Nitrophenols disrupt the expression and activity of biotransformation enzymes (CYP3A and COMT) in chicken ovarian follicles in vivo and in vitro.

Nitrophenols are environmental pollutants and xenobiotics, the main sources of which are diesel exhaust fumes and pesticides. The biotransformation processes that take place in the liver are defence mechanisms against xenobiotics, such as nitrophenols. Our previous study showed that the chicken ovary is an additional xenobiotic detoxification place and that nitrophenols disrupt steroidogenesis in chicken ovarian follicles. Therefore, the present study aimed to determine the in vivo and in vitro effects of 4-nitrophenol (PNP) and 3-methyl-4-nitrophenol (PNMC) on the expression and activity of phase I (CYP3A) and phase II (COMT) biotransformation enzymes in chicken ovary. In an in vivo study, hens were treated with a vehicle or 10 mg PNP or PNMC/kg b.wt. per day for 6 days. In an in vitro study, prehierarchical white and yellowish follicles, as well as the granulosa and theca layers of the three largest preovulatory follicles (F3, F2 and F1), were isolated and then incubated in a control medium or medium supplemented with PNP (10-6 M) or PNMC (10-6 M) for 24 or 48 h. Both in vivo and in vitro studies showed that nitrophenols exert tissue- and compound-dependent (PNP or PNMC) effects on CYP3A and COMT gene (real-time PCR) protein (Western blot) expression and their activity (colorimetric methods). The inhibitory effect of nitrophenols in vivo on the activity of biotransformation enzymes suggest that the ovary has the capacity to metabolise PNP and PNMC.

The environmental pollutant 3-methyl-4-nitrophenol reduces the regulatory T cells in the intestine.

Dysfunction of immune regulation plays a crucial role in the pathogenesis of many immune disorders in the body. The underlying mechanism is still not completely understood. Environmental pollution contributes to immune de-regulation. 3-methyl-4-nitrophenol (MNP) is one of the major environmental pollutants. This study aims to investigate the role of MNP in compromising immune regulatory functions in the intestine. A food allergy (FA) mouse model was established using ovalbumin (OVA) as the specific antigen. The activities of regulatory T cells in the mouse intestine were evaluated by flow cytometry and enzyme-linked immunosorbent assay. We found that MNP reduced the CD4+ Foxp3+ Treg frequency, increased Th17 cells, and converted Tregs to Th17 cells in the intestine. MNP induced the expression of IL-6 in regulatory T cells (Tregs). Estrogen receptor (ER) mediated the effects of MNP on promoting IL-6 expression in Tregs. The IL-6 in synergy with transforming growth factor (TGF)-ß to convert Tregs to Th17 cells. The concomitant exposure of MNP and OVA induced FA like response in mice. Modulation of the ER-STAT3-IL-6 signal pathway attenuated mouse FA response. In summary, MNP, an environmental pollutant, acts as an immunoadjuvant for developing FA. By activation of the estrogen receptor, MNP induces Tregs to express IL-6. IL-6 in synergy with TGF-ß converts Tregs to Th17 cells.

Gene expression profiles of two testicular somatic cell lines respond differently to 4-nitrophenol mediating vary reproductive toxicity.

4-Nitrophenol (PNP) has been extensively used in manufacturing for several decades. Its toxic effects on the male reproductive system have been reported, but the underlying mechanisms remain unclear. In this study, we utilized two testicular somatic cell lines (TM3 and TM4 cells) to explore the possible toxic effects of PNP on the male reproductive system. The activity of the cells after exposure to different doses of PNP (0.01, 0.1, 1, 10 and 100 µM) was evaluated. PNP treatment at 10 µM significantly inhibited cell viability, and 10 µM PNP was thus selected for subsequent experiments. Although PNP (10 µM) inhibited cell proliferation, promoted cell apoptosis, and changed the cell cycle distribution and ultrastructure in both types of cells, these effects were more significant in the TM4 cells. In addition, an Agilent mouse mRNA array was used to identify the gene expression differences between the control and PNP (10 µM) exposed TM3 and TM4 cells. The microarray analysis identified 67 and 1372 differentially expressed genes mainly concentrated in endothelial cell morphogenesis and anatomical structure development in TM3 cells and associated with cardiovascular system development and circulatory system development in TM4 cells. Moreover, a pathway analysis revealed that PNP not only predominately affected meiotic recombination and meiosis in TM3 cells, but also influenced axon guidance and developmental biology in TM4 cells. These results suggest that TM3 and TM4 cells exhibit different responses to PNP, which might mediate different toxic mechanisms.

