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  • 1
    Online Resource
    Online Resource
    Flexible clock systems: adjusting the temporal programme
    The Royal Society ; 2017
    In:  Philosophical Transactions of the Royal Society B: Biological Sciences Vol. 372, No. 1734 ( 2017-11-19), p. 20160254-
    Details
    In: Philosophical Transactions of the Royal Society B: Biological Sciences, The Royal Society, Vol. 372, No. 1734 ( 2017-11-19), p. 20160254-
    Abstract: Under natural conditions, many aspects of the abiotic and biotic environment vary with time of day, season or even era, while these conditions are typically kept constant in laboratory settings. The timing information contained within the environment serves as critical timing cues for the internal biological timing system, but how this system drives daily rhythms in behaviour and physiology may also depend on the internal state of the animal. The disparity between timing of these cues in natural and laboratory conditions can result in substantial differences in the scheduling of behaviour and physiology under these conditions. In nature, temporal coordination of biological processes is critical to maximize fitness because they optimize the balance between reproduction, foraging and predation risk. Here we focus on the role of peripheral circadian clocks, and the rhythms that they drive, in enabling adaptive phenotypes. We discuss how reproduction, endocrine activity and metabolism interact with peripheral clocks, and outline the complex phenotypes arising from changes in this system. We conclude that peripheral timing is critical to adaptive plasticity of circadian organization in the field, and that we must abandon standard laboratory conditions to understand the mechanisms that underlie this plasticity which maximizes fitness under natural conditions. This article is part of the themed issue ‘Wild clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals’.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    URL: Article
    DOI: 10.1098/rstb.2016.0254
    RVK:
    WA 15000
    Language: English
    Publisher: The Royal Society
    Publication Date: 2017
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  • 2
    Online Resource
    Online Resource
    Diurnality as an energy-saving strategy: energetic consequences of temporal niche switching in small mammals
    The Company of Biologists ; 2015
    In:  Journal of Experimental Biology Vol. 218, No. 16 ( 2015-08-01), p. 2585-2593
    Details
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 218, No. 16 ( 2015-08-01), p. 2585-2593
    Abstract: Endogenous daily (circadian) rhythms allow organisms to anticipate daily changes in the environment. Most mammals are specialized to be active during the night (nocturnal) or day (diurnal). However, typically nocturnal mammals become diurnal when energetically challenged by cold or hunger. The circadian thermo-energetics (CTE) hypothesis predicts that diurnal activity patterns reduce daily energy expenditure (DEE) compared with nocturnal activity patterns. Here, we tested the CTE hypothesis by quantifying the energetic consequences of relevant environmental factors in mice. Under natural conditions, diurnality reduces DEE by 6–10% in energetically challenged mice. Combined with night-time torpor, as observed in mice under prolonged food scarcity, DEE can be reduced by ∼20%. The dominant factor determining the energetic benefit of diurnality is thermal buffering provided by a sheltered resting location. Compared with nocturnal animals, diurnal animals encounter higher ambient temperatures during both day and night, leading to reduced thermogenesis costs in temperate climates. Analysis of weather station data shows that diurnality is energetically beneficial on almost all days of the year in a temperate climate region. Furthermore, diurnality provides energetic benefits at all investigated geographical locations on European longitudinal and latitudinal transects. The reduction of DEE by diurnality provides an ultimate explanation for temporal niche switching observed in typically nocturnal small mammals under energetically challenging conditions. Diurnality allows mammals to compensate for reductions in food availability and temperature as it reduces energetic needs. The optimal circadian organization of an animal ultimately depends on the balance between energetic consequences and other fitness consequences of the selected temporal niche.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.119354
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2015
    detail.hit.zdb_id: 1482461-9
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  • 3
    Online Resource
    Online Resource
    The flexible clock: predictive and reactive homeostasis, energy balance and the circadian regulation of sleep–wake timing
    The Company of Biologists ; 2017
    In:  Journal of Experimental Biology Vol. 220, No. 5 ( 2017-03-01), p. 738-749
    Details
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 220, No. 5 ( 2017-03-01), p. 738-749
