Efectos de ecdisona y de la aclimatación a baja temperatura, sobre el crecimiento y la tasa metabólica de juveniles de la langosta de agua dulce Cherax quadricarinatus (Decapoda, Parastacidae)

Growth, metabolic rate, and energy reserves of Cherax quadricarinatus (von Martens, 1868) juveniles were evaluated in crayfish acclimated for 16 weeks to either 25 ºC (temperature near optimum) or 20 ºC (marginal for the species). Additionally, the modulating effect of ecdsyone on acclimation was studied. After 12 weeks of exposure, weight gain of both experimental groups acclimated to 25 ºC (control: C25, and ecdysone treated: E25) was significantly higher than that of those groups acclimated to 20 ºC (C20 and E20). A total compensation in metabolic rate was seen after acclimation from 25 ºC to 20 ºC; for both the control group and the group treated with ecdysone. A Q10 value significantly higher was only observed in the group acclimated to 20 ºC and treated with ecdysone. A reduction of glycogen reserves in both hepatopancreas and muscle, as well as a lower protein content in muscle, was seen in both groups acclimated to 20 ºC. Correspondingly, glycemia was always higher in these groups. Increased lipid levels were seen in the hepatopancreas of animals acclimated to 20 ºC, while a higher lipid level was also observed in muscle at 20 ºC, but only in ecdysone-treated crayfish.RESUMEN. Efectos de ecdisona y de la aclimatación a baja temperatura, sobre el crecimiento y la tasa metabólica de juveniles de la langosta de agua dulce Cherax quadricarinatus (Decapoda, Parastacidae). Se evaluaron las reservas energéticas, el crecimiento y la tasa metabólica de langostas juveniles de agua dulce Cherax quadricarinatus (von Martens, 1868), aclimatadas durante 16 semanas tanto a 25°C (temperatura cercana al óptimo) como a 20°C (temperatura marginal para la especie). Adicionalmente, se evaluó el efecto modulador de la ecdisona sobre la aclimatación. Luego de 12 semanas de exposición, la ganancia en peso de ambos grupos experimentales aclimatados a 25°C (control: C25, y tratados con ecdisona: E25) fue significativamente mayor que la de los grupos aclimatados a 20°C (C20 and E20). Se verificó una compensación total en la tasa metabólica, luego de la aclimatación desde 25 a 20°C, tanto para el grupo control como para el tratado con ecdisona. Solamente se observó un valor de Q10 significativamente mayor en el grupo aclimatado a 20°C y tratado con ecdisona. En ambos grupos aclimatados a 20°C, se determinó un reducción en la reservas de glucógeno, tanto en hepatopancreas como en músculo, así como un menor contenido de proteína en músculo. Correspondiente, la glucemia resultó siempre más elevada en esos grupos, que también mostraron un mayor nivel de lípidos en el hepatopancreas, siendo mayor el nivel de lípidos en músculo sólo para los juveniles aclimatados a 20°C y tratados con ecdisona.Fil: Chaulet, Anouk. Consejo Nacional de Invest.cientif.y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; Argentina;Fil: Vatnick, Itzick. Widener University Department of Biology; Estados Unidos de América;Fil: Rodriguez, Enrique Marcelo. Presidencia/directorio - Conicet. Gerencia de Des.cient.y Tec.. Oficina de Coordinacion Administrativa Cdad. Universitaria. Instituto de Biodiversidad y Biologia Experimental y Aplicada; Argentina

Survival, growth, and physiological responses of advanced juvenile freshwater crayfish (Cherax quadricarinatus), reared at low temperature and high salinities

The effects of stress caused by low temperature, high salinities, and a combination of both low temperatures and high salinities were evaluated in advanced (~. 5. g) juvenile freshwater crayfish (Cherax quadricarinatus). Ten animals were weighed and assigned to each of the following combination of two temperature and three salinity treatments: 27 °C (optimum for this species) or 20 °C and 0, 5, and 10. g/L salt concentrations. After 30. days in each treatment, oxygen consumption and weight were recorded, together with hemolymph levels of glucose, sodium, potassium, and free amino acids (FAA). Glycogen level was determined in hepatopancreas and abdominal muscle, while FAA levels were measured in abdominal muscle and hemolymph. A significant decrease of weight gain was seen at the combination of 20 °C and 10. g/L salinity. A marked hyperglycemia was seen at the lower temperature, at any salinity tested. At the same temperature, there was a concomitant decrease of glycogen, in both hepatopancreas and muscle. Both sodium and potassium hemolymphatic levels significantly increased with increasing salinity, but only at 20 °C. No changes were seen in hemolymphatic FAA levels, but they increased in abdominal muscle at higher salinities, in correspondence with the sodium hemolymphatic increase, in order to regulate cellular osmolarity. Although advanced juveniles of C. quadricarinatus did not exhibit reduced survival or growth at 20 °C or 10. g/L salinity, the combination of relatively low temperature and high salinity significantly reduces growth, suggesting that the combination of these two factors is a stressful condition for these crayfish juveniles.Fil: Prymaczok, Natalia Cecilia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Chaulet, Anouk. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Medesani, Daniel Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Rodriguez, Enrique Marcelo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentin

Effects of both ecdysone and the acclimation to low temperature, on growth and metabolic rate of juvenile freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae)