Recovery of the nitrifying ability of acclimated biomass exposed to para-nitrophenol.

Para-nitrophenol (PNP) is often detected in industrial wastewater that is discharged into municipal wastewater treatment plants. Intermittent discharge of PNP into municipal treatment facilities puts their biological process at risk of inhibition, and the risk is especially great for nitrification. In this work, nitrifying biomass was acclimated to PNP. The acclimated biomass retained most of its ammonium-removal activity when it was exposed to PNP at up to 100 mg/L, while the normal (unacclimated) biomass had nearly complete inhibition. PNP was effectively biodegraded by the acclimated biomass, but the normal biomass had minimal PNP biodegradation. After PNP disappeared, the acclimated biomass recovered its ability for NH4+-N removals within one to two days, but the normal biomass did not fully recovery even after seven days. The acclimated biomass had superior ability to sustain nitrification due to its ability to biodegrade PNP and its selection of nitrifying bacteria more resistant to PNP. The PNP-acclimated community was enriched in genera that could have been active in the biodegradation of PNP, such as Chloroflexi. Although the abundance of well-known nitrifiers, Nitrosomonas and Nitrospira, decreased, Nitrosospira and other genera within the Proetobacteria phylum increased, presumably because they were more resistant to PNP.

A Toxic Unit and Additive Index Approach to Understanding the Interactions of 2 Piscicides, 3-Trifluoromethyl-4-Nitrophenol and Niclosamide, in Rainbow Trout.

The toxic unit and additive index approaches were used to understand how 2 pesticides, 3-trifluoromethyl-4-nitrophenol (TFM) and 2,5-dichloro-4-nitrosalicylanilide (niclosamide; Nic), interact in mixtures. Our first objective was to determine whether the interaction was strictly additive or greater than additive at doses comparable to those used to control invasive sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes, and our second was to compare the utility of the toxic unit and additive index models for determining how TFM and Nic interacted. Typically, TFM is mixed with Nic (1-2%, w/v) to increase its potency and reduce TFM use. However, there is little information on how the 2 chemicals interact. Using a well-studied, resident nontarget fish, the rainbow trout (Oncorhynchus mykiss), we conducted toxicity tests with TFM, Nic, and TFM:Nic (100:1, w/v; TFM/1% Nic) mixtures over 12 h to determine if the interaction was strictly additive, less than additive (antagonistic), or greater than additive (synergistic). The toxic unit and additive index approaches indicated synergistic interactions at environmentally relevant concentrations, suggesting that both are valid approaches for predicting how TFM and Nic interact. The toxic unit approach was simpler to conceptualize and to calculate, and we recommend that it be used when describing how TFM and Nic, and other similar organic compounds, interact with each other in aquatic ecosystems. Environ Toxicol Chem 2021;40:1419-1430. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Toxicity of selected airborne nitrophenols on eukaryotic cell membrane models.

Nitroaromatics belong to the group of toxic components of aerosol particles and atmospheric hydrometeors that enter the atmosphere through biomass burning and fuel combustion. In the present work, we report on the cytotoxic effects of a 2-, 3- and 4-nitrophenol mixture on a model eukaryotic-like cell membrane and compared it with in vitro cellular models BEAS-2B (immortalized bronchial epithelial cells) and A549 (cancerous alveolar epithelial cells). A selected model biomembrane comprised of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine), DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) and POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) was studied. The electrochemical-based method, combined with atomic force microscopy (AFM) and phase-contrast microscopy imaging, allowed to get insights into the mechanism of cellular function disruption caused by airborne nitrophenols. The efficacy of the method is supported by the data obtained from in vitro experiments performed on cell models. The nitrophenol mixture exhibited cytotoxic effects at concentrations above 100 µg mL-1, as demonstrated by phase-contrast microscopy in real lung cell lines. Electrochemical impedance spectroscopy (EIS) revealed the formation of membrane defects at a nitrophenol concentration of 200 µg mL-1. AFM imaging confirmed the model membrane disintegration and phospholipids rearrangement in the presence of nitrophenols. These observations indicate that particle-bound nitrophenols induce substantial changes in cell membranes and make them more permeable to aerosol, resulting in major cellular damage in the lungs when inhaled. The study provides initial evidence of cellular membrane damage induced by three important nitrated phenols present in the environment.

