The effect of ethanol on temperature selection in the goldfish, Carassius auratus

The effect of ethanol on behavioral thermoregulation in the goldfish, Carassius auratus, was studied by adding ethanol to a horizontal aquatic temperature gradient which allowed each fish to select its preferred temperature within a range of about 9 degrees C to 33 degrees C. Alternating exposure to 1.0% (v/v) ethanol and water showed that fish (10 to 15 g) responded to ethanol by selecting lower temperatures. Onset and disappearance of the effect occurred within 10 min of exposure to or removal from ethanol. Fish exposed to 1.0% ethanol for 3 hr did not show acute tolerance. When fish were exposed to increasing concentrations of ethanol from 0.0% to 1.7%, the lowest concentration to elicit a response was 0.5% ethanol. The magnitude of the response plateaued at 0.7% ethanol. At this concentration and above, selected temperatures remained about 2 degrees C below temperatures selected by controls. Because thermoregulatory responses of fish are behavioral and relatively easy to observe and quantify, goldfish offer a useful model for the study of ethanol effects on central nervous system control of thermoregulation. Ethanol produces a prompt, stable, and reproducible depression of selected temperature by lowering the thermoregulatory set point in the goldfish.     

Effects of ethanol and sodium phenobarbital on conflict behavior of goldfish (Carassius auratus)

Hungry goldfish learned to press a lever for worms obtainable on a 2 min variable-interval schedule of reinforcement. Conflict was induced by rewarding with a worm and punishing with an electric shock any lever responses made in the presence of a flashing light. The resulting suppression of responding was attenuated in fish exposed to sodium phenobarbital. Ethanol solutions were generally without effect.     

Responses of AChE and GST activities to insecticide coexposure in Carassius auratus

Organophosphates and carbamates are widely used pesticides and play an important role in global agriculture. The misuse of these compounds has caused environmental problems and has had a negative impact on wildlife. In this study, the in vivo effects of commercial chlorpyrifos and isoprocarb on acetylcholinesterase (AChE) and glutathione S‐transferase (GST) activities in goldfish (Carassius auratus) were investigated. Muscle and brain AChE activity was significantly inhibited by chlorpyrifos and isoprocarb (alone and in combination) after 2, 5, 10, and 15 days of exposure, and obvious concentration‐response and time‐response relationships were obtained. Gill GST activity was significantly inhibited by chlorpyrifos and isoprocarb (single compounds and in combination), however, concentration dependence and time dependence were not apparent. The joint effect of chlorpyrifos/isoprocarb was additive with regard to AChE activity inhibition and was antagonistic with regard to GST activity inhibition. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.     

Effects of atrazine on sex steroid dynamics, plasma vitellogenin concentration and gonad development in adult goldfish (Carassius auratus)

Sexually mature goldfish (Carassius auratus) of both sexes were exposed to two doses (100 and 1000 microg/l) of the widely used herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) for a period of 21 days and effects on the concentrations of gonad and plasma sex steroids (testosterone (T), 17beta-estradiol (E2) and 11-ketotestosterone (11-KT)), plasma vitellogenin (VTG) and gonad histo-morphology assessed. Atrazine did not show any obvious estrogenic effect in males, as determined by a lack of vitellogenin induction. There were, however, effects of atrazine on plasma androgen concentrations (androgen dynamics) and tissue (plasma and gonad) estrogen concentrations in male goldfish; exposure to 1000 microg/l atrazine induced suppression in both testosterone and 11-ketotestosterone, and resulted in elevated 17beta-estradiol, after 21 day of exposure. Further, these suppressive effects on plasma androgens and the induction in estrogen were dose- and time-related. The highest atrazine exposure dose induced structural disruption in the testis and both 100 and 1000 microg/l induced elevated levels of atresia in ovaries.     

