Persistent Cell-Autonomous Circadian Oscillations in Fibroblasts Revealed by Six-Week Single-Cell Imaging of PER2::LUC Bioluminescence

Biological oscillators naturally exhibit stochastic fluctuations in period and amplitude due to the random nature of molecular reactions. Accurately measuring the precision of noisy oscillators and the heterogeneity in period and strength of rhythmicity across a population of cells requires single-cell recordings of sufficient length to fully represent the variability of oscillations. We found persistent, independent circadian oscillations of clock gene expression in 6-week-long bioluminescence recordings of 80 primary fibroblast cells dissociated from PER2::LUC mice and kept in vitro for 6 months. Due to the stochastic nature of rhythmicity, the proportion of cells appearing rhythmic increases with the length of interval examined, with 100% of cells found to be rhythmic when using 3-week windows. Mean period and amplitude are remarkably stable throughout the 6-week recordings, with precision improving over time. For individual cells, precision of period and amplitude are correlated with cell size and rhythm amplitude, but not with period, and period exhibits much less cycle-to-cycle variability (CV 7.3%) than does amplitude (CV 37%). The time series are long enough to distinguish stochastic fluctuations within each cell from differences among cells, and we conclude that the cells do exhibit significant heterogeneity in period and strength of rhythmicity, which we measure using a novel statistical metric. Furthermore, stochastic modeling suggests that these single-cell clocks operate near a Hopf bifurcation, such that intrinsic noise enhances the oscillations by minimizing period variability and sustaining amplitude

Ih Current Is Necessary to Maintain Normal Dopamine Fluctuations and Sleep Consolidation in Drosophila

HCN channels are becoming pharmacological targets mainly in cardiac diseases. But apart from their well-known role in heart pacemaking, these channels are widely expressed in the nervous system where they contribute to the neuron firing pattern. Consequently, abolishing Ih current might have detrimental consequences in a big repertoire of behavioral traits. Several studies in mammals have identified the Ih current as an important determinant of the firing activity of dopaminergic neurons, and recent evidences link alterations in this current to various dopamine-related disorders. We used the model organism Drosophila melanogaster to investigate how lack of Ih current affects dopamine levels and the behavioral consequences in the sleep∶activity pattern. Unlike mammals, in Drosophila there is only one gene encoding HCN channels. We generated a deficiency of the DmIh core gene region and measured, by HPLC, levels of dopamine. Our data demonstrate daily variations of dopamine in wild-type fly heads. Lack of Ih current dramatically alters dopamine pattern, but different mechanisms seem to operate during light and dark conditions. Behaviorally, DmIh mutant flies display alterations in the rest∶activity pattern, and altered circadian rhythms. Our data strongly suggest that Ih current is necessary to prevent dopamine overproduction at dark, while light input allows cycling of dopamine in an Ih current dependent manner. Moreover, lack of Ih current results in behavioral defects that are consistent with altered dopamine levels

Effect of chick weight, geometric mean diameter and sodium level in prestarter diets (1 to 7 days) on broiler perfomance up to 21 days of age

Seven hundred and twenty Ross 308 chicks were raised in a controlled environment room, distributed in a factorial design with 3 hatching chick weights (37, 40 and 44 g), 3 geometric mean diameter (GMD) (0.561; 0.783 and 0.997 mm) and 4 total sodium levels (Na) (0.12; 0.24; 0.36 and 0.48%) in the pre-starter diet (1 to 7 days). From 8 to 21 days (d) one single basal diet was used for all treatments. The thirty seven-gram chicks had the smallest yolk sack weight at 4d, smallest body weight (BW) and feed intake (FI) at 7d and 21d, but the same feed conversion (FC) than the other groups of hatching weight. Chicks receiving diet with intermediate GMD had the greatest BW and FI at 7d, but at 21d this effect was no longer seen. The diet with finest particle size resulted in birds with the smallest gizzard weight at 7d. The 0.12%Na diet was statistically different from the other Na levels, resulting in chicks at 7d with the worst FC and lowest body weights. At 21d, BW still was the lowest for this group of chicks. Birds with 0.48%Na produced more watery excreta and less dry matter in the carcass at 7d. Water consumption (C H2O) was influenced linearly by chick weight up to 0.36%Na level. In the 0.48%Na level, 40 and 44 g chicks had similar C H2O, which was different from 37-g chicks. For best performance, Na values were set from 0.31 to 0.48%. The three studied factors influenced quality of pre-starter diet and consequently chick performance

'Smart Homes'

No Abstract. This Encyclopedia entry notes the origin of smart homes in ‘intelligent buildings’. It tracks a change in focus away from mechanisation, automation and energy usage; towards understandings of the interactions between buildings and their occupants - especially the case with communications technologies and associated devices. There is now a growing realisation of the merit that smart homes can have for older people. This entry points to the potential of smart homes to empower people and facilitate their inclusion within smart cities and communities. In sum the entry strongly argues the case against a narrow, technocratic views of smart homes in order that their physical design and incorporated technologies should facilitate life-long living. The Encyclopedia entry starts with Definition. The term “smart home” has been defined in various ways. A smart home is a concept represented by a dwelling equipped with communication networks, sensors, appliances, and devices that can be remotely monitored, accessed, or controlled and which provides services that respond to specific user needs (Balta-Ozkan et al. 2014). The purpose of those services, through the use of sensors, controls, and actuators, has primarily been in the cause of monitoring and affecting security, controlling temperature, humidity, air quality, and energy usage. Gann et al. (1999), with an eye to a broader role that would support occupants, defined smart homes as “about using the latest information and communications technology to link all the mechanical and digital devices available and create a truly interactive house.” The authors pointed to such homes as not just those that were newly built and with an aim “not to automate for the sake of it but to build up a specification that responds to real needs which people may have.” They identified particular beneficiaries including people with disabilities and older people, also offering a model user specification. ENISA (European Union Agency for Network and Information Security), recognizing the new dimension that is arising on account of artificial intelligence, pointed (2014) to smart homes as “equipped with technology that provides the occupants with comprehensive information about the state of their home and allows them to control all connected devices, including remotely. . . a smart home may also be able to ‘learn’ the preferences of the inhabitants and adapt to them.” In any case, smart homes are increasingly incorporating devices that can support the monitoring or independent living for occupants including older people and persons with different abilities (Majumder et al. 2017). In this broader context, Fisk (2003, p. 179) affirmed that “at its broadest a smart home is one where smart technologies are installed and where those technologies facilitate automatic or user-initiated communication involving a range of appliances,sensors, actuators and switches.” He added that “such communication takes place in ways that can empower people and, in so doing, improve their quality of life.