Waterborne metal levels in four freshwater lakes from Harmony Point, Nelson Island, Antarctica.

The aim of this study is to analyze the waterborne metal levels in four lakes (one endorheic and three exorheic) of Harmony Point, Nelson Island, Antarctica. Water samples were analyzed by using a quadrupole type inductively coupled plasma mass spectrometer and an inductively coupled plasma optical emission spectrometer. The levels of As, Cu, Mn, Mo, and V were significantly lower and those of Cr, Mg, Na, and Sr were significantly higher in the endorheic lake than in the other lakes. Most water samples presented levels of Ag, Be, Cd, Pb, Se, Tl, and U below the limit of quantification, while for Ba, Co, and Ni around half of the samples were below this limit. The waterborne metal levels were not significantly different between the exorheic lakes. Waterborne metal levels in the freshwater lakes from Harmony Point did not show any clear relationship with their levels in the soil of the region or with bird guano, and overall, their levels indicate an environment without anthropogenic influence. Apparently, the Na levels are influenced by salt spray from the ocean, as they are related to the distance of the lakes from the ocean.

Protium heptaphyllum essential oil from the fruit as a sedative and anesthetic in Rhamdia quelen: influence in cardiac frequency, biochemical, and oxidative parameters.

This study aimed to evaluate the effects of Protium heptaphyllum fruit essential oil (PHEO) on the physiology of silver catfish (Rhamdia quelen) during anesthesia and recovery, through studying echocardiograms, oxidative status, and metabolic parameters. Three experiments were performed: (1) 50 silver catfish juveniles were submitted to anesthesia and recovery tests with 300, 400, 500, 600, and 700 mg L-1 of PHEO. (2) Echocardiogram analysis was performed in anesthetized and non-anesthetized fish. (3) Biochemical parameters were evaluated at 0, 30, 60, and 120 min of recovery after being anesthetized for 3 min with 600 mg L-1 PHEO. Times to sedation and deep anesthesia were reduced with PHEO increasing concentrations. The echocardiogram showed a higher cardiac rate in anesthetized fish. Plasma glucose levels increased in control fish through recovery time, but anesthetized fish showed lower levels than controls at 120 min of recovery. Metabolic parameters such as plasma and hepatic glucose did not show changes considering the recovery time of up to 120 min. Hepatic glycogen, lactate, and triglycerides reduced their levels over recovery times. Fish anesthetized enhanced superoxide dismutase activity and thiobarbituric acid reactive substances levels but decreased reduced glutathione (GSH) levels at 30 min compared to controls. After 60 min, GSH values were significantly higher in anesthetized fish than in controls. These results suggest that PHEO at 600 mg L-1 is an effective anesthetic for the rapid handling of silver catfish, providing stable metabolic parameters and enhanced antioxidant responses during recovery. Echocardiogram analysis confirms the anesthetic effect, supporting PHEO as a viable and efficient option for fish anesthesia in aquaculture. The use of PHEO in aquaculture can enhance fish welfare by reducing stress during handling and transportation, potentially leading to improved growth, health, and survival rates.

Oxidative responses in small juveniles of Colossoma macropomum anesthetized and sedated with Ocimum gratissimum L. essential oil.

This study evaluated the use of essential oil of Ocimum gratissimum (EOOG) for anesthesia and in transport of Colossoma macropomum. Experiment 1, Test 1, anesthesia induction and recovery times were determined using different EOOG concentrations (0, 20, 50, 100, 200, 300 mg L-1), with two size classes: Juveniles I (0.86 g) and Juveniles II (11.46 g) (independent tests in a completely randomized design). Based on the results of Test 1, in Test 2 Juveniles II were exposed to EOOG concentrations: 0, 20, 100 mg L-1. Tissue samples were collected immediately after induction and 1 h post-recovery, to assess oxidative status variables. Experiment 2, Juveniles I (0.91 g) and Juveniles II (14.76 g) were submitted to transport in water with different concentrations of EOOG (0, 5, 10 mg L-1) (independent tests in a completely randomized design). The effects on oxidative status variables were evaluated. Concentrations between 50 and 200 mg L-1 EOOG can be indicated for Juveniles I, while concentrations between 50 and 100 mg L-1 EOOG for Juveniles II. The concentration of 100 mg L-1 EOOG was able to prevent oxidative damage in the liver. In Experiment 2, the concentrations of 5 and 10 mg L-1 EOOG added to the transport water caused sedation for both studied size classes of juveniles and did not cause oscillations in water quality variables nor any mortality. The concentration of 10 mg L-1 EOOG improved the oxidative status. It can be concluded that EOOG can be used for anesthesia and transport of C. macropomum.