    Abstract: The Darwinian fitness of mammals living in a rhythmic environment depends on endogenous daily (circadian) rhythms in behavior and physiology. Here, we discuss the mechanisms underlying the circadian regulation of physiology and behavior in mammals. We also review recent efforts to understand circadian flexibility, such as how the phase of activity and rest is altered depending on the encountered environment. We explain why shifting activity to the day is an adaptive strategy to cope with energetic challenges and show how this can reduce thermoregulatory costs. A framework is provided to make predictions about the optimal timing of activity and rest of non-model species for a wide range of habitats. This Review illustrates how the timing of daily rhythms is reciprocally linked to energy homeostasis, and it highlights the importance of this link in understanding daily rhythms in physiology and behavior.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.130757
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2017
    detail.hit.zdb_id: 1482461-9
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  • 4
    Online Resource
    Online Resource
    Binge Alcohol Drinking Alters Synaptic Processing of Executive and Emotional Information in Core Nucleus Accumbens Medium Spiny Neurons
    Frontiers Media SA ; 2021
    In:  Frontiers in Cellular Neuroscience Vol. 15 ( 2021-11-16)
    Details
    In: Frontiers in Cellular Neuroscience, Frontiers Media SA, Vol. 15 ( 2021-11-16)
    Abstract: The nucleus accumbens (NAc) is a forebrain region mediating the positive-reinforcing properties of drugs of abuse, including alcohol. It receives glutamatergic projections from multiple forebrain and limbic regions such as the prefrontal cortex (PFCx) and basolateral amygdala (BLA), respectively. However, it is unknown how NAc medium spiny neurons (MSNs) integrate PFCx and BLA inputs, and how this integration is affected by alcohol exposure. Because progress has been hampered by the inability to independently stimulate different pathways, we implemented a dual wavelength optogenetic approach to selectively and independently stimulate PFCx and BLA NAc inputs within the same brain slice. This approach functionally demonstrates that PFCx and BLA inputs synapse onto the same MSNs where they reciprocally inhibit each other pre-synaptically in a strict time-dependent manner. In alcohol-naïve mice, this temporal gating of BLA-inputs by PFCx afferents is stronger than the reverse, revealing that MSNs prioritize high-order executive processes information from the PFCx. Importantly, binge alcohol drinking alters this reciprocal inhibition by unilaterally strengthening BLA inhibition of PFCx inputs. In line with this observation, we demonstrate that in vivo optogenetic stimulation of the BLA, but not PFCx, blocks binge alcohol drinking escalation in mice. Overall, our results identify NAc MSNs as a key integrator of executive and emotional information and show that this integration is dysregulated during binge alcohol drinking.
    Type of Medium: Online Resource
    ISSN: 1662-5102
    URL: Article
    DOI: 10.3389/fncel.2021.742207
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2452963-1
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  • 5
    Online Resource
    Online Resource
    Temporal niche switching and reduced nest attendance in response to heat dissipation limits in lactating common voles (Microtus arvalis)
    Elsevier BV ; 2014
    In:  Physiology & Behavior Vol. 128 ( 2014-04), p. 295-302
    Details
    In: Physiology & Behavior, Elsevier BV, Vol. 128 ( 2014-04), p. 295-302
    Type of Medium: Online Resource
    ISSN: 0031-9384
    URL: Article
    DOI: 10.1016/j.physbeh.2014.01.019
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
    detail.hit.zdb_id: 2008755-X
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  • 6
    Online Resource
    Online Resource
    Dim light in the evening causes coordinated realignment of circadian rhythms, sleep, and short-term memory
    Proceedings of the National Academy of Sciences ; 2021
    In:  Proceedings of the National Academy of Sciences Vol. 118, No. 39 ( 2021-09-28)
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 118, No. 39 ( 2021-09-28)
    Abstract: Light provides the primary signal for entraining circadian rhythms to the day/night cycle. In addition to rods and cones, the retina contains a small population of photosensitive retinal ganglion cells (pRGCs) expressing the photopigment melanopsin (OPN4). Concerns have been raised that exposure to dim artificial lighting in the evening (DLE) may perturb circadian rhythms and sleep patterns, and OPN4 is presumed to mediate these effects. Here, we examine the effects of 4-h, 20-lux DLE on circadian physiology and behavior in mice and the role of OPN4 in these responses. We show that 2 wk of DLE induces a phase delay of ∼2 to 3 h in mice, comparable to that reported in humans. DLE-induced phase shifts are unaffected in Opn4 −/− mice, indicating that rods and cones are capable of driving these responses in the absence of melanopsin. DLE delays molecular clock rhythms in the heart, liver, adrenal gland, and dorsal hippocampus. It also reverses short-term recognition memory performance, which is associated with changes in preceding sleep history. In addition, DLE modifies patterns of hypothalamic and cortical cFos signals, a molecular correlate of recent neuronal activity. Together, our data show that DLE causes coordinated realignment of circadian rhythms, sleep patterns, and short-term memory process in mice. These effects are particularly relevant as DLE conditions―due to artificial light exposure―are experienced by the majority of the populace on a daily basis.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2101591118
