Search

This study investigated the impact of micropollutants on fish health from Segredo hydroelectric reservoir (HRS) along the Iguaçu River, Southern Brazil, contaminated by urban, industrial, and agricultural activities. This is the first comprehensive study assessment in the river after the severe drought in the 2020s in three fish species from different trophic levels Astyanax spp. (water column depth/omnivorous), Hypostomus commersoni (demersal/herbivorous), and Pimelodus maculatus (demersal/omnivorous). Animals, water, and sediment samples were collected from three distinct sites within the reservoir: Floresta (upstream), Iratim (middle), and Station (downstream). The chemical analysis revealed elevated concentrations of metals (Al, Cu, Fe) and the metalloid As in water, or Cu, Zn, and As in sediment, surpassing Brazilian regulatory limits, while the organic pollutants as DDT, PAHs, PCBs, and PBDEs were found under the Brazilian regulatory limits. The metal bioaccumulation was higher in gills with no significant differences among sites. The species Astyanax spp. and H. commersoni displayed variations in hepatosomatic index (HSI) and P. maculatus in the condition factor index (K) between sites, while adverse effects due to micropollutants bioaccumulation were observed by biochemical, genotoxic, and histopathological biomarkers. The principal component analysis and integrated biomarker response highlighted the upstream site Floresta as particularly inhospitable for biota, with distinctions based on trophic level. Consequently, this multifaceted approach, encompassing both fish biomarkers and chemical analyses, furnishes valuable insights into the potential toxic repercussions of micropollutant exposure. These findings offer crucial data for guiding management and conservation endeavors in the Iguaçu River., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

A histological examination is an important tool in embryology, developmental biology, and correlated areas. Despite the amount of information available about tissue embedding and different media, there is a lack of information regarding best practices for embryonic tissues. Embryonic tissues are considered fragile structures, usually small in size, and frequently challenging to position correctly in media for the subsequent histological steps. Here, we discuss the embedding media and procedures that provided us with appropriate preservation of tissue and easier orientation of embryos at early development. Fertilized Gallus gallus eggs were incubated for 72 h, collected, fixed, processed, and embedded with paraplast, polyethylene glycol (PEG), or historesin. These resins were compared by the precision of tissue orientation, the preview of the embryos in the blocks, microtomy, contrast in staining, preservation, average time, and cost. Paraplast and PEG did not allow correct embryo orientation, even with agar-gelatin pre-embedded samples. Additionally, structural maintenance was hindered and did not allow detailed morphological assessment, presenting tissue shrinkage and disruption. Historesin provided precise tissue orientation and excellent preservation of structures. Assessing the performance of the embedding media contributes significantly to future developmental research, optimizing the processing of embryo specimens and improving results.

