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Topic: Photoperiodic

In the News (Thu 16 Feb 12)

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	Frontiers in Zoology \| Full text \| Control of annual reproductive cycle in the subtropical house sparrow (Passer ...
		The role of day length (=photoperiod) in control of the initiation and termination of events associated with seasonal reproduction is shown in a number of species breeding both at high and low latitudes [for references see [1-9]].
		The photoperiodic entrainment of the circadian rhythmicity, which can be different under different zeitgeber conditions, sets the timing of the photoinductible phase [60], and the interaction of the latter with the light regulates gonad development cycle in photoperiodic birds [12,31-33].
		It appears that increasing photoperiods induce initial slow growth phase and not the final fast or exponential growth phase of ovary, which is influenced by supplementary factors [1,43]; full reproductive competence in females is often determined by the stimuli from mate, nest site and food availability [8,61-63].
	www.frontiersinzoology.com /content/3/1/12 (7447 words)

	Photoperiodic information acquired and stored in vivo is retained in vitro by a circadian oscillator, the avian pineal ...
		Photoperiodic information acquired and stored in vivo is retained in vitro by a circadian oscillator, the avian pineal gland -- Brandstätter et al.
		Photoperiodic information acquired and stored in vivo is retained in vitro by a circadian oscillator, the avian pineal gland
		Photoperiodic patterns imposed on house sparrows during in vivo synchronization additionally modulated in vitro melatonin
	www.pnas.org /cgi/content/full/97/22/12324 (3643 words)

	Photoperiodic response of pea aphid Acyrthosiphon pisum
		Exposure of pea aphids to diel photoperiods with photophase from 0 to 24 hours reveals the photoperiodic response of the long-day type, determining female morph and sex of the offspring and, also, fecundity and duration of reproduction.
		The distinctions between the photoperiodic responses and peculiarities of reproduction in apterous and alate viviparous females are described and assumed to be related to the different ecological roles of these female morphs in the population (1999b, 2003).
		Yerlykova N.N. Peculiarities of the photoperiodic response of unisexual clone of pea aphid Acyrthosiphon pisum Harris (Homoptera, Aphididae).
	www.zin.ru /labs/expent/pr_acyrt.html (532 words)

	BioMed Central \| Full text \| Seasonal ovulatory activity exists in tropical Creole female goats and Black Belly ewes ...
		It is known that light changes during pregnancy may affect the progeny's photoperiod sensitivity, especially regarding the onset of puberty in sheep [23-25] and in rodents [26].
		The spontaneous ovulatory activity demonstrated in the present experiment by the Black-Belly ewes from the TR group were very different from those registered earlier in their natural breeding conditions on the island of Martinique in the tropics, where they cycled all year round [15].
		The Creole goats from the simulated tropical photoperiod did not display here the same results as females of the same flock raised in their natural breeding conditions on the island of Guadeloupe in the tropics, where they also cycled almost continuously [17].
	www.biomedcentral.com /1472-6793/4/12 (5063 words)

	Reproductive Biology and Endocrinology \| Full text \| Melatonin blocks inhibitory effects of prolactin on photoperiodic ...
		For example, photoperiodically induced rise in LH coincides with the onset of breeding [1,2], and rise in prolactin coincides with the late breeding and early post-breeding periods [4,5].
		We propose that the role of melatonin in avian photoperiodism is indirect.
		We sought to investigate this by examining the effects of exogenous melatonin on prolactin-induced suppression of photoperiodic response in a migratory bird species, the redheaded bunting (Emberiza bruniceps), in which melatonin is not directly involved in the photoperiodic time measurement based on circadian rhythm of photosensitivity [22,23].
	www.rbej.com /content/2/1/79 (4528 words)

	Interaction Between Photoperiod and an Endogenous Seasonal Factor in Influencing the Diel Locomotor Activity of the ...
		photoperiod was spontaneous and, irrespective of the experimental
		The influence of photoperiod on oocyte growth and its role in the control of the reproductive cycle of the polychaete Harmothoe imbricata (L).
		Photoperiod induced phase shifts of the endogenous clock controlling reproduction in the rainbow trout: a circannual phase response curve.
	www.biolbull.org /cgi/content/full/206/2/103 (4341 words)

	Photoperiodic control of seasonal development and dormancy in tropical stem-succulent trees
		These observations suggested that endo-dormancy and bud break might be induced by declining and increasing photoperiods after the autumn and spring equinoxes, respectively.
		Conversely, exposure to a 13-h photoperiod induced bud break of dormant apical buds in saplings and cuttings in January, whereas plants maintained in the natural day length of < 11.7 h remained dormant.
		Photoperiodic control of endo-dormancy of vegetative buds in stem succulents is thus supported by field observations and experimental variation of the photoperiod.
	heronpublishing.com /tree/summaries/volume21/a21-213.html (342 words)

