RESUMEN
The present study was conducted to evaluate the effects of fasting on responses of oxidative biomarkers and antioxidant defenses using different organs and tissues of Colossoma macropomum. The fish were divided into two groups: fed (control) and fasting (7 days). After 7 days, the fish were sampled for assessment of oxidative stress biomarkers (MDA-lipid peroxidation and PCO-protein carbonyl) and antioxidant defenses (SOD-superoxide dismutase; CAT-catalase; GPX-glutathione peroxidase; and GST-glutathione-S -transferase) in the liver, intestine, gills, muscle, brain, and plasma. The results showed an increase in MDA, PCO, SOD, and GPX concentrations in the liver and intestine of fasting fish. In contrast, in the branchial tissue, there was a reduction in the activity of SOD and CAT enzymes in fasting fish. There was also a reduction in CAT activity in the muscle of fasting fish, while in the brain, there were no changes in oxidative stress biomarkers. Plasma showed a relatively low antioxidant response. In conclusion, our results confirm that a 7-day fasting period induced tissue-specific antioxidant responses, but the increase in antioxidant responses was only for the SOD and GPX enzymes of the liver and intestine. Additionally, the liver and intestine were the most responsive tissues, whereas the plasma was the least sensitive to oxidative stress.
Asunto(s)
Antioxidantes , Characiformes , Animales , Antioxidantes/metabolismo , Estrés Oxidativo/fisiología , Catalasa/metabolismo , Superóxido Dismutasa/metabolismo , Glutatión Peroxidasa/metabolismo , Peroxidación de Lípido , Hígado/metabolismo , Ayuno , Biomarcadores/metabolismo , Glutatión Transferasa/metabolismoRESUMEN
The daily variations of temperature are one of the main synchronizers of the circadian rhythms. In addition, water temperature influences the embryonic and larval development of fish and directly affects their metabolic processes. The application of thermocycles to fish larvae has been reported to improve growth and the maturation of the digestive system, but their effects on metabolism are poorly understood. The aim of the present study was to evaluate the effect of two different temperature regimes, cycling versus constant, on the daily rhythms of metabolic factors of Nile tilapia (Oreochromis niloticus) larvae. For this purpose, fertilized eggs were divided into two groups: one reared in a 31 °C:25 °C day:night thermocycle (TCY) and another group maintained in a constant 28 °C temperature (CTE). The photoperiod was set to a 12:12 h light/dark cycle. Samples were collected every 4 h during a 24-h cycle on days 4, 8 and 13 post fertilization (dpf). The expression levels of alanine aminotransferase (alt), aspartate aminotransferase (ast), malic enzyme, glucose-6-phosphate dehydrogenase (g6pd), phosphofructokinase (pfk) and pyruvate kinase (pk) were analyzed by qPCR. Results showed that, in 13 dpf animals, most of the genes analyzed (alt, ast, malic, g6pd and pfk) showed daily rhythms in TCY, but not in the group kept at constant temperature, with most acrophases detected during the feeding period. An increase in nutrient metabolism around feeding time can improve food utilization and thus increase larval performance. Therefore, the use of thermocycles is recommended for tilapia larviculture.
