共查询到20条相似文献，搜索用时 31 毫秒
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分析光照对泌乳期小鼠下丘脑视上核(SCN)及乳腺组织内生物钟基因Clock表达的影响.采用荧光定量RT-PCR法测定不同光照条件下SCN和乳腺组织中Clock基因的昼夜表达规律.试验发现Clock基因的mRNA不但在SCN,而且在乳腺组织也具有昼夜节律性表达.在光照-黑暗交替光制下,SCN和乳腺组织Clock基因的mRNA表达的峰值相位存在约6 h的相位差;在全黑暗条件下,Clock基因的mRNA表达存在昼夜节律,SCN和乳腺组织Clock基因的mRNA表达的峰值相位基本同步.结果显示,Clock基因的昼夜节律表达具内源性特征;光照影响Clock基因mRNA的表达. 相似文献
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Environmental temperature cycles are a universal entraining cue for all circadian systems at the organismal level with the exception of homeothermic vertebrates. We report here that resistance to temperature entrainment is a property of the suprachiasmatic nucleus (SCN) network and is not a cell-autonomous property of mammalian clocks. This differential sensitivity to temperature allows the SCN to drive circadian rhythms in body temperature, which can then act as a universal cue for the entrainment of cell-autonomous oscillators throughout the body. Pharmacological experiments show that network interactions in the SCN are required for temperature resistance and that the heat shock pathway is integral to temperature resetting and temperature compensation in mammalian cells. These results suggest that the evolutionarily ancient temperature resetting response can be used in homeothermic animals to enhance internal circadian synchronization. 相似文献
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Entrainment of the circadian clock in the liver by feeding 总被引：2，自引：0，他引：2
Circadian rhythms of behavior are driven by oscillators in the brain that are coupled to the environmental light cycle. Circadian rhythms of gene expression occur widely in peripheral organs. It is unclear how these multiple rhythms are coupled together to form a coherent system. To study such coupling, we investigated the effects of cycles of food availability (which exert powerful entraining effects on behavior) on the rhythms of gene expression in the liver, lung, and suprachiasmatic nucleus (SCN). We used a transgenic rat model whose tissues express luciferase in vitro. Although rhythmicity in the SCN remained phase-locked to the light-dark cycle, restricted feeding rapidly entrained the liver, shifting its rhythm by 10 hours within 2 days. Our results demonstrate that feeding cycles can entrain the liver independently of the SCN and the light cycle, and they suggest the need to reexamine the mammalian circadian hierarchy. They also raise the possibility that peripheral circadian oscillators like those in the liver may be coupled to the SCN primarily through rhythmic behavior, such as feeding. 相似文献
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Yamazaki S Numano R Abe M Hida A Takahashi R Ueda M Block GD Sakaki Y Menaker M Tei H 《Science (New York, N.Y.)》2000,288(5466):682-685
In multicellular organisms, circadian oscillators are organized into multitissue systems which function as biological clocks that regulate the activities of the organism in relation to environmental cycles and provide an internal temporal framework. To investigate the organization of a mammalian circadian system, we constructed a transgenic rat line in which luciferase is rhythmically expressed under the control of the mouse Per1 promoter. Light emission from cultured suprachiasmatic nuclei (SCN) of these rats was invariably and robustly rhythmic and persisted for up to 32 days in vitro. Liver, lung, and skeletal muscle also expressed circadian rhythms, which damped after two to seven cycles in vitro. In response to advances and delays of the environmental light cycle, the circadian rhythm of light emission from the SCN shifted more rapidly than did the rhythm of locomotor behavior or the rhythms in peripheral tissues. We hypothesize that a self-sustained circadian pacemaker in the SCN entrains circadian oscillators in the periphery to maintain adaptive phase control, which is temporarily lost following large, abrupt shifts in the environmental light cycle. 相似文献
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Light pulses that shift rhythms induce gene expression in the suprachiasmatic nucleus 总被引：22，自引：0，他引：22
Lighting cycles synchronize (entrain) mammalian circadian rhythms by altering activity of cells in the suprachiasmatic nucleus (SCN) of the hypothalamus, a circadian pacemaker. Exposure of hamsters and rats to light pulses at those phases of the circadian rhythm during which light can shift the rhythm caused increased immunoreactivity for the product of the immediate-early gene c-fos in cells in the region of the SCN that receives retinal fibers. Light pulses also increased messenger RNA for the Fos protein and for the immediate-early protein NGFI-A in the rat SCN. Similar increases in mRNA for NGFI-A were seen in the SCN of hamsters. Thus cells in this portion of the SCN undergo alterations in gene expression in response to retinal illumination, but only at times in the circadian cycle when light is capable of influencing entrainment. 相似文献
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基于元分析与结构域注释的大豆胞囊线虫抗性基因挖掘 总被引：2，自引：0，他引：2
【目的】挖掘大豆胞囊线虫(Heterodera glycines Ichinohe,SCN)抗性基因,并分析其在不同大豆品种中及同一品种的不同组织中的表达情况,探讨其在抗SCN反应中的作用。【方法】采用图谱整合软件BioMercator2.1将不同来源的QTL整合到遗传图谱GmComposite2003上,并通过元分析的方法获得一致性QTL。运用抗病基因注释的方法获得一致性QTL内包含的抗性候选基因,同时采用分子生物学手段克隆预测得到的基因,并采用半定量RT-PCR的方法进行表达分析。【结果】通过元分析获得了27个一致性位点,根据hmmsearch的搜索结果显示,共得到77个SCN抗性候选基因,其中PK-LRR-TM和PK类的抗病基因为主要的类型,共占总数的77%。选择Gm16上抗病基因簇内的基因进行克隆,其中4个获得扩增产物,半定量RT-PCR结果表明,Glyma16g31490.1只在抗线虫品种L-10中表达,而在感线虫品种黑农37中不表达,且在L-10根中的表达量明显高于叶片中的表达量。【结论】克隆得到4个SCN抗性基因与其它植物PK-LRR-TM类抗病基因具有较高的相似度。Glyma16g31490.1在不同品种及同一品种不同组织间的表达量存在差异,推测其在SCN抗性过程中可能发挥一定的作用,也进一步证明了利用元分析与结构域注释的方法挖掘SCN抗性基因是一种有效的方法。 相似文献
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Ramsey NF 《Science (New York, N.Y.)》1990,248(4963):1612-1619
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An inherited functional circadian clock in zebrafish embryos 总被引：1，自引：0，他引：1
Circadian clocks are time-keeping systems found in most organisms. In zebrafish, expression of the clock gene Period3 (Per3) oscillates throughout embryogenesis in the central nervous system and the retina. Per3 rhythmic expression was free-running and was reset by light but not by the developmental delays caused by low temperature. The time of fertilization had no effect on Per3 expression. Per3 messenger RNA accumulates rhythmically in oocytes and persists in embryos. Our results establish that the circadian clock functions during early embryogenesis in zebrafish. Inheritance of maternal clock gene products suggests a mechanism of phase inheritance through ovogenesis. 相似文献
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Transcriptional regulatory networks in Saccharomyces cerevisiae 总被引：2，自引：0，他引：2
Lee TI Rinaldi NJ Robert F Odom DT Bar-Joseph Z Gerber GK Hannett NM Harbison CT Thompson CM Simon I