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
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  • 7
    Online Resource
    Online Resource
    Data_Sheet_1.docx
    Frontiers Media SA ; 2022
    In:  Frontiers in Cellular Neuroscience Vol. 16 ( 2022-12-15)
    Details
    In: Frontiers in Cellular Neuroscience, Frontiers Media SA, Vol. 16 ( 2022-12-15)
    Abstract: Animals studies support the notion that striatal cholinergic interneurons (ChIs) play a central role in basal ganglia function by regulating associative learning, reward processing, and motor control. In the nucleus accumbens (NAc), a brain region that mediates rewarding properties of substance abuse, acetylcholine regulates glutamatergic, dopaminergic, and GABAergic neurotransmission in naïve mice. However, it is unclear how ChIs orchestrate the control of these neurotransmitters/modulators to determine the synaptic excitability of medium spiny neurons (MSNs), the only projecting neurons that translate accumbens electrical activity into behavior. Also unknown is the impact of binge alcohol drinking on the regulation of dopamine D1- and D2 receptor-expressing MSNs (D1- and D2-MSNs, respectively) by ChIs. To investigate this question, we optogenetically stimulated ChIs while recording evoked and spontaneous excitatory postsynaptic currents (sEPSCs) in nucleus accumbens core D1- and D2-MSN of ChAT.ChR2.eYFPxDrd1.tdtomato mice. In alcohol-naïve mice, we found that stimulating NAc ChIs decreased sEPSCs frequency in both D1- and D2-MSNs, presumably through a presynaptic mechanism. Interestingly, ChI stimulation decreased MSN synaptic excitability through different mechanisms in D1- vs. D2-MSNs. While decrease of ChI-mediated sEPSCs frequency in D1-MSNs was mediated by dopamine, the same effect in D2-MSNs resulted from a direct control of glutamate release by ChIs. Interestingly, after 2 weeks of binge alcohol drinking, optogenetic stimulation of ChIs enhanced glutamate release in D1-MSNs, while its effect on D2-MSNs remained unchanged. Taken together, these data suggest that cholinergic interneurons could be a key target for regulation of NAc circuitry and for alcohol consumption.
    Type of Medium: Online Resource
    ISSN: 1662-5102
    URL: Article
    URL: Article
    DOI: 10.3389/fncel.2022.1010121
    DOI: 10.3389/fncel.2022.1010121.s001
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
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  • 8
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    Online Resource
    Cell-Type-Specific Circadian Bioluminescence Rhythms in Dbp Reporter Mice
    SAGE Publications ; 2022
    In:  Journal of Biological Rhythms Vol. 37, No. 1 ( 2022-02), p. 53-77
    Details
    In: Journal of Biological Rhythms, SAGE Publications, Vol. 37, No. 1 ( 2022-02), p. 53-77
    Abstract: Circadian rhythms are endogenously generated physiological and molecular rhythms with a cycle length of about 24 h. Bioluminescent reporters have been exceptionally useful for studying circadian rhythms in numerous species. Here, we report development of a reporter mouse generated by modification of a widely expressed and highly rhythmic gene encoding D-site albumin promoter binding protein ( Dbp). In this line of mice, firefly luciferase is expressed from the Dbp locus in a Cre recombinase-dependent manner, allowing assessment of bioluminescence rhythms in specific cellular populations. A mouse line in which luciferase expression was Cre-independent was also generated. The Dbp reporter alleles do not alter Dbp gene expression rhythms in liver or circadian locomotor activity rhythms. In vivo and ex vivo studies show the utility of the reporter alleles for monitoring rhythmicity. Our studies reveal cell-type-specific characteristics of rhythms among neuronal populations within the suprachiasmatic nuclei ex vivo. In vivo studies show Dbp-driven bioluminescence rhythms in the liver of Albumin-Cre;Dbp KI/+ “liver reporter” mice. After a shift of the lighting schedule, locomotor activity achieved the proper phase relationship with the new lighting cycle more rapidly than hepatic bioluminescence did. As previously shown, restricting food access to the daytime altered the phase of hepatic rhythmicity. Our model allowed assessment of the rate of recovery from misalignment once animals were provided with food ad libitum. These studies confirm the previously demonstrated circadian misalignment following environmental perturbations and reveal the utility of this model for minimally invasive, longitudinal monitoring of rhythmicity from specific mouse tissues.