Investigation on Endocrine Disruption of the Larval Lampricide 3-Trifluoromethyl-4-Nitrophenol: Short-Term Reproduction Assay with Fathead Minnow (Pimephales promelas).

3-Trifluoromethyl-4-nitrophenol (TFM) has been used for more than 60 yr to control the invasive parasitic sea lamprey (Petromyzon marinus) in the Great Lakes Basin (USA/Canada). In the early 1990s, researchers reported that TFM induced vitellogenin in fish and that TFM was an agonist for the rainbow trout estrogen receptor. To support continued registration of TFM for sea lamprey control, regulatory agencies required further testing to evaluate potential endocrine disruption effects. Fathead minnow (Pimephales promelas) were exposed to TFM at measured concentrations of 0.0659, 0.181, 0.594, 1.79, and 5.11 mg active ingredient (a.i.)/L for 21 d. No-observable- and lowest-observable-effect concentrations (NOEC and LOEC, respectively) were determined to be 1.79 mg/L or greater for each endpoint. Male survival in the highest treatment group was reduced relative to the controls. Percentage of egg fertility was reduced in the highest treatment group, resulting in an estimated NOEC of 1.79 mg/L. Whereas no effect on the gonadosomatic index (GSI) was observed for males, female GSI was increased in the 5.11-mg/L treatment. Vitellogenin production was not altered relative to the controls for all TFM treatment groups. However, female testosterone was elevated in the 5.11-mg/L treatment. The results suggest that prolonged exposure to TFM at concentrations exceeding 1.79 mg/L has the potential to disrupt endocrine function. Biologically relevant effects were found at the highest exposure concentration following a 21-d exposure. However, the duration of exposure in our study is not consistent with typical treatment durations (12 h) for sea lamprey control. Environ Toxicol Chem 2020;39:1599-1607. © 2020 SETAC.

Effects of p-nitrophenol on enzyme activity, histology, and gene expression in Larimichthys crocea.

p-Nitrophenol (PNP) is one type of environmental pollutant, which is difficult to degrade and soluble in water. To investigate the effects of PNP on economically important marine fish species, we subjected Larimichthys crocea juvenile to five different concentrations of PNP for 96 h, and the semi-lethal concentration (LC50) was 6.218 mg/L. Then we collected the liver, kidney, and gill tissues to determine enzyme activity and gene expression levels, and analyzed histological changes. In histological analysis, the gills showed curling of lamella, epithelial lifting and hyperplasia; the parenchymal structure of hepatocytes was significantly damaged, with severe vacuolation and loss of original structure. The renal cells were damaged too, with congestion and renal tubular necrosis. Catalase and superoxide dismutase both showed an up- and down-tendency with the rise of concentration in the three tissues, and GSH-px had similar trend in the kidney, which decreased at 8 mg/L in the liver but showed no significant differences in the gills. Malondialdehyde of three tissues was increased with an increase in PNP concentration. The expression of four detoxification (cyp450, gst, gpx, hsp70) and one immune-related (mhc II) genes was induced at low PNP concentrations but inhibited at high PNP concentrations in the kidney. In liver, cyp450, hsp70 and mhc II showed similar trend but gst and gpx didn't increase at low PNP concentrations. Our results indicate that the fish possesses the ability to detoxify PNP; however, at high concentrations, PNP still causes serious damage to them. Our data not only help in understanding the ability of L. crocea to detoxify PNP but also should serve as a basis for the study of toxic effects of nitrobenzenes on marine fish.

4-nitrophenol exposure in T24 human bladder cancer cells promotes proliferation, motilities, and epithelial-to-mesenchymal transition.

