Acute and chronic toxicity of the benzoylurea pesticide, lufenuron, in the fish, Colossoma macropomum

Chronic exposure to low concentration of diflubenzuron and pyriproxyfen induces brain oxidative stress and inflammation and alters locomotion in zebrafish (Danio rerio)

Diflubenzuron (DFB1) and pyriproxyfen (PPF) are pesticides widely used in agriculture and urban environments to control insect actions. The aim of this study was to evaluate the effects of chronic 30-day exposure to DFB (0.025 and 0.125 mg/L) and PPF (0.379 and 0.758 mg/L) on the behavior of juvenile zebrafish (Danio rerio). Fish were exposed to insecticides from early stage (4 h post fertilization) to 30 days post fertilization (dpf). At 45 dpf, fish were evaluated in the novel tank test, social behavior test, and mirror aggressive test. Brain gene expression related to oxidative stress and inflammation was also evaluated. DFB reduced locomotor parameters in the novel tank and aggression tests, while it induced to hyperactivity in the social behavior test. PPF reduced anxiety-like behavior, measured by the time spent in risky areas of the novel tank, and reduced aggression against the mirror image. There was a significant reduction in mRNA levels of the nfe2l2 gene (∼0.54 fold downregulated) and increase in levels of cat (PPF ∼1.8 fold change), gsr (PPF ∼1.5 fold change), gpx1a (PPF ∼1.6 and DFB 1.1 fold change), tnf-α (PPF 1.9 and DFB 2.2 fold change), and il-6 (PPF ∼1.2 and DFB 2.3 fold change). These endpoints are indicative of the threatening effects of insecticides to aquatic organisms and the need for alternative methods to control pests by using less harmful and safer substances for animal and human well-being, as well as for the environment.

Unraveling Key Amino Acid Residues Crucial for PxGSTs1 Conferring Benzoylurea Insecticide Resistance in Plutella xylostella

The widespread use of benzoylurea insecticides (BUs) has led to significant resistance issues in various agricultural pests. Previous studies have demonstrated that the overexpression of sigma glutathione S-transferase 1 (PxGSTs1) can confer resistance to novaluron in Plutella xylostella; however, the underlying molecular mechanism remains unclear. This study investigates the role of glutathione S-transferase PxGSTs1 in mediating resistance to BUs in P. xylostella. Using a combination of RNA interference and transgenic Drosophila models, we demonstrated that the overexpression of PxGSTs1 significantly contributes to the resistance against BUs. Functional assays revealed that PxGSTs1 binds to these insecticides with varying affinities. Structural analysis through homology modeling and molecular docking identified the importance of hydrogen bonding and pi-pi stacking in resistance mechanisms. Site-directed mutagenesis confirmed the critical role of Ser65 and Tyr97 in these interactions. Our findings provide a molecular basis for the development of novel BUs and inform strategies for managing BU resistance in P. xylostella.

Dalai A, Borugadda VB. Adsorption of Lufenuron 50-EC Pesticide from Aqueous Solution Using Oil Palm Shell-Derived Activated Carbon

The use of Lufenuron 50-EC pesticide in oil palm crops affects water quality and aquatic life. This study investigated the adsorption of Lufenuron 50-EC from an aqueous solution using activated carbon derived from oil palm shells (OPSs). Activated carbon (AC) was prepared through physical and chemical activation processes in carbon dioxide environments, using potassium hydroxide (KOH) as a chemical activating agent. The resulting AC was characterized using standard techniques. The most favorable operating parameters were physical activation at 900 °C for 2 h, achieving a BET surface area of 548 m2/g. For chemical activation, at 800 °C, 1 h, and an impregnation ratio (KOH/biochar) of 2:1 (w/w), a BET surface area of 90 m2/g was obtained, which was smaller than that achieved by physical activation. The use of KOH reduced the surface area but generated a high presence of functional groups on the AC surface, which is important for adsorption processes. The AC produced achieved high Lufenuron adsorption yields, reaching a maximum of 96.93%. AC produced at 900 °C with 2 h showed the best performance. Therefore, OPS is an excellent precursor for producing AC with favorable characteristics for pollutant adsorption in aqueous solutions, especially for the insecticide Lufenuron.