Possible disruption of pheromonal communication by humic acid in the goldfish,Carassius auratus

Humic acids are large, complex, organic molecules which are ubiquitous components of aquatic environments as products of degradation of plant material. In aqueous solution they form microvesicles. As many teleost pheromones are steroidal in nature, we hypothesised that they would preferentially dissolve in the organic, hydrophobic core of these vesicles instead of in water and therefore be unavailable for detection. This would have obvious and profound effects on many aspects of fish biology. To test this hypothesis we recorded electro-olfactogram (EOG) response of the goldfish (Carassius auratus) olfactory epithelium to the pheromones 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P), its sulphated conjugate (17,20β-P-SO₄) and prostaglandin F₂ (PGF₂), all at 10⁻¹¹ to 10⁻⁸ M, in the absence and presence of humic acids (1–1000 mg l⁻¹). At nearly all concentrations of humic acid tested, there was a significant attenuation of the amplitude of the initial (phasic) response to 17,20β-P compared to 17,20β-P alone. At higher concentrations of humic acid, the EOG response to 17,20β-P was often completely obliterated, suggesting that the concentration of the pheromone available to the olfactory epithelium was below the threshold of detection. Exposure of the olfactory epithelium to humic acid did not cause any short-term loss of sensitivity to 17,20β-P per se. Furthermore, simultaneous recording of electro-encephalograms from the olfactory bulb demonstrated that the nervous activity evoked by the same concentration of 17,20β-P was less intense in the presence of humic acid than its absence. PGF₂ is non-steroidal and much more soluble in water. In contrast to 17,20β-P, only the higher concentrations of humic acid (100 and 1000 mg l⁻¹) significantly diminished the EOG amplitude. 17,20β-P-SO₄ is detected via a distinct olfactory mechanism to the free form. Given that the sulphate group increases the water solubility, we predicted that the effect of humic acid would be reduced. However, the effect of humic acid on EOG amplitude in response to 17,20β-P-SO₄ was similar to that of the free form. We suggest that the steroid portion of the molecule adsorbs onto the surface of the humic acid microvesicles and is still effectively unavailable for olfactory detection. In conclusion, humic acid may significantly reduce the concentration of 17,20β-P and 17,20β-P-SO₄ available for detection by Carassius auratus in natural environments. Furthermore, as many teleost pheromones are steroid derivatives, this phenomenon may be applicable to chemical communication systems in teleosts in general.     

Reproductive and stress hormone levels in goldfish (Carassius auratus) exposed to oil sands process-affected water

Athabasca oil sands mining in northern Alberta produces process-affected waters that are characterized by the presence of naphthenic acids, polycyclic aromatic hydrocarbons, and high salinity. The purpose of this study was to examine the impact of these process-affected waters on reproductive and stress related endpoints in mature goldfish, Carassius auratus. In two separate studies, testosterone and 17beta-estradiol levels in the plasma were significantly reduced in both male and female goldfish caged for 19 days in process-affected waters relative to controls. This effect was most pronounced in goldfish caged at a site containing mature fine tailing and tailings pond water (P5). Ovarian and testicular tissues from fish in the caging studies were incubated in vitro to evaluate potential differences in basal steroid production levels and responsiveness to human chorionic gonadotropin (hCG). Basal levels of testosterone were reduced significantly in males and females from P5 compared with the control pond (P1) demonstrating that the gonads from exposed fish had a diminished steroidogenic capacity. Gonadal tissues of fish from all ponds responded similarly to hCG suggesting that the steroid biosynthetic pathway remained functionally intact. Plasma cortisol levels were significantly higher in male goldfish caged in a pond containing mature fine tailings and capped with uncontaminated water (P3) and in P5 compared with P1. Collectively, these studies suggest that waste products of oil sands mining have the potential to disrupt the normal endocrine functioning in exposed fish through alterations to both reproductive and glucocorticoid hormone biosynthesis. In additional laboratory studies, exposure of goldfish to a naphthenic acid extract for 7 days failed to replicate the effects of processes-affected waters on plasma steroid levels and the causative agent(s) responsible for the effects on steroid biosynthesis remains to be identified.     

Neuropeptide Y has a stimulatory action on feeding behavior in goldfish (Carassius auratus).

