Heavy metal contamination in a highly consumed Brazilian fish: immunohistochemical and histopathological assessments

Histological biomarkers and microbiological parameters of an estuarine fish from the Brazilian Amazon coast as potential indicators of risk to human health

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.

Metal Cross-contamination relationships between sediments and Loricariidae species (Siluriform) in a Neotropical riverine system

Human activities have changed the natural rates at which metals are moved and accumulated in both land and water environments, resulting in negative impacts on local wildlife. In this study, concentrations of Cr, Ni, Cd, Pb, Cu, Mn, Co, and Zn were evaluated in water and riverbed sediment samples collected from the Verde River basin (VR), as well as in tissue samples from five native Loricariidae species. Sediment samples collected from the central section of the VR riverbed indicated the presence of metal concentrations, which were primarily attributed to scattered pollution sources linked to rural activities in the surrounding areas. The bioconcentration factor in the Loricariids liver presented the highest average values for Zn (1.27 to 58.21), Co (0.48 to 14.91) and Cu (1.15 to 11.14). The same pattern was observed in the muscle, but in a lower proportion. Regarding the bioaccumulation factor, Co (1.54 to 34.84), Cu (5.85 to 25.22) and Zn (0.64 to 18.08) attained the highest average values in the liver. The co-inertia analysis examined the spatial distribution of metal concentrations in riverbed sediments and in tissues of Loricariids from the upper, middle, and lower stretches of the river, including the river mouth. The analysis revealed varying patterns, with samples from some regions showing higher bioaccumulation levels. This suggests that riverbed sediments are a primary source of metal contamination in Loricariids from these areas. The pollution has had a significant impact on the bioaccumulation of metals in the VR' Loricariids, which are good indicators of sediment-associated metal bioaccumulation. The metal concentrations recorded in both the riverbed sediments and Loricariids surpassed international and Brazilian limits set for aquatic health and safe human consumption. Given the importance of the Verde River in terms of its ecological, social, cultural, and economic roles, it is essential to implement biomonitoring and control measures to safeguard both terrestrial and aquatic resources.

Histopathology and changes in the expression of metallothioneins, heat shock proteins and inducible nitric oxide synthase in Prochilodus costatus from a neotropical river contaminated by heavy metals

The most recent dam rupture in Brazil released tons of mining tailings into the upper course of the Paraopeba River, affecting this river in an unprecedented way. The present study aimed to evaluate the influence of heavy metals on Prochilodus costatus, an important commercial species in Brazil, four years after the dam colapse. To this end, biomarkers of heavy metals, oxidative stress, and environmental stress were analyzed, and histological analyses of target organs were performed. The results demonstrated critical contamination of fish from the Paraopeba River. Increased expression of Metallothioneins - MTs, Heat Shock Protein - HSP70, and inducible nitric oxide synthase - iNOS, as well as greater rates of histological changes in the liver, spleen, and gonads, were observed in P. costatus. These findings demonstrate that, despite past contamination, the metals present in mining tailings have significantly increased the contamination of the Paraopeba River basin.

Assessing the water quality in a World Heritage Site using biomarkers in top fish predators

The use of biomarkers in fish for biomonitoring is a valuable approach to reveal effects of human impacts on biota health. Top predator fish are effective models for monitoring human activities' impacts on aquatic ecosystems. The Guaraguaçu River is the largest river-system on coastal region of South Brazil and a World Heritage site. The river receives contaminants from disorderly urban growth, including discharges of domestic sewage and small fishery boats, particularly during the tourist season. Our study aimed to assess impact of anthropogenic activities on water quality in the Guaraguaçu River by analyzing environmental contamination biomarkers in the top fish predator Hoplias malabaricus. Fish were collected using a fyke net trap across sectors representing a gradient of anthropic impact: sector 1 - pristine; sector 2 - impacted; and sector 3 - less impacted. Water samples were collected to analyze the presence of trace elements and pesticide. Biomarkers of the antioxidant system, histopathology, genotoxicity, neurotoxicity, and concentration of trace elements were analyzed in fish tissues. In water samples Al, Fe and Mn were detected, but no pesticides were found. In fish muscle, zinc and iron were detected. Brain acetylcholinesterase activity decreased in impacted sectors, indicating neurotoxic effects. The antioxidant system increased activity in gills and liver, and damage from lipoperoxidation was observed, particularly in sector 2 when compared to sector 1, suggesting oxidative stress. Histopathological biomarkers revealed lesions in the liver and gills of fish in impacted sectors. Micronuclei, a genotoxicity biomarker, were observed in organisms from all sectors. Our results demonstrate detrimental effects of poor water quality on biota health, even when contaminants are not detected in water.