Effects of trichlorfon on ecotoxicological biomarkers in farmed Colossoma macropomum (tambaqui)

Producers of fish have been looking for viable alternatives for the management of Colossoma macropomum (tambaqui) in confinement systems in order to avoid the harm and subsequent losses caused by parasitic diseases. One alternative used by farmers is pesticides, such as trichlorfon, which has a genotoxic effect. Thus, this study aimed to evaluate the changes in gene expression due to the side effects of trichlorfon in tambaqui. Two treatments were used based on LC50-96h of 0.870 mg/L using 30% and 50% trichlorfon with exposure periods of 48, 72 and 96 h. For differential expression of the genes in the liver, real-time PCR was performed for the AChE, GST, CYP2J6, CYP2C8, 18S and GAPDH genes. After 96 h of exposure to trichlorfon, an alteration in the gene expression profile of the antioxidant defense system (GST) of the tambaqui was observed. It was also observed that this organophosphate did not affect the expression of genes related to the isoenzymes that are responsible for the biotransformation of xenobiotics in phase I (2J6 and 2C8) and cholinesterase AChE. It was concluded that the reduction in gene expression of GST suggests a decrease in metabolization capacity in phase II.

Lufenuron treatment temporarily represses gene expression and affects the SUMO pathway in liver of Atlantic salmon

Lufenuron is a benzoylurea insecticide currently in use to combat sea lice infestation in salmon aquaculture in Chile. With pending approval in Norway, the aim of this work was to study the uptake and toxicity of lufenuron in liver tissue of Atlantic salmon. Juvenile salmon weighing 40 g were given a standard 7-day oral dose, and bioaccumulation and transcriptional responses in the liver were examined 1 day after the end-of-treatment (day 8) and after 1 week of elimination (day 14). Bioaccumulation levels of lufenuron were 29 ± 3 mg/kg at day 8 and 14 ± 1 mg/kg at day 14, indicating relatively rapid clearance. However, residues of lufenuron were still present in the liver after 513 days of depuration. The exposure gave a transient inhibition of transcription in the liver at day 8 (2437 significant DEGs, p-adj < .05), followed by a weaker compensatory response at day 14 (169 significant DEGs). Pathways associated with RNA metabolism such as the sumoylation pathway were most strongly affected at day 8, while the apelin pathway was most profoundly affected at day 14. In conclusion, this study shows that lufenuron easily bioaccumulates and that a standard 7-day oral dose induces a transient inhibition of transcription in liver of salmon.

Ameliorative effect of avocado oil against lufenuron induced testicular damage and infertility in male rats

Lufenuron is a benzoylurea pesticide that causes significant histological and histochemical damage in mammals. Avocado is a common food in the human diet that contains antioxidant and antitumor properties. In male rats, avocado oil's protection against lufenuron-induced reproductive deterioration, oxidative stress, and DNA damages was investigated. Twenty-eight mature male rats were selected and distributed into four groups: Group 1, control group were administered distilled water orally; Group 2 received 4 ml/kg avocado; Group 3 was given lufenuron (1.6 mg/kg), and Group 4 was given avocado oil/lufenuron. The findings show that lufenuron treatment reduces reproductive hormone levels, sperm count, motility, viability and causes negative histopathological changes in testicular tissue, such as decreased epithelial height and increased luminal diameter degenerated spermatogenesis. Furthermore, lufenuron reduced the content of antioxidant enzymes while increasing the level of malondialdehyde, nitric oxide and corresponding DNA damage. Results showed that lufenuron is associated with testicular function impairment, which leads to infertility. Treatment with avocado oil improved reproductive hormone secretions, enzymatic activity, histological and DNA damage parameters in testis tissues, reducing the negative effects of lufenuron, proving that it may have a therapeutic role against lufenuron-mediated testicular toxicity.