Although health hazards of 4-nitrophenol (PNP) exposure have been reported, the adverse effects of PNP exposure on cancer biological features are still unknown. We investigated the effects of administration of PNP in T24 human bladder cancer cells. The results showed that PNP exposure promoted cellular proliferation, migration and invasion, inhibited adhesion and apoptosis in vitro. Using quantitative real-time PCR, we found that (1) the mRNA expression levels of cell-cycle regulators PCNA, cyclin D1 and COX-2 were increased in PNP-treated cells compared to controls, however, that of pro-apoptotic gene Bax was decreased; (2) the expression level of EMT-associated gene E-cadherin was decreased in PNP-treated cells, whereas those of N-cadherin, vimentin, snail, and slug were increased; (3) the expression levels of cancer-promoting genes HIF-1, IL-1ß, VEGFα and K-Ras were enhanced, but those of tumor suppressors p53, PTEN and BRCA were decreased. There was a positive association between PNP exposure times and the promotion effects. Finally, we found that the expression level of PPARγ (γ1 isoform) was increased in PNP-treated T24 cells. GW9662, a specific PPARγ antagonist, attenuated PNP-induced cell migration and invasion. These findings indicate that PNP exposure may promote bladder cancer growth and progression involving PPARγ signaling. PPARγ is a potential target for development of novel intervention study on environment pollution. Environ. Mol. Mutagen. 61:316-328, 2020. © 2019 Wiley Periodicals, Inc.

Swift reduction of 4-nitrophenol by easy recoverable magnetite-Ag/layered double hydroxide/starch bionanocomposite.

The main source of nitroaromatic compounds in nature is anthropogenic activities. In the present report, a facile and green method was employed to fabricate highly efficient catalyst to turn toxic nitrophenols to more safe aminophenols. The Fe3O4/Ag@Ca-Al LDH hybrid (FAL hybrid) was synthesized by the Fe3O4 and Ag nanoparticles supported on layer double hydroxide (LDH) and the bionanocomposite (BNC) of this hybrid and starch was prepared via an in situ growth method. The FAL hybrid and BNC were characterized by different techniques. The reduction reaction of 4-nitrophenol in the presence of these catalysts indicated that both of them have high catalytic activity due to their large numbers of hydroxyl groups as capping agent. The comparison rate kinetics study between 4-nitrophenol and 2-nitrophenol showed that the FALS-BNC has higher potential in the case of the para derivative. Also, catalysts were recovered without difficulty and reused after completion of the reduction reaction.

Acute toxicity of the insecticide methyl parathion and its hydrolytic product p-nitrophenol to the native Australian cladoceran Daphnia carinata.

The toxicity of an organophosphorus (OP) insecticide, methyl parathion (MP), and its hydrolysis product, p-nitrophenol (PNP), to the native Australian cladoceran species, Daphnia carinata, was assessed. Both MP and PNP were stable in cladoceran water during the test period. D. carinata was sensitive to both MP and PNP; however, the parent compound was more toxic than its metabolite. This is the first study that demonstrated the acute toxicity of MP and PNP towards an Australian daphnid species. The present investigation emphasizes the need for including the native taxa as non-target test organisms while evaluating the toxicity of environmental pollutants.

Control of invasive sea lampreys using the piscicides TFM and niclosamide: Toxicology, successes & future prospects.