The risk of exposure to toxic metals is a known concern to human populations. The overexposure to Mn can lead to a pathological condition, with symptoms similar to Parkinson's disease. Although toxicity of Mn has been reported, studies in neonates are scarce but necessary, as Mn can cross biological barriers. The present study evaluated if chronic perinatal exposure to Mn at low doses lead to neurotoxic effects in mice, after direct and indirect exposure. Couples of mice were exposed to Mn (0.013, 0.13, and 1.3 mg kg -1 .day -1 ) for 60 days prior to mating, as well as during gestation and lactation. The offspring was distributed into two groups: animals that were not exposed after weaning - parental exposure only (PE); and animals subject to additional 60-day exposure through gavages after weaning - parental and direct exposure (PDE). Neurological effects were evaluated by Mn quantification, behavior tests and biochemical markers in the brain. PDE animals had alterations in short/long-term memory and increased anxiety-like behavior. Exposure to Mn triggered a decrease of glutathione-s-transferase and increase of cholinesterase activity in different regions of the brain. These findings highlight the risk of exposure to low doses of Mn over a generation and at early stages of development., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The wastewater contamination of urban rivers is a concern for biodiversity and a consequence from poor urban conservation policies. In the current study, the impact of urban and industrial activities was investigated in Iguaçu river (Southern Brazil) using juvenile Oreochromis niloticus, after trophic and chronic exposure (25, 50 and 100 %), over 81 days. After exposure liver, gills, gonads, brain, muscle, and blood were sampled for chemical, biochemical, histopathological, genotoxic and molecular analyses. Water levels of persistent organic pollutants such as polychlorinated biphenyls, organochlorine pesticides, polycyclic aromatics hydrocarbon (PAHs) and metals were investigated. The redox unbalance, histopathological and increase in vitellogenin expression in fish revealed both the bioavailability of micropollutants and their harmful effects. According to the results, the level of Iguaçu river pollution negatively impacts the health of O. niloticus revealing and highlighting the risk of this pollution exposure to biota and human populations., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The morphogenesis of the head of vertebrates is a process that involves rapid growth and dynamic movements of various cell populations, including the neural crest cells (NCC). These pluripotent cells generated during neurulation have high proliferative and migratory capacity but xenobiotic agents can affect these migratory periods and cause congenital malformations. Lead (Pb) is the most common toxic metal in the environment and a potent teratogen that can affect growth and induce malformations. Despite the known toxic effects of Pb, there is a gap in knowledge about the impact of realistic concentrations of Pb at critical periods of early development. Here, we evaluated mortality, embryonic morphology, NCC migration, and the amount of Pb deposition in chicken embryos after 3 to 4 days of exposure. One of the most interesting observations in this study is that only about 34% of the injected Pb was present in the embryos after 4 days. We observed that exposure to Pb, even under low concentrations, increased mortality and the occurrence of malformations during embryonic development, especially in the cephalic region (CR). Although Pb was found widely distributed in the CR, no relation between its presence and the migration routes of cephalic NCC was observed. But the number of NCC and their migratory distance were reduced. These changes are consistent and explain the morphological anomalies described in this study, which also correlates with the morphofunctional abnormalities reported in the literature. Therefore, this study highlights the concern of exposure to low concentrations of this metal., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Despite being an essential trace element with great importance for vital metabolic activities, the manganese (Mn) can also cause damage to organ systems. However, data on the effect of this metal on the male reproductive system are limited, especially using relevant doses to human exposure. The present study aimed to evaluate and compare the effects of Mn exposure on the testicular structure of mice. Three experiments were conducted: (I) direct exposure to realistic doses (0.013, 0.13, and 1.3 mg/kg/day of MnCl 2 ); (II) parental and direct exposure to realistic doses (as in experiment I), where the animals were exposed during intrauterine development and from lactation until reproductive maturity; (III) direct exposure to high doses (15, 30, and 60 mg/kg/day of MnCl 2 ). Biometric, histopathological, histomorphometric and stereological parameters of the testis were evaluated, in addition to sperm morphology. Bioinformatic analyses were performed to identify potential Mn binding sites in 3β-HSD and P450ssc, as well as their protein-protein interaction network. The results obtained were compared using the integrated biomarker response index (IBR). There was an increase of seminiferous tubules pathologies in all experimental conditions tested, with effects on tubular volume, as well as a reduction in tubular diameter. The IBR analyses showed that parental and direct exposure had a significant negative effect on the testicular structure due to the exposure of this metal to sensitive periods of animal development. This study suggests that Mn has the potential to alter the morphological parameters of the testes, affecting the spermatogenesis in mice., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Manganese (Mn) is essential for animal development and homeostasis. However, anthropogenic activities increase the concentration of Mn in the environment and lead to increased risk of exposure to high doses of the metal. Thus, this study aimed to evaluate the effect of high doses of Mn on the male reproductive system of swiss mice. The 22-day old mice were randomly sorted into four groups and exposed to 0 (control), 15, 30 and 60 mg of MnCl 2 /kg/day, via daily gavages for 45 days. After the exposure, the mice were euthanized and sperm, hormonal and oxidative stress endpoints were evaluated in the testis, seminal vesicle and hypothalamus. Exposure to Mn promoted weight reduction of androgen-dependent organs, as well as alteration of the levels of fecal androgenic metabolites. Sperm parameters were drastically affected in all treated groups and the antioxidants tested (catalase and glutathione-disulfide reductase activities, and non-protein thiols content) decreased in the testis. However, only a few endpoints were altered in the seminal vesicle. For the hypothalamus, there was a reduction in acetylcholinesterase activity, suggesting a neurotoxic potential of Mn. In conclusion, Mn may affect the hypothalamic-gonadal axis by impairing the development of androgen-dependent organs, testicular redox status and Leydig cell maturation., 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 © 2020 Elsevier B.V. All rights reserved.)