Retinal Toxicity Induced by Chemical Agents

Vision is an important sense for humans, and visual impairment/blindness has a huge impact in daily life. The retina is a nervous tissue that is essential for visual processing since it possesses light sensors (photoreceptors) and performs a pre-processing of visual information. Thus, retinal cell dysfunction or degeneration affects visual ability and several general aspects of the day-to-day of a person's lives. The retina has a blood-retinal barrier, which protects the tissue from a wide range of molecules or microorganisms. However, several agents, coming from systemic pathways, reach the retina and influence its function and survival. Pesticides are still used worldwide for agriculture, contaminating food with substances that could reach the retina. Natural products have also been used for therapeutic purposes and are another group of substances that can get to the retina. Finally, a wide number of medicines administered for different diseases can also affect the retina. The present review aimed to gather recent information about the hazard of these products to the retina, which could be used to encourage the search for more healthy, suitable, or less risky agents.

Behavioural Responses and Mortality of Mozambique Tilapia Oreochromis mossambicus to Three Commonly Used Macadamia Plantation Pesticides

The use of pesticides in agricultural systems may have deleterious effects on surrounding environments. Aquatic systems are no exception and are increasingly polluted through the leaching of pesticides from agricultural activities. However, the pesticide pollution effects on key aquatic species have not been studied in many regions. In southern Africa, increasing pesticide use associated with macadamia tree Macadamia integrifolia farming presents a growing risk to surrounding aquatic ecosystems. This study assessed behavioural responses of an important and widely-distributed freshwater fish, Mozambique tilapia Oreochromis mossambicus, following exposure to three commonly used macadamia pesticides (i.e., Karate Zeon 10 CS, Mulan 20 SP, Pyrinex 250 CS) at different concentrations (0.7–200 µL, 0.3–1000 mg, and 0.7–8750 µL, respectively) over 24 h. Behavioural responses, i.e., swimming erratically, surfacing, vertical positioning, loss of equilibrium, being motionless and mortality were observed after pesticides exposure. Lethal dose 50 (LD50) values of Karate Zeon 10 CS, Mulan 20 SP and Pyrinex 250 CS were 2.1 µL (per water litre dilution—WLD), 5.2 mg (WLD) and 21.5 µL (WLD), respectively. These concentrations are therefore expressed as a maximal threshold usage in the environment around macadamia farms and a minimum distance of the plantations to water systems should be considered. Further studies should examine effects on other fish species and aquatic invertebrates to inform on pesticide pollution threats and mitigation plans for the region.

Diflubenzuron leads to apoptotic cell death through ROS generation and mitochondrial dysfunction in bovine mammary epithelial cells

Pesticides, which are used in agriculture and forestry to eliminate insects, are a major cause of environmental pollution. Among them, diflubenzuron (DFB), 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl) urea, is a common benzoylurea insecticide that hinders larval development, primarily in Aedes aegypti larvae. Many experts have announced the biological toxicity of DFB in various species. However, the toxicity of benzoylurea pesticides, including DFB, to bovine mammary epithelial cells (MAC-T) is unclear. Therefore, in this study, we confirmed the cytotoxic effects of DFB on the viability and proliferation of MAC-T cells. Additionally, we observed that DFB induced lipid peroxidation through reactive oxygen species (ROS) production, resulting in an increase in transcriptional gene expression related to inflammatory response. Moreover, we demonstrated mitochondrial dysfunction including depolarization of the mitochondrial membrane, perturbation of calcium homeostasis, and, eventually, apoptosis. Furthermore, we identified DFB-triggered signaling pathways related to ROS generation and cell proliferation, as well as their interactions, by treating the cells with pharmacological inhibitors in combination with DFB. DFB attenuated the phosphorylation of AKT, P70S6K, S6, and ERK1/2 and facilitated the phosphorylation of JNK and c-Jun. These results show that DFB can induce apoptotic cell death via ROS generation and mitochondrial dysfunction in MAC-T cells.