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Cíclidos , Ritmo Circadiano , Temperatura , Animales , Cíclidos/crecimiento & desarrollo , Cíclidos/metabolismo , Cíclidos/fisiología , Cíclidos/genética , Ritmo Circadiano/fisiología , Larva/crecimiento & desarrollo , Larva/metabolismo , Fotoperiodo , Glucosafosfato Deshidrogenasa/metabolismo , Glucosafosfato Deshidrogenasa/genética , Aspartato Aminotransferasas/metabolismo , Alanina Transaminasa/metabolismoRESUMEN
The effects of thermal shock on hematological, biochemical and antioxidant responses were evaluated in liver tissue of juvenile tambaqui (Colossoma macropomum) and tambatinga (â C. macropomum × â Piaractus brachypomus). Forty juveniles of tambaqui and 40 juveniles of tambatinga, of the same age and with an initial weight of 23.3 ± 6.7 g, were randomly distributed in eight 28L circular tanks. A tank (n = 10 fish) of tambaqui and a tank (n = 10 fish) of tambatinga were then used to obtain basal data. The other animals were subjected to thermal shock with sudden temperature reduction from 28 to 18 ºC. Blood and tissue were then collected after 1, 6 and 24 h from the onset of thermal shock. No mortality was observed during the experimental period. Thermal shock increased triglyceride levels after 24 h of stress for tambaqui and reduced values for tambatinga. There was an effect on plasma glucose only for fish group (P < 0.0001) and collection time (P < 0.0001) with a peak observed for the hybrid after 6 h. The interaction of factors for SOD indicated greater activity for tambatinga at the 6 h collection and lower at basal and 1 h collections. There was an interaction for CAT (P = 0.0020) with less activity for tambatinga at 1 h. However, thermal shock and hybridization did not influence GST and TBARS levels in liver tissue. Therefore, the results suggest that the hybrid, tambatinga, is more efficient at promoting adjustments of biochemical responses and antioxidant enzymes during thermal shock.
Asunto(s)
Hígado , Estrés Oxidativo , Animales , Hígado/metabolismo , Characiformes/sangre , Respuesta al Choque Térmico , Glucemia , Triglicéridos/sangre , Triglicéridos/metabolismo , Hibridación Genética , Antioxidantes/metabolismo , Superóxido Dismutasa/metabolismoRESUMEN
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.
Asunto(s)
Ocimum , Aceites Volátiles , Animales , Aceites Volátiles/farmacología , Ocimum/química , Estrés Oxidativo/efectos de los fármacos , Characiformes , Anestesia/veterinaria , Hígado/metabolismo , Hígado/efectos de los fármacosRESUMEN
This study evaluated the growth and physiological response of proactive and reactive Colossoma macropomum juveniles in a recirculating aquaculture system (RAS). In Phase 1 of the experiment (50 days of cultivation), juveniles, weighing 2.16 ± 0.52 g, were stocked in 12 28-L tanks to test the following treatments: proactive (PT), reactive (RT) and mixed (MT) composed of reactive (MRT) and proactive (MPT) animals. In Phase 2 of the experiment (40 days of cultivation), the animals were transferred to 175-L tanks with the same treatments as Phase 1. The animals were fed twice a day with commercial diet during both phases. After Phase 1, MPT animals showed higher growth than MRT animals (P < 0.05), and higher weight gain and daily weight than PT animals (P < 0.05). After Phase 2, PT animals showed higher weight gain and daily weight gain than RT and MT animals (P < 0.05), as did MPT animals compared to PT animals. Performance for RT animals was superior (P < 0.05) to that of MRT animals. Glucose (P < 0.04) and cholesterol (P < 0.01) were higher for RT animals compared to PT animals. Cholesterol was higher for MPT animals compared to MRT animals (P < 0.01), while plasma protein was lower (P < 0.001). Glucose (P < 0.001) and cholesterol (P < 0.01) were higher for MPT animals compared to PT animals and for MRT animals compared to RT animals (glucose P < 0.02, cholesterol P < 0.01). After 90 days of cultivation, proactive animals cultivated separately presented better performance. When cultivated together, reactive animals experienced a decrease in performance and both stress coping styles showed more signs of stress.
