sub-lethal toxicity effects of CuO-NPs on blood parameters, as well as their influence on the gill tissue and liver of goldfish (Carassius auratus). Goldfish were exposed to varying concentrations of CuO-NPs (10, 20, 30, 40, 60, 80, and 100 mg/L) for 96 h. The Probit software was employed to determine the LC 50 (lethal concentration causing 50% fish mortality) by monitoring and documenting fish deaths at 24, 48, 72, and 96-hour intervals. Subsequently, sub-lethal concentrations of 5% LC 50 (T1), 10% LC 50 (T2), and 15% LC 50 (T3) of CuO-NPs were administered based on the LC 50 level to investigate their effects on haematological parameters, encompassing the number of red blood cells and white blood cells, hematocrit and haemoglobin levels, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. Additionally, histopathological examinations were conducted on the gill and liver tissues of the studied fish. Results indicated concentration-response of fish mortalities. In general, changes in the blood biochemical parameters of fish exposed to sub-lethal concentrations of CuO-NPs included a significant decrease in leukocyte count and glucose level and an increase in protein and triglyceride levels. Furthermore, an escalation in tissue damage such as gill apical and basal hyperplasia, lamellae attachment, squamous cell swelling, blood cell infiltration, and cellular oedema in gills tissue. and bleeding, increased sinusoidal space, necrosis, lateralization of the nucleus, cell swelling, and water retention in the liver. The findings showed dose-dependent increasing toxicity in goldfish specimens exposed to CuO-NPs., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Nodular gill disease (NGD) is an emerging condition associated with amoeba trophozoites in freshwater salmonid farms. However, unambiguous identification of the pathogens still must be achieved. This study aimed to identify the amoeba species involved in periodic NGD outbreaks in two rainbow trout (Oncorhynchus mykiss) farms in Northeastern Italy. During four episodes (February-April 2023), 88 fish were euthanized, and their gills were evaluated by macroscopic, microscopic and histopathological examination. The macroscopic and microscopic severity of the lesions and the degree of amoebae infestation were scored and statistically evaluated. One gill arch from each animal was put on non-nutrient agar (NNA) Petri dishes for amoeba isolation, cultivation and subsequent identification with SSU rDNA sequencing. Histopathology confirmed moderate to severe lesions consistent with NGD and mild to moderate amoeba infestation. The presence of amoebae was significantly correlated with lesion severity. Light microscopy of cultured amoebae strains and SSU rDNA analysis revealed the presence of a previously characterized amoeba Naegleria sp. strain GERK and several new strains: two strains from Hartmannelidae, three vannelid amoebae from the genus Ripella and cercozoan amoeba Rosculus. Despite the uncertainty in NGD etiopathogenesis and amoebae pathogenic role, identifying known and new amoebae leans towards a possible multi-aetiological origin., (© 2024 The Authors. Journal of Fish Diseases published by John Wiley & Sons Ltd.)

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., (© 2024. The Author(s).)