Redox profile of silver catfish challenged with Aeromonas hydrophila and treated with hexane extract of Hesperozygis ringens (Benth.) Epling through immersion bath.

The growing increase in the fish farming sector has favored the establishment of bacterial outbreaks caused by Aeromonas hydrophila in several species. The hexane extract of Hesperozygis ringens (HEHR) (Lamiaceae) leaves increased the survival rate of silver catfish (Rhamdia quelen) experimentally infected by A. hydrophila. However, it is noteworthy that no reports have been found on the possible mechanisms of action of this extract in infected fish. This study aimed to evaluate the effect of the HEHR, administered through single immersion bath, on lipid peroxidation and antioxidant defenses in muscle and liver tissue of silver catfish challenged with A. hydrophila. The results showed that the oxidative status of silver catfish was altered, although oxidative stress was not triggered during the experiment. HEHR at 30 mg/L (HEHR30) was not characterized as a pro-oxidant agent in the presence of infection, unlike florfenicol and HEHR at 15 mg/L treatments in some cases. In short, HEHR30 provided an important increase in hepatic catalase activity, characterizing one of the possible mechanisms involved in the greater survival of fish experimentally infected by A. hydrophila. Additionally, HEHR30 did not induce lipid peroxidation, nor reduced antioxidant defenses of silver catfish infected or not by A. hydrophila.

Impairment on fillet fatty acid profile and oxidative damage in pirarucu, Arapaima gigas, acutely exposed to extreme ambient temperature.

Climatic events are affecting the Amazon basin and according to projections it is predicted the intensification of climate changes through increases in temperature and carbon dioxide (CO2). Recent evidence has revealed that exposure to an extreme climate scenario elicits oxidative damage in some fish species, impairing their metabolism and physiology, contributing to their susceptibility. Thus, the comprehension of physiological alterations in Arapaima gigas (pirarucu) to the climatic changes forecasted for the next 100 years is important to evaluate its capability to deal with oxidative stress. The objective of this work was to determine whether antioxidant defense system is able to prevent muscle oxidative damage of pirarucu exposed 96 h to extreme climate scenario, as well as the effects of this exposition on muscle fatty acid levels. Lipid peroxidation and reactive oxygen species significantly increase in the muscle of pirarucus exposed to an extreme climate scenario compared to control, while muscle superoxide dismutase, catalase, and glutathione peroxidase were significantly lower. Total amount of saturated fatty acids (SFAs) was significantly higher in pirarucu exposed to an extreme climate scenario compared to control, while total content of monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) was significantly lower. Exposure to an extreme climate scenario causes muscular oxidative stress and that the antioxidant systems are inefficient to avoid oxidative damage. In addition, the increase of total SFAs and the decrease of MUFAs and PUFAs probably intend to maintain membrane fluidity while facing high temperature and CO2 levels.

The Effects of Stocking Density and Food Deprivation on Mucous Cells and Lysozyme Activity in the Skin and Gills of Silver Catfish.

This study aimed to identify the regions of the body surface of silver catfish (Rhamdia quelen) with a higher population of mucous cells in the skin. Additionally, the effects of stressful conditions, such as different stocking densities and food deprivation, on the proliferative response of mucous cells in the skin and gill epithelium and their impact on cutaneous mucous lysozyme activity were investigated. Silver catfish were divided into four experimental groups: high stocking density (32 kg/m3) and fed (HSD-F), high stocking density and fasted (HSD-FS), low stocking density (2.5 kg/m3) and fed (LSD-F), and low stocking density and fasted (LSD-FS). Fish in the fed groups received commercial feed twice a day, amounting to 1% of the tank biomass. After a 14-day experimental period, the fish were anesthetized and euthanized. Samples of cutaneous mucous and skin fragments from seven different points and the second left branchial arch were collected. Histological slides of the skin and gills were stained with PAS + Alcian Blue at pH 2.5, and the epidermal mucous lysozyme activity was assessed using the turbidimetric method. The ventral point in front of the ventral fin was found to be the optimal location for collecting cutaneous epithelia due to its higher density of mucous cells. The population of mucous cells in both the skin and gills varied based on the collection point and treatment applied. The highest lysozyme activity in the epidermal mucous was observed in fish from the HSD-F group. Overall, these findings suggest that stocking density and food deprivation create stressful conditions for silver catfish, which modulate their mucosal response to each situation.

Dietary Supplementation with R-(+)-Limonene Improves Growth, Metabolism, Stress, and Antioxidant Responses of Silver Catfish Uninfected and Infected with Aeromonas hydrophila.