Asunto(s)
Acuicultura , Animales , Acuicultura/métodos , Characiformes/fisiología , Characiformes/crecimiento & desarrollo , Aumento de Peso , Colesterol/sangre , Colesterol/análisis , Alimentación Animal/análisis , Dieta/veterinariaRESUMEN
This study evaluated the effects of live prey concentration (nauplii of Artemia sp.), water salinity, and weaning age on survival, growth, and stress resistance rate (Rs) of Piaractus brachypomus under larviculture in a recirculating aquaculture system (RAS). Larvae aged 6 days post-hatching (1.64 ± 0.11 mg) were distributed in 28-L tanks (five larvae L-1), in two RASs. The experiment was carried in a 2 × 2 × 2 factorial arrangement, as follows: two feeding strategies (sudden transition from live food to commercial food after 10 (FT10) and 20 (FT20) days of larviculture with Artemia); two daily initial prey concentrations (P350 = 350 and P700 = 700 nauplii larva-1, these being increased every 5 days); and two water salinities (S0 = fresh water and S2 = 2 g of salt L-1). Weight (W), total length (TL), and daily specific growth rate (SGR) were evaluated after 10, 20, 30, and 40 days of larviculture. After 40 days of larviculture, survival was evaluated and a test of air exposure was performed to determine stress resistance rate (Rs). Noteworthy results during this period are the lowest specific daily growth rate (SGR) after weaning for FT10 and the best growth results for S2 and P700. After 40 days, weight (W) and total length (TL) showed effects of P, FT, and S with higher values for P700, FT20, and S2 (P < 0.05). The interaction P × FT × S also had effects on survival and Rs at the end of the experiment, with higher survival and Rs for P700FT20S2 (P < 0.05). Larviculture of P. brachypomus in RAS, in association with the three managements-live prey concentration P700, salinity S2, and age at feed transition FT20-promotes maximization of survival, growth, and stress resistance rate of the animals. The larviculture of P. brachypomus in RAS must be carried out with an initial concentration of live prey of 700 nauplii larva-1, at a salinity of 2 g of salt L-1 and with the feeding transition starting in 20 days of larviculture, for maximization intensive larviculture of this species.
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Salinidad , Agua , Animales , Destete , Larva , Acuicultura/métodosRESUMEN
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.
Asunto(s)
Anestésicos , Cíclidos , Aceites Volátiles , Animales , Aceites Volátiles/farmacología , Hipnóticos y Sedantes , Anestésicos/farmacología , Biometría , Etanol , Triglicéridos , AguaRESUMEN
We investigated blood gas, hematological and biochemical parameters, and gill morphology of Lophiosilurus alexandri juveniles submitted to hypoxia for 48 h, followed by recovery for 48 h. A total of 48 juveniles (360.0 ± 141.6 g) were distributed among eight tanks (120 L) and subjected to hypoxia condition (water with dissolved oxygen at 2.12 ± 0.90 mg L-1) or normoxia (at 5.60 ± 0.31 mg L-1). Blood gas values (pH, PvCO2, PvO2, sO2, HCO3-, stHCO3-, and base excess) in hypoxia were significantly different from normoxia, while for lactate and the electrolytes (K+, Na+, Cl-, and Ca2+) there was no significant change among treatments. The erythrocytes differed significantly between normoxia and hypoxia at 72 h (24 h of recovery), while for hemoglobin and hematocrit there were no significant differences. There was a significant difference in glucose, triglycerides, and cholesterol for both normoxia and hypoxia, while plasma protein remained unchanged. All gill components (epithelial cells, erythrocytes, pillar cells, mucous cells, ionocytes, undifferentiated cells, and blood capillary lumen) differed significantly between normoxia and hypoxia. A reduction in the length of the primary lamella was observed in the hypoxia and recovery treatments, when compared to normoxia. The secondary branchial lamella showed no significant difference for both treatments. Juveniles of Lophiosilurus alexandri adapted well to hypoxia for 48 h, as they were able to adjust most of their physiological variables to survive this stress condition. After 48 h of hypoxia recovery, fish showed parameters similar to animals in normoxia. Thus, the present study shows that the tolerance to hypoxia conditions of L. alexandri, together with other important beneficial characteristics of the species, such as the high meat quality and high commercial value, demonstrates its great potential for production among regional species.