Environmentally relevant concentrations of boscalid exposure affects the neurobehavioral response of zebrafish by disrupting visual and nervous systems

Boscalid is a persistent fungicide that is frequently detected in surface waters and may be neurotoxic to aquatic organisms. Herein, we evaluated the effects of environmentally relevant boscalid concentrations to zebrafish to explore its potentially neurotoxic mechanisms of effect. Behavioral responses (swimming, phototaxis, and predation), histopathology, transcriptomics, biochemical parameter analysis and gene expression of larval and adult zebrafish following boscalid treatment were assessed. We found that boscalid significantly inhibited the locomotor ability and phototactic response of larvae after an 8-d exposure, and altered the locomotor activity, predation trajectories and ability in adults after a 21-d exposure. It was noted that predation rates of zebrafish were significantly decreased by 30% and 100% after exposure to 0.1 and 1.0 mg/L boscalid, respectively. Adverse alterations in the cell differentiation of eyes and brain injury were also observed in both larvae and adults following boscalid exposure. The expression of genes related to neurodevelopment, neurotransmission, eye development, and visual function, in conjunction with RNA-Seq results, indicated that boscalid may impair visual phototransduction and nervous system processes in larval zebrafish. Conclusively, boscalid exposure may affect the neurobehavioral response of zebrafish by impairing proper visual and nervous system function.

[Recent developments of pesticide adsorbents based on cyclodextrins]

The invention and application of pesticides have greatly increased the yield of crops, greatly contributing to ensuring people's basic livelihoods and gradually improving their livelihoods to a well-off level. However, foods, water sources, and soil, containing high levels of pesticide residues, result in increasingly serious pollution. Pesticide residues usually have the characteristics of micro toxicity, difficult biodegradation, and bioaccumulation, and thus pose serious threat to living organisms and ecosystems. In recent years, pesticide pollution has earned worldwide focus. Thus, methods for the efficient detection of trace pesticides and reduction of the harm caused by pesticide pollution are urgently required. Researchers have used catalysis, electrochemistry, membrane separation, adsorption, and other methods to enrich pesticides from complex matrices. Among these, adsorbents have attracted much attention owing to their advantages of simple operation steps, rapid treatment process, and low amounts of organic solvents required. Research on adsorption materials has always been a very active field, and is also the key to the success of separation and enrichment of pesticides from complex matrices. Development of adsorbents with the advantages of simple synthesis, environment-friendliness, high stability, and strong reusability is of great significance. There has been some progress in the field of pesticide adsorption using supramolecular compounds. Cyclodextrin is a macrocyclic compound with a cavity after crown ether, which can form inclusion complexes via host guest interactions as the main body. Cyclodextrin can also be modified by etherification, esterification, oxidation, and other chemical reactions to improve its adsorption performance. Pesticides can be classified into organic and inorganic substances. One of the most widely used inorganic fungicides is the Bordeaux solution, whose main component is Cu2+. Organic fungicides, insecticides, herbicides, and plant growth regulators are basically organic molecules, whose hydroxyl and carboxyl groups can form complexes with Cu2+. As a matrix, cyclodextrin not only increases the surface area of the materials, but also provides the binding sites of hydroxyl and carboxyl groups, which guarantees efficient enrichment of Cu2+. Organic pesticides with high polarity, high electron density, and strong hydrophobicity could be better adsorbed. In this paper, the application of cyclodextrin-based adsorbents in pesticide adsorption was reviewed, and on this basis, reference to future development directions and application prospects were provided. The adsorption capacity of individual pesticide adsorbents based on cyclodextrin, as reviewed in this paper, is not high enough. Therefore, improving the adsorption capacity is currently a major research target. Some of the above-mentioned adsorbents have unclear degradation mechanisms and can easily cause secondary pollution. Therefore, the development of environment-friendly pesticide adsorbents that are easy to regenerate is a promising research direction for the future. After adsorption, some detection methods are used to determine whether the pesticide residues are up to the standard; however, the detection instruments are expensive. Therefore, the development of a combined detection mechanism that can reduce workload and cost is a promising research direction. Finally, the development of smart cyclodextrin-based adsorbents is also an efficient and rapid method to reduce the cost of detecting residual pesticide concentrations and the risk of pesticide pollution. For example, intelligent materials, whose color changes can be observed by the naked eye, not only adsorb pesticides, but also respond according to the concentration of residual pesticides.