R-(+)-limonene is a monoterpene from plants of the genus Citrus with diverse biological properties. This research evaluated the effects of dietary supplementation with R-(+)-limonene on growth, metabolic parameters in plasma and liver, and the antioxidant and stress responses in silver catfish, Rhamdia quelen, challenged or not with Aeromonas hydrophila. Fish were fed for 67 days with different doses of R-(+)-limonene in the diet (control 0.0, L0.5, L1.0, and L2.0 mL/kg of diet). On the 60th day, a challenge with A. hydrophila was performed. R-(+)-limonene in the diet potentiated the productive performance of the fish. The metabolic and antioxidant responses indicate that R-(+)-limonene did not harm the health of the animals and made them more resistant to the bacterial challenge. Histological findings showed the hepatoprotective effect of dietary R-(+)-limonene against A. hydrophila. Igf1 mRNA levels were upregulated in the liver of fish fed with an L2.0 diet but downregulated with bacterial challenge. The expression levels of crh mRNA were higher in the brains of fish fed with the L2.0 diet. However, the L2.0 diet downregulated crh and hspa12a mRNA expression in the brains of infected fish. In conclusion, the results indicated that R-(+)-limonene can be considered a good dietary supplement for silver catfish.

Impact of dietary supplementation with Cinnamomum cassia essential oil on silver catfish (Rhamdia quelen): Toxicological effects and muscle antioxidant and fatty acid profiles.

The aim of this study was to determine the biological effects of dietary supplementation with 0.05% and 0.1% cinnamon essential oil extracted from Cinnamomum cassia on silver catfish (Rhamdia quelen). The final body weight, weight gain, and specific growth rate were significantly higher in fish supplemented with 0.05% cinnamon essential oil than in the control(untreated) group. Muscle reactive oxygen species and lipid peroxidation levels were significantly lower in fish supplemented with 0.05% cinnamon essential oil but higher at the 0.1% concentration. Muscle antioxidant capacity against peroxyl radicals (ACAP) and superoxide dismutase activity were significantly higher in fish supplemented with 0.05% cinnamon essential oil, while ACAP levels were lower in fish supplemented with 0.1%. The total saturated fatty acid content was significantly higher in the muscle of supplemented fish than in controls, while the total monounsaturated fatty acid content was significantly higher only in fish fed 0.1% cinnamon essential oil. Finally, the total content of polyunsaturated fatty acids was significantly lower in fish fed 0.1% essential oil. Thus, data demonstrated that 0.05% C. cassia essential oil improves fish health by improving performance and muscle oxidant/antioxidant status. Higher doses of cinnamon essential oil produced oxidative stress in muscle, suggesting toxicity at the 0.1% level. Although this cinnamon essential oil diet exerted positive health effects, this diet impaired the muscle fatty acid profile, suggesting adverse impacts on human health.

CRYOPRESERVED SEMEN OF Piaractus orinoquensis (Serrasalmidae): POST-THAW STORAGE TIMES AND ACTIVATING SOLUTIONS / Semen congelado de Piaractus orinoquensis (Serrasalmidae): Almacenamiento posdescongelación y soluciones activadoras

ABSTRACT Piaractus orinoquensis is a native species from the Colombian Orinoquia and several studies have contributed to the standardization of protocols for seminal cryopreservation of this species. The main goal of this study was to evaluate the sperm motility, duration of sperm motility (DM), pH, sperm membrane integrity (SMI) and fertility of semen cryopreserved for seven years and subjected to different post-thaw storage times (PST). Semen from five males (3.04 ± 0.3 kg) was diluted 1:4 (semen:diluent) with 10 % dimethylsulfoxide, 5.5 % glucose and 12 % egg yolk in 4 mL macrotubes and frozen in liquid nitrogen. Four PST were evaluated: 0, 15, 45 and 60 min. The sperm cells were activated with 1 % NaHCO3 (SB) and 0.9 % NaCl (SC) to determine sperm motility, DM, fertility rate, SMI and pH through PST. Significative motility reduction (p < .05) was observed through the PST and between the PST of 0 and 60 min for DM, both for treatments activated with SB and with SC. The SMI had a significant reduction (p < .05) after 60 min of post-thaw storage and the pH did not vary during PST. The fertility rate decreased significantly (p < .05) between time 0 and 60 min of PST. PST affects the seminal quality and fertility of P. orinoquensis, the best fertilization results were obtained by activating post-thawing sperm motility with 1 % SB. The long-term cryopreserved semen (seven years) of the species maintains its fertilization capacity with values like those obtained with fresh sperm.