A review on heavy metal-induced toxicity in fishes: Bioaccumulation, antioxidant defense system, histopathological manifestations, and transcriptional profiling of genes

AIM

This review provides information about heavy metal occurrence in the environment, destructive mechanisms, and lethal effects on fish.

SUMMARY

Heavy metals (HMs) are one of the major causes of environmental contamination globally. The advancement of industries has led to the emanation of toxic substances into the environment. HMs are stable, imperishable compounds and can accumulate in different fish organs when they reach the aquatic regimes. The most ubiquitous HMs are chromium, arsenic, mercury, cadmium, lead, copper, and nickel which can pollute the environment and affect the physiology of fishes. Accumulation of metals in the fish organs causes structural lesions and functional disturbances. Contamination of heavy metals induces oxidative stress, histopathological manifestations, and altered transcriptional gene regulation in the exposed fishes.

CONCLUSION

Heavy metal bioaccumulation leads to different anomalies in the non-target species. Metal toxicity may cause aquatic organisms to exhibit cellular dysfunction and disturb ecological equilibrium.

Occupational risks associated with chronic kidney disease of non-traditional origin (CKDnt) in Brazil: it is time to dig deeper into a neglected problem

In the past decades, an epidemic of chronic kidney disease (CKD) has been associated with environmental and occupational factors (heat stress from high workloads in hot temperatures and exposure to chemicals, such as pesticides and metals), which has been termed CKD of non-traditional origin (CKDnt). This descriptive review aims to present recent evidence about heat stress, pesticides, and metals as possible causes of CKDnt and provide an overview of the related Brazilian regulation, enforcement, and health surveillance strategies. Brazilian workers are commonly exposed to extreme heat conditions and other CKDnt risk factors, including increasing exposure to pesticides and metals. Furthermore, there is a lack of adequate regulation (and enforcement), public policies, and strategies to protect the kidney health of workers, considering the main risk factors. CKDnt is likely to be a significant cause of CKD in Brazil, since CKD's etiology is unknown in many patients and several conditions for its development are present in the country. Further epidemiological studies may be conducted to explore causal associations and estimate the impact of heat, pesticides, and metals on CKDnt in Brazil. Moreover, public policies should prioritize reducing workers´ exposure and promoting their health and safety.

Differential gene expression and developmental pathologies associated with persistent organic pollutants in sentinel fish in Troutman Lake, Sivuqaq, Alaska

Persistent organic pollutants (POPs) are lipophilic compounds that bioaccumulate in animals and biomagnify within food webs. Many POPs are endocrine disrupting compounds that impact vertebrate development. POPs accumulate in the Arctic via global distillation and thereby impact high trophic level vertebrates as well as people who live a subsistence lifestyle. The Arctic also contains thousands of point sources of pollution, such as formerly used defense (FUD) sites. Sivuqaq (St. Lawrence Island), Alaska was used by the U.S. military during the Cold War and FUD sites on the island remain point sources of POP contamination. We examined the effects of POP exposure on ninespine stickleback (Pungitius pungitius) collected from Troutman Lake in the village of Gambell as a model for human exposure and disease. During the Cold War, Troutman Lake was used as a dump site by the U.S. military. We found that PCB concentrations in stickleback exceeded the U.S. Environmental Protection Agency's guideline for unlimited consumption despite these fish being low trophic level organisms. We examined effects at three levels of biological organization: gene expression, endocrinology, and histomorphology. We found that ninespine stickleback from Troutman Lake exhibited suppressed gonadal development compared to threespine stickleback (Gasterosteus aculeatus) studied elsewhere. Troutman Lake stickleback also displayed two distinct hepatic phenotypes, one with lipid accumulation and one with glycogen-type vacuolation. We compared the transcriptomic profiles of these liver phenotypes using RNA sequencing and found significant upregulation of genes involved in ribosomal and metabolic pathways in the lipid accumulation group. Additionally, stickleback displaying liver lipid accumulation had significantly fewer thyroid follicles than the vacuolated phenotype. Our study and previous work highlight health concerns for people and wildlife due to pollution hotspots in the Arctic, and the need for health-protective remediation.