The implication of ROS production on triflumuron-induced oxidative stress and genotoxicity in human colon carcinoma (HCT-116) cells

The aim of this study is to evaluate the cytotoxic and the genotoxic effects of triflumuron (TFM) on human colon carcinoma cells (HCT-116). Indeed, TFM is used to protect vegetables, fruits, and domestic animals against a large spectrum of parasites causing animal and human disorders. However, studies revealing its toxicity and its mode of action in mammalian systems remain very limited. We monitored our work with the cytotoxicity assay starting with the cell viability test, the ROS generation, the malondialdehyde (MDA) production, the DNA fragmentation, and the measurement of some antioxidant enzymes activities such as catalase, superoxide dismutase, and the glutathione S-transferase. Also, we measured the mitochondrial transmembrane potential. We showed that TFM induced a dose-dependent cell death. This decrease in cell viability was accompanied by a significant reduction in the mitochondrial membrane potential. We also have shown that TFM induced oxidative stress as revealed by the generation of reactive oxygen species, the increase of the MDA levels, and the activation of the antioxidant enzymes. Moreover, our results indicated that TFM induced DNA damage in HCT-116 cells as monitored by the comet assay. We demonstrate, for the first time, the cytotoxic and the genotoxic potentials of TFM on human cultured cells.

Humoral immune responses and gill antioxidant-related gene expression of common carp (Cyprinus carpio) exposed to lufenuron and flonicamide

The aim of this study was to investigate plasma proteins, total immunoglobulin (Ig), lysozyme and complement (ACH50) levels, and gill superoxide dismutase (SOD) and catalase (CAT) gene expression in common carp (Cyprinus carpio), following exposure to lufenuron (LUF) and flonicamide (FL). Fish were distributed in 12 tanks as three quadrupled treatments: control (fish were kept in pesticide-free water), LUF [fish exposed to 10% of LUF LC50 (4.3 mg/L)], and FL [fish exposed to 10% of FL LC50 (0.1 mg/L)]. The plasma parameters were assessed after 7 and 21 days exposure to pesticides, whereas the gene expressions were assessed after 21 days. The results showed that LUF exposure significantly decreased plasma total protein and globulin levels compared to the control group. Both pesticide significantly decreased plasma total Ig levels compared to the control group; however, LUF exhibited a greater effect. There were no significant effects of pesticides or sampling time on plasma ACH50 activity. Pesticides and sampling time interacted to affect plasma lysozyme activity. Seven days after exposure, both pesticides significantly increased lysozyme activity, and the effect of FL was greater than LUF. Nevertheless, there was no significant difference in plasma lysozyme activities among the pesticides, 21 days after the exposure. Both pesticides significantly decreased SOD and CAT gene expression, nevertheless, FL exhibited greater effects than LUF. In conclusion, both pesticides induced immunosuppression in the fish, though such effects were more severe in LUF group, compared to the FL. These pesticides negatively affect expression of gill antioxidant genes, and the FL effects were greater than the LUF.

