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

Dietary Lipid Saturation Influences Environmental Temperature Preference But Not Resting Metabolic Rate In The Djungarian Hamster (Phodopus Sungorus)

Heterothermic rodents increase self-selection of diets rich in polyunsaturated fatty acids (PUFAs) when exposed to cold, short days, or short-day melatonin profiles, and Djungarian hamsters (Phodopus sungorus) do so in long days in response to cold exposure alone. To determine whether Djungarian hamsters are also capable of selecting a thermal environment in response to dietary lipid composition, continuously normothermic hamsters were fed either a PUF-rich diet or a diet rich in saturated fatty acids (SFAs) for 6-10 wk and given a choice of thermal environments. As predicted, SF-fed hamsters were more likely than PUFA-fed hamsters to occupy the single heated corner of their cage (P = 0.0005) and were most likely to show this diet-related difference in behavior when T a fell within the thermal neutral zone. Respirometry revealed no effect of diet on whole-animal or mass-specific resting metabolic rate or on lower critical temperature. The results are more consistent with the homeoviscous adaptation hypothesis, which predicts that organisms should make physiological and/or behavioral adjustments that preserve membrane fluidity within a relatively small range, than with the membrane pacemaker hypothesis, which predicts that high PUFA content in membrane phospholipids should increase basal metabolic rate

Liver Land: An Exploration of Liver as Foie Gras in France

The Newman Exploration Travel Fund granted me an opportunity to go to Francefor two weeks to research the production and consumption of foie gras—one ofthe most hotly contested conflicts in culinary ethics—for a chapter in a book I amwriting about the liver. More than any other organ, the liver functions as a totemicfood. The liver sits at the intersection of animal ethics, sustainability, sociopoliticalprestige, and nationalism. Think about the “liver and onions” of the Americanworking class, the chicken liver pâtés beloved by Jewish migrants, the allegedhealing properties of cod liver, the traditional Chinese prescription of chicken liverfor menstrual problems, and, of course, foie gras. To understand the cultural heftof the liver, no country is more important than France, the motherland of fattyliver. 2022 Newman Exploration Travel Fund (NEXT) Award, Graduate Studenthttps://openscholarship.wustl.edu/next_posters/1001/thumbnail.jp

Salinity preferences of Diamondback Terrapin (Malaclemys terrapin) headstarts: A laboratory study

Salt marshes along the eastern coast of the USA are challenging environments due to their tidal nature,which causes constant fluctuations in the salinity levels of their brackish water. Diamondback Terrapins (Malaclemysterrapin) can inhabit these salt marshes due to their ability to tolerate highly saline water. The physiological mechanismsunderlying this ability are well known in adults, but have not been thoroughly explored in hatchlings and juveniles,which cannot grow when exposed to high salinity. We examined salinity preferences of hatchlings and juveniles in thelaboratory and concluded that hatchlings do not exhibit salinity preferences and develop this trait as juveniles

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

Ion fluxes across the pitcher walls of three Bornean Nepenthes pitcher plant species: flux rates and gland distribution patterns reflect nitrogen sequestration strategies

Nepenthes pitcher plant species differ in their prey capture strategies, prey capture rates, and pitcher longevity. In this study, it is investigated whether or not interspecific differences in nutrient sequestration strategy are reflected in the physiology and microstructure of the pitchers themselves. Using a non-invasive technique (MIFE), ion fluxes in pitchers of Nepenthes ampullaria Jack, Nepenthes bicalcarata Hook.f., and Nepenthes rafflesiana Jack were measured. Scanning electron microscopy was also used to characterize the distribution of glandular and other structures on the inner pitcher walls. The results demonstrate that nutrient sequestration strategy is indeed mirrored in pitcher physiology and microstructure. Species producing long-lived pitchers with low prey capture rates (N. ampullaria, N. bicalcarata) showed lower rates of NH4+ uptake than N. rafflesiana, a species producing short-lived pitchers with high capture rates. Crucially, species dependent upon aquatic commensals (N. ampullaria, N. bicalcarata) actively manipulated H+ fluxes to maintain less acid pitcher fluid than found in ‘typical’ species; in addition, these species lacked the lunate cells and epicuticular waxes characteristic of ‘typical’ insectivorous congeners. An unexpected finding was that ion fluxes occurred in the wax-covered, non-glandular zones in N. rafflesiana. The only candidates for active transport of aqueous ions in these zones appear to be the epidermal cells lying beneath the lunate cells, as these are the only sites not visibly coated with epicuticular waxes