Triclosan (TCS), an antimicrobial additive in various personal and health care products, has been widely detected in aquatic environment around the world. The present study investigated the impacts of TCS in the gills of the fish, Cyprinus carpio employing histopathological, biochemical, molecular docking and simulation analysis. The 96 h LC 50 value of TCS in C. carpio was found to be 0.968 mg/L. Fish were exposed to 1/1000 th (1 µg/L), 1/100 th (10 µg/L), and 1/10 th (100 µg/L) of 96 h LC 50 value for a period of 28 days. The histopathological alterations observed in the gills were hypertrophy, hyperplasia, edematous swellings, and fusion of secondary lamellae in TCS exposed groups. The severity of these alterations increased with both the concentration as well as the duration of exposure. The present study revealed that the activity of antioxidant enzymes such as superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and reduced glutathione content decreased significantly (p < 0.05) in both concentration and duration dependent manner. However, a significant (p < 0.05) increase in the activity of the metabolic enzymes such as acid phosphatase and alkaline phosphatase was observed in all three exposure concentrations of TCS from 7 to 28 days. The activity of acetylcholinesterase declined significantly (p < 0.05) from 7 to 28 days whereas the content of acetylcholine increased significantly at the end of 28 day. The experimental results were further confirmed by molecular docking and simulation analysis that showed strong binding of TCS with acetylcholinesterase enzyme. The study revealed that long-term exposure to sublethal concentrations of TCS can lead to severe physiological and histopathological alterations in the fish., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The stingrays of the genus Himantura imbricata are present in all of the world's oceans, but the toxicity of their venoms has not yet been thoroughly characterized. The zebrafish as a toxicology model can be used for general toxicity testing of drugs and the investigation of toxicological mechanisms. The aim of this study was to evaluate the effect of crude venom from the stingray H. imbricata on the zebrafish Danio rerio. Juvenile zebrafish were injected with different concentrations of venom from H. imbricata via subcutaneous injections. The venom's effects were established via histological examination and hemolytic activity in zebrafish. The histopathological analysis revealed significant tissue damage in the organs of the zebrafish injected with venom, including liver necrosis and kidney degeneration. A blood examination revealed echinocytes, hemolysis, and nuclear abnormalities. Bodyweight estimations and histopathological attributes of the gills, heart, muscle, liver, intestine, eye, and brain were determined. The histological staining studies of the gills, liver, and intestine were measurably higher in the venom groups compared with the other two groups. Aggregately, the result shows that zebrafish may act as a valuable biomarker for alterations impelled by H. imbricata venom. The work delivers a useful model with substantial pharmacological potential for new drugs and a better comprehension of research on stingray venom., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The widespread application of herbicides raises concerns about their impact on non-target aquatic organisms. This study aimed to evaluate the toxicity of a commercially available herbicide formulation containing Bromoxynil+MCPA (2-Methyl-4-chlorophenoxyacetic acid) on Cirrhinus mrigala (economically significant fish). A total of 210 juvenile fish were subjected to a triplicate experimental setup, with 70 fish allocated to each replicate, exposed to seven different concentrations of herbicide: 0 mg/L, 0.133 mg/L, 0.266 mg/L, 0.4 mg/L, 0.5 mg/L, 0.66 mg/L, and 0.8 mg/L, respectively, for a duration of 96 h. The median lethal concentration (LC50) was determined to be 0.4 mg/L. Significant hematological alterations were observed, including decreases in RBC counts, hemoglobin, hematocrit, and lymphocyte counts, along with an increase in erythrocyte indices. Biochemical analysis revealed elevated levels of neutrophils, WBCs, bilirubin, urea, creatinine, ALT, AST, ALP, and glucose in treated groups. Morphological abnormalities in erythrocytes and histopathological changes in gills, liver, and kidneys were noted. Pathological alterations in gills, liver and kidneys including epithelial cell uplifting, lamellar fusion, hepatolysis, and renal tubule degeneration were observed. Oxidative stress biomarkers such as TBARS (Thiobarbituric Acid Reactive Substance), ROS (Reactive Oxygen Species), and POD (Peroxides) activity increased, while antioxidant enzymatic activities decreased as toxicant doses increased from low to high concentrations. The study reveals that Bromoxynil+MCPA significantly disrupts physiological and hematobiochemical parameters in Cirrhinus mrigala, which highlights the substantial aquatic risks. In conclusion, the herbicide formulation induced significant alterations in various fish biomarkers, emphasizing their pivotal role in assessing the environmental impact of toxicity. This multi-biomarker approach offers valuable insights regarding the toxicological effects, thereby contributing substantially to the comprehensive evaluation of environmental hazards., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Parabens are being used as preservatives due to their antifungal and antimicrobial effects. They are emerging as aquatic pollutants due to their excessive use in many products. The purpose of this study was to determine the toxic effect of ethyl paraben (C9H10O3) on the hematobiochemical, histological, oxidative, and anti-oxidant enzymatic and non-enzymatic activity; the study also evaluates the potential of ethyl paraben to cause genotoxicity in Rohu Labeo rohita. A number of 15 fish with an average weight of 35.45±1.34g were placed in each group and exposed to ethyl paraben for 21 days. Three different concentrations of ethyl paraben, i.e., T1 (2000μg/L), T2 (4000 μg/L), andT3 (6000 μg/L) on which fish were exposed as compared to the control T0 (0.00 μg/L). Blood was used for hematobiochemical and comet assay. Gills, kidneys, and liver were removed for histological alterations. The results showed a significant rise in all hemato-biochemical parameters such as RBCs, WBCs, PLT count, blood sugar, albumin, globulin, and cholesterol. An increase in aspartate aminotransferase (AST) and alanine transaminase (ALT) levels directed the hepatocytic damage. Histological alterations in the liver, gills and kidneys of fish were found. Ethylparaben induces oxidative stress by suppressing antioxidant enzyme activity such as SOD, GSH, CAT and POD. Based on the comet assay, DNA damage was also observed in blood cells, resulting in genotoxicity. Findings from the present study indicate that ethyl paraben induces hemato-biochemical alterations, tissue damage, oxidative stress, and genotoxicity., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Akmal et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The present study aimed to analyse the integrated histopathological lesions (IHLs) of the gill, liver and intestine of Catla catla exposed to the different doses of UV-B radiation. Gill exhibited the lesions like hypertrophy, hyperplasia, vacuolation, fusion of the gill filaments, rupture in the gill lamellae, epithelial cell lifting and necrosis. The UV-B-exposed liver of Catla showed the lesions like the degeneration of nucleus, the disarrangement of hepatocytes, sinusoidal vacuolation, epitheliod histiocyst, hepatocellular adenoma, exocrine adenoma, cyst formation and diffused epithelial necrosis (DEN). UV-B-exposed intestine showed the lesions like the distortion of columnar epithelial cells (CECs), distortion in lamina propria (LP), disruption in brush border (BB), vacuolation in LP, the presence of submucosal mass (SM), the degeneration of nucleus, the presence of tactoid bodies, the presence of aschoff nodules and metatypical cell carcinoma. These histopathological alterations can be considered as the main blocking alterations of the growth and absorption as well as the final production of fish which can cause a serious loss in total yield to fish farmers which can interrupt the profitable economical production of fish., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

