RESUMO

In this study, we described immediate/acute reactions to stress-related chemical cues (SC - Stress Cue) in fish. Specifically, we evaluated the effects of SC on ventilation rate (VR) and feeding behavior in Nile tilapia (Oreochromis niloticus), a highly relevant species for world aquaculture, therefore, to understand the diversity of stressful contexts and stress responses in this species have important practical applications (stress reduction). Stress cue was obtained from conspecifics exposed to a handling stressor. Stress was confirmed by measuring plasma cortisol levels. The responses to SC were contrasted to chemical control cues: a cue originated from non-stressed conspecifics and pure water (vehicle control). We observed that Nile tilapia exposed to SC had an increase in VR, but without effects on feeding behavior (feeding latency and ingestion). Thus, the SC is a stressor that induces readily stress response (VR increase), suggesting sympathetic activation, but did not change feeding performance. In practical terms, it is positive because although social propagation of stress via SC elicits a stress response, it did not harm appetite.

RESUMO

Glyphosate-based herbicides are widely used in agricultural systems. Although the target organism are particularly plant organisms, there are numerous studies showing adverse effects in aquatic animals, such as inhibition of acetyl cholinesterase, effects on kidney, liver, and gill and stressors effects. This study analyzed the effects of commercial formulation of glyphosate on feeding behavior in Pacu (Piaractus mesopotamicus). Fish were exposed to three glyphosate concentrations (0.2, 0.6, and 1.8 ppm) for 15 days. At concentrations of 0.2 and 0.6 ppm, food intake decreased on day 13 and then returned to normal on day 15. At the highest glyphosate-based herbicide concentration, 1.8 ppm, food consumption decreased dramatically and did not recover on day 15. This study showed that glyphosate-based herbicide at sub-lethal concentrations can affect feed intake in pacu and consequently inhibits its growth.

Assuntos

RESUMO

Este estudio tuvo como objetivo evaluar la respuesta de las proteínas del plasma de la sangre de tilapia macho y hembra, a dosis de 20Gy, expuestos a la radiación gamma. Se observó un patrón diferencial entre los sexos. La reducción e incluso la eliminación de ciertas bandas fueram detectadas por electroforesis en gel de agarosa.(AU)

This study aimed to evaluate the response of plasma proteins from blood of male and female tilapia at a dose of 20Gy, exposed to gamma radiation. A differential pattern between the sexes was observed. A reduction and even elimination of certain bands were detected by electrophoresis in agarose gel.(AU)

O presente trabalho teve por objetivo avaliar a resposta de proteínas plasmáticas de sangue de tilápias macho e fêmea, à dose de 20Gy expostas à radiação gama. Observou-se um padrão diferencial entre os sexos, bem como diminuição e até mesmo supressão de determinadas bandas detectadas por eletroforese em gel de agarose.(AU)

Assuntos

RESUMO

Este estudio tuvo como objetivo evaluar la respuesta de las proteínas del plasma de la sangre de tilapia macho y hembra, a dosis de 20Gy, expuestos a la radiación gamma. Se observó un patrón diferencial entre los sexos. La reducción e incluso la eliminación de ciertas bandas fueram detectadas por electroforesis en gel de agarosa.

This study aimed to evaluate the response of plasma proteins from blood of male and female tilapia at a dose of 20Gy, exposed to gamma radiation. A differential pattern between the sexes was observed. A reduction and even elimination of certain bands were detected by electrophoresis in agarose gel.

O presente trabalho teve por objetivo avaliar a resposta de proteínas plasmáticas de sangue de tilápias macho e fêmea, à dose de 20Gy expostas à radiação gama. Observou-se um padrão diferencial entre os sexos, bem como diminuição e até mesmo supressão de determinadas bandas detectadas por eletroforese em gel de agarose.

Assuntos

RESUMO

La investigación de especies de peces sometidas a radiación ionizante es aún escasa. Elpresente trabajo tuvo como objetivo evaluar la resistencia de tilapias sometidas a dosis deradiación gamma de cuerpo entero: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy y 154Gy. Para cadaintervalo de dosis, se utilizaron dos espécimenes machos. Los peces que recibieron dosis de5Gy, 10Gy y 20Gy, se comportaron normalmente durante la alimentación, sin alteraciones enel patrón de sus desplazamientos en el acuario y sin mostrar lesiones neurológicas o muertes.Los que recibieron 39Gy, 77Gy y 154Gy demostraron falta de apetito y signos dedesorientación espacial, como promedio, 11 días después de la irradiación. En cuatro de losseis sujetos se observó el surgimiento de lesiones en la superficie del cuerpo del tejido blando.Los peces que recibieron 39Gy desarrollaran tumores y en un pez que recibió 77Gy aparecióuna lesión cutánea en la región de la aleta dorsal. De los que recibieron 154Gy, un pez tuvolesiones cutâneas, aparentemente necróticas, cerca de la cola. La supervivencia del grupo querecibió 39Gy fue un promedio de 12,5 días, entre los que recibieron 77Gy, 11,5 días y en elgrupo de 154Gy, 10 días..

Surveys about the response of fish species subjected to ionizing radiation are still sparse. Thepresent work aimed to evaluate the resistance of tilapia subjected to gamma radiation dosesabsorbed in the whole body: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy and 154Gy. For eachdosing interval, two male specimens were used. Fishes that received doses 5Gy, 10Gy and20Gy, showed a normal behavior on food intake and in pattern of displacement in theaquarium, showing neither neurological damages nor deaths. Those who received 39Gy,77Gy and 154Gy, demonstrated lack of appetite and signs of spatial disorientation 11 daysafter radiation, on average. In four of the six subjects the development of lesions in the softtissue body surface was observed. Fishes that received 39Gy developed tumors and an animalwho received 77Gy developed a cutaneous lesion near the dorsal fin. For those who received154Gy, a fish developed an apparently necrotic cutaneous lesion near the tail. In the groupthat received 39Gy, the survival period was an average of 12.5 days, for the fishes whichreceived 77Gy; 11.5 days and in the group of 154Gy, 10 days.

Pesquisas com espécies de peixes submetidas à radiação ionizante são ainda raras. Nopresente trabalho, objetivou-se avaliar a resistência de tilápias submetidas a doses de radiaçãogama absorvida em corpo inteiro: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy e 154Gy. Para cadaintervalo de dose, foram utilizados dois exemplares machos. Os peixes que receberam asdoses 5Gy, 10Gy e 20Gy comportaram-se normalmente quanto à alimentação e padrão dedeslocamento no aquário; não apresentando comprometimento neurológico e nem óbitos. Osque receberam 39Gy, 77Gy e 154Gy demonstraram inapetência e sinais de desorientaçãoespacial, em média, em 11 dias após radiação. Em quatro dos seis exemplares, observou-se odesenvolvimento de lesões tegumentares na superfície corpórea. Os que receberam 39Gy,desenvolveram lesões tumorais; um dos que receberam 77Gy, desenvolveu lesão tegumentarpróximo à nadadeira dorsal. Dos que receberam 154Gy, um peixe desenvolveu lesãotegumentar aparentemente necrótica próximo à cauda. A sobrevivência do grupo que recebeu39Gy foi em média 12,5 dias, os que receberam 77Gy, 11,5 dias e o grupo de 154Gy, 10 dias.

RESUMO

La investigación de especies de peces sometidas a radiación ionizante es aún escasa. El presente trabajo tuvo como objetivo evaluar la resistencia de tilapias sometidas a dosis de radiación gamma de cuerpo entero: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy y 154Gy. Para cada intervalo de dosis, se utilizaron dos espécimenes machos. Los peces que recibieron dosis de 5Gy, 10Gy y 20Gy, se comportaron normalmente durante la alimentación, sin alteraciones en el patrón de sus desplazamientos en el acuario y sin mostrar lesiones neurológicas o muertes. Los que recibieron 39Gy, 77Gy y 154Gy demostraron falta de apetito y signos de desorientación espacial, como promedio, 11 días después de la irradiación. En cuatro de los seis sujetos se observó el surgimiento de lesiones en la superficie del cuerpo del tejido blando. Los peces que recibieron 39Gy desarrollaran tumores y en un pez que recibió 77Gy apareció una lesión cutánea en la región de la aleta dorsal. De los que recibieron 154Gy, un pez tuvo lesiones cutâneas, aparentemente necróticas, cerca de la cola. La supervivencia del grupo que recibió 39Gy fue un promedio de 12,5 días, entre los que recibieron 77Gy, 11,5 días y en el grupo de 154Gy, 10 días(AU)

Surveys about the response of fish species subjected to ionizing radiation are still sparse. The present work aimed to evaluate the resistance of tilapia subjected to gamma radiation doses absorbed in the whole body: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy and 154Gy. For each dosing interval, two male specimens were used. Fishes that received doses 5Gy, 10Gy and 20Gy, showed a normal behavior on food intake and in pattern of displacement in the aquarium, showing neither neurological damages nor deaths. Those who received 39Gy, 77Gy and 154Gy, demonstrated lack of appetite and signs of spatial disorientation 11 days after radiation, on average. In four of the six subjects the development of lesions in the soft tissue body surface was observed. Fishes that received 39Gy developed tumors and an animal who received 77Gy developed a cutaneous lesion near the dorsal fin. For those who received 154Gy, a fish developed an apparently necrotic cutaneous lesion near the tail. In the group that received 39Gy, the survival period was an average of 12.5 days, for the fishes which received 77Gy; 11.5 days and in the group of 154Gy, 10 days(AU)

