Seasonal Regulation of Metabolism: The Effect of Wintertime Fasting and Autumnal Fattening on Key Central Regulators of Metabolism and the Metabolic Profile of the Raccoon Dog (Nyctereutes Procyonoides)

Investigations into the mechanisms regulating obesity are frantic and novel translational approaches are needed. The raccoon dog (Nyctereutes procyonoides) is a canid species representing a promising model to study metabolic regulation in a species undergoing cycles of seasonal obesity and fasting. To understand the molecular mechanisms of metabolic regulation in seasonal adaptation, we analyzed key central nervous system and peripheral signals regulating food intake and metabolism from raccoon dogs after autumnal fattening and winter fasting. Expressions of neuropeptide Y (NPY), orexin-2 receptor (OX2R), pro-opiomelanocortin (POMC) and leptin receptor (ObRb) were analyzed as examples of orexigenic and anorexigenic signals using qRT-PCR from raccoon dog hypothalamus samples. Plasma metabolic profiles were measured with 1H NMR-spectroscopy and LC-MS. Circulating hormones and cytokines were determined with canine specific antibody assays. Surprisingly, NPY and POMC were not affected by the winter fasting nor autumn fattening and the metabolic profiles showed a remarkable equilibrium, indicating conserved homeostasis. However, OX2R and ObRb expression changes suggested seasonal regulation. Circulating cytokine levels were not increased, demonstrating that the autumn fattening did not induce subacute inflammation. Thus, the raccoon dog developed seasonal regulatory mechanisms to accommodate the autumnal fattening and prolonged fasting making the species unique in coping with the extreme environmental challenges.

An chronobiological evaluation of the risks of cancelling Daylight Saving Time

The long term impact of seasonal regulation of clocks (Daylight Saving Time) is analyzed showing that it helped to mitigate the exposition of human activity to the dawn hours of the winter. The increased risks induced by circadian misalignment around transition dates are balanced with the reducing risks over a season induced by a more effective alignment of the human activity to the starting point of the photoperiod.

Growth, winter preparations and timing of emergence in temperate zone Odonata: control by a succession of larval response patterns

As warm-adapted insects of tropical origin, Odonata cope with cold periods by seasonal regulation and diapause. A model for larval-overwintering species is proposed with three response patterns related to the timing of emergence, which can be predicted from seasonal cues during the last few stadia. For emergence during the present season, there is an often time-constrained preemergence development, accelerated by long days and higher temperatures. In regulatory development, emergence is postponed to the next season, and a complex of diapause-like delays controlled by photoperiod and temperature prevents premature emergence. Instead, development converges on a winter diapause in sizes suitable for emergence during the following year. Long days are particularly delaying, and thermal responses are variable, sometimes inverted. In early development, with rapid growth, emergence is usually not predicted to season, but short-day winter diapauses may occur, and precocious preparations for a penultimate winter may be predictive. Thermal responses are steep, extremely so if a short-day diapause is suppressed by higher temperatures. Other physiological and also behavioural properties may differ between response patterns. Changes in photoperiod and temperature control the timing of seasonal events, and the transition from regulatory to pre-emergence development follows the increase in temperature and photoperiod after winter, which is an important time-setter. Interactions of larval size, photoperiod, temperature and previous changes affect development rate, and long-term constant conditions often end in regulatory diapauses. Proximate mechanisms of cohort splitting and the implications of the model for design and interpretation of experiments are discussed.

Profitability improvement of a reservoir power station based on virtual reservoir bidding

Compared with a run-of-river power station, a reservoir power station (RPS), with the capacity of a seasonal regulation function and more, has the unique and irreplaceable attributes of its role in the power grid and society at large. However, under the current power system and market environment in China, these attributes cannot be effectively utilised, resulting in heavy losses to enterprises. It is inevitable for RPSs to participate in the market; therefore, how to improve the profitability of RPS enterprises has become an urgent problem requiring a solution. Based on the control effect on run-off of RPS in a river basin, a new cascade hydropower bidding method and the associated bidding process are proposed. The market entities of the new bidding method are composed of cascade hydropower joints with the RPS as the boundary. The bidding unit benefit-sharing mechanism is constructed, and the accounting method for the benefit-sharing price of the RPS is established, which finally achieves the goal of improving the profitability of the RPS enterprise.

Seasonal regulation of river discharge by the cascade reservoirs in the Lancang River and its effect on downstream freshwater and estuarine saltwater intrusion

This study assesses the seasonal regulation of river discharge by hydropower dam-induced cascade reservoirs in the Lancang River and its effect on downstream freshwater and estuarine saltwater intrusion. There are eight main reservoirs in the Lancang River, with a total regulation capacity of 25.67 billion m3, which regulates river discharge by conserving water in the flood season and releasing water in the dry season. River discharge during the dry season from 1960 to 2009 accounted for 21% of the annual discharge before the cascade reservoirs were constructed and increased to 33% from 2010 to 2015 after the cascade reservoirs were constructed at the Jinghong hydrological station, which is the lowermost station in the Lancang River. During the 2016 extreme drought in the lower Mekong River basin, the river discharge increased by 550, 367, 1283, 969, and 524 m3/s in January, February, March, April, and May, respectively, regulated by the cascade reservoirs at the Jinghong hydrological station. Considering runoff, tides, wind, and continental shelf currents, a high-resolution three-dimensional numerical model was used to simulate the effect of regulation of river discharge by the cascade reservoirs in the Lancang River on the saltwater intrusion in the Mekong River Delta (MRD). The simulation results show that the seasonal regulation of river discharge by the cascade reservoirs in the Lancang River weakens estuarine saltwater intrusion during the dry season, especially in the sand bar areas, which is much more significant in the extreme dry season of 2016. The seasonal regulation of river discharge by the reservoirs in the Lancang River makes the seasonal distribution of downstream river discharge more uniform, favoring downstream freshwater utilization and alleviating flood disasters and saltwater intrusion in the MRD.

Comparative physiology of five tropical montane songbirds reveals differential seasonal acclimatisation and cold adaption

The physiology of tropical birds is poorly understood, particularly in how it relates to local climate and changes between seasons. This is particularly true of tropical montane species, which may have sensitive thermal tolerances to local microclimates. We studied metabolic rates (using open flow respirometry), body mass and haemoglobin concentrations of five sedentary Mesoamerican songbirds between the summer and winter at two elevations (1550 m and 1950 m, respectively). We asked whether there were uniform seasonal shifts in physiological traits across species, and whether higher elevation species displayed evidence for cold tolerance. Seasonal shifts in metabolic rates differed between the three species for which data were collected. Basal metabolic rates in one species – black-headed nightingalethrushes Catharus mexicanus – were up-regulated in summer (~19% increase of winter metabolism), however two other species displayed no seasonal regulation. No species exhibited shifts in haemoglobin concentrations across season or across elevation, whereas body mass in two species was significantly higher in the summer. One species restricted to higher elevations – ruddy-capped nightingale-thrushes C. frantzii – displayed physiological traits indicative of cold-tolerance. Although only summer data were available for this species (C. frantzii), metabolic rates were constant across temperatures tested (5-34°C) and haemoglobin concentrations were significantly higher compared to the other four species. Our results suggest that seasonal acclimatisation in physiological traits is variable between species and appear unrelated to changes in local climate. As such, the distinct physiological traits observed in ruddy-capped nightingale-thrushes likely relate to historic isolation and conserved physiological traits rather than contemporary climatic adaption.