We investigated disease trends of concern for fish or public health in a 5-y (2017-2021) prospective survey of fish in Cook County, IL, inland lakes. Lesions were assessed in relation to fish species, lake type and location, season and collection year, and lake water chemistry parameters. Fish included bullheads ( n  = 98), common carp ( n  = 99), bluegill ( n  = 114), and largemouth bass ( n  = 118). Annually, fish collection and point-source water sampling were conducted in spring, summer, and fall from both seepage and impoundment lakes. Examinations included autopsy, wet-mount cytologic assessment for ectoparasites, and histopathology. No lesions of public health concern were detected. The most common abnormalities were branchitis (261 of 429; 60.8%) and endoparasitism (312 of 429; 72.7%). Branchitis was mild in most cases (189 of 261; 72.4%) and concurrent with branchial parasitism in 175 of 261 (67%) cases. Monogeneans were the most common gill parasites but did not influence branchitis severity (Kruskal-Wallis, p  = 0.484). Using generalized ordered logistic regression, predictors of branchitis severity included fish species ( p  < 0.001), the interaction of lake or location and alkalinity ( p  < 0.001), and water temperature or season ( p  < 0.001). Endoparasites included tissue larval trematodes (metacercaria), nematodes, and cestodes (plerocercoids), enteric acanthocephalans, gastric trematodes, renal myxosporidia, biliary and gall bladder myxosporidia, enteric cestodes, and tissue microsporidia. Using generalized ordered logistic regression, variables influencing endoparasitism severity included species ( p  < 0.001), year ( p  < 0.001), chloride level ( p  = 0.009), and the interaction of year and chloride level ( p  < 0.001). Our results suggested overall good health of fish in sampled Cook County inland lakes and provide a foundation for continued monitoring of ecosystem and public health in the urban environment., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

This study evaluated the impacts of sulfamethoxazole (SMX) on antioxidant, immune, histopathological dynamic changes, and gut microbiota of zebrafish. SMX was carried out five groups: 0 (C), 3 mg/L (T3), 6 mg/L (T6), 12 mg/L (T12), and 24 mg/L (T24), with 5 replicates per group for an 8-weeks chronic toxicity test. It was found that SMX is considered to have low toxicity to adult zebrafish. SMX with the concentration not higher than 24 mg/L has no obvious inhibitory effect on the growth of fish. Under different concentrations of SMX stress, oxidative damage and immune system disorder were caused to the liver and gill, with the 12 and 24 mg/L concentration being the most significant. At the same time, it also causes varying degrees of pathological changes in both intestinal and liver tissues. As the concentration of SMX increases, the composition and abundance of the gut microbiota in zebrafish significantly decrease., (© 2024. The Author(s).)

Nanotechnology is an advancing and emerging field of all environmental, medical, and industrial applications. Magnesium oxide nanoparticles have been widely used in medicine, consumer products, industrial products, textiles, ceramics, alleviation of heartburn, stomach ulcers, and bone regeneration. In the present study, acute toxicity (LC 50 ) of MgO nanoparticles and hematological and histopathological changes in Cirrhinus mrigala was analyzed. The lethal concentration for 50% of MgO nanoparticles was 4.2321 mg/L. Hematological parameters such as white blood cells, red blood cells, hematocrit, hemoglobin, platelets, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration, as well as histopathological abnormalities in gills, muscle, and liver were observed on the 7th and 14th days of exposure. The WBC, RBC, HCT, Hb, and platelets count increased on the 14th day of exposure compared to the control and 7th day of exposure. The MCV, MCH, and MCHC levels decreased on the 7th day of exposure compared to the control and increased on the 14th day. Histopathological changes of MgO nanoparticles in gills, muscle, and liver highly damaged in the quantity of 3.6 mg/L compared to 12 mg/L on 7th and 14th days of exposure. This study finds the level of exposure in hematology and histopathological changes in tissues in relation to the exposure of MgO NPs., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)