RESUMEN Piaractus orinoquensis es una especie de la Orinoquía Colombiana en la cual se han realizado numerosos estudios para estandarizar protocolos de crioconservación seminal. El objeto de este estudio fue evaluar la motilidad espermática, duración de la motilidad espermática (DM), pH, integridad de membrana espermática (SMI) y fertilidad de semen crioconservado por siete años, sometido a diferentes tiempos de almacenamiento posdescongelación (PST). Semen de 5 machos (3,4 ± 0,3 kg) fue diluido 1:4 (semen: diluyente) con dimetilsulfóxido 10 %, glucosa 5,5 %, yema de huevo 12 %, en macrotubos de 4 mL y congelado en nitrógeno líquido. Cuatro PST fueron evaluados: 0, 15, 45 y 60 min. Las células espermáticas fueron activadas con NaHCO3 1% (SB) y NaCl 0,9 % (SC) para determinar motilidad espermática, DM, tasa de fertilización, SMI y pH a través de PST. Se observó reducción significativa de motilidad (p < ,05) a través del PST, también en DM entre tiempo 0 y tiempo 60 min. de PST en semen activado con SB y SC. SMI tuvo una reducción significativa (p < ,05) luego de 60 min. de almacenamiento posdescongelación y el pH no varió durante el PST. La tasa de fertilización decayó significativamente (p < ,05) entre 0 y 60 minutos de PST. La calidad seminal y fertilidad en P. orinoquensis fue afectada por PST. Los mejores resultados de fertilización se obtuvieron activando la motilidad con SB. El semen crioconservado a largo plazo (siete años), conservó su capacidad fertilizante con valores similares a los obtenidos con semen fresco.

Stress response of Rhamdia quelen to the interaction stocking density - Feeding regimen.

This study aimed to verify the effect of different feeding and stocking conditions during 14 days on the gene expression of several hormones and enzymes related to the stress cascade and metabolic parameters in silver catfish Rhamdia quelen under the following experimental conditions: 1) fed at low stocking density (2.5 kg m-3, LSD-F); 2) fed at high stocking density (32 kg m-3, HSD-F); 3) food-deprived at LSD (LSD-FD); and 4) food-deprived at HSD (HSD-FD). Fish from LSD-F and HSD-F groups were fed daily (1 % of their body mass), while fish from food-deprived groups (LSD-FD and HSD-FD) were not fed during the experimental time. Plasma metabolic parameters (glucose, lactate, triglycerides, and proteins) and hepatosomatic index (HSI) were evaluated. In addition, mRNA expression of genes related to the stress axis (crh, pomca, pomcb, nr3c2, star, hsd11b2 and hsd20b), heat shock protein family (hsp90 and hspa12a), sodium-dependent noradrenaline transporter (slc6a2), and growth axis (gh and igf1) were also assessed. Specific growth rate and HSI decreased in food-deprived fish regardless of stocking density. The HSD-FD group showed weight loss compared to the HSD-F, LSD-F, and LSD-FD groups. Plasma glucose and triglycerides were reduced in food-deprived groups, while lactate and protein levels did not change. The expression of key players of the stress response (crh, pomca, pomcb, hsd11b2, nr3c2, and hsp90b) and growth (gh and igf1) pathways were differently regulated depending on the experimental condition, whereas no statistical difference between treatments was found for hsd20b, scl6a2, hspa12a, and star mRNAs expression. This study suggests that LSD acts as a stressor affecting negatively the physiological status of fed fish, as demonstrated by the reduction in growth rates, altered metabolic orchestration, and a higher crh mRNA expression. In addition, food deprivation also increased mRNA expression of other assessed genes (nr3c2, hsp90b, pomca, and pomcb) in fish from the HSD group, indicating higher responsiveness to stress in this stocking density when combined with food deprivation.

Hesperozygis ringens essential oil as an anesthetic for Colossoma macropomum during biometric handling / Óleo essencial de Hesperozygis ringens como anestésico para Colossoma macropomum durante manipulação biométrica

This study evaluated the effectiveness of the essential oil of Hesperozygisringens (EOHR) for anesthesia of Colossomamacropomum by documenting hematological and blood biochemical responses after biometric handling. In Experiment 1, juveniles (14.12 ± 3.53 g) were exposed to different concentrations of EOHR: 0 (control), 75, 150, 300 and 450 µL L-1 (n=10 fish for each concentration), to determine times for induction and recovery from anesthesia, as well as its effects on ventilatory frequency (VF). Based on these results, Experiment 2 evaluated the effects of 0 (control), 75 (with induction and recovery times outside that recommended for fish anesthesia) and 150 µL L-1 EOHR (within recommended times) on hematological and biochemical variables of juveniles (20.52 ± 3.47 g) after anesthesia and after 24 h of recovery (n = 6 fish for each concentration and collection time). Survival was 100%. Induction time showed a quadratic effect of EOHR concentration. Recovery time did not differ among EOHR concentrations. Concentrations between 150 and 450 µL L-1 EOHR caused rapid induction (< 3 min) and recovery (< 5 min). EOHR concentration affected VF. The concentration of 150 µL L-1 EOHR had little influence on hematological and biochemical parameters of C. macropomum of 20 g.