Pesquisas com espécies de peixes submetidas à radiação ionizante são ainda raras. No presente trabalho, objetivou-se avaliar a resistência de tilápias submetidas a doses de radiação gama absorvida em corpo inteiro: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy e 154Gy. Para cada intervalo de dose, foram utilizados dois exemplares machos. Os peixes que receberam as doses 5Gy, 10Gy e 20Gy comportaram-se normalmente quanto à alimentação e padrão de deslocamento no aquário; não apresentando comprometimento neurológico e nem óbitos. Os que receberam 39Gy, 77Gy e 154Gy demonstraram inapetência e sinais de desorientação espacial, em média, em 11 dias após radiação. Em quatro dos seis exemplares, observou-se o desenvolvimento de lesões tegumentares na superfície corpórea. Os que receberam 39Gy, desenvolveram lesões tumorais; um dos que receberam 77Gy, desenvolveu lesão tegumentar próximo à nadadeira dorsal. Dos que receberam 154Gy, um peixe desenvolveu lesão tegumentar aparentemente necrótica próximo à cauda. A sobrevivência do grupo que recebeu 39Gy foi em média 12,5 dias, os que receberam 77Gy, 11,5 dias e o grupo de 154Gy, 10 dias(AU)

Assuntos

RESUMO

La investigación de especies de peces sometidas a radiación ionizante es aún escasa. El presente trabajo tuvo como objetivo evaluar la resistencia de tilapias sometidas a dosis de radiación gamma de cuerpo entero: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy y 154Gy. Para cada intervalo de dosis, se utilizaron dos espécimenes machos. Los peces que recibieron dosis de 5Gy, 10Gy y 20Gy, se comportaron normalmente durante la alimentación, sin alteraciones en el patrón de sus desplazamientos en el acuario y sin mostrar lesiones neurológicas o muertes. Los que recibieron 39Gy, 77Gy y 154Gy demostraron falta de apetito y signos de desorientación espacial, como promedio, 11 días después de la irradiación. En cuatro de los seis sujetos se observó el surgimiento de lesiones en la superficie del cuerpo del tejido blando. Los peces que recibieron 39Gy desarrollaran tumores y en un pez que recibió 77Gy apareció una lesión cutánea en la región de la aleta dorsal. De los que recibieron 154Gy, un pez tuvo lesiones cutâneas, aparentemente necróticas, cerca de la cola. La supervivencia del grupo que recibió 39Gy fue un promedio de 12,5 días, entre los que recibieron 77Gy, 11,5 días y en el grupo de 154Gy, 10 días

Surveys about the response of fish species subjected to ionizing radiation are still sparse. The present work aimed to evaluate the resistance of tilapia subjected to gamma radiation doses absorbed in the whole body: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy and 154Gy. For each dosing interval, two male specimens were used. Fishes that received doses 5Gy, 10Gy and 20Gy, showed a normal behavior on food intake and in pattern of displacement in the aquarium, showing neither neurological damages nor deaths. Those who received 39Gy, 77Gy and 154Gy, demonstrated lack of appetite and signs of spatial disorientation 11 days after radiation, on average. In four of the six subjects the development of lesions in the soft tissue body surface was observed. Fishes that received 39Gy developed tumors and an animal who received 77Gy developed a cutaneous lesion near the dorsal fin. For those who received 154Gy, a fish developed an apparently necrotic cutaneous lesion near the tail. In the group that received 39Gy, the survival period was an average of 12.5 days, for the fishes which received 77Gy; 11.5 days and in the group of 154Gy, 10 days

Pesquisas com espécies de peixes submetidas à radiação ionizante são ainda raras. No presente trabalho, objetivou-se avaliar a resistência de tilápias submetidas a doses de radiação gama absorvida em corpo inteiro: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy e 154Gy. Para cada intervalo de dose, foram utilizados dois exemplares machos. Os peixes que receberam as doses 5Gy, 10Gy e 20Gy comportaram-se normalmente quanto à alimentação e padrão de deslocamento no aquário; não apresentando comprometimento neurológico e nem óbitos. Os que receberam 39Gy, 77Gy e 154Gy demonstraram inapetência e sinais de desorientação espacial, em média, em 11 dias após radiação. Em quatro dos seis exemplares, observou-se o desenvolvimento de lesões tegumentares na superfície corpórea. Os que receberam 39Gy, desenvolveram lesões tumorais; um dos que receberam 77Gy, desenvolveu lesão tegumentar próximo à nadadeira dorsal. Dos que receberam 154Gy, um peixe desenvolveu lesão tegumentar aparentemente necrótica próximo à cauda. A sobrevivência do grupo que recebeu 39Gy foi em média 12,5 dias, os que receberam 77Gy, 11,5 dias e o grupo de 154Gy, 10 dias