The present study aimed to analyze the effect of multigenerational exposure to Mn at realistic doses on the functional quality of the male reproductive system of mice. Females and males (generation F0) were treated for 60 days with MnCl 2 , via gavage, at the doses of 0, 0.013, 0.13, and 1.3 mg/kg/day. Treatment of F0 dams continued throughout gestation and lactation periods. At the time of weaning, the offspring (F1 generation) was divided into: animals that were not exposed after weaning - parental exposure (PE); and those exposed via parental generation and directly (PDE) for additional 60 days, at the same dose of F0 generation. F0 and F1 males were euthanized for assessment of sperm parameters and redox changes in the reproductive system. There was a decrease in the sperm concentration of the F0 generation. In addition, the sperm parameters of F1 generation were drastically affected. The activity of antioxidant enzymes was significantly reduced in PE animals. It was possible to verify that the biochemical damages were higher in the PE individuals, as demonstrated by the integrated biomarker response index. Our results show that Mn, even at low doses, is able to promote a reduction in sperm quality over a generation., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Perfluorooctanoic acid (PFOA) and cadmium (Cd) are persistent environmental pollutants, bioaccumulative, and capable of crossing the placental barrier. There is evidence of developmental toxicity induced by PFOA and Cd, but their effects on early development are still poorly understood. In the present study, chicken embryos were exposed to PFOA, Cd, and a mixture of PFOA + Cd from blastula stage up to 72 h of incubation. Embryo mortality and morphology were assessed. PFOA and Cd exposure increased mortality and induced malformations, mainly in the cephalic region, the neural tube, and the ventral body wall. After mixed exposure the effect was observed mostly in the neural tube and the cephalic region. However, the mechanism remains unknown. Because of the resemblance between human and chick development, it was possible to correlate the observed alterations in chickens with known human congenital malformations. Therefore, PFOA and Cd are neurotoxic to chicken embryos inducing morphological abnormalities and are possibly neurotoxic to human embryos., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Aquatic organisms are usually exposed to a mixture of xenobiotics that may exert a large effect even in low concentrations, and when information is obtained exclusively from chemical analyses the prediction of the deleterious effects is potentially hindered. Therefore, the application of complementary monitoring methods is a priority. Here, in addition to chemical analyses, an active biomonitoring study using multiple biomarker responses in Nile tilapia Oreochromis niloticus was conducted to assess the effects of a contamination gradient along four reservoirs in Iguaçu River. Chemical analysis in the muscle showed high levels of metals in fish from the reservoir closest to an industrialized and environmentally degraded area, however fish exposed to all studied reservoirs showed hepatic alterations (necrosis and inflammatory processes). Also, significant variations of biochemical biomarkers were observed with no clear indication of contamination gradient, since an indicative of higher impact was found in an intermediary reservoir, including high concentrations of biliary polycyclic aromatic hydrocarbons (PAHs). However, nuclear morphological alterations (NMA) were less frequent at the same reservoir. Thus, the multi-biomarker approach allied to active biomonitoring is a practical and important tool to assess deleterious effects of contamination in freshwater, providing data for monitoring and conservation protocols., (Copyright © 2017 Elsevier Inc. All rights reserved.)