    Type of Medium: Online Resource
    ISSN: 0748-7304 , 1552-4531
    URL: Article
    DOI: 10.1177/07487304211069452
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2018064-0
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  • 9
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    Methods for Detecting PER2:LUCIFERASE Bioluminescence Rhythms in Freely Moving Mice
    SAGE Publications ; 2022
    In:  Journal of Biological Rhythms Vol. 37, No. 1 ( 2022-02), p. 78-93
    Details
    In: Journal of Biological Rhythms, SAGE Publications, Vol. 37, No. 1 ( 2022-02), p. 78-93
    Abstract: Circadian rhythms are driven by daily oscillations of gene expression. An important tool for studying cellular and tissue circadian rhythms is the use of a gene reporter, such as bioluminescence from the reporter gene luciferase controlled by a rhythmically expressed gene of interest. Here we describe methods that allow measurement of circadian bioluminescence from a freely moving mouse housed in a standard cage. Using a LumiCycle In Vivo (Actimetrics), we determined conditions that allow detection of circadian rhythms of bioluminescence from the PER2 reporter, PER2::LUC, in freely behaving mice. The LumiCycle In Vivo applies a background subtraction that corrects for effects of room temperature on photomultiplier tube (PMT) output. We tested delivery of d-luciferin via a subcutaneous minipump and in the drinking water. We demonstrate spikes in bioluminescence associated with drinking bouts. Further, we demonstrate that a synthetic luciferase substrate, CycLuc1, can support circadian rhythms of bioluminescence, even when delivered at a lower concentration than d-luciferin, and can support longer-term studies. A small difference in phase of the PER2::LUC bioluminescence rhythms, with females phase leading males, can be detected with this technique. We share our analysis scripts and suggestions for further improvements in this method. This approach will be straightforward to apply to mice with tissue-specific reporters, allowing insights into responses of specific peripheral clocks to perturbations such as environmental or pharmacological manipulations.
    Type of Medium: Online Resource
    ISSN: 0748-7304 , 1552-4531
    URL: Article
    DOI: 10.1177/07487304211062829
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2018064-0
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  • 10
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    Online Resource
    Ambient temperature shapes reproductive output during pregnancy and lactation in the common vole ( Microtus arvalis ): a test of the heat dissipation limit theory
    The Company of Biologists ; 2011
    In:  Journal of Experimental Biology Vol. 214, No. 1 ( 2011-01-01), p. 38-49
    Details
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 214, No. 1 ( 2011-01-01), p. 38-49
    Abstract: The heat dissipation limit theory suggests that heat generated during metabolism limits energy intake and, thus, reproductive output. Experiments in laboratory strains of mice and rats, and also domestic livestock generally support this theory. Selection for many generations in the laboratory and in livestock has increased litter size or productivity in these animals. To test the wider validity of the heat dissipation limit theory, we studied common voles (Microtus arvalis), which have small litter sizes by comparison with mice and rats, and regular addition of wild-caught individuals of this species to our laboratory colony ensures a natural genetic background. A crossover design of ambient temperatures (21 and 30°C) during pregnancy and lactation was used. High ambient temperature during lactation decreased milk production, slowing pup growth. The effect on pup growth was amplified when ambient temperature was also high during pregnancy. Shaving fur off dams at 30°C resulted in faster growth of pups; however, no significant increase in food intake and or milk production was detected. With increasing litter size (natural and enlarged), asymptotic food intake during lactation levelled off in the largest litters at both 21 and 30°C. Interestingly, the effects of lactation temperature on pup growth where also observed at smaller litter sizes. This suggests that vole dams trade-off costs associated with hyperthermia during lactation with the yield from investment in pup growth. Moreover, pup survival was higher at 30°C, despite lower growth, probably owing to thermoregulatory benefits. It remains to be seen how the balance is established between the negative effect of high ambient temperature on maternal milk production and pup growth (and/or future reproduction of the dam) and the positive effect of high temperatures on pup survival. This balance ultimately determines the effect of different ambient temperatures on reproductive success.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    URL: Article
    DOI: 10.1242/jeb.044230
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2011
    detail.hit.zdb_id: 1482461-9
    SSG: 12
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