Reproductive toxicity induced by lead exposure: Effects on gametogenesis and sex steroid signaling in teleost fish

Lead (Pb) is an emerging contaminant widely distributed in aquatic environments, which has serious effects on human and animal health. In this study, we determined whether Pb exposure affects gametogenesis, sex steroids, estrogen (ERα and ERβ), and androgen (AR) receptors. Adult specimens of Astyanax bimaculatus were exposed in duplicate to 15, 50, and 100 μg/L of lead acetate, whereas the control group was not exposed. After 28 days of exposure, fish were euthanized and samples of the gonads, liver, and blood were collected for analysis. The results indicated a reduction in the gonadosomatic index as well as the diameters of the vitellogenic follicles and seminiferous tubules in the exposed groups. Morphometry of gametogenesis revealed inhibition of the secondary oocyte growth and a reduction in the number of spermatozoa in the 50 and 100 μg/L Pb-treated groups. In females, plasma 17β-estradiol (E2) increased following 15 and 50 μg/L Pb treatment, whereas males exhibited an increase in E2 and 11-ketotestosterone following treatment with 15 and 100 μg/L Pb, respectively. Vitellogenin was significantly reduced in females exposed to 100 μg/L Pb, but metallothionein levels were unchanged. ERα, ERβ, and AR were immunolocalized in the somatic and germ cells, with increased ovarian expression of ERα and Erβ in the 100 μg/L Pb-treated group, but no significant difference in AR among the groups. In males, only ERα increased in the 100 μg/L Pb-treated group. These results indicate that Pb exposure impairs gametogenesis, disrupts estrogen receptor signaling, and affects the expression of major reproductive biomarkers in A. bimaculatus.

Acute toxicity of palm oil mill effluent on zebrafish (Danio rerio Hamilton-Buchanan, 1822): Growth performance, behavioral responses and histopathological lesions

Evaluating the toxicity of Palm Oil Mill Effluent (POME) is critical as part of the effort to develop waste management regulations for the palm oil industry. In this study, we investigated the acute toxicity of POME on growth performance, behavioral response, and histopathology of gill and liver tissues of zebrafish (Danio rerio). In total, 550 adult male zebrafish were used for the toxicity experiment including range finding test, acute toxicity test, growth performance and behaviour test. Static non-renewal acute toxicity bioassays were conducted by exposing fish to POME (1.584-9.968 mL/L) for 96 h. Growth performance, behavior response, and histopathological lesions in untreated and POME treated (96-h LC50: 5.156 mL/L) fish were measured at 24, 48, 72 and 96 h. Time-dependent significant decline in body length and body weight of POME-exposed zebrafish was observed. Furthermore, several behavioral changes were recorded, including hyperactivity, loss of balance, excessive mucus secretion, and depigmentation. Decreasing operculum movement and oxygen consumption rate as well as alterations in gill tissues (i.e. hyperplasia, hypertrophy, hemorrhage, and necrosis) of POME-exposed zebrafish were observed, suggesting a dysfunction in respiratory performance. On the other hand, liver tissue alterations (congestion, hemorrhage, hyperplasia, shrinkage of hepatocytes, hydrophilic degeneration, and necrosis) indicated a disruption in detoxification performance. We conclude that exposure to POME at acute concentration caused histopathological lesions both in gill and liver tissue along with changes in fish behaviors which disrupted respiratory and detoxification performance, resulting in mortality and reduced growth of zebrafish. These findings might provide valuable information for guiding POME management and regulation.

Brumadinho dam collapse induces changes in the microbiome and the antibiotic resistance of the Paraopeba River (Minas Gerais, Brazil)