	Conflicting effects of exercise on the establishment of a short-photoperiod phenotype in Syrian hamster -- Menet et al. ...
		Indeed, the integration of the photoperiodic change by the SCN is accelerated when hamsters have free access to a wheel.
		Photoperiod differentially regulates the expression of Per1 and ICER in the pars tuberalis and the suprachiasmatic nucleus of the Siberian hamster.
		Pineal melatonin in the Djungarian hamster: photoperiodic regulation of a circadian rhythm.
	ajpregu.physiology.org /cgi/content/full/288/1/R234 (5648 words)

	hydro-electric integration of the higher plant
		The amphiphotoperiodic response in B is modified to day neutral by changing the temperature from 20 to 12° C. These data clearly indicate that photoperiodic behavior is extremely fleixible in adapting to specific environmental conditions.
		The phytochrome photoreceptors, involved in photoperiodic control of development, could via changes in pyridine nucleotide pool sizes and changes in nucleotide ratios regulate transcription-translational loops by redox and phosphorylation controlled transcription factors.
		This is the basis for the evolution of latitudinal ecotypes of Chenopodium rubrum with specific period lengths for their circadian rhythms and the division of the circadian cycle in a photophile- and scotophile-element that is specific for photoperiodic control.
	www.biologie.uni-freiburg.de /data/bio2/wagner/wagfor1d.html (1350 words)

	Photoperiodic Effects on Gonadotropin-Releasing Hormone (GnRH) Content and the GnRH-Immunoreactive Neuronal System of ...
		Alterations in neuroendocrine function during photoperiod induced testicular atrophy and recrudescence in the golden hamster.
		Photoperiod and steroid-dependent adjustments in hypothalamic gonadotropic hormone-releasing hormone, dopamine, and norepinephrine content in male deer mice.
		Photoperiodic Regulation of Histamine H3 Receptor and VGF Messenger Ribonucleic Acid in the Arcuate Nucleus of the Siberian Hamster
	www.biolreprod.org /cgi/content/full/60/2/272 (3744 words)

	Photoperiodically Driven Changes in Fos Expression within the Basal Tuberal Hypothalamus and Median Eminence of ...
		Ensuring that tuberal hypothalamus activation is caused by photoperiodic induction and is not a consequence of the bird being
		Lee W, Watanabe M, Glass JD (1995) Photoperiod affects the expression of neural cell adhesion molecule and polysialic acid in the hypothalamus of the siberian hamster.
		Meddle SL, Follett BK (1995b) Activation of the basal tuberal hypothalamus of castrated Japanese quail preceding photoperiodically driven luteinising hormone (LH) release.
	www.jneurosci.org /cgi/content/full/17/22/8909 (7437 words)

	Porphyra growth and photoperiod
		The release of conchospores from conchosporangia is triggered by short photoperiods with slightly less than 12 hours of light.
		The effects of photoperiod are also crucial in the release of conchospores from the Conchocelis stage.
		The response to photoperiod may have evolved as a result to ensure survival in a volatile environment.
	www.mbari.org /staff/conn/botany/reds/lisa/pperiod.htm (403 words)

	Phytochrome mediates the external light signal to repress FT orthologs in photoperiodic flowering of rice -- Izawa et ...
		SE1 is the sole output of circadian clocks in the photoperiodic
		Phase setting of circadian clocks is determined by both light-on and light-off signals, whereas the decrease in levels of the Pfr form starts with the light-off signal.
		For flowering-time measurements, sterile seeds were germinated in the chamber with given photoperiod conditions until flowering.
	www.genesdev.org /cgi/content/full/16/15/2006 (7941 words)

	JONATHAN D JOHNSTON: Photoperiodic prolactin secretion (Journal of Endocrinology)
		2003 Photoperiod differentially regulates circadian oscillators in central and peripheral tissues of the Syrian hamster.
		Steger RW and Bartke A. 1991 Temporal sequence of neuroendocrine events associated with the transfer of male golden hamsters from a stimulatory to a nonstimulatory photoperiod.
		2001 Photoperiodic regulation of prolactin gene expression in the Syrian hamster by a pars tuberalis-derived factor.
	journals.endocrinology.org /joe/180/0351/joe1800351.htm (1082 words)

