Physiological and biochemical adaptations to training in Rana pipiens

Fifteen Rana pipiens were trained on a treadmill thrice weekly for 6.5 weeks to assess the effects of training on an animal that supports activity primarily through anaerobiosis. Endurance for activity increased 35% in these frogs as a result of training ( P =0.006, Fig. 1). This increased performance was not due to enhanced anaerobiosis. Total lactate produced during exercise did not differ significantly for the trained or untrained animals in either gastrocnemius muscle (2.77±0.21 and 2.82±0.13 mg/g, respectively) or whole body (1.32±0.10 and 1.47±0.06 mg/g, respectively). Glycogen depletion also did not differ between the two groups (Fig. 2c). The primary response to training appeared to involve augmentation of aerobic metabolism, a response similar to that reported for mammals. Gastrocnemius muscles of trained frogs underwent a 38% increase over those of untrained individuals in the maximum activity of citrate synthase (14.5±1.0 and 10.5±0.9 μmoles/(g wet wt·min); P =0.008). This enzyme was also positively correlated with the level of maximum performance for all animals tested ( r =0.61, P <0.01) and with the degree of improvement in the trained animals ( r =0.72, P <0.05). In addition to an increased aerobic capacity, the trained animals demonstrated a greater removal of lactate from the muscle 15 min after fatigue (Fig. 2b).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47124/1/360_2004_Article_BF00710002.pd

Performance of transition metal-doped CaCO3 during cyclic CO2 capture-and-release in low-pressure H2O vapour and H2O plasma

The effects of transition metal doping of calcium carbonate on the subsequent performance of the material during CO2 release and recapture have been evaluated for calcination under low-pressure (~0.1 mbar) water vapour and water plasma conditions. The initial samples were prepared by precipitation method from analytical grade carbonate, calcium and transition metal (Fe, Co, Zn, Cu and Ni) containing precursors. The release-recapture properties of the sorbents were monitored over five cycles involving calcination at 1200 K and carbonation at 825 K. The most noteworthy effects were observed for the Zn-doped samples, which exhibited rapid CO2 recapture. Calcination in H2O plasma was tested to evaluate the potential for in-situ material processing as a means to counteract material degradation. The impact of plasma exposure during calcination on the looping performance was mixed and dependent on the specific sample composition. The performance of the Zn-doped CaCO3 was consistently improved by plasma calcination, yielding high uptake and better retention of carrying capacity over the five cycles. All samples exhibited a deterioration in carrying capacity over repeated cycles. The Zn-doped samples also performed best in this respect (least loss of carrying capacity). The beneficial effects of Zn-doping were dependent on the Zn-content of the precursor solutions used for material synthesis

Effects of foraging mode and season on the energetics of the Marine Iguana, Amblyrhynchus cristatus

1, Marine Iguanas (Amblyrhynchus cristatus) inhabiting the rocky shores of the Galapagos Islands apply two foraging strategies, intertidal and subtidal foraging, in a seasonal climate. Effects of both foraging strategy and seasonality on the daily energy expenditure (DEE) were measured using doubly labelled water. 2, Difference in foraging mode did not result in significant differences in DEE. 3, On Santa FC the DEE in the warm season was significantly higher than in the cool season (57.8 +/- 21.8 kJ kg(-0.8) day(-1) vs 38.0 kJ kg(-0.8) day(-1)). This difference can be explained by body temperature. A model estimate of the body temperature was used to predict monthly DEE figures, giving a year round budget. On average a l-kg iguana would need only 47 kJ day(-1), or 17 mJ year(-1). This is lower than previous estimates in which body temperatures were not taken into account. 4, The water flux of the Marine Iguana increases with increasing foraging time. The linear rise per minute foraging is roughly two times as high for subtidally foraging animals as for intertidal foragers

Short- and long-term consequences of thermal variation in the larval environment of anurans

To survive adverse or unpredictable conditions in the ontogenetic environment, many organisms retain a level of phenotypic plasticity that allows them to meet the challenges of rapidly changing conditions. Larval anurans are widely known for their ability to modify behaviour, morphology and physiological processes during development, making them an ideal model system for studies of environmental effects on phenotypic traits. Although temperature is one of the most important factors influencing the growth, development and metamorphic condition of larval anurans, many studies have failed to include ecologically relevant thermal fluctuations among their treatments. We compared the growth and age at metamorphosis of striped marsh frogs Limnodynastes peronii raised in a diurnally fluctuating thermal regime and a stable regime of the same mean temperature. We then assessed the long-term effects of the larval environment on the morphology and performance of post-metamorphic frogs. Larval L. peronii from the fluctuating treatment were significantly longer throughout development and metamorphosed about 5 days earlier. Frogs from the fluctuating group metamorphosed at a smaller mass and in poorer condition compared with the stable group, and had proportionally shorter legs. Frogs from the fluctuating group showed greater jumping performance at metamorphosis and less degradation in performance during a 10-week dormancy. Treatment differences in performance could not be explained by whole-animal morphological variation, suggesting improved contractile properties of the muscles in the fluctuating group