Asunto(s)
Bagres , Hipoxia , Animales , Bagres/fisiología , Branquias , Hematócrito , OxígenoRESUMEN
This study aimed to evaluate the essential oil of Ocimum gratissimum L. (EOOG) for anesthesia and in the transport of Oreochromis niloticus. Experiment I determined the time of anesthesia induction and recovery during anesthesia of O. niloticus exposed to different concentrations of EOOG (0, 30, 90, 150, and 300 mg L-1). Based on data from Experiment I, Experiment II evaluated the effect of 0, 30, and 90 mg L-1 EOOG on blood parameters and oxidative stress immediately after anesthesia induction and 1 h after recovery. Experiment III evaluated the effect of 0, 5, and 10 mg L-1 EOOG on blood variables immediately after 4.5 h of transport of juveniles. Concentrations between 90 and 150 mg L-1 EOOG were efficient for anesthesia and recovery. The use of 90 mg L-1 of EOOG prevented an increase in plasma glucose. Other changes in blood parameters and oxidative stress are discussed. The use of 10 mg L-1 EOOG in transport increased plasma glucose and decreased hematocrit values immediately after transport. It is concluded that the use of 90 and 150 mg L-1 EOOG causes anesthesia and recovery in O. niloticus within the time intervals considered ideal. The use of 90 mg L-1 EOOG favored stable plasma glucose soon after anesthesia induction and 1 h after recovery, but caused changes in the antioxidant defense system by increasing hepatic and kidney ROS. The transport of 12 g O. niloticus for 4.5 h can be performed with concentration of 5 mg L-1 of EOOG.
Asunto(s)
Anestésicos , Cíclidos , Ocimum , Aceites Volátiles , Aceites de Plantas , Anestesia , Animales , Glucemia , Encéfalo/metabolismo , Proteínas de Peces/metabolismo , Branquias/metabolismo , Riñón/metabolismo , Hígado/metabolismo , Estrés Oxidativo , Hojas de la Planta , Especies Reactivas de Oxígeno , Superóxido Dismutasa/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismoRESUMEN
The objective of the present study was to evaluate the physiological responses of juvenile Lophiosilurus alexandri submitted to osmotic and thermic shock. Thirty juveniles were used for each test, of which 10 were not subjected to stress and remained in normal conditions (fresh water at 28.0 °C). The others were submitted to stress shock (saline water of 10.0 g of salt/L or water cooled to 18.0 °C). Blood samples were taken at 0 h (no exposure to the stress factor) and 1 h and 24 h after the tests. At 24 h, the survivorship was 100% in both tests. In both the osmotic and thermic shock tests, cortisol and glucose levels were higher at 1 h but then decreased after 24 h. Lactate dehydrogenase showed differences in the temperature test, but there was no difference between 1 and 24 h after exposure to osmotic shock (P > 0.05). The difference was recorded in blood gas variables (pH, PvCO2, PvO2, hemoglobin, sO2, BE, tCO2, HCO3-, and stHCO3-) and electrolytes (Na+, Ca++, nCa++, and K+) in both experiments. With regard to hematology and blood biochemistry, exposure to thermal shock did not affect (P > 0.05) ALP, total plasma protein, hematocrit, and ALT and AST at 1 h and 24 h. ALP and total protein in the blood of fish submitted to the osmotic shock were lowest (P < 0.05) at 24 h. Leukocyte and erythrocyte counts exhibited differences after osmotic shock, in contrast to erythrocyte counts of the temperature test, which did not change in 24 h (P > 0.05). Juveniles of L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose), while the others (hematological, biochemical, and gasometric) varied in compensation for normal physiological reestablishment.