	Importance of Photoperiodic Signal Quality to Entrainment of the Circannual Reproductive Rhythm of the Ewe -- Barrell ...
		Photoperiodic requirements for timing onset and duration of the breeding season of the ewe.
		Importance of changing photoperiod and melatonin secretory pattern in determining the length of the breeding season in the Suffolk ewe.
		Photoperiodism in the Japanese quail: the termination of seasonal breeding by photorefractoriness.
	www.biolreprod.org /cgi/content/full/63/3/769 (3563 words)

	THE INFLUENCE OF TIMING AND DURATION OF PHOTOPERIODIC LIGHTING ON THE WINTER FLOWERING OF CARNATIONS
		The carnation stands, which bore 180–200 shoots carrying 3–7 pairs of leaves, were given photoperiodic lighting between 5 August and 8 September in treatments where the starting time and duration were varied.
		Within the first croppin period, the photoperiodic lighting influenced the quantitative distribution of productivity in all treatments by reducing the October production but increasing that of December.
		The quantity of blooms produced during November, January or February was, depending on the starting time and duration of the photoperiodic treatment, either increased or influenced insignificantly by it.
	www.actahort.org /books/71/71_11.htm (213 words)

	Karen A. Hicks (Site not responding. Last check: 2007-11-04)
		Daylength, or photoperiod, affects the onset of reproductive development in many flowering plants, and the mechanism of this regulation is thought to involve an internal biological clock.
		We are using a genetic approach to elucidate the mechanism of photoperiodic flowering in Arabidopsis thaliana, a model plant that is a member of the mustard family.
		Current projects include the isolation and characterization of mutants that are altered in photoperiodic regulation of flowering, and the mapping and positional cloning of new genes identified by mutation.
	biology.kenyon.edu /hicks/hickshome.htm (1827 words)

	A Blog Around The Clock : Clock Tutorial #16: Photoperiodism - Models and Experimental Approaches
		Although not the only parameter, the changing length of the photoperiod ('daylength') is the most predictive environmental cue for the seasonal timing of physiology and behavior, most notably for timing of migration, hibernation and reproduction.
		However, in skeleton photoperiods, it is often impossible to mimic long photoperiods as the circadian system tends to entrain to the shorter of the two possible interpretations of the skeleton photoperiods.
		Various experimental paradigms, including skeleton photoperiods and resonance cycles, demonstrated that it is not the total amount of light, but the precise temporal placing of the light that induces the photoperiodic response, giving the circadian system a role in the measurement and interpretation of daylength.
	scienceblogs.com /clock/2006/08/clock_tutorial_16_photoperiodi.php (2247 words)

	Genetic shift in photoperiodic response correlated with global warming -- Bradshaw and Holzapfel, ...
		We estimated critical photoperiod in populations collected in 1972 and 1996 by using static daylengths.
		We estimated critical photoperiod in populations collected in 1988 and 1993 by using changing daylengths.
		Evolutionary Divergence of Circadian and Photoperiodic Phenotypes in the Pitcher-Plant Mosquito, Wyeomyia smithii.
	www.pnas.org /cgi/content/full/241391498v1 (2406 words)

	Maternal transfer of photoperiodic information in Siberian hamsters. II. The nature of the maternal signal, time of ... (Site not responding. Last check: 2007-11-04)
		Development was examined in several photoperiods following manipulation of gestational and lactational photoperiods; development was influenced by the gestational, but not lactational, photoperiod.
		Second, effects of the gestational photoperiod were observed in young reared in constant light (LL) from Day 15.
		Depriving the young of ambient photoperiodic information after Day 15 allows a more direct assessment of the signal received from their dams.
	www.arclab.org /medlineupdates/abstract_2758085.html (253 words)

	HIOMT drives the photoperiodic changes in the amplitude of the melatonin peak of the Siberian hamster -- Ribelayga et ...
		HIOMT drives the photoperiodic changes in the amplitude of the melatonin peak of the Siberian hamster -- Ribelayga et al.
		The previous observations demonstrate that photoperiodic changes in the amplitude of the nocturnal peak of Mel are not related
		Cloning and expression of serotonin N-acetyltransferase (NAT) in photoperiodic Siberian hamsters.
	ajpregu.physiology.org /cgi/content/full/278/5/R1339 (4497 words)

	EFFECTS OF DURATION AND TIME OF FOOD AVAILABILITY ON PHOTOPERIODIC RESPONSES IN THE MIGRATORY MALE BLACKHEADED BUNTING ...
		It entrains the circadian rhythm of photoperiodic photosensitivity
		Kumar, V. and Tewary, P. Response to experimental photoperiods by a migratory bunting, Emberiza melanocephala.
		Tewary, P. and Kumar, V. Photoperiodic responses of a subtropical migratory finch, the flheaded bunting (Emberiza melanocephala).
	jeb.biologists.org /cgi/content/full/204/16/2843 (3813 words)