The rupture of the Córrego do Feijão dam in Brumadinho (January 25, 2019) caused serious damage to the Paraopeba River and compromised the quality of its waters for human consumption. However, the possible effects of the dam collapse on the river microbiome and its antibiotic resistance profiles are unknown. The present study aims to analyse the possible shifts in microbial diversity and enhancement of antibiotic resistance in the Paraopeba River. To this end, two sampling campaigns (February and May 2019) were performed to obtain water across the entire Paraopeba River (eight sampling locations: Moeda, Brumadinho, Igarapé, Juatuba, Varginha, Angueretá, Retiro Baixo and Três Marias; ~464 km). This sampling scheme enabled determining the effects of the disaster on the river microbiome. Total DNA and microbial isolation were performed with these water samples. The 16S rRNA-based microbiome analyses (n = 24; 2.05 million 16S rRNA reads) showed changes in microbial diversity immediately after the disaster with the presence of metal-indicating bacteria (Acinetobacter, Bacillus, Novosphingobium, and Sediminibacterium). Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) identification of bacterial isolates (n = 170) also disclosed possible indicators of faecal contamination across the Paraopeba (Cloacibacterium, Bacteroides, Feaecalibacterium, Bifidobacterium, Citrobacter, Enterobacter, Enterococcus and Escherichia). Antibiotic resistance increased significantly to ampicillin, ampicillin/sulbactam, amoxicillin/clavulanate, ceftriaxone, and cefalotin among isolates obtained in May after the disaster. The effects of toxic mud on microbiomes were felt at all points sampled up to Anguereta. The ore mud may have exacerbated the growth of different antibiotic-resistant, metal-resistant, and faecal-indicating bacteria in the Paraopeba River.

Sequential exposures of single walled carbon nanotubes and heavy metal ions to macrophages induce different cytotoxicity

The probability of occupational exposure rises with the increasing production and biomedical application of carbon nanotubes (CNTs). Thus, the risk of co-exposure of nanomaterials with environmental pollutants is also increasing. Although many studies have focused on the combined toxicity of nanomaterials and pollutants, more attention has been paid to the toxicity of nanomaterials after adsorbing pollutants or the toxicity of nanomaterials and pollutants exposed simultaneously. Few studies have been conducted on the toxicity and toxicity mechanisms of nanomaterials and environmental pollutants following sequential exposure. In this study, we employed THP-1 cells to investigate how pristine single walled CNTs (p-SWCNTs) and oxidized single walled CNTs (SWCNT-COOHs) pretreatments at a non-lethal dose of 10 μg/mL affect cell responses to metal ions (i. e., Pb²⁺, Cu²⁺, and Cr(VI)). We found that p-SWCNTs caused more significant damage to cell membrane integrity than SWCNT-COOHs, which led to higher metallothionein (MT) levels and increased transport of metal ions into cells. Pretreatment of p-SWCNTs in cells significantly increased the cytotoxicity of Pb²⁺, Cu²⁺, and Cr(VI) by 2-4-fold, whereas SWCNT-COOHs pretreated cells showed no noteworthy changes in response to heavy metals, which were further confirmed by the cellular reactive oxygen species (ROS) assays. These findings indicate that understanding the effects of the exposure sequence of engineered nanomaterials and environmental pollutants on their toxicity provides an excellent complement to combined toxicity evaluation.

Comparative assessment of human health risk associated with heavy metals bioaccumulation in fish species (Barbus grypus and Tenualosa ilisha) from the Karoon River, Iran: Elucidating the role of habitat and feeding habits

Concentrations of Cd, Ni, and Pb were measured in the liver and muscle tissues of benthic omnivorous (Barbus grypus) and pelagic herbivorous (Tenualosa ilisha) fish collected from two sampling sites along the Karoon River, Khuzestan Province, southwest of Iran. Potential human health risks were evaluated by measuring the estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and target cancer risk (TR). The results highlight the important role of habitat and feeding habits in the uptake of HMs by the two species. The EDI for all HMs exceeded the oral reference doses (RfDo) provided by the USEPA, indicating the two fish species are not entirely safe for human consumption. The THQ values were within the permissible limit (< 1), while HI values (> 1) showed there was non-carcinogenic risk for consumers. The TR values for Pb were within the acceptable range (1.00E-06-1.00E-04) for both species.