The invasion of the Laurentian Great Lakes of North America by sea lampreys (Petromyzon marinus) in the early 20th century contributed to the depletion of commercial, recreational and culturally important fish populations, devastating the economies of communities that relied on the fishery. Sea lamprey populations were subsequently controlled using an aggressive integrated pest-management program which employed barriers and traps to prevent sea lamprey from migrating to their spawning grounds and the use of the piscicides (lampricides) 3-trifluoromethyl-4-nitrophenol (TFM) and niclosamide to eliminate larval sea lampreys from their nursery streams. Although sea lampreys have not been eradicated from the Great Lakes, populations have been suppressed to less than 10% of their peak numbers in the mid-1900s. The ongoing use of lampricides provides the foundation for sea lamprey control in the Great Lakes, one of the most successful invasive species control programs in the world. Yet, significant gaps remain in our understanding of how lampricides are taken-up and handled by sea lampreys, how lampricides exert their toxic effects, and how they adversely affect non-target invertebrate and vertebrates species. In this review we examine what has been learned about the uptake, handling and elimination, and the mode of TFM and niclosamide toxicity in lampreys and in non-target animals, particularly in the last 10 years. It is now clear that the mode of TFM toxicity is the same in non-target fishes and lampreys, in which TFM interferes with oxidative phosphorylation by the mitochondria leading to decreased ATP production. Vulnerability to TFM is related to abiotic factors such as water pH and alkalinity, which we propose changes the relative amounts of the bioavailable un-ionized form of TFM in the gill microenvironment. Niclosamide, which is also a molluscicide used to control snails in areas prone to schistosomiasis infections of humans, also likely works by uncoupling oxidative phosphorylation, but less is known about other aspects of its toxicology. The effects of TFM include reductions in energy stores, particularly glycogen and high energy phosphagens. However, non-target fishes readily recover from sub-lethal TFM exposure as demonstrated by the rapid restoration of energy stores and clearance of TFM. Although both TFM and niclosamide are non-persistent in the environment and critical for sea lamprey control, increasing public and institutional concerns about pesticides in the environment makes it imperative to explore other means of sea lamprey control. Accordingly, we also address possible "next-generation" strategies of sea lamprey control including genetic tools such as RNA interference and CRISPR-Cas9 to impair critical physiological processes (e.g. reproduction, digestion, metamorphosis) in lamprey, and the use of green chemistry to develop more environmentally benign chemical methods of sea lamprey control.

The common field lampricide 3-trifluoromethyl-4-nitrophenol is a potential radiosensitizer in fish cells.

PURPOSE: To evaluate if the common field lampricide 3-trifluoromethyl-4-nitrophenol (TFM) that is intended to eradicate the invasive species sea lampreys in the Great Lakes has the potential to sensitize radiation responses in cells from non-targeted native fish MATERIALS AND METHODS: The TFM toxicity was assessed acutely and chronically with the clonogenic fish cell line eelB. The acute toxicity (24-h exposure) was determined by the fluorescent cell viability probe Alamar Blue. The chronic toxicity was determined either by Alamar Blue (7-d exposure) or the clonogenic survival assay (14-d exposure). Pre- and post-exposure of fish cells to environmentally relevant TFM concentrations following gamma irradiation were performed. Clonogenic survival was determined to assess the damage level of radiation-induced reproductive cell death. RESULTS: The chronic toxicity tests were more sensitive than the acute toxicity tests. The 14-d EC50 using the clonogenic survival endpoint was 2.09 ±â€¯0.28 µg/mL and was statistically similar to the 7-d EC50 (1.85 ±â€¯0.07 µg/mL) based on the Alamar Blue-based cytotoxicity endpoint. Post-exposure of cells to environmentally relevant TFM concentrations following irradiation did not have any effect as compared to the irradiation alone group. In contrast, pre-exposure of cells to TFM following irradiation had a negative additive effect when the total radiation dose was 2 Gy, but not 0.1 or 0.5 Gy. CONCLUSION: Our results suggest that the common field lampricide TFM is a potential radiation sensitizer in cells from non-targeted native fish. This could be a health problem of concern for non-targeted native fish if a large accidental radioactive release occurs.

End-product inhibition of skatole-metabolising enzymes CYP1A, CYP2A19 and CYP2E1 in porcine and piscine hepatic microsomes.

The hepatic cytochrome p450 enzymes 1 A, 2A19 and 2E1 is very important for the elimination of skatole from the body of pigs. Impaired skatole metabolism, results in skatole accumulation, which give rise to off flavor of the meat. Several metabolites of skatole has been identified, however the role of these metabolites in the inhibition of the skatole metabolizing enzymes are not documented. Using microsomes from pigs and fish, we determined the ability of several skatole metabolites to inhibit CYP1 A, CYP2A19 and CYP2E1 dependent activity. Our results show that 2-aminoacetophenone is an inhibitor of porcine CYP2A19 and CYP2E1 activity, but not the piscine orthologues. In conclusion, there is species specific differences in the inhibition of CYP1 A and CYP2A19 dependent metabolism of probe substrates. This is relevant to the evaluation of different model systems and to the reduction of off flavor of meat.

Exposure to the lampricide TFM elicits an environmental stress response in yeast.