Este estudo avaliou a eficiência do óleo essencial de Hesperozygis ringens (EOHR) para anestesia de Colossoma macropomum, documentando as respostas hematológicas e bioquímicas do sangue após o manuseio biométrico. No experimento 1, juvenis (14,12 ± 3,53 g) foram expostos a diferentes concentrações de EOHR: 0 (controle), 75, 150, 300 e 450 µL L-1 (n = 10 peixes para cada concentração), para determinar os tempos de indução e recuperação da anestesia, bem como seus efeitos na frequência ventilatória (VF). Com base nesses resultados, o experimento 2 avaliou os efeitos de 0 (controle), 75 (com tempos de indução e recuperação fora do recomendado para anestesia de peixes) e 150 µL L-1 EOHR (dentro dos tempos recomendados) sobre variáveis hematológicas e bioquímicas de juvenis (20,52 ± 3,47 g) após a anestesia e após 24h de recuperação (n = 6 peixes para cada concentração e tempo de coleta). A sobrevivência foi de 100%. O tempo de indução mostrou efeito quadrático da concentração de EOHR. O tempo de recuperação não diferiu entre as concentrações de EOHR. Concentrações entre 150 e 450 µL L-1 EOHR causaram rápida indução (< 3 min) e recuperação (< 5 min). As concentrações de EOHR afetaram a VF. A concentração de 150 µL L-1 de EOHR teve pouca influência nos parâmetros hematológicos e bioquímicos de C. macropomum de 20 g.

Anesthetic and sedative efficacy of essential oil of Hesperozygis ringens and the physiological responses of Oreochromis niloticus after biometric handling and simulated transport.

This study aimed to evaluate different concentrations of the essential oil of Hesperozygis ringens (EOHR) and its effects on anesthesia and transport of Oreochromis niloticus. Experiment I evaluated the concentrations of 0, 150, 300, 450, and 600 µL L-1 EOHR for times of induction and recovery from anesthesia and ventilatory frequency (VF) of O. niloticus (26 g), with 10 repetitions each in a completely randomized design. Based on the results of Experiment I, Experiment II submitted fish (25 g) to three treatments-control (clean water), ethanol (5 mL ethyl alcohol), and 600 µL L-1 EOHR-and then handling for biometry. Blood was collected 1 and 24 h after exposure and handling to analyze hematological and biochemical parameters in a completely randomized design in a factorial arrangement (3 × 2). Experiment III submitted fish (35 g) to simulated transport (4.5 h) with 0, 10, or 20 µL L-1 EOHR and determined the effects on blood variables. Concentrations of 450 and 600 µL L-1 EOHR provoked deep anesthesia in juvenile O. niloticus and provided induction and recovery times within the limits considered ideal for fish. However, this essential oil was not able to attenuate the effects of stress caused by biometric handling. EOHR was able to attenuate the effects of stress from simulated transport, with 10 µL L-1 EOHR being responsible for causing a decrease in protein, triglycerides, and cholesterol values immediately after transport of O. niloticus.

Influence of pH on physiological and behavioral responses of Pomacea canaliculata.

The physiological and behavioral responses of Pomacea canaliculata exposed to different pH values (4, 5, 6, 7, 8, 9, and 10) were evaluated. Survival, behavior (avoidance), metabolites (mantle), net ion fluxes (Na+ and K+), and ATPase activity (gills) were the parameters analyzed. The final survival rates were 100% (pH 4-9) and 90% (pH 10), and the groups did not differ significantly. Avoidance behavior was not identified in animals exposed to an extreme pH compared to pH 7. The main changes observed in the metabolites were in those exposed to an alkaline pH. Glucose (pH 9) and total protein (pH 9 and 10) levels increased, and lactate decreased (pH 9 and 10) compared to a neutral pH. There was an increase in Na+ efflux at pH 4, 5, and 8 and an influx at pH 9 and 10. Extreme pH values (4 and 10) also caused an increase in K+ efflux. At pH values outside the neutrality range (pH 7), there was a significant decrease in the activities of Na+/K+-ATPase (4, 5, 6, 9, and 10) and H+-ATPase (pH 4, 5, 9, and 10). Variations in environmental pH did not cause statistically significant mortality or avoidance behavior in P. canaliculata at the analyzed times. However, due to changes in energy metabolism (glucose and lactate, mainly) and ionoregulation, these can be considered sensitive biomarkers of stress in this species.

Essential oil of Aloysia citriodora Paláu and citral: sedative and anesthetic efficacy and safety in Rhamdia quelen and Ctenopharyngodon idella.