Exposição crônica ao cloridrato de metformina e à glibenclamida causa alterações comportamentais, glicêmicas e de mortalidade em Hemigrammus caudovittatus e Danio rerio

RESUMO Hemigrammus caudovittatus e Danio rerio foram expostos aos hipoglicemiantes orais (HOs) cloridrato de metformina a 40µg/L e 120µg/L e glibenclamida a 0,13µg/L e 0,39µg/L durante 100 dias. Foram avaliados os efeitos tóxicos dos fármacos em relação ao peso, ao comportamento animal, à glicemia e à mortalidade. H. caudovittatus expostos à menor concentração dos fármacos apresentaram aumento significativo (P<0,05) no evento Respiração Aérea. Ainda, foi observado aumento no comportamento Descansar quando os animais foram expostos à glibenclamida a 0,39µg/L. Em D. rerio expostos ao cloridrato de metformina a 120µg/L, foi observado aumento (P<0,05) no comportamento Descansar. A glibenclamida provocou redução (P<0,05) na glicemia de H. caudovittatus. Ambos os fármacos causaram efeito letal na espécie D. rerio, contudo a glibenclamida foi mais tóxica, causando 100% de mortalidade em 30 dias de exposição. Os animais que vieram a óbito apresentaram congestão nos arcos branquiais e hemorragia. Os HOs foram desenvolvidos para apresentarem efeitos fisiológicos em mamíferos, entretanto efeitos tóxicos foram encontrados nas duas espécies de peixe estudadas. Isso levanta a preocupação sobre possíveis efeitos tóxicos de HOs e sobre quais métodos serão utilizados para a sua degradação no ambiente aquático.

Acute exposure to chlorpyrifos and glyphosate induces changes in hemolymph biochemical parameters in the crayfish, Astacus leptodactylus (Eschscholtz, 1823)

Acute and subacute toxicity tests for chlorpyrifos and glyphosate were performed on the crayfish, Astacus leptodactylus. The crayfish were divided into a control group and four experimental groups with exposure from 50.18 to 301.11 μg L-1 of chlorpyrifos for 96 h under semi-static test conditions. In the same experiment, the crayfish were exposed to different concentrations of glyphosate (from 0.0, 8.14 to 13.05 mg L-1) for 96 h. Mortality was recorded, and the median lethal concentrations (LC50) were calculated using probit analysis. The 96 h LC50 values of chlorpyrifos and glyphosate to A. leptodactylus were 49.55 ± 4.66 μg L-1 and 7.83 ± 0.50 mg L-1, respectively. The results showed that chlorpyrifos was a few hundred times more toxic than glyphosate for the crayfish. Then, the crayfish were exposed to different subacute concentrations of chlorpyrifos (12.5 and 25 μg L-1) and glyphosate (2 mg L-1 and 4 mg L-1) for seven days, and their toxicity was evaluated through several hemolymph biochemical parameters. Chlorpyrifos and glyphosate exposure caused a significant (P < 0.01) increase in the activity of lactate dehydrogenase (LDH), and gamma-glutamyl transferase (GGT). The results showed a significant (P < 0.01) decrease in acetylcholinesterase (AChE), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and phenoloxidase (PO) activities in the hemolymph of the crayfish exposed to chlorpyrifos and glyphosate. The total protein and cholesterol levels showed a significant decrease (P < 0.01) in the hemolymph of the crayfish after seven days of exposure to chlorpyrifos and glyphosate. There was a significant increase in triglycerides and glucose levels in treated crayfish. These results show that chlorpyrifos is highly toxic, while glyphosate is moderately toxic to A. leptodactylus. According to the results, subacute concentrations of chlorpyrifos and glyphosate could lead to a collapse of cellular homeostasis and changes in the hemolymph biochemical parameters in the crayfish. Physiological changes caused by exposure to chlorpyrifos and glyphosate in A. leptodactylus may have direct effects on the survival of these organisms.