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Bagres , Respuesta al Choque Térmico , Ósmosis/fisiología , Estrés Fisiológico , Animales , Hematócrito , Hidrocortisona/sangreRESUMEN
This study aimed to evaluate hematological, biochemical, and gasometric parameters of tambaqui juveniles (Colossoma macropomum) exposed to hypoxia and subsequent recovery. Six animals were subjected to normoxia (basal) treatment with dissolved oxygen (DO) 6.27 ± 0.42 mg L-1. Water flow and aeration were reduced for 3 days (hypoxia), during which DO was 0.92 ± 0.37 mg L-1. Water flow and aeration were then reestablished with DO remaining similar to basal. The treatments were as follows: normoxia (basal); 24 h after initiating hypoxia (24H); 72 h after initiating hypoxia (72H); 24 h after reestablishing normoxia (24R); 48 h after reestablishing normoxia (48R); and 96 after reestablishing normoxia (96R). The highest glucose level was recorded at 24H (P < 0.05); the highest lactate level was at 72R; and the highest blood pH was at 24H and 72H (P < 0.05). The highest concentration of PvCO2 was at 24H (P < 0.05), while at 96R it was equivalent to basal (P > 0.05). The variable PvO2 was only higher than basal at 24R (P < 0.05). Juvenile C. macropomum managed to reestablish the main stress indicators (glucose and lactate) at 96R, while the other indicators varied during the study, with homeostatic physiology being reestablished during the recovery period.
Asunto(s)
Characiformes , Estrés Fisiológico , Anaerobiosis , Animales , Glucemia/análisis , Characiformes/sangre , Ácido Láctico/sangre , Oxígeno/análisis , Agua/análisisRESUMEN
Follicular atresia is a hormonally controlled degenerative process involving apoptosis of the somatic and germ cells. Since different signaling pathways can induce cell death, the aim of the present study was to investigate cell death signaling and crosstalk between autophagic, apoptotic, and lysosomal proteins during follicular atresia in Nile tilapia. For this, females were kept in controlled conditions for 21 days, and ovary samples were collected weekly. The atretic follicles (AF) were analyzed in three regression phases: Early, advanced, and late. Under electron microscopy, the follicular cells exhibited numerous protein synthesis organelles in the early AF. Immunoreactivity for Bcl2, Beclin1, Lc3, and Cathepsin D increased significantly in advanced AF (p < .001), when follicular cells were in intense yolk phagocytosis. In this phase, autophagosomes and autolysosomes were frequently observed. In the late AF, follicular cells had a markedly electron-lucid cytoplasm and immunoreactivity for Bax and TUNEL assay indicated an elevated apoptosis rate. Colocalisation of Lamp1/Cathepsin D and Lc3/Caspase-3 suggests dynamic crosstalk between the autophagy, apoptosis, and lysosome pathways. Taken together, the data indicate that autophagy plays a role in the homeostasis and clearance of the follicular cells preceding Cathepsin D mediated apoptosis during follicular atresia in Nile tilapia.
Asunto(s)
Apoptosis , Catepsina D/metabolismo , Proteínas de Peces/metabolismo , Atresia Folicular/metabolismo , Folículo Ovárico/enzimología , Tilapia/metabolismo , Animales , FemeninoRESUMEN
The present study evaluated the effects of low salinity on the early larval development of Oreochromis niloticus, specifically histological damage to white muscle, morphology of the yolk-sac surface and trunk area, and molecular expression of apoptosis and cell proliferation biomarkers. Newly hatched larvae were submitted to four salinity treatments for a period of 48 or 72 h, in duplicate: (S0) freshwater, (S2) 2 g l-1, (S4) 4 g l-1, and (S6) 6 g l-1NaCl. Larval development was examined using histology, electron microscopy, enzyme-linked immunosorbent assay (ELISA), and morphometry. At the yolk-sac surface, larvae of S4 and S6 displayed alterations to the apical opening of chloride cells that may be related to osmotic expenditure caused by the increased salinity. Caspase-3 expression did not differ significantly among treatments, however significantly lower proliferating cell nuclear antigen (PCNA) expression (P < 0.05) suggested minor cell proliferation in larvae of S4 and S6 compared with S0 and S2. Furthermore, there was a significant reduction in both trunk area and percentage of normal white muscle fibres (WF) in larvae of S4 and S6. Vacuolated areas and myofibrils concentrated at the cell periphery and found in the white muscle from larvae exposed to saline environments suggested disturbance to muscle development. Oedema and mononuclear infiltrate were also observed in the white muscle of S4 and S6 larvae. Together these results indicated that treatments with 4 and 6 g l-1 NaCl may cause osmoregulation expenditure, morphological alterations to the yolk-sac surface and histological damage to skeletal muscle that negatively affected the early larval development of O. niloticus.