OBJECTIVE: To verify the efficacy of citral in inducing sedation and anesthesia in silver catfish (Rhamdia quelen) and grass carp (Ctenopharyngodon idella) and to assess the safety of essential oil (EO) of Aloysia citriodora and citral in inducing and maintaining anesthesia in silver catfish. STUDY DESIGN: Clinical study, randomized, parallel, multi-arm with control group in target species. ANIMALS: A total of 96 juvenile and 72 adult silver catfish and 80 juvenile grass carp were used. METHODS: Silver catfish and grass carp were exposed to different concentrations of citral, 15-675 and 15-600 µL L-1, respectively, during the maximum period of 30 minutes to verify sedation and anesthesia induction and recovery times. In addition, for anesthetic induction, silver catfish were exposed to the EO of A. citriodora and citral at 225 µL L-1 for 3.5 minutes. Then, fish were transferred to an anesthesia maintenance solution at 50 µL L-1 for 10 minutes to assess hematologic and biochemical variables at 60 minutes, 2 and 6 days after treatment. RESULTS: Citral only induced sedation from 15, 25 and 40 µLL-1 in both species. Anesthesia without mortality was induced in silver catfish at 50-600 µL L-1 and grass carp at 75-450 µL L-1. At 675 and 600 µL L-1, mortality was recorded in silver catfish and grass carp, respectively. The EO of A. citriodora and citral were safe in inducing and maintaining anesthesia in silver catfish, with mean corpuscular hemoglobin concentration being the only variable that varied in relation to time and treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Citral was effective in inducing sedation and anesthesia in both species. In addition, A. citriodora EO and citral were safe in inducing and maintaining anesthesia in silver catfish. Both agents are promising substances for the development of new drugs for fish.

Evaluation of the in vivo safety of tucumã oil nanocapsules in an experimental model of silver catfish Rhamdia quelen.

The aim of this study was to evaluate the toxicity of tucumã oil nanocapsules from the Amazon region in silver catfish, Rhamdia quelen. Fish were exposed to water treated with different concentrations of tucumã nanocapsules, white, solubilized oil and surfactant vehicles. After three days of exposure, fish were euthanized and liver, gills and brain removed for analysis of the dichlorofluorescein, nitric oxide and PicoGreen® assays. Plasma was collected for assay of hepatic transaminases. The nanocapsules had a diameter of 221 ± 1.27 nm, confirmed by atomic force microscopy. The oil nanocapsules were not toxic to this species of fish, but white nanocapsules and surfactant increased the levels of reactive oxygen species. Thus, nanocapsules are promising for the transport of tucumã oil. In view of the anti-inflammatory properties of this oil, it is possible to envisage its application in skin diseases for example, since they present essentially inflammatory conditions.HighlightsThe most abundant carotenoid in tucumã oil was all-trans-beta-carotene.Nanocapsules are good carriers for tucumã oil.Tucumã oil nanocapsules does nothas toxicity effect in catfish.

Effect of Lippia grata essential oil as a feed additive on the performance of tambatinga juveniles / Efeito do óleo essencial de Lippia grata como aditivo alimentar sobre o desempenho de juvenis de tambatinga

Lippia grata (formerly known as Lippia gracillis) is an aromatic plant native to Brazil, with leaves rich in essential oils that possess significant biological activities. We evaluated the effect of essential oil of L. grata (EOLG) as a dietary additive on the growth, somatic indices, and biochemical parameters of juveniles (5.25 ± 0.26 g) of tambatinga, a hybrid fish obtained by crossing tambaqui (Colossoma macropomum) with pirapitinga (Piaractus brachypomum) of great economic importance in north and northeastern Brazil. We evaluated four dietary treatments, consisting of EOLG supplemented at 0.0, 0.5, 1.0, and 2.0 mL kg-1, over 60 days. Carcass yield was significantly higher in fish fed all EOLG diets compared to those fed the control diet (0.0 mL kg-1). Animals that received the 0.5 mL kg-1 treatment gained significantly more weight and showed a higher specific growth rate than those treated with 1.0 and 2.0 ml kg-1 EOLG, although none differed significantly from the control. The feed conversion rate was significantly lower in the 0.5 than in the 1.0 mL kg-1 treatment. Compared with higher concentrations, the diet containing 0.5 mL kg-1 EOLG increased the use of muscle glycogen, glucose, and lactate to meet energy demands, avoiding the use of muscle protein. Our results suggest that dietary supplementation with EOLG significantly improves carcass yield in tambatinga juveniles but that concentrations above 0.5 mL kg-1 may compromise growth rates and carbohydrate metabolism in this fish.(AU)