	RESEARCH OVERVIEW
		In many plant species, this developmental transition is regulated by photoperiod as shown in this model of photoperiodic floral induction in a typical short-day plant.
		The recent discovery of multiple genes encoding phytochrome has renewed an interest in the role of phytochrome in photoperiodic floral induction and has raised the intriguing possibility that one or more of these phytochromes may be specifically involved in the photoperiodic timekeeping mechanism that underlies floral induction.
		In mammals, melatonin has been determined to function as a "night signal" or "hormone of darkness" in that this molecule appears to be the primary chemical messenger regulating photoperiodic phenomena.
	www-plb.ucdavis.edu /labs/oneill/researchdesc.html (932 words)

	Photoperiodic effects on body mass, energy balance and hypothalamic gene expression in the bank vole -- Peacock et al. ...
		Photoperiodic effects on body mass, energy balance and hypothalamic gene expression in the bank vole -- Peacock et al.
		Data for short-day photoperiod (SD) females and LD individuals are expressed as a percent of the level in SD males, and presented as means ±
		Photoperiod regulates arcuate nucleus POMC, AGRP, and leptin receptor mRNA in Siberian hamster hypothalamus.
	jeb.biologists.org /cgi/content/full/207/1/165 (6204 words)

	Short photoperiod inhibition of growth in body mass and reproduction in ACI, BUF, and PVG inbred rats -- Francisco et ...
		Short photoperiod inhibition of growth in body mass and reproduction in ACI, BUF, and PVG inbred rats -- Francisco et al.
		Johnston PG and Zucker I 1979 Photoperiodic influences on gonadal development and maintenance in the cotton rat, Sigmodon hispidus.
		Wallen EP and Turek FW 1981 Photoperiodicity in the male albino laboratory rat.
	www.reproduction-online.org /cgi/content/full/128/6/857 (2805 words)

	Accumulation of a Clock-Regulated Transcript during Flower-Inductive Darkness in Pharbitis nil -- Sage-Ono et al. 116 ...
		To clarify the molecular basis of the photoperiodic induction of flowering in the short-day plant Pharbitis nil cv Violet,
		Recent studies of Arabidopsis have demonstrated the importance of molecules that are present at low levels in the photoperiodic
		Imamura S (1967) Photoperiodic induction and the floral stimulus.
	www.plantphysiol.org /cgi/content/full/116/4/1479 (4316 words)

	FKF1 is essential for photoperiodic-specific light signalling in Arabidopsis : Nature (Site not responding. Last check: 2007-11-04)
		Day-length assessment involves the photoperiodic control of flowering in Arabidopsis thaliana, whereby the coincidence of light and high expression of CONSTANS (CO) induces the expression of FLOWERING LOCUS T (FT), leading to flowering in long-day conditions
		Although controlling CO expression is clearly a key step in day-length discrimination, the mechanism that generates day-length-dependent CO expression remains unknown.
		It is likely that the circadian control of FKF1 expression and the light regulation of FKF1 function coincide to control the daytime CO waveform precisely, which in turn is crucial for day-length discrimination by Arabidopsis.
	www.nature.com /doifinder/10.1038/nature02090 (299 words)

	Shortened Seasonal Photoperiodic Cycles Accelerate Aging of the Diurnal and Circadian Locomotor Activity Rhythms in a ...
		Shortened Seasonal Photoperiodic Cycles Accelerate Aging of the Diurnal and Circadian Locomotor Activity Rhythms in a Primate -- Cayetanot et al.
		Shortened Seasonal Photoperiodic Cycles Accelerate Aging of the Diurnal and Circadian Locomotor Activity Rhythms in a Primate
		photoperiodic rhythm ("annual" duration of 5 months) in accelerated
	jbr.sagepub.com /cgi/content/abstract/20/5/461 (372 words)

	Photoperiodic Regulation of Seasonal Breeding in Birds -- SHARP 1040 (1): 189 -- Annals of the New York Academy of ...
		Photoperiodic Regulation of Seasonal Breeding in Birds -- SHARP 1040 (1): 189 -- Annals of the New York Academy of Sciences
		pineal gland is not essential for the reproductive photoperiodic
		The current model of the avian photoperiodic response
	www.annalsnyas.org /cgi/content/abstract/1040/1/189 (323 words)

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