The pesticide 3-trifluoromethyl-4-nitrophenol (TFM) is used to control sea lamprey populations in the Great Lakes and Lake Champlain. Little is known about the effects of this pesticide on gene expression in eukaryotic species. This study used microarray analysis to determine the effects of short term, high dose TFM exposure on gene expression in Saccharomyces cerevisiae. Yeast grown in standard glucose-containing media showed significant variation in gene expression in pathways related to cytoplasmic translation with the majority of these genes being downregulated. These findings were supported by the analysis of a similar but glucose-free experiment revealing that these cytoplasmic translation genes, mostly ribosomal subunit expressing genes, were similarly downregulated. The repression of the ribosomal subunit genes suggests that TFM exposure, regardless of glucose availability, evokes features of the environmental stress response in yeast.

Establishment of a p-nitrophenol oxidation-based assay for the analysis of CYP2E1 activity in intact hepatocytes in vitro.

CYP2E1 is a mammalian cytochrome P450 enzyme, which oxidizes a structurally diverse class of endogenous and exogenous (xenobiotic) compounds. Best studied is the role of CYP2E1 in phase I metabolism of xenobiotics including alcohol. CYP2E1 metabolizes ethanol and is active in generating reactive oxygen species (ROS) and subsequent oxidative stress in the hepatic tissues. Several studies have shown and discussed the importance of CYP2E1 in the hepatotoxic actions of alcohol. However, the vast majority assessed the CYP2E1 activity only in isolated microsomes. Here, we aimed to develop and optimize a fast and easy method to assess alcohol-induced CYP2E1 activity in hepatocytes in vitro applying oxidation of para-nitrophenol to para-nitrocatechol as specific substrate probe. Using hepatoma cells with and without stable CYP2E1 expression and primary human hepatocytes, we established specific methodology to assess CYP2E1 catalytic activity and its induction by ethanol in a small number of cells and in a very short time.

Post-exposure effects of the piscicide 3-trifluoromethyl-4-nitrophenol (TFM) on the stress response and liver metabolic capacity in rainbow trout (Oncorhynchus mykiss).

The piscicide 3-trifluoromethyl-4-nitrophenol (TFM) has been used to control invasive sea lamprey (Petromyzon marinus) populations in the Great Lakes for almost 60 years. Applied to rivers and streams containing larval lampreys, TFM seldom harms non-target fishes, but the effects of sub-lethal treatments on fish physiology are not well understood. We examined the effects of 9 h exposure to TFM on the stress axis and liver metabolic capacity of rainbow trout (Oncorhynchus mykiss) using in vivo and in vitro approaches. The fish that had been acutely exposed to TFM in vivo had increased plasma cortisol levels at 12 h post-treatment, but TFM exposure did not interfere with in vitro cortisol production in head kidney preparations. Subjecting trout to an acute handling stressor 12 h post-TFM exposure resulted in a relative attenuation of the plasma cortisol and glucose response compared to pre-stress levels. We conclude that routine TFM treatments can lead to elevations of plasma cortisol following exposure, plus a relative dampening of the stress response in rainbow trout, with high cortisol levels lasting at least 12 h post-treatment. Since the ability of the fish to produce cortisol and the liver metabolic capacity were not compromised following TFM exposure, it is likely that their ability to cope with other stressors is not altered in the long-term.

Assessing off-target cytotoxicity of the field lampricide 3-trifluoromethyl-4-nitrophenol using novel lake sturgeon cell lines.