The purpose of the present study was to elucidate the possible role of neuropeptide Y (NPY) in the feeding regulation in fish. We examined the effects of intracerebroventricular (i.c.v.) or intraperitoneal (i.p.) neuropeptide Y administration on food intake in satiated goldfish, at different time intervals postinjection (0-2, 2-8 and 0-8 h). Food intake was significantly increased by i.c.v. administered neuropeptide Y (1 microg) at 2 h postinjection, while no significant differences in food intake were observed after i.p. treatment. The neuropeptide Y receptor antagonist, neuropeptide Y-(27-36), totally counteracted the stimulatory action of neuropeptide Y on feeding. The possible involvement of neuropeptide Y in the eating behavior evoked by food deprivation has been investigated. Food deprivation by either 24 or 72 h significantly increased feeding, and the neuropeptide Y receptor antagonist attenuated such feeding stimulation. From our findings, we suggest, first, that neuropeptide Y is involved in feeding central regulation in goldfish, acting via specific neuropeptide Y receptors, and second, that hypothalamic neuropeptide Y would be released in response to food deprivation, contributing to generate the consequent eating behavior stimulation in Carassius auratus.     

Leucocytes and leucopoietic capacity in goldfish,Carassius auratus,exposed to sublethal levels of cadmium

By comparison with animals in essentially cadmium-free water (< 2 μg Cd²⁺/l) goldfish exposed for 3 wk to 90, 270 and 445 μg Cd²⁺/l (5, 15 and 25% 240-h LC₅₀) exhibited significant reductions in total leucocyte counts. These were the result of decreases in lymphocyte and thrombocyte numbers. Mitogenic response to administered PHA as well as sharp decreases in blast cell numbers suggested that lympho- and thrombopenia reflect, in part at least, decreased proliferative capacity. By contrast, neutrophil, cosinophil and basophil numbers increased in cadmium-intoxicated fish. Cadmium apparently reduced PHA-related changes in granulocyte abundances.     

Effect of sewage on blood parameters and the resistance against bacterial infection of goldfish,Carassius auratus

Effects of raw and treated sewages on blood parameters and on the resistance against bacterial infection of goldfish (Carassius auratus) were investigated. All fish exposed to 50% raw and 100% treated sewages died within 3 days. Plasma ammonia and lactate increased after 3 days' exposure to 10% raw and 20% treated sewages, though no fish died within 30 days. On day 30, the numbers of red blood cells, granulocytes and lymphocytes, activity of phagocytic cells, Hb, and plasma protein showed lower values than those of the control. Similar changes in blood parameters were observed in goldfish exposed to 5% raw and 10% treated sewages for 30 days, though to a lesser extent. No changes in these parameters were found in fish exposed to 5% treated sewage, whereas higher values for chloride, manganese, and bromide, and lower values for potassium and zinc, were observed on day 30, compared to those of the control. Fish exposed to 5% treated sewage for 30 days prior to an intraperitoneal challenge with Aeromonas salmonicida showed decreased survival rates. These results suggest that fish exposed to sewage, even to 5% treated sewage, are subject to suppression of the immune response. © 1997 by John Wiley & Sons, Inc. Environ Toxicol Water Qual 12: 43–51, 1997     

Oxidative stress responses in gills of goldfish,Carassius auratus,exposed to the metribuzin-containing herbicide Sencor

Metribuzin belongs to the family of asymmetrical triazine compounds and is an active ingredient in many commercial herbicides including Sencor. Effects on goldfish (Carassius auratus L.) of exposure for 96 h to 7.14, 35.7 or 71.4 mg L⁻¹ Sencor 70 WG (corresponding to 5, 25 and 50 mg L⁻¹ of metribuzin) were examined by evaluating oxidative stress markers and activities of antioxidant and associated enzymes in gills. Fish exposed to the lowest Sencor concentration (7.14 mg L⁻¹) showed a 94% increase in levels of protein carbonyls in gills as well as 45% and 144% increases in the activities of glutathione peroxidase and glutathione-S-transferase. Exposure to the highest Sencor concentration (71.4 mg L⁻¹) resulted in reduced levels of protein carbonyls by 56% and lipid peroxides by 40%, as compared with controls, but enhanced levels of low and high molecular mass thiols by 71% and 36%, respectively. The activities of superoxide dismutase, glutathione peroxidase and glutathione-S-transferase were increased in gills of goldfish exposed to 71.4 mg L⁻¹ Sencor. At any concentration tested, Sencor did not affect the activities of glutathione reductase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase or acetylcholine esterase in gills. The results of this study indicate that acute exposure of goldfish to Sencor had effect on free radical processes in gills and glutathione-dependent antioxidants effectively protect proteins and lipids from oxidation.     