Lippia grata (previamente conhecida como Lippia gracillis) é uma planta aromática nativa do Brasil, com folhas ricas em óleos essenciais que possuem atividades biológicas significativas. Avaliamos o efeito do óleo essencial de L. grata (OELG) como aditivo alimentar sobre o crescimento, índices somáticos e parâmetros bioquímicos de juvenis (5,25 ± 0,26 g) de tambatinga, um hibrido obtido do cruzamento de tambaqui (Colossoma macropomum) com pirapitinga (Piaractus brachypomum) com grande importância econômica no norte e nordeste do Brazil. Foram avaliados quatro tratamentos dietéticos consistindo na suplementação com OELG em 0,0; 0,5; 1,0 e 2,0 mL kg-1 durante 60 dias. O rendimento de carcaça foi significativamente maior nos peixes alimentados com todas as dietas contendo OELG em comparação à dieta controle. Os animais do tratamento 0,5 mL kg-1 ganharam significativamente mais peso e apresentaram maior taxa de crescimento específico do que aqueles tratados com 1,0 e 2,0 mL kg-1 OELG, embora nenhum tenha diferido significativamente do controle. A taxa de conversão alimentar foi significativamente menor no tratamento 0,5 mL kg-1 do que no tratamento 1,0 mL kg-1. Comparada com as concentrações mais altas, a dieta contendo 0,5 mL kg-1 OELG aumentou o uso de glicogênio muscular, glicose e lactato para suprir as demandas energéticas, evitando o uso de proteína muscular. Nossos resultados sugerem que a suplementação dietética com OELG melhora significativamente o rendimento de carcaça de juvenis de tambatinga, mas concentrações acima de 0,5 mL kg-1 podem comprometer as taxas de crescimento e metabolismo de carboidratos desses peixes.(AU)

Antinutritional effect of lectin from faveira (Parkia platycephala) seeds in tambatinga (Colossoma macropomum x Piaractus brachypomus) / Efeito antinutricional da lectina de sementes de faveira (Parkia platycephala) em tambatinga (Colossoma macropomum x Piaractus brachypomus)

This study investigated the possible antinutritional effects of Parkia platycephala lectin (0, 20, 40, or 60 mg kg-1 of diet) on tambatinga feeding for 60 days as well as methods of inactivating this protein. Weight gain, specific growth rate, and relative weight gain decreased, and the feed conversion rate increased with the increase in dietary lectin. The hepatic glycogen levels of fish fed 60 mg kg-1 were higher than those of fish fed 20 and 40 mg kg-1. Diets containing 40 and 60 mg kg-1 increased muscle glucose levels compared to the control group. Fish-fed diets containing lectin showed reduced muscle glycogen compared to those receiving the control diet. Fish fed 60 mg kg-1 presented lower muscle protein levels than those fed 20 mg kg-1. In vitro tests showed that the hemagglutination activity of lectin was inhibited by d-mannose, d-glucose, and α-methyl-d-mannopyranoside. Thermal treatment at 50­60°C was sufficient to reduce the action of lectin, as well as a pH below and above the 6­7 range. Therefore, the use of P. platycephala meals as a dietary ingredient for tambatinga with no lectin inac-tivation is not recommended as it can negatively affect the fish's biochemical parameters and growth. Acid or alkaline solutions can be an alternative for inactivating the protein and improving its use by fish and other animals.(AU)

Este estudo investigou possíveis efeitos antinutricionais da lectina de Parkia platycephala (0, 20, 40 ou 60 mg kg-1 de dieta) na alimentação de tambatinga por 60 dias, bem como métodos de inativação dessa proteína. O ganho de peso, a taxa de crescimento específico e o ganho de peso relativo diminu-íram, enquanto o índice de conversão alimentar aumentou com o incremento de lectina na dieta. Os níveis de glicogênio hepático dos peixes alimentados com 60 mg kg-1 foram superiores aos dos que ingeriram 20 e 40 mg kg-1. Dietas contendo 40 e 60 mg kg-1 aumentaram os níveis de glicose muscular em comparação com os que receberam a dieta controle. Nos animais cuja dieta continha lectina, redu-ziu-se o glicogênio muscular em comparação com os da dieta controle. Os espécimes alimentados com 60 mg kg-1 apresentaram menor nível de proteína muscular do que aqueles que consumiram 20 mg kg-1. Testes in vitro mostraram que a atividade de hemaglutinação da lectina foi inibida por D-mano-se, D-glicose e α-metil-D-manopiranosídeo. O tratamento térmico entre 50 e 60°C foi suficiente para reduzir a ação da lectina, assim como o pH abaixo de 6 e acima de 7. Portanto, usar farelo de P. pla-tycephala como ingrediente em dieta para tambatinga sem inativação da lectina não é recomendado, pois pode afetar negativamente os parâmetros bioquímicos e o crescimento dos exemplares. Soluções ácidas ou alcalinas podem ser uma alternativa para inativar a proteína e melhorar sua utilização em peixes e outros animais.(AU)

Eugenol and Lippia alba essential oils as effective anesthetics for the Amazonian freshwater stingray Potamotrygon wallacei (Chondrichthyes, Potamotrygonidae).