Asunto(s)
Cíclidos/crecimiento & desarrollo , Larva/efectos de los fármacos , Salinidad , Cloruro de Sodio/farmacología , Animales , Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Agua Dulce , Branquias/citología , Branquias/efectos de los fármacos , Branquias/crecimiento & desarrollo , Larva/crecimiento & desarrollo , Larva/ultraestructura , Microscopía Electrónica , Músculo Esquelético/citología , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/crecimiento & desarrollo , Osmorregulación/efectos de los fármacosRESUMEN
The present study evaluates whether increased water temperature induces reproduction by Lophiosilurus alexandri under controlled conditions, and investigates the effects of this procedure on sexual steroids, hematological profile and behavior. A 44-week experiment was performed with four wild males and 12 wild females that had been acclimatized to captive conditions. Water temperature was maintained at 24.4⯱â¯1.0⯰C for weeks 1-22, and then at 29.0⯱â¯1.1⯰C for weeks 22-44. Spawn weight, number of eggs/spawn and hatching rate were satisfactory and ranged 27.5-127.5â¯g, 1209-5183 and 83-89%, respectively. Hematocrit, leukocytes and glucose were not influenced by increased water temperature, while higher values for erythrocytes were observed for both sexes. The lowest value for plasma protein was for females maintained at 29.0⯰C, while the lowest value for testosterone was obtained at the end of the study period at a temperature in 29.0⯰C. Serum values of 17ß-estradiol were higher in females than in males, however, there was no evidence of variation as a function of experimental temperature or interaction with sex. The reproductive behavior of L. alexandri in captivity is described for the first time. The present study demonstrates that adult individuals are able to maintain a stable hematological profile during an increase in mean water temperature from 24.4⯰C to 29.0⯰C, even during the reproductive period, and still produce good quality larvae. Nonetheless, whether spawning was associated with increased 17ß-estradiol levels could not be determined.
Asunto(s)
Bagres/fisiología , Reproducción , Temperatura , Aclimatación , Animales , Conducta Animal , Proteínas Sanguíneas/metabolismo , Recuento de Eritrocitos , Estradiol/sangre , Femenino , Masculino , Testosterona/sangreRESUMEN
The present study aimed to evaluate the physiological and metabolic stress responses of juvenile Lophiosilurus alexandri submitted to an air exposure test. The subjects consisted of 72 juveniles. Blood samples were taken at: 0 h-fish not exposed to air; 0.5 h-fish shortly after exposure to air for 30 min (prior to returning to the tank); 1.5 h (90 min), 24, 48, and 96 h after the initiation of exposure to air for 30 min. After 96 h, survivorship was 100%. Cortisol and glucose levels were higher at 0.5 h, returning to baseline at 48 and 24 h, respectively. Lactate dehydrogenase levels were highest at 1.5 h after exposure to air, returning to normal values in 24 h. Several changes were recorded in gasometric blood values and electrolytes. With regard to hematology and blood chemistry, exposure to air did not affect globular volume and AST throughout the 96 h of the experiment. The values for alkaline phosphatase were highest at 0, 1.5, and 24 h. Total protein was similar between 0 and 1.5 h and lowest at 96 h, while ALT was highest at 0.5 h. Leukocytes were highest at 0.5, 1.5, 48, and 96 h, while erythrocytes were highest at 96 h. After 96 h, juvenile L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose and lactate dehydrogenase), while other indicators (hematological, biochemical, and gasometric) exhibited compensatory variation for normal physiological re-establishment.