Thyroxine, levothyroxine, and thyroxine complexed into cyclodextrin changed animal behavior, oxygen consumption, and photopic electroretinogram of Colossoma macropomum

The toxic effects of thyroxine (T₄F), levothyroxine (L-T₄), and thyroxine complexed into β-cyclodextrin (β-CD-T₄) on the biological parameters of tambaqui (Colossoma macropomum) were evaluated. The animals were exposed to a chronic toxicity test based on concentrations of influent (60 ng/L) for 2 months. Weight, total length, animal behavior, oxygen consumption, photopic electroretinogram (ERG), and the Flicker exam were evaluated. No significant differences were observed (p > 0.05) on the weight and total length measurements between all groups studied. Behavioral observations of the animals exposed to L-T₄ and β-CD-T₄ complex showed a reduction (p < 0.05) in slow swimming and an increase in staying motionless events. The animals exposed to the β-CD-T₄ complex presented the highest O₂ consumption. L-T₄ and β-CD-T₄ promoted a reduction in the ability of the animals to respond to stimuli in the photoreceptors according to the photopic ERG examination. Data from the experimental Flicker exam showed no significant differences (p > 0.05) in all groups studied. It can be concluded that the complexation of T₄ into β-CD and L-T₄ modified the toxicity of this hormone, promoting changes in the behavior, oxygen consumption, and electrophysiological responses of the exposed animals, suggesting that inclusion complexes should be submitted to new toxicity tests to ensure higher safety.

The complexation of steroid hormones into cyclodextrin alters the toxic effects on the biological parameters of zebrafish (Danio rerio)

The objective of this study was to evaluate the toxic effects of progesterone (P₄F) and estradiol (E₂F) and the effect of these steroid hormones complexed into cyclodextrins, commercially available drugs, such as micronized progesterone (P₄M) and transdermal estradiol (E₂T), and evaluate them as endocrine disruptors through biological parameters of Danio rerio. An acute toxicity test was performed with hormones using D. rerio embryos according to OECD 236 guidelines. The heart rate, mortality, and teratogenic effects were evaluated. In addition, a chronic toxicity test was assayed with adult animals for evaluation of animal behavior, reproductive capacity, and electrophysiological responses of the retina. Analysis of the results of the acute toxicity test with embryos exposed to progestins and estrogens showed that free hormones caused a higher percentage of teratogenic effects such as pericardial edema, yolk sac edema, and spinal deformation. Behavioral evaluation (30-60 days) of adult animals exposed to P₄M, E₂F, and E₂T demonstrated higher frequencies of aggressive behaviors such as Chase away, Persecution, Escape, and Attack. Analysis of reproductive capacity did not show significant differences in the number of viable eggs, and no significant changes were observed in the electrophysiological responses of the retina. According to these results, there is a higher toxicity effect of hormones in the free form when compared to the commercial forms and inclusion complexes. This indicates that complexation into cyclodextrin reduced the toxicity of the hormones according to the parameters studied.

Transchem project - Part I: Impact of long-term exposure to pendimethalin on the health status of rainbow trout (Oncorhynchus mykiss L.) genitors

Pendimethalin is a herbicide active substance commonly used in terrestrial agricultural systems and is thus detected at high concentrations in the surface water of several European countries. Previous studies reported several histopathological changes, enzymatic antioxidant modulation and immunity disturbance in fish exposed to this pesticide. The objective of this work was to investigate the direct effects of long-term exposure to environmental concentrations of pendimethalin over a period of 18 months in rainbow trout (Oncorhynchus mykiss) genitors. To do so, an experimental system consisting of eight similar 400 L tanks with a flow-through of fresh river water was used to perform daily chemical contamination. Fish were exposed to 850 ng/L for one hour and the pendimethalin concentration was then gradually diluted during the day to maintain optimal conditions for the fish throughout the experiment and to achieve a mean theoretical exposure level of around 100 ng L^-1 per day. Every November, males and females were stripped to collect eggs and sperm and two new first generations of offspring were obtained. Kinetic sampling revealed differences in immune system parameters and antioxidative defences in the contaminated trout compared to the controls, due to pesticide exposure combined with seasonal changes related to gamete maturation. Moreover, reproductive capacity was significantly affected by exposure to the herbicide; a time lag of more than five weeks was observed for egg maturation in contaminated females and high bioconcentrations of pendimethalin were measured in eggs and sperm. Chemical transfer from genitors to offspring via gametes may affect embryo development and negatively impact the early stages of development.