Accumulation and toxicity of CuO and ZnO nanoparticles through waterborne and dietary exposure of goldfish (Carassius auratus)

Dietary and waterborne exposure to copper oxide (CuO) and zinc oxide (ZnO) nanoparticles (NPs) was conducted using a simplified model of an aquatic food chain consisting of zooplankton (Artemia salina) and goldfish (Carassius auratus) to determine bioaccumulation, toxic effects, and particle transport through trophic levels. Artemia contaminated with NPs were used as food in dietary exposure. Fish were exposed to suspensions of the NPs in waterborne exposure. ICP‐MS analysis showed that accumulation primarily occurred in the intestine, followed by the gills and liver. Dietary uptake was lower, but was found to be a potential pathway for transport of NPs to higher organisms. Waterborne exposure resulted in about a 10‐fold higher accumulation in the intestine. The heart, brain, and muscle tissue had no significant Cu or Zn. However, concentrations in muscle increased with NP concentration, which was ascribed to bioaccumulation of Cu and Zn released from NPs. Free Cu concentration in the medium was always higher than that of Zn, indicating CuO NPs dissolved more readily. ZnO NPs were relatively benign, even in waterborne exposure (p ≥ 0.05). In contrast, CuO NPs were toxic. Malondialdehyde levels in the liver and gills increased substantially (p < 0.05). Despite lower Cu accumulation, the liver exhibited significant oxidative stress, which could be from chronic exposure to Cu ions. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 119–128, 2015.     

Effects of polymer-coated metal oxide nanoparticles on goldfish (Carassius auratus L.) neutrophil viability and function

Abstract

Exposure effects from polyacrylic acid (PAA) metal-oxide nanoparticles (TiO₂, CeO₂, Fe₂O₃, ZnO) on fish neutrophil viability and effector functions (degranulation, respiratory burst, inflammatory gene expression) were investigated using primary kidney goldfish (Carassius auratus L.) neutrophils as a model. Several studies have reported cytotoxic effects of NPs but there are limited reports on their potential to perturb the innate immune system of aquatic organisms. PAA-TiO₂ significantly decreased neutrophil viability in a time and dose-dependent manner at all measured time points (0–48?h) and concentrations (0–200?µg/mL). Maximum viability decreased by (mean?±?SEM): 67.1?±?3.3%, 78.4?±?4.2% and 74.9?±?5.0% when exposed to 50, 100 and 200?µg/mL for 48?h, respectively. PAA-ZnO also significantly decreased neutrophil viability but only at 48?h exposures at higher concentrations. Neutrophil degranulation increased by approximately 3% after 30?min and by 8% after 4?h when exposed to sublethal doses (10?µg/mL) of PAA-CeO₂ or PAA-Fe₂O₃. All PAA-NPs induced an increase in neutrophil respiratory burst when exposed to 10?µg/mL for 30 and 60?min, however, PAA-Fe₂O₃ was the only NP where the response was significant. Lastly, NPs altered the expression of a number of pro-inflammatory and immune genes, where PAA-TiO₂ most significantly increased the mRNA levels of pro-inflammatory genes (il-1b, ifng) in neutrophils by 3 and 2.5 times, respectively. Together, these data demonstrate that goldfish neutrophils can be negatively affected from exposures to PAA-coated NPs and are functionally responsive to specific core-material properties at sublethal doses. These changes could perturb the innate response and affect the ability of fish to respond to pathogens.     

Refuse leachate exposure causes changes of thyroid hormone level and related gene expression in female goldfish (Carassius auratus)

To elucidate the potential thyroid disrupting effects of refuse leachate on females, female goldfish (Carassius auratus) were exposed to 0.5% diluted leachates from each step of a leachate treatment process (i.e. raw leachate before treatment, after membrane bioreactor treatment, and the final treated leachate) for 21 days. Raw leachate exposure caused disturbances in the thyroid cascade of female fish, as evidenced by the elevated plasma 3,3ʹ,5-triiodo-l-thyronine (p < 0.05) and thyroid-stimulating hormone (p < 0.01) levels as well as up-regulated hepatic and gonadal type I deiodinase (p < 0.01), type II deiodinase (p < 0.01) and thyroid receptor (p < 0.05) mRNA levels. Thyroid disrupting potency decreased markedly as raw leachate progressed through the “membrane bioreactor + reverse osmosis” treatment but could still be detected in the treated leachate. As our results indicated, thyroid system in female goldfish was more sensitive to leachate exposure than that of the male fish.     