Chronic hypoxia and Cu2+ exposure induce gill remodeling of largemouth bass through endoplasmic reticulum stress, mitochondrial damage and apoptosis

Hypoxia and Cu²⁺ pollution often occur simultaneously in aquatic ecosystems and jointly affect physiology of fish. As the respiratory and ion exchange tissue of fish, how gill responds to the stress induced by these two abiotic environmental factors is still unclear. We have conducted a study by exposing largemouth bass (Micropterus salmoides) to hypoxia (2.0 mg·L^-1) and/or Cu²⁺ (0.5 mg·L^-1) for 28 days to answer this question. We subsequently studied respiratory rate, Cu²⁺ transport, endoplasmic reticulum (ER) stress, mitochondrial damage, and morphology in gill tissue on day 7, 14, 21 and 28. We found that hypoxia exposure increased the respiratory rate of largemouth bass, reflecting the response of largemouth bass to cope with hypoxia. Of note, Cu²⁺ entered gill by specifically binding to CTR1 and its accumulation dramatically in gill disrupted the response of largemouth bass to hypoxia. Hypoxia and/or Cu²⁺ exposure led to ER stress and mitochondrial damage in gills of largemouth bass. ER stress and mitochondrial damage induced apoptosis by activating caspase-8 and caspase-9 signaling pathways, respectively. Apoptosis induced by hypoxia and Cu²⁺ exposure had a positive and synergistic effect on gill remodeling by reducing interlamellar cell masses. In addition, Cu²⁺ exposure induced hypoxia-like remodeling to gill morphology through mechanisms similar to hypoxia exposure. Most of gene expression changed mainly within 21 days and recovered to the control level on day 28, reflecting the acclimation of largemouth bass to hypoxia and/or Cu²⁺ exposure at gene expression level. Overall, our research suggests that chronic hypoxia and Cu²⁺ exposure could induce gill remodeling of largemouth bass through ER stress, mitochondrial damage and apoptosis. The outcomes could provide an insight for fish environmental adaptation and environmental toxicology.

Water hardness alleviates the stress response caused by waterborne zinc in goldfish Carassius auratus

In this study, the combined effect of waterborne Zn and water hardness on the stress response in the goldfish Carassius auratus was investigated. Goldfish were exposed to Zn concentrations of 0.5, 1.0, and 3.0 mg/L and water hardness of 90, 270, and 450 mg/L CaCO₃ for 1, 3, 7, and 14 d. After exposure, it was determined that higher the Zn concentration, the more obvious the stress response. However, the stress response reduced with increasing water hardness. An increase in the Zn concentration caused stress responses in fish according to the increase in the mRNA expressions of corticotropin-releasing hormone and adrenocorticotropic hormone and cortisol level in the hypothalamus-pituitary-interrenal axis. The expression of these factors was the highest on day 7 and decreased on day 14. Furthermore, to evaluate the stress change in the liver tissue, we analyzed alanine aminotransferase, aspartate aminotransferase, and heat shock protein 70 concentrations to determine the damage caused by Zn and the change in water hardness. Immunohistochemistry staining for Na⁺/K⁺-ATPase in the gills showed that the gill activity was inhibited by Zn, and an increase in water hardness could improve Na⁺/K⁺-ATPase. In conclusion, we found that increasing water hardness is a successful method to reduce the stress response in goldfish caused by Zn.

Detecting Aquatic Pollution Using Histological Investigations of the Gills, Liver, Kidney, and Muscles of Oreochromis niloticus

The present study aimed to determine the degree of changes in the histological architecture of the liver, gills, kidneys, and muscles of fish Oreochromis niloticus collected from different polluted river sites. Fish samples collected from the Faisalabad Fish Hatchery and upstream of Chakbandi drain acted as a control. Necrosis, hemorrhage, and epithelial hyperplasia were observed in the gills of fish inhabiting the river downstream of the Chakbandi drain entrance. Liver tissues were found to be affected by vacuolated cytoplasm, bile duct proliferation, melanomacrophages, and necrosis. In kidney tissues, shrinkage of the renal cortex, necrosis, and destructive renal tubules were observed. Histopathology of muscles indicates the presence of hypertrophy and swollen myofibers. In contrast, upstream specimens of fish exhibited mild tissue alterations. Histopathology of gills tissue showed vacuolization. Liver tissues indicated the presence of hypertrophy and more frequent Kupffer cells than usual. The vacuolation was also observed in kidney tissues. Muscle tissues expressed splitting of muscle fibres and degeneration in muscle bundles. However, sections of tissues collected from farmed fish have normal morphology and no anomalies. The histopathological assessment indicated various cellular, biochemical, and histological changes in response to the contamination in the vicinity of the fish.