ABSTRACT. Growth, metabolic rate, and energy reserves of Cherax quadricarinatus (von Martens, 1868) juveniles were evaluated in crayfish acclimated for 16 weeks to either 25°C (temperature near optimum) or 20°C (marginal for the species). Additionally, the modulating effect of ecdsyone on acclimation was studied. After 12 weeks of exposure, weight gain of both experimental groups acclimated to 25°C (control: C25, and ecdysone treated: E25) was significantly higher than that of those groups acclimated to 20°C (C20 and E20). A total compensation in metabolic rate was seen after acclimation from 25°C to 20°C; for both the control group and the group treated with ecdysone. A Q 10 value significantly higher was only observed in the group acclimated to 20°C and treated with ecdysone. A reduction of glycogen reserves in both hepatopancreas and muscle, as well as a lower protein content in muscle, was seen in both groups acclimated to 20°C. Correspondingly, glycemia was always higher in these groups. Increased lipid levels were seen in the hepatopancreas of animals acclimated to 20°C, while a higher lipid level was also observed in muscle at 20°C, but only in ecdysone-treated crayfish. KEYWORDS. Energy reserves, growth, metabolic rate, Q 10 . RESUMEN. Efectos de ecdisona y de la aclimatación a baja temperatura, sobre el crecimiento y la tasa metabólica de juveniles de la langosta de agua dulce Cherax quadricarinatus (Decapoda, Parastacidae). Se evaluaron las reservas energéticas, el crecimiento y la tasa metabólica de langostas juveniles de agua dulce Cherax quadricarinatus (von Martens, 1868), aclimatadas durante 16 semanas tanto a 25°C (temperatura cercana al óptimo) como a 20°C (temperatura marginal para la especie). Adicionalmente, se evaluó el efecto modulador de la ecdisona sobre la aclimatación. Luego de 12 semanas de exposición, la ganancia en peso de ambos grupos experimentales aclimatados a 25°C (control: C25, y tratados con ecdisona: E25) fue significativamente mayor que la de los grupos aclimatados a 20°C (C20 and E20). Se verificó una compensación total en la tasa metabólica, luego de la aclimatación desde 25 a 20°C, tanto para el grupo control como para el tratado con ecdisona. Solamente se observó un valor de Q 10 significativamente mayor en el grupo aclimatado a 20°C y tratado con ecdisona. En ambos grupos aclimatados a 20°C, se determinó un reducción en la reservas de glucógeno, tanto en hepatopancreas como en músculo, así como un menor contenido de proteína en músculo. Correspondiente, la glucemia resultó siempre más elevada en esos grupos, que también mostraron un mayor nivel de lípidos en el hepatopancreas, siendo mayor el nivel de lípidos en músculo sólo para los juveniles aclimatados a 20°C y tratados con ecdisona. PALABRAS-CLAVE. Reservas energéticas, crecimiento, tasa metabólica, Q 10 . Metabolic rate of invertebrates depends on several intrinsic and extrinsic factors. Intrinsic factors include: age, gender, weight, degree of locomotor activity and internal work. Extrinsic factors include: ambient temperature, photoperiod, impact of stressors and food availability. Temperature clearly exerts a major influence on metabolic rate of poikilothermic species. However, most poikilotherms display compensatory mechanisms against temperature change; several species are even capable of full compensation and hold their metabolic rate at the same level they had at a higher temperature after an acclimation period to the new lower temperatur

Effects of both ecdysone and the acclimation to low temperature, on growth and metabolic rate of juvenile freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae)

Growth, metabolic rate, and energy reserves of Cherax quadricarinatus (von Martens, 1868) juveniles were evaluated in crayfish acclimated for 16 weeks to either 25ºC (temperature near optimum) or 20ºC (marginal for the species). Additionally, the modulating effect of ecdsyone on acclimation was studied. After 12 weeks of exposure, weight gain of both experimental groups acclimated to 25ºC (control: C25, and ecdysone treated: E25) was significantly higher than that of those groups acclimated to 20ºC (C20 and E20). A total compensation in metabolic rate was seen after acclimation from 25ºC to 20ºC; for both the control group and the group treated with ecdysone. A Q10value significantly higher was only observed in the group acclimated to 20ºC and treated with ecdysone. A reduction of glycogen reserves in both hepatopancreas and muscle, as well as a lower protein content in muscle, was seen in both groups acclimated to 20ºC. Correspondingly, glycemia was always higher in these groups. Increased lipid levels were seen in the hepatopancreas of animals acclimated to 20ºC, while a higher lipid level was also observed in muscle at 20ºC, but only in ecdysone-treated crayfish

In vitro effects of both dopaminergic and enkephalinergic antagonists on the ovarian growth of Cherax quadricarinatus (Decapoda, Parastacidae), at different periods of the reproductive cycle

The in vitro effect of both spiperone (dopaminergic antagonist) and naloxone (enkephalinergic antagonist), was assayed on small pieces of ovary dissected from C. quadricarinatus females, with the eventual addition of some neuroendocrine organs, such as thoracic ganglion or eyestalk tissue. The incorporation of tritiated leucine by the ovary was measured in order to estimate the ovarian growth. During the post-reproductive period, both mentioned antagonists were able to significantly stimulate the ovary in the presence of thoracic ganglion, but did not produce any significant effect in the preparation containing ovary and eyestalk tissue, or only ovary. No significant effects of the assayed antagonists were noted during the pre-reproductive period. These results were in accordance with previous models describing the neuroendocrine control of crustacean reproduction, and represent new findings about the hormonal context in different periods of the reproductive cycle of crayfish. Besides, by means of the experimental combination of the tested antagonists with dopamine or met-enkephalin, a new model dealing with the interaction of these two neurotransmitters on the hormonal secretion of thoracic ganglion has been proposed.Fil: Cahansky, Alejandra Valeria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Medesani, Daniel Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chaulet, Anouk. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodriguez, Enrique Marcelo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin