共查询到20条相似文献,搜索用时 31 毫秒
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Karl Holm Thomas Källman Niclas Gyllenstrand Harald Hedman Ulf Lagercrantz 《BMC plant biology》2010,10(1):109
Background
The endogenous circadian clock allows the organism to synchronize processes both to daily and seasonal changes. In plants, many metabolic processes such as photosynthesis, as well as photoperiodic responses, are under the control of a circadian clock. Comparative studies with the moss Physcomitrella patens provide the opportunity to study many aspects of land plant evolution. Here we present a comparative overview of clock-associated components and the circadian network in the moss P. patens. 相似文献2.
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Background
Circadian clocks are internal daily time keeping mechanisms that allow organisms to anticipate daily changes in their environment and to organize their behavior and physiology in a coherent schedule. Although circadian clocks use temperature compensation mechanisms to maintain the same pace over a range of temperatures, they are also capable of synchronizing to daily temperature cycles. This study identifies key properties of this process. 相似文献4.
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Diego Forni Uberto Pozzoli Rachele Cagliani Claudia Tresoldi Giorgia Menozzi Stefania Riva Franca R Guerini Giacomo P Comi Elisabetta Bolognesi Nereo Bresolin Mario Clerici Manuela Sironi 《Genome biology》2014,15(10)
Background
The temporal coordination of biological processes into daily cycles is a common feature of most living organisms. In humans, disruption of circadian rhythms is commonly observed in psychiatric diseases, including schizophrenia, bipolar disorder, depression and autism. Light therapy is the most effective treatment for seasonal affective disorder and circadian-related treatments sustain antidepressant response in bipolar disorder patients. Day/night cycles represent a major circadian synchronizing signal and vary widely with latitude.Results
We apply a geographically explicit model to show that out-of-Africa migration, which led humans to occupy a wide latitudinal area, affected the evolutionary history of circadian regulatory genes. The SNPs we identify using this model display consistent signals of natural selection using tests based on population genetic differentiation and haplotype homozygosity. Signals of natural selection driven by annual photoperiod variation are detected for schizophrenia, bipolar disorder, and restless leg syndrome risk variants, in line with the circadian component of these conditions.Conclusions
Our results suggest that human populations adapted to life at different latitudes by tuning their circadian clock systems. This process also involves risk variants for neuropsychiatric conditions, suggesting possible genetic modulators for chronotherapies and candidates for interaction analysis with photoperiod-related environmental variables, such as season of birth, country of residence, shift-work or lifestyle habits.Electronic supplementary material
The online version of this article (doi:10.1186/s13059-014-0499-7) contains supplementary material, which is available to authorized users. 相似文献6.
Ila Mishra 《Biological Rhythm Research》2017,48(5):723-738
AbstractThe two dominant environmental oscillations shape biology and survival of species: the day–night cycle and the succession of the seasons in the year. Organisms have adapted to anticipate these variations by evolving internal circadian (ca.- about, diem- day) and circannual clocks. The former enables the organisms to regulate physiological functions on a daily basis, and the latter on the annual basis. In mammals, the suprachiasmatic nuclei (SCN) of the anterior hypothalamus contain master pacemaker and orchestrate peripheral clocks in synchrony with the daily 24 h light-dark cycle, while in birds circadian pacemake is an interacting system principally located in the retina, pineal and the hypothalamus. In this mini review, we discuss the role of circadian clocks in regulation of seasonal timing in higher vertebrates, with reference to birds and mammals. 相似文献
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Background
In insects, circadian clocks have been implicated in affecting life history traits such as pre-adult development time and adult lifespan. Studies on the period (per) mutants of Drosophila melanogaster, and laboratory-selected lines of Bactrocera cucurbitae suggested a close link between circadian clocks and development time. There is a possibility of clock genes having pleiotropic effects on clock period and pre-adult development time. In order to avoid such pleiotropic effects we have used wild type flies of same genotype under environments of different periodicities, which phenotypically either speeded up or slowed down the eclosion clock of D. melanogaster. 相似文献10.
Insects, like most organisms, have an internal circadian clock that oscillates with a daily rhythmicity, and a timing mechanism
that mediates seasonal events, including diapause. In research published in BMC Biology, Ikeno et al. show that downregulation of the circadian clock genes period and cycle affects expression of ovarian diapause in the insect Riptortus pedestris. They interpret these important results as support for Erwin Bünning's (1936) hypothesis that the circadian clock constitutes
the basis of photoperiodism. However, their observations could also be the result of pleiotropic effects of the individual
clock genes. 相似文献
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《Chronobiology international》2013,30(4):433-451
In the not too distant past, it was common belief that rhythms in the physical environment were the driving force, to which organisms responded passively, for the observed daily rhythms in measurable physiological and behavioral variables. The demonstration that this was not the case, but that both plants and animals possess accurate endogenous time-measuring machinery (i.e., circadian clocks) contributed to heightening interest in the study of circadian biological rhythms. In the last few decades, flourishing studies have demonstrated that most organisms have at least one internal circadian timekeeping device that oscillates with a period close to that of the astronomical day (i.e., 24h). To date, many of the physiological mechanisms underlying the control of circadian rhythmicity have been described, while the improvement of molecular biology techniques has permitted extraordinary advancements in our knowledge of the molecular components involved in the machinery underlying the functioning of circadian clocks in many different organisms, man included. In this review, we attempt to summarize our current understanding of the genetic and molecular biology of circadian clocks in cyanobacteria, fungi, insects, and mammals. (Chronobiology International, 17(4), 433–451, 2000) 相似文献
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John E Moore 《BMC microbiology》2001,1(1):32-4
Background
The past three decades have witnessed the rise of Campylobacter enteritis in man from virtual obscurity to notoriety, with present isolation rates superseding those of other enteric pathogens such as Salmonella spp. and Shigella spp. in most developed countries. Although campylobacters are not completely new to applied bacteriology, they have evaded traditional isolation techniques used for the isolation of pure cultures, apart from single isolations that were free from competing organisms. Offals, in particular liver have been decribed as both a source of campylobacters, as well as a route of transmission of this organism to human. Therefore, the aim of this study was to develop an optimum method for the recovery of Campylobacter spp. from porcine liver. 相似文献16.
Kevin J. Emerson Sabrina J. Dake William E. Bradshaw Christina M. Holzapfel 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(4):385-391
For over 70 years, researchers have debated whether the ability to use day length as a cue for the timing of seasonal events
(photoperiodism) is related to the endogenous circadian clock that regulates the timing of daily events. Models of photoperiodism
include two components: (1) a photoperiodic timer that measures the length of the day, and (2) a photoperiodic counter that
elicits the downstream photoperiodic response after a threshold number of days has been counted. Herein, we show that there
is no geographical pattern of genetic association between the expression of the circadian clock and the photoperiodic timer
or counter. We conclude that the photoperiodic timer and counter have evolved independently of the circadian clock in the
pitcher-plant mosquito Wyeomyia smithii and hence, the evolutionary modification of photoperiodism throughout the range of W. smithii has not been causally mediated by a corresponding evolution of the circadian clock.
相似文献
Kevin J. EmersonEmail: |
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Background
Although the gene encoding for glutamine synthetase (gln A) is essential in several organisms, multiple glnA copies have been identified in bacterial genomes such as those of the phylum Actinobacteria, notably the mycobacterial species. Intriguingly, previous reports have shown that only one copy (gln A1) is essential for growth in M. tuberculosis, while the other copies (gln A2, gln A3 and gln A4) are not. 相似文献18.
Elena Simionato Pierre Kerner Nicolas Dray Martine Le Gouar Valérie Ledent Detlev Arendt Michel Vervoort 《BMC evolutionary biology》2008,8(1):170
Background
Functional studies in model organisms, such as vertebrates and Drosophila, have shown that basic Helix-loop-Helix (bHLH) proteins have important roles in different steps of neurogenesis, from the acquisition of neural fate to the differentiation into specific neural cell types. However, these studies highlighted many differences in the expression and function of orthologous bHLH proteins during neural development between vertebrates and Drosophila. To understand how the functions of neural bHLH genes have evolved among bilaterians, we have performed a detailed study of bHLH genes during nervous system development in the polychaete annelid, Platynereis dumerilii, an organism which is evolutionary distant from both Drosophila and vertebrates. 相似文献19.
Background
Plants respond to extracellularly perceived abiotic stresses such as low temperature, drought, and salinity by activation of complex intracellular signaling cascades that regulate acclimatory biochemical and physiological changes. Protein kinases are major signal transduction factors that have a central role in mediating acclimation to environmental changes in eukaryotic organisms. In this study, we characterized the function of the sucrose nonfermenting 1-related protein kinase2 (SnRK2) SAPK4 in the salt stress response of rice. 相似文献20.