In the current study, water quality of five river sites in Parana River basin (Brazil), utilized for public water supply, was assessed through a set of biomarkers in fish Astyanax spp. Population growth and inadequate use of land are challenges to the preservation of biodiversity and resources such as water. Some physicochemical parameters as well as somatic indexes, gills and liver histopathology, genotoxicity, and biochemical biomarkers were evaluated. The highest gonadosomatic index (GSI) and antioxidant parameters (catalase and glutathione S-transferase activities, non-protein thiols), as well as the lowest damage to biomolecules (lipid peroxidation, protein carbonylation, DNA damage) were observed in site 0 (Piava River), which is located at an environmental protected area. Site 1, located in the same river, but downstream site 0 and outside the protection area, presents some level of impact. Fish from site 2 (Antas River), which lack of riparian forest and suffer from silting, presented the highest micronucleus incidence and no melanomacrophages. Differently, individuals from site 3 (Xambrê River) and site 4 (Pinhalzinho River) which receive surface runoff from Umuarama city, urban and industrial sewage, have the highest incidences of liver and gill histopathological alterations, including neoplasia, which indicated the worst health conditions of all sites. In particular, site 4 had high levels of total nitrogen and ammonia, high turbidity, and very low oxygen levels, which indicate important chemical impact. Comparison of the biomarkers in fish allowed classification of the five sites in terms of environmental impact and revealed that sites 3 and 4 had particular poor water quality.

The Iguaçu River, located at the Southern part of Brazil, has a great socioeconomic and environmental importance due to its high endemic fish fauna and its potential to generate hydroelectric power. However, Iguaçu River suffers intense discharge of pollutants in the origin of the river. In a previous report, the local environmental agency described water quality to improve along the river course. However, no study with integrated evaluation of chemical analysis and biological responses has been reported so far for the Iguaçu River. In the current study, three different Brazilian fish species (Astyanax bifasciatus, Chrenicicla iguassuensis, and Geophagus brasiliensis) were captured in the five cascading reservoirs of Iguaçu River for a multi-biomarker study. Chemical analysis in water, sediment, and muscle indicated high levels of bioavailable metals in all reservoirs. Polycyclic aromatic hydrocarbons (PAHs) were detected in the bile of the three fish species. Integration of the data through a FA/PCA analysis demonstrated the poorest environmental quality of the reservoir farthest from river's source, which is the opposite of what has been reported by the environmental agency. The presence of hazardous chemicals in the five reservoirs of Iguaçu River, their bioaccumulation in the muscle of fish, and the biological responses showed the impacts of human activities to this area and did not confirm a gradient of pollution between the five reservoirs, from the source toward Iguaçu River's mouth. Therefore, diffuse source of pollutants present along the river course are increasing the risk of exposure to biota and human populations.

The Tubarão River rises in Santa Catarina, Brazil, and has been historically affected by coal mining activities around its springhead. To evaluate its water conditions, an investigation regarding a possible decontamination gradient associated with the increased river flow toward the estuary, as well as the influence of seasonality over this gradient was performed through a series of biomarkers (vitellogenin, comet assay, lipid peroxidation, protein carbonylation, gluthatione, gluthatione S-transferase, acetylcholinesterase, light microscopy in liver, and scanning electron microscopy in gills) and chemical analysis (polycyclic aromatic hydrocarbons (PAHs) in bile and metal analysis in sediment) in the cichlid Geophagus brasiliensis. Two collections (summer and winter) were made in four distinct sites along the river, while sediments were sampled between those seasons. As expected, the contamination linked exclusively to mining activities was not observed, possibly due to punctual inputs of contaminants. The decontamination gradient was not observed, although seasonality seemed to have a critical role in the responses of biomarkers and availability of contaminants. In the summer, the fish presented higher histopathological damages and lower concentrations of PAHs, while in the winter they showed both higher genetic damage and accumulation of PAHs. The Tubarão suffers impacts from diverse activities, representing health risks for wild and human populations.