Lampricides are currently being applied to streams and rivers to control the population of sea lamprey, an invasive species, in the Great Lakes. The most commonly used lampricide agent used in the field is 3-trifluoromethyl-4-nitrophenol (TFM), which targets larval sea lamprey in lamprey-infested rivers and streams. The specificity of TFM is due to the relative inability of sea lamprey to detoxify the agent relative to non-target fishes. There is increasing concern, however, about non-target effects on fishes, particularly threatened populations of juvenile lake sturgeon (LS; Acipenser fulvescens). There is therefore a need to develop models to better define lake sturgeon's response to TFM. Here we report the establishment of five LS cell lines derived from the liver, gill, skin and intestinal tract of juvenile LS and some of their cellular characteristics. All LS cell lines grew well at 25 °C in Leibovitz's (L)- 15 medium supplemented with 10% FBS. All cell lines demonstrated high senescence-associated ß-galactosidase activity and varying levels of Periodic acid Schiff-positive polysaccharides, indicating substantial production of glycoproteins and mucosubstances by the cells. Comparative toxicity of TFM in the five LS cell lines was assessed by two fluorescent cell viability dyes, Alamar Blue and CFDA-AM, in conditions with and without serum and at 24 or 72 h exposure. Deduced EC50 values were compared between the cell lines and to the reported in vivo LC50s. Tissues sensitive to the effects of TFM in vivo correlated with cell lines from the same tissues being most sensitive to TFM in vitro. EC50 values for the LSliver-e cells was significantly lower than the EC50 for the rainbow trout (RBT) liver cells RTL-W1, reaffirming the in vivo observation that LS was generally more TFM-sensitive than rainbow trout. Our data suggests that whole-fish sensitivity of LS to TFM is likely attributable to sensitivity at the cellular level. Thus, LS cell lines, as well as those of RBT, can be used to screen and evaluate the toxicity of the next generation of lampricides on non-target fish such as lake sturgeon.

Decomposition byproducts induced by gamma radiation and their toxicity: the case of 2-nitrophenol.

The induced degradation and detoxification of 2-nitrophenol (2-NP) in aqueous media by gamma irradiation were carefully evaluated in this study. Gamma radiation at absorbed doses as low as 20 kGy was able to degrade 2-NP to reach a removal of at least 85% across the investigated range of concentration (50-150 ppm). 2-NP breaks down to aromatic-based compounds with increasing number of byproducts upon increasing the radiation treatment from the absorbed dose of 50% decomposition (D50) to the absorbed dose of 90% decomposition (D90), after which no byproducts could be detected, indicating the formation of undetectable aliphatic hydrocarbons, insoluble, or volatile byproducts. Toxicology studies showed that the degradation of 2-NP under absorbed doses up to D90 resulted in a more toxic byproduct than the parent compound, and a remarkable reduction in the toxicity was observed with the irradiated samples with absorbed doses above D90. Varying the pH of the media to acidic or basic conditions did not significantly alter the degradation behavior of 2-NP. However, a notable improvement of the detoxification was associated with the samples of acidic pH. Adding 0.5% of H2O2 to 2-NP solutions had a positive effect by reducing D90 by a factor of nine and diminishing the toxicity by twofolds.

Influence of body size, metabolic rate and life history stage on the uptake and excretion of the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) by invasive sea lampreys (Petromyzon marinus).

Invasive sea lamprey (Petromyzon marinus) are controlled in the Great Lakes using the lampricide 3-trifluoromethyl-4-nitrophenol (TFM), which is applied to streams infested with larval lamprey. However, lamprey that survive treatments (residuals) remain a challenge because they may subsequently undergo metamorphosis into parasitic juvenile animals that migrate downstream to the Great Lakes, where they feed on important sport and commercial fishes. The goal of this study was to determine if body size and life stage could potentially influence sea lamprey tolerance to TFM by influencing patterns of TFM uptake and elimination. Because mass specific rates of oxygen consumption (M˙O2) are lower in larger compared to smaller lamprey, we predicted that TFM uptake would be negatively correlated to body size, suggesting that large larvae would be more tolerant to TFM exposure. Accordingly, TFM uptake and M˙O2 were measured in larvae ranging in size from 0.2-4.2g using radio-labelled TFM (14C-TFM) and static respirometry. Both were inversely proportional to wet mass (M), and could be described usingthe allometric power relationship: Y=aMb, in which M˙O2=1.86M0.53 and TFM Uptake=7.24M0.34. We also predicted that body size would extend to rates of TFM elimination, which was measured following the administration of 14C-TFM (via intraperitoneal injection). However, there were no differences in the half-lives of elimination of TFM (T 1/2-TFM). There were also no differences in M˙O2 or TFM uptake amongst size-matched larval, metamorphosing (stages 6-7), or post-metamorphic (juvenile) sea lamprey. However, the T1/2-TFM was significantly lower in larval than post-metamorphic lamprey (juvenile), indicating the larval lamprey cleared TFM more efficiently than juvenile lamprey. We conclude that larger larval sea lamprey are more likely to survive TFM treatments suggesting that body size might be an important variable to consider when treating streams with TFM to control these invasive species.