Morphological and Functional Alterations Induced by Two Ecologically Relevant Concentrations of Lead on Danio rerio Gills

Lead (Pb), due to its high toxicity and bioaccumulation tendency, is one of the top three pollutants of concern for both humans and wildlife and occupies second place in the Priority List of Hazardous Substances. In freshwater fish, Pb is mainly absorbed through the gills, where the greatest accumulation occurs. Despite the crucial role of gills in several physiological functions such as gas exchange, water balance, and osmoregulation, no studies evaluated the effects of environmentally relevant concentrations of Pb on this organ, and existing literature only refers to high levels of exposure. Herein we investigated for the first time the molecular and morphological effects induced by two low and environmentally relevant concentrations of Pb (2.5 and 5 μg/L) on the gills of Danio rerio, a model species with a high translational value for human toxicity. It was demonstrated that Pb administration at even low doses induces osmoregulatory dysfunctions by affecting Na⁺/K⁺-ATPase and AQP3 expression. It was also shown that Pb upregulates MTs as a protective response to prevent cell damage. Modulation of SOD confirms that the production of reactive oxygen species is an important toxicity mechanism of Pb. Histological and morphometric analysis revealed conspicuous pathological changes, both dose- and time-dependent.

Ecotoxicological impacts of the Fundão dam failure in freshwater fish community: Metal bioaccumulation, biochemical, genetic and histopathological effects

This study investigates the ecotoxicological impacts of the Fundão dam rupture, one of the major environmental disaster that occurred in Brazil and in the world mining industry history, through multi-biomarkers responses and metals bioaccumulation in the fish community of different trophic levels. Specimens of the fishes (omnivorous/herbivorous and carnivorous) were collected along the Doce River channel and its affluent Guandú River, and in different lakes and coastal lagoons adjacent to the river channel, in the Espirito Santo State, Southeast of Brazil. Four sampling collections were carried out over two years (2018 to 2020, during dry and rainy seasons). For both trophic groups the biomarkers responses indicated physiological alterations related to metals exposure and showed strong seasonal variations. The principal component analysis and integrated biomarker response index showed that DNA damage and lipid peroxidation were more associated with dry season 2 (Sep/Oct 2019) and the oxidative damage in proteins, metallothioneins concentration and the activity of superoxide dismutase in the gills showed a greater association with rainy season 2 (Jan/Feb 2020). On the other hand, the enzymes of energy metabolism, catalase and histological damage in the liver and the gills, were more associated with the dry and rainy campaigns of the first year of monitoring. The multivariate approach also suggested a temporal intensification in the bioaccumulation of metals and biological effects in the lacustrine environments. Thus, these results demonstrate that the release of mineral residues from the rupture of the Fundão mine dam affects the health status of the fish from the Doce River basin, provoking metals bioaccumulation, hepatic and branchial damage in the fish besides inducing of enzyme activity related to metal contamination, even four years after the rupture.

Chemical pollution impairs the health of fish species and fishery activities along the Algeria coastline, Mediterranean Sea

Chronic exposure to multiple pollutants affects aquatic organisms, even at low concentrations, and can impair fishery activities along marine coastlines. The bioavailability of toxic metals and the presence of metals and polycyclic aromatic hydrocarbons (PAHs) in both water and sediment can explain the worst-case scenario of fish health and fishery production decline along the Algeria coastline. The hepatosomatic index (HIS), gonadosomatic index (GSI), and condition factor (K) in the studied species from the Algiers, Bou Ismail, and Zemmouri bays are the first indicators of the poor environmental health along the studied region. These findings could be explained by the bioavailability of Zn, Cu, Cr, Mn, Hg, and Ni and the detection of PAHs in the water and sediment of these bays. Additionally, histopathological damage in the liver is described in sardine (Sardina pilchardus), anchovy (Engraulis encrasicolus), and sardinelle (Sardinella aurita) highlights the current study in the investigation of the risk of exposure to biota or human populations. The occurrence of permanent lesions in the livers of fish impairs organ function and increases the incidence of diseases affecting the fish community. Furthermore, the factor analysis with principal component analysis (FA/PCA) dataset explains the physiological disturbances described in all studied species. These findings revealed that Zemmouri bay is the most affected by chemicals, suggesting that S. pilchardus is the most sensitive species. Finally, the results showed that the bioavailability of chemicals present in the studied bays confirms poor water quality, which can explain the decrease in fishery production along the Algerian Coastline.