Asunto(s)
Aire , Bagres/fisiología , Animales , Bagres/sangre , Recuento de Eritrocitos/veterinaria , Glucosa/metabolismo , Hidrocortisona/metabolismo , L-Lactato Deshidrogenasa/metabolismo , Recuento de Leucocitos/veterinaria , Sobrevida , Factores de TiempoRESUMEN
The effect of temperature on muscle development and gill tissue were investigated in larval and juvenile of Lophiosilurus alexandri, a carnivorous Neotropical fish species. Larvae and juveniles were reared at temperatures of 23, 26, 29 and 32⯰C for 15 and 35 days, respectively. The larvae were fed Artemia nauplii, while the juveniles received a formulated diet. In both stages, high temperatures resulted in increased fiber diameter of white muscle. Moreover, a pronounced effect of hypertrophy was observed in later stages of development. No alterations to minimum fiber diameter, and similar mosaic standards of muscle growth dynamics, were observed in larvae kept at 23-32⯰C, suggesting that hyperplasia was not effected during early stages of development. Gills were analyzed by Degree of Tissue Change (DTC), which is based on the severity of lesions. Significant morphological changes were observed in gills when juveniles were kept at 32⯰C, which was considered moderate tissue damage. Temperature modulates cellularity in L. alexandri larvae and juveniles, with pronounced alterations of hypertrophy of white muscle fibers in later stages of development when exposed to elevated temperatures. Higher temperatures may also induce muscle growth dynamics with increased recruitment of new white fiber, increased fiber diameter in the early stages and induced gill lesions.
Asunto(s)
Bagres/crecimiento & desarrollo , Branquias/crecimiento & desarrollo , Desarrollo de Músculos , Temperatura , Agua , Animales , Fibras Musculares Esqueléticas/citología , Fibras Musculares Esqueléticas/fisiologíaRESUMEN
Lophiosilurus alexandri is an endemic catfish from the São Francisco River Basin (Brazil) popularly known as pacamã, which has economic potential for aquaculture farming. The mitochondrial genome was sequenced for the threatened Neotropical catfish L. alexandri. Assembly into scaffolds using MIRA and MITObim software produced the whole, circularized mitochondrial genome, which comprises 16,445 bp and presents the typical gene arrangement of Teleostei mitochondria. A phylogenomic analysis was performed after the concatenation of all proteins obtained from whole mitogenomes of 20 Siluriformes and two outgroups. The results confirmed the monophyly of nine families of catfishes and also clustered L. alexandri as a sister group to the family Pimelodidae, thus confirming the monophyly of the superfamily Pimelodoidea. This is the first mitochondrial phylogenomics study for Pimelodoidea and the first mitogenome described for the Pseudopimelodidae family, representing an important resource for phylogeography, evolutionary biology, and conservation genetics studies in Neotropical fishes.
RESUMEN
Spermatogenesis is a finely regulated process that involves the interaction of several cellular mechanisms to ensure the proper development and maturation of germ cells. This study assessed autophagy contribution and its relation to apoptosis in fish spermatogenesis during starvation. To that end, Nile tilapia males were subjected to 0 (control), 7, 14, 21, and 28 days of starvation to induce autophagy. Testes samples were obtained for analyses of spermatogenesis by histology, electron microscopy, immunohistochemistry, and western blotting. Sperm quality was assessed using a computer-assisted sperm analysis (CASA) system. Data indicated a significant reduction in gonadosomatic index, seminiferous tubule area, and spermatozoa proportion in fish subject to starvation compared to the control group. Immunoblotting revealed a reduction of Bcl2 and Beclin 1 associated with increased Bax and Caspase-3, mainly after 21 and 28 days of starvation. LC3 and P62 indicated reduced autophagic flux in these starvation times. Immunolabeling for autophagic and apoptotic proteins occurred in all development stages of the germ cells, but protein expression varied throughout starvation. Beclin 1 and Cathepsin D decreased while Bax and Caspase-3 increased in spermatocytes, spermatids, and spermatozoa after 21 and 28 days. Autophagic and lysosomal proteins colocalization indicated the fusion of autophagosomes with lysosomes and lysosomal degradation in spermatogenic cells. The CASA system indicated reduced sperm motility and velocity in animals subjected to 21 and 28 days of starvation. Altogether, the data support autophagy acting at different spermatogenesis stages in Nile tilapia, with decreased autophagy and increased apoptosis after 21 and 28 days of starvation, which results in a decrease in the spermatozoa number and sperm quality.
