This study shows that dietary β-carotene reduces time to metamorphosis in a critically endangered frog, independent of growth effects. Supplementing captive frogs with dietary β-carotene could assist with amphibian conservation breeding programs globally.
From this institutional dataset, a significant proportion of patients continued chemotherapy past 8 cycles, and appeared to derive benefit from longer duration of treatment. Toxicity rates were higher in this group, but manageable as evidenced by second-line treatment rates. Discontinuation of chemotherapy for reasons other than toxicity or progression may result in loss of disease control and impact survival in this population; these data suggest the use of continued chemotherapy to disease progression in patients with advanced BTC is a favorable option.
Escape-response behaviour is essential to ensure an individual's survival during a predator attack, however, these behaviours are energetically costly and may cause oxidative stress. Oxidative stress can be reduced by supplementing an individual's diet with exogenous antioxidants or through regular moderate exercise training, which stimulates the upregulation of the endogenous antioxidant system. Two studies have tested the simultaneous effects of dietary antioxidant supplementation and exercise training on animal escape-response behaviour. The present study investigated the effects of dietary carotenoids and exercise training on the escape-response behaviour of Southern Corroboree frogs. Frogs were fed either a carotenoid-supplemented or unsupplemented diet and were exposed to repeated escape-response trials (training) for five consecutive weeks. Carotenoid-supplemented individuals outperformed unsupplemented individuals in initial hopping speed, length of the first hop and hopping distance, however, the performance of frogs in each treatment group became statistically similar after training. Within treatment groups, exercise training significantly improved the hopping speed of unsupplemented frogs, with speeds almost doubling between training weeks one and five. By contrast, exercise training did not significantly improve the hopping speed of carotenoid-supplemented frogs. Our results provide some of the first evidence that exercise training improves escape performance, and that dietary antioxidants may inhibit training-induced benefits.
Organismal performance can be significantly affected by the nutritional conditions experienced during different life-stages. The Silver Spoon Hypothesis predicts that individuals will always perform better as adults when they experience advantageous conditions during development. In contrast, the Environmental Matching Hypothesis predicts that individuals will perform better if they experience similar conditions during development and adulthood. Past tests of these hypotheses have focussed on the effect of food quantity on growth and development, with little attempt to investigate the effect of individual nutrients on behavioural traits. This study aimed to test the predictions of the Environmental Matching and Silver Spoon Hypotheses by investigating the influence of carotenoid supplementation at different life-stages on the foraging performance of Pseudophryne corroboree. To assess foraging performance, adults were presented with prey in either a cryptic or conspicuous foraging matrix. There was no effect of diet treatment on time to first movement towards prey, number of stalking events, time spent actively foraging, proportion of successful strikes, proportion of prey consumed or number of pedal luring events. These findings indicate that carotenoid supplementation at different life-stages does not influence the foraging performance of P. corroboree, providing no support for either the Silver Spoon or Environmental Matching Hypotheses.
AbstractOrganismal performance can be significantly affected by the nutritional conditions experienced during different life-stages. The Silver Spoon Hypothesis predicts that individuals will always perform better as adults when they experience advantageous conditions during development. In contrast, the Environmental Matching Hypothesis predicts that individuals will perform better if they experience similar conditions during development and adulthood. Past tests of these hypotheses have focussed on the effect of food quantity on growth and development, with little attempt to investigate the effect of individual nutrients on behavioural traits. This study aimed to test the predictions of the Environmental Matching and Silver Spoon Hypotheses by investigating the influence of carotenoid supplementation at different life-stages on the foraging performance of Pseudophryne corroboree. To assess foraging performance, adults were presented with prey in either a cryptic or conspicuous foraging matrix. There was no effect of diet treatment on time to first movement towards prey, number of stalking events, time spent actively foraging, proportion of successful strikes, proportion of prey consumed or number of pedal luring events. These findings indicate that carotenoid supplementation at different life-stages does not influence the foraging performance of P. corroboree, providing no support for either the Silver Spoon or Environmental Matching Hypotheses.
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