Recovery trend to co-exposure of iron oxide nanoparticles (γ-Fe2O3) and glyphosate in liver tissue of the fish Poecilia reticulata

Citrate-coated iron oxide nanoparticles (IONPs) have potential use in environmental remediation, with possibilities in decontaminating aquatic environments exposed to toxic substances. This study analyzed IONPs associated to Roundup Original, a glyphosate-based herbicide (GBH), and pure glyphosate (GLY), through ultrastructural and histopathological biomarkers in liver tissue, from females of Poecilia reticulata exposed to: iron ions (0.3 mg/L) (IFe) and IONPs (0.3 mgFe/L) associated with GLY (0.65 mg/L) and GBH (0.65 mgGLY/L (IONP + GBH1) and 1.30 mgGLY/L (IONP + GBH2)) for a period of 7, 14 and 21 days, followed by an equal post-exposure period only in reconstituted water. For the assays, the synthetized IONPs had crystalline and rounded shape with an average diameter of 2,90 nm, hydrodynamic diameter 66,6 mV, zeta potential -55,4 and diffraction profile of maghemite (γ-Fe2O3). The data obtained by biomarkers indicated a high inflammatory response in all treatments. These same parameters, considered during the post-exposure period indicated recovery in reaction patterns of circulatory disturbances and regressive changes, resulting in average reductions of 37,53 points in IFe, 21 points in IONP + GBH1, 15 points in IONP + GBH2 and 11 points in IONP + GLY in total histopathological index of liver after 21 days post-exposure. However, although the cellular and tissue responses were significant, there was no change in the condition factor and hepatosomatic index, denoting resilience of the experimental model.

Heavy metals affecting Neotropical freshwater fish: A review of the last 10 years of research

The expansion of urban centers, the increase in the use of chemicals in agriculture, and the significant expansion of industry has dumped increasing amounts of heavy metals into aquatic ecosystems, directly and indirectly affecting the entire food web in freshwater environments. In freshwater fish, many studies conducted worldwide have shown that these pollutants can cause alterations from the molecular level to behavioral, in all stages of life, including in future generations. Despite the great diversity of freshwater fish in the Neotropical region, few studies addressing the influence of metals on native species have been carried out. The last decade of studies showed that the effects of metals in neotropical species can be from the molecular to the behavioral level. Metals like Arsenic, Cadmium, Copper, Lead, Mercury, Chromium and Zinc have often been detected in environmental studies and evaluated in experimental approaches. Metabolically active organs showed higher levels of accumulation. In addition, some environmental studies have shown that ecologic and trophic conditions can be determinant in the level of exposure to metals. Oxidative stress, genotoxicity and several histopathological alterations were the most recurrent effects detected in target organs.

Subacute exposure to lead promotes disruption in the thyroid gland function in male and female rats

Exposure to heavy metals, such as lead, is a global public health problem. Lead has a long historic relation to several adverse health conditions and was recently classified as an endocrine disruptor. The aim of this study was to investigate the effects of subacute exposure to lead on the thyroid gland function. Adult male and female Wistar rats received a lead acetate solution containing 10 or 25 mg/kg, by gavage, three times a week, for 14 days. One week later, behavioral testing showed no alterations in anxiety and motor-exploratory parameters, as evaluated by Open-Field and Plus-Maze Tests, but impairment in learning and memory was found in the male 25 mg/kg lead-treated group and in both female lead-treated groups, as evaluated by the Inhibitory Avoidance Test. After one week, serum levels of tT3 were reduced in the 25 mg/kg female group and in the 10 mg∕ kg male group. However, tT4 levels were increased in the 25 mg/kg male group and in both female treated groups. TSH levels did not change and lead serum levels were undetectable. Morphologic alterations were observed in the thyroid gland, including abnormal thyroid parenchyma follicles of different sizes, epithelial stratification and vacuolization of follicular cells, decrease in colloid eosinophilia and vascular congestion, accompanied by morphometric alterations. An increase in collagen deposition was also observed. No differences were observed in TPO activity or protein expression, H₂O₂ generation by NADPH oxidases or hepatic D1 mRNA expression. However, thyroid NIS protein expression was considerably decreased in the male and female lead-treated groups, while TSHr expression was decreased in the 25 mg/kg female lead-treated group. These findings demonstrated that subacute exposure to lead acetate disrupts thyroid gland function in both sexes, leading to morphophysiological impairment and to changes in learning and memory abilities.