Molecular cloning of CYP1A gene and its expression by benzo(a)pyrene from goldfish (Carassius auratus)

We cloned and sequenced the cytochrome P450 1A (CYP1A) gene from goldfish (Carassius auratus). It has a 1581 bp open reading frame that encodes a 526 amino acid protein with a theoretical molecular weight of 59.02 kDa. The CYP1A amino acid sequence clusters in a monophyletic group with other fish CYP1As, and more closely related to zebrafish CYP1A (91% identity) than to other fish CYP1As. Exposure to benzo(a)pyrene (BaP) by intraperitoneal injection increased biliary BaP metabolites and liver CYP1A gene expression. BaP exposure also increased CYP1A gene expression in extrahepatic organs, including intestine, and gill, which are sensitive to aqueous and dietary exposure to Arylhydrocarbon receptor (AhR) agonists. Therefore, goldfish CYP1A identified in this study offers basic information for further research related to biomarker use of CYP1A of goldfish.     

Differential ablation of sensory receptors underlies ototoxin‐induced shifts in auditory thresholds of the goldfish (Carassius auratus)

In recent years, fish models have become popular for investigations of ototoxic agents. However, the vast majority of such studies have focused on anatomical changes in lateral line hair cells after drug adminitration. Using the goldfish (Carassius auratus), we confirm that the acquisition of auditory evoked potentials offers a rapid and non‐invasive method for quantifying ototoxin‐induced changes in hearing sensitivity. Gentamicin (100 mg ml^?1) was the drug of choice as it is a well‐studied human ototoxin. Auditory threshold elevation was observed between 300 and 600 Hz and was accompanied by significant reductions in hair cell ciliary bundle densities in specific regions of the utricle and saccule. The correlations between structure and function suggest that differential susceptibility of sensory hair cells to acute gentamicin treatment underlies the frequency‐specific elevation of auditory thresholds. We propose that fish auditory systems should be used alongside the lateral line, for the assessment of ototoxicity in new‐developed drugs. Copyright © 2010 John Wiley & Sons, Ltd.     

Hexavalent chromium‐induced multiple biomarker responses in liver and kidney of goldfish,Carassius auratus

Hexavalent chromium [Cr (VI)] is a constituent of chromite ore. Although it is known to have several industrial and technological applications, its release into the aquatic environment as a result of chemical spill or inadequate waste discharge may hamper the health of aquatic organisms. In this study, we have investigated the effects of Cr (VI) on multiple biomarkers responses in goldfish under subchronic exposure conditions. Laboratory‐acclimatized fish were exposed to 4.25 ppm and 8.57 ppm Cr (VI) for four weeks using a continuous flow‐through system. During exposure, fish samples were collected on a weekly basis and analyzed for multiple biomarkers including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), metallothionein (MT), and total protein in liver and kidney. Study results indicated that the CAT activity and total protein levels in Cr (VI) ‐ treated goldfish did not significantly differ (P > 0.05) from their respective controls during experimentation. However, highly significant up‐regulations (P < 0.05) of SOD, GPx, and MT expression in Cr (VI) ‐ treated goldfish were recorded at different exposure times depending on Cr (VI) concentration, test organ, and/or biomarker of interest. For example, significantly higher liver GPx levels were found at weeks 2 and 3 in the 4.25 ppm concentration, and at weeks 3 and 4 in the 8.57 ppm, while kidney GPx levels were significantly higher at weeks 1, 2 and 3 in the 4.25 ppm concentration, and at weeks 2, 3 and 4 in the 8.57 ppm concentration. In summary, Cr (VI)‐induced oxidative stress was characterized by statistically significant increases in SOD, GPx, and MT expression in goldfish tissues; with the kidney showing a relatively higher sensitivity to Cr (VI) toxicity compared with the liver. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2011.