Assuntos

RESUMO

Although sex of mature fish is known to influence aggression, this issue has so far been neglected in juveniles. Here, we tested this sex effect and showed that it does not significantly affect intraspecific aggression in juveniles of the cichlid Nile tilapia. To reach this conclusion, we measured the latency period before onset of confrontation, the frequency and types of aggressive interactions, the duration of a dispute, and the probability of becoming dominant. This was done on pairs of Nile tilapia that varied by sex: females×females, males×males, and females×males. In a double blind approach, after pairing, the sex of each individual was histologically verified and contrasted with behavioral data.

Assuntos

RESUMO

In this study, we show that the fish Nile tilapia displays an antipredator response to chemical cues present in the blood of conspecifics. This is the first report of alarm response induced by blood-borne chemical cues in fish. There is a body of evidence showing that chemical cues from epidermal 'club' cells elicit an alarm reaction in fish. However, the chemical cues of these 'club' cells are restricted to certain species of fish. Thus, as a parsimonious explanation, we assume that an alarm response to blood cues is a generalized response among animals because it occurs in mammals, birds and protostomian animals. Moreover, our results suggest that researchers must use caution when studying chemically induced alarm reactions because it is difficult to separate club cell cues from traces of blood.

Assuntos

RESUMO

Time-place learning based on food association was investigated in eight food-restricted Nile tilapias. Each fish was individually housed for 10 days in an experimental tank for adjustments to laboratory conditions, and fed daily in excess. Feeding was then interrupted for 17 days. Training was then started, based on a food-restricted regime in a tank divided into three interconnected compartments. Daily food was offered in one compartment (left or right side) of the tank in the morning and on the opposite side in the afternoon, for a continuous 30-day period. Frequency of choices on the right side was measured on days 10, 20 and 30 (during these test days, fish were not fed). Following this 30-day conditioning period, the Nile tilapias were able to switch sides at the correct period of the day to get food, suggesting that food restriction facilitates time-place learning discrimination.

Assuntos

RESUMO

Time-place learning based on food association was investigated in the cichlids angelfish (Pterophyllum scalare) and pearl cichlid (Geophagus brasiliensis) reared in isolation, therefore eliminating social influence on foraging. During a 30-day period, food was placed in one side of the aquarium (containing three compartments) in the morning and in the opposite side in the afternoon. Learning was inferred by the number of correct side choices of all fish in each day of test (15th and 30th). During the test day fish were not fed. The angelfish learned to switch sides at the correct day period in order to get food, suggesting this species has time-place learning ability when individually reared. On the other hand, the same was not observed for pearl cichlid.

Assuntos

RESUMO

In this study was tested the effect of betaine on the growth performance of the piauçu fish. For this, twenty-one fish (mean ± SD: body weight: 14.9 ± 1.3 g) were randomly distributed in one out of three experimental treatments (n = 7 each; 1 fish/aquarium): without betaine added in the food (control); 3.6 g betaine/Kg of food; 7.1 g betaine/Kg of food. The fish were exposed to experimental conditions for 60 days. Fish presented significant growth throughout experimentation, but no statistically significant difference was found for any parameter analyzed among the treatments, except for condition factor, which was higher in control group than betaine ones. Accordingly, it was concluded that betaine had no enhancing effect on growth of piauçu.

Testamos o efeito da betaína na performance de crescimento do peixe piauçu. Para tal, 21 espécimes (média ± DP: peso corpóreo: 14,9 ± 1,3 g) foram distribuídos aleatoriamente em um entre três tratamentos (n = 7 cada; 1 peixe/aquário): ração sem acréscimo de betaína (controle), 3,6 g betaína/Kg de ração, 7,1 g betaína/Kg de ração. Os peixes foram submetidos às condições experimentais por 60 dias. Os peixes apresentaram crescimento estatisticamente significativo ao longo do experimento, porém nenhuma diferença estatística foi encontrada para qualquer parâmetro analisado, exceto para o fator de condição o qual foi maior no grupo controle do que nos grupos tratados com betaína. De acordo com isso, concluímos que a betaína não melhora o crescimento do piauçu.