Asunto(s)
Cíclidos , Masculino , Animales , Caspasa 3/metabolismo , Cíclidos/metabolismo , Beclina-1/genética , Beclina-1/metabolismo , Proteína X Asociada a bcl-2/metabolismo , Motilidad Espermática , Semen/metabolismo , Espermatozoides/metabolismo , Espermatogénesis , Espermátides , AutofagiaRESUMEN
Edwardsiella tarda is a crucial pathogenic bacterium in tropical aquaculture. This bacterium was recently isolated from tambaqui (Colossoma macropomum), a commercially important fish species in Brazil. This study assessed the antimicrobial susceptibility, pathogenicity, and genetic diversity of the tambaqui-derived E. tarda isolates. Fourteen bacterial isolates isolated from tambaqui were identified as E. tarda by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and dnaJ gene sequencing. Antimicrobial susceptibility tests were conducted against seven drugs using the disc diffusion assay. The pathogenicity test conducted by intraperitoneal injection of 2.4 × 107 colony-forming units (CFU) fish-1 of E. tarda (ED38-17) into tambaqui juveniles eventually revealed that neither clinical signs nor death were present. However, splenomegaly and whitish areas in the spleen and kidneys were observed. The histological investigation also revealed granulomatous splenitis, nephritis, and hepatitis occurring internally. Repetitive extragenic palindromic-PCR fingerprinting separated the 14 isolates into three genetic groups. The antibiogram revealed that all E. tarda isolates were wild-type (WT) to florfenicol (FLO), norfloxacin (NOR), neomycin (NEO), erythromycin (ERY), and oxytetracycline (OXY); however, some were non-wild-type to sulfamethoxazole/trimethoprim (7.1%) and amoxicillin (21.4%). Therefore, through experimental infection, E. tarda ED38-17 could induce pathogenic effects in C. macropomum. Additionally, three distinct genetic types were found, and the E. tarda isolates were WT to FLO, NOR, NEO, ERY, and OXY. These findings raise awareness of a bacteria causing unseen lesions, a pathogen that will potentially impact tambaqui aquaculture in the future.
RESUMEN
The objective of this study was to evaluate the acute toxicity of formalin and its level of therapeutic safety in early stages of Lophiosilurus alexandri. Experiment 1, larvae 7 days after hatching (DAH) were exposed to 43.2, 86.4, 172.8, 345.6, 691.2, 1404.0â¯mg/L of formalin. Experiment 2, juveniles with 22 DAH exposed to 54, 108, 216, 432, 648â¯mg/L. Experiment 3, 45 DAH exposed to 86.4, 172.8, 345.6, 691.2, 1036.8â¯mg/L. The experiments had a control without addition of formalin and all were carried out in duplicate. The LC50-12â¯h were: Experiment 1â¯=â¯108.86â¯mg/L; 2: 152.74â¯mg/L; 3: 244.38â¯mg/L of formalin. The respective safety levels were: Experiment 1â¯=â¯66.22â¯mg/L (1â¯h), 10.89â¯mg/L (12â¯h); 2â¯=â¯49.17â¯mg/L (2â¯h), 15.27â¯mg/L (12â¯h); 3â¯=â¯68.89â¯mg/L (2â¯h), 24.44â¯mg/L (12â¯h). The results showed that the developmental stage influenced the sensitivity of animals to formalin.