Abstract: Introduction: Energy conservation is a key priority for organisms having to face seasonal or stochastic shortages in resource supplies. Because mitochondrial bioenergetics constitute the functional link between environmental resources, whole body energy expenditure and animal performances (e.g. growth, locomotion, thermoregulation), these organelles may represent an important proximate factor responsible for energy savings during fast. Materials and Methods: We studied mitochondrial bioenergetics (oxidative phosphorylation activity, ATP synthesis efficiency, oxidative capacity) of skeletal muscle mitochondria from birds (penguins and ducks) during the course of fasting/refeeding periods. Results: Bioenergetics analysis of pectoralis and gastrocnemius muscles revealed that mitochondria are more energy efficient shortly after the beginning of fast, indicating that skeletal muscles of fasted birds consume fewer nutrients to sustain their energy-demanding processes. This adjustment of mitochondrial efficiency was fully reversed by refeeding and would be under the control of thyroid hormones. Discussion/conclusion: Skeletal muscle mitochondria from fasted birds decrease the cost of ATP synthesis by minimizing the needs for energy substrates. The mitochondrial energy transduction processes prove to be highly flexible, suggesting that birds would adjust the cost of mitochondrial metabolism in order to cope with their nutritional status.

Abstract: Cambridge Core – Planetary Science and Astrobiology – The Earth's Inner Core – by Hrvoje Tkal?i?

Abstract: Tide gauge measurements provide data for routine tidal predictions in ports as well as for extreme events such as storm surges and tsunamis. Along with satellite altimeter measurements, tide gauges also provide measurements used for sea-level rise estimates. This is particularly important for impact assessment in low-lying coastlines of south Asia as well as islands such as the Maldives in the Indian Ocean.