View of a mouse clock gene ticking

Yamaguchi, Shun; Kobayashi, Masaki; Mitsui, Shigeru; Ishida, Yoshiki; Horst, Gijsbertus T. J. van der; Suzuki, Misao; Shibata, Shigenobu; Okamura, Hitoshi

doi:10.1038/35055628

Cited by 92 publications

(65 citation statements)

References 4 publications

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“…Since imaging of luminescence or fluorescence of transgenic or injected reporter proteins is applicable not only to transcriptional regulation but also to intracellular signalling cascades (Zaccolo et al 2000, Nagai et al 2001, this now raises the possibility of studying intracellular endocrine physiology in populations of normal cells. Ultimately, such studies could extend to in vivo systems, in which viral gene transfer could be followed by luminescence imaging in the intact animal (Yamaguchi et al 2001, Wu et al 2002, providing insight into the temporal regulation of cellular processes during physiological responses at the cellular level.…”

Section: Discussionmentioning

confidence: 99%

Real-time imaging of gene promoter activity using an adenoviral reporter construct demonstrates transcriptional dynamics in normal anterior pituitary cells

Stirland

Seymour

Windeatt

et al. 2003

Journal of Endocrinology

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Although analysis of luciferase activity using luminescence imaging has provided new insights into the dynamic regulation of gene expression in living tissues, studies in vitro have relied on stably transfected clonal cell lines, limiting the choice of cell type and species, or DNA microinjection, which is arduous and highly selective. We report here the first use of a recombinant adenovirus in which the firefly luciferase reporter gene was regulated by the prolactin gene promoter, to study temporal dynamics of promoter activity. This vector was used to infect the pituitary GH3 cell line, and also primary cultures of Syrian hamster pituitary cells. We show that adenovirally transduced cells retained normal regulation of the promoterreporter transgene by appropriate signals. Furthermore, microscopic imaging studies indicated that both clonal and primary pituitary cells were transduced efficiently, giving readily detectable luminescence signals in real-time over long periods. Finally, analysis of single-cell expression patterns indicated that prolactin promoter activity was highly dynamic with pulses in gene expression, revealing that the transcriptional instability seen in clonal cells is a feature of normal pituitary cells. Adenoviral vectors offer a valuable tool for studies of gene regulation where conventional transgenesis and clonal cell lines are not available.

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Section: Discussionmentioning

confidence: 99%

Real-time imaging of gene promoter activity using an adenoviral reporter construct demonstrates transcriptional dynamics in normal anterior pituitary cells

Stirland

Seymour

Windeatt

et al. 2003

Journal of Endocrinology

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“…Therefore, expression of the transgene matched perfectly with the endogenous gene. The system was later on used to monitor circadian gene expression in a living mouse [54]. An optic fiber cord linked to a photomultiplier device was placed just above the SCN.…”

Section: Lessons From Micementioning

confidence: 99%

The daily rhythm of mice

2011

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Edited by Martha Merrow and Michael BrunnerKeywords: Clock mutant mice Metabolism Cancer Neurological disease Mood Obesity a b s t r a c tThe house mouse Mus musculus represents a valuable tool for the analysis and the understanding of the mammalian circadian oscillator. Forward and reverse genetics allowed the identification of clock components and the verification of their function within the circadian clockwork. In many cases unforeseen links were discovered between a particular circadian regulatory protein and various diseases or syndromes. Thus, this model system is not only perfectly suited to pinpoint the components of the mammalian circadian clock, but also to unravel metabolic, physiological, and pathological processes linked to the circadian timing system.

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“…While research on the proximate control of circadian rhythms has made enormous progress during the past decade (e.g. Brandstätter et al 2001;Yamaguchi et al 2001), the mechanisms underlying circannual rhythms are only beginning to be understood (Lincoln et al 2003(Lincoln et al , 2006Kondo et al 2006). wrote: 'The problems [with understanding circannual rhythms] stem partly from our almost complete ignorance of the physiological processes involved in generating circannual rhythmicity.'…”

Section: (D) Proximate Mechanisms Underlying Circannual Rhythmsmentioning

confidence: 99%

Avian circannual clocks: adaptive significance and possible involvement of energy turnover in their proximate control

Wikelski

Martin

Scheuerlein

et al. 2007

Phil. Trans. R. Soc. B

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Endogenous circannual clocks are found in many long-lived organisms, but are best studied in mammal and bird species. Circannual clocks are synchronized with the environment by changes in photoperiod, light intensity and possibly temperature and seasonal rainfall patterns. Annual timing mechanisms are presumed to have important ultimate functions in seasonally regulating reproduction, moult, hibernation, migration, body weight and fat deposition/stores. Birds that live in habitats where environmental cues such as photoperiod are poor predictors of seasons (e.g. equatorial residents, migrants to equatorial/tropical latitudes) rely more on their endogenous clocks than birds living in environments that show a tight correlation between photoperiod and seasonal events. Such population-specific/interspecific variation in reliance on endogenous clocks may indicate that annual timing mechanisms are adaptive. However, despite the apparent adaptive importance of circannual clocks, (i) what specific adaptive value they have in the wild and (ii) how they function are still largely untested. Whereas circadian clocks are hypothesized to be generated by molecular feedback loops, it has been suggested that circannual clocks are either based upon (i) a de-multiplication ('counting') of circadian days, (ii) a sequence of interdependent physiological states, or (iii) one or more endogenous oscillators, similar to circadian rhythms. We tested the de-multiplication of days (i) versus endogenous regulation hypotheses (ii) and (iii) in captive male and female house sparrows (Passer domesticus). We assessed the period of reproductive (testicular and follicular) cycles in four groups of birds kept either under photoperiods of LD 12 L : 12 D (period length: 24 h), 13.5 L : 13.5 D (27 h), 10.5 L : 10.5 D (23 h) or 12 D : 8 L : 3 D : 1 L (24-h skeleton photoperiod), respectively, for 15 months. Contrary to predictions from the de-multiplication hypothesis, individuals experiencing 27-h days did not differ (i.e. did not have longer) annual reproductive rhythms than individuals from the 21-or 24-h day groups. However, in line with predictions from endogenous regulation, birds in the skeleton group had significantly longer circannual period lengths than all other groups. Birds exposed to skeleton photoperiods experienced fewer light hours per year than all other groups (3285 versus 4380) and had a lower daily energy expenditure, as tested during one point of the annual cycle using respirometry. Although our results are tantalizing, they are still preliminary as birds were only studied over a period of 15 months. Nevertheless, the present data fail to support a 'counting of circadian days' and instead support hypotheses proposing whole-organism processes as the mechanistic basis for circannual rhythms. We propose a novel energy turnover hypothesis which predicts a dependence of the speed of the circannual clock on the overall energy expenditure of an organism.

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View of a mouse clock gene ticking

Cited by 92 publications

References 4 publications

Real-time imaging of gene promoter activity using an adenoviral reporter construct demonstrates transcriptional dynamics in normal anterior pituitary cells

Real-time imaging of gene promoter activity using an adenoviral reporter construct demonstrates transcriptional dynamics in normal anterior pituitary cells

The daily rhythm of mice

Avian circannual clocks: adaptive significance and possible involvement of energy turnover in their proximate control

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