This study assessed the potential of eugenol and the essential oil of Lippia alba (EOLA) in providing suitable anesthetic induction and recovery times, and their consequent effects on the blood and respiratory physiology, as well as the gill architecture of an Amazonian freshwater stingray, Potamotrygon wallacei, shortly after reaching the recovery and 48 h later. Juveniles of P. wallacei were exposed to increasing concentrations of eugenol (75, 100, 125, and 150 µL L-1) and EOLA (150, 175, 200, and 225 µL L-1) in an immersion bath. Anesthetic induction was found to be faster with the use of eugenol compared to EOLA. On the other hand, the stingrays anesthetized with eugenol displayed a longer recovery time than those exposed to EOLA. The highest concentrations of eugenol caused moderate to severe histological changes in the gills. No significant changes were found for hematocrit and plasma energy metabolites in the stingrays anesthetized with all concentrations of both eugenol and EOLA shortly after reaching the recovery from the ansthesia, when compared to those recovered after 48 h. Investigations regarding the potential use of these natural anesthetics are unprecedented for freshwater stingray species, and 200 µL L-1 EOLA is recommended as the most suitable anesthetic for use in juveniles of P. wallacei.

Linalool induces relaxation of the mantle of golden apple snail (Pomacea canaliculata).

The objective of this study was to evaluate the possible relaxing effect of essential oils (EOs) (Aloysia triphylla and Lippia alba) and phytochemicals (citral and linalool) in the gastropod Pomacea canaliculata. Animals were exposed to compounds at the concentrations range of 25-750 µL L-1. Magnesium chloride (MgCl2, 10-50 g L-1) and control group (ethanol 6.75 mL L-1, highest concentration used for treatment dilution) were also tested. The EOs, citral and MgCl2 had no relaxing effect at the concentrations range tested, and citral caused aversive behavior (closure of the operculum) from 90 µL L-1. Exposure to linalool at 25, 50, 100, 200 and 400 µL L-1 relaxed 28, 76, 88, 96 and 100% of the animals, respectively. The concentrations of 25, 50 and 400 µL L-1 differed statistically from each other, while 100 and 200 µL L-1 were equal to 50 and 400 µL L-1. All animals recovered up to 40 min, except at of 400 µL L-1. Linalool is effective for relaxing P. canaliculata and can be useful in management techniques that require relaxation. However, further studies are needed to certify whether linalool is appropriate for maintaining animal welfare in invasive procedures that require total insensitivity.

Dietary supplementation with nerolidol improves the antioxidant capacity and muscle fatty acid profile of Brycon amazonicus exposed to acute heat stress.

An increase in water temperature in the Amazon River has elicited concerns about commercially important fish species associated with food security, such as matrinxã (Brycon amazonicus). Studies have demonstrated the positive effects of diets supplemented with plant-based products that combat heat stress-induced oxidative damage. The aim of this study was to determine whether dietary supplementation with nerolidol prevents or reduces muscle oxidative damage and impairment of the fillet fatty acid profile of matrinxã exposed to heat stress. Plasma and muscle reactive oxygen species (ROS) and lipid peroxidation (LPO) levels were significantly higher in fish exposed to heat stress compared to fish not exposed to heat stress, while plasma superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity was significantly lower. The total content of saturated fatty acids (SFA) in fillets was significantly higher in fish exposed to heat stress compared to fish not exposed to heat stress, while he total content of polyunsaturated fatty acids (PUFA) was significantly lower. Nerolidol prevented the increase of muscle LPO and plasma ROS and LPO levels in fish exposed to heat stress, and partially prevented the increase in muscle ROS levels. Diets containing nerolidol prevented the inhibition of muscle GPx activity in fish exposed to heat stress, and partially prevented the decrease of plasma GPx activity. The nerolidol-supplemented diet prevented the increase of fillet SFA in fish exposed to heat stress, while partially preventing the decrease of PUFA. We conclude that acute heat stress at 34 °C for 72 h causes plasma and muscular oxidative damage, and that homeoviscous adaptation to maintain membrane fluidity can represent a negative impact for fish consumers. A nerolidol diet can be considered a strategy to prevent heat stress-induced oxidative damage and impairment of muscle fatty acid profiles.