Melanoblasts are positively stimulated to migrate in the dorsolateral pathway of the avian embryo by ephrins, but are inhibited by PNA-binding glycoconjugates. We analyzed the potential role of these molecules in the Japanese Silky fowl, which displays intense internal pigmentation. The distribution of ephrin ligands was analyzed using Eph receptor-human Fc fusion proteins. Glycoconjugates were labeled using PNA-FITC. In Japanese Silky embryos, ventral areas, including the anterior- and posterior-half somites, expressed ephrin-B1 in a pattern that correlates with the atypical migratory pathways taken by Japanese Silky melanoblasts. White Leghorn embryos displayed little to no ephrin-Bs in the ventral paths. Conversely, PNA-binding barrier tissues, proposed to prevent melanoblasts from migrating ventrally in White Leghorn, are missing or have significant gaps in Japanese Silky embryos. Thus, studies of a naturally occurring pigmentation mutant confirm that a combination of cues regulates melanoblast migration in the chick embryo., (Crown Copyright © 2013. Published by Elsevier GmbH. All rights reserved.)

Curcumin, a lipophilic compound found in the plant Curcuma longa L., exhibits a wide range of pharmacological activity; however, its therapeutic use has been limited because of its low bioavailability following oral administration. The aim of this study was to evaluate the viscoelastic characteristics and biocompatibility of a curcumin/xanthan:galactomannan hydrogel (X:G) system after topical application on chick embryo chorioallantoic membrane (CAM), a system established with a view toward curcumin nasal or topical pharmaceutical applications or possible administration in cosmetics or foods. A rheological analysis indicated that incorporation of curcumin did not alter the viscoelastic characteristics of the X:G hydrogel, suggesting that there was no change in the structure of the gel network. X:G hydrogels did not induce CAM tissue injury and the curcumin/X:G hydrogel system was also highly biocompatible. We conclude that the X:G hydrogel represents a potential matrix for curcumin formulations., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The toxic potential of cadmium (Cd) is well-documented for young and adult vertebrates, but it is still poorly understood in the early stages of development. In this study, cadmium effects were investigated on Gallus gallus embryos after injection of CdCl(2) (5μM and 50μM) within the egg air chamber, and incubation for 48 and 72h. After exposure, morphological and enzymatic analyses for glucose-6-phosphate dehydrogenase (G6PDH) and glutathione S-transferase (GST) were performed. Critical morphological abnormalities occurred after exposure to the highest concentration of cadmium, mainly in the cephalic region, indicating the powerful teratogenic effect of Cd to chick embryos. Cd exposure did not alter enzymatic activities when compared to the control group, but the levels of G6PDH activity were highest in older embryos at stage 19, indicating that antioxidant defenses are not so robust in the earliest embryo stages., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The Japanese Silky chicken (SK) shows dermal and visceral hyperpigmentation. This study characterizes ultrastructurally the melanin granules developing in dermal melanocytes of the dorsal skin of SK, in an attempt to better understand the processes of melanogenesis in these permanently ectopic cells. The steps of melanogenesis are similar to those described for epidermal melanocytes, with melanosomes going from stage I to IV but, in SK, the maturation occurs in the cell body, as well as in the cytoplasmic processes. At stage III, the deposition of melanin is cumulative and can aggregate in rounded structures, which combine to turn into the mature granule. The final destiny of mature melanosomes is still unclear, although it was observed that dermal macrophages can accumulate melanin granules in their phagosomes. Even with the close proximity between melanocytes and other dermal cells, the transference of melanosomes was not observed. Our findings indicate that melanogenesis in dermal melanocytes in SK has the same morphological characteristics found in epidermal melanocytes, but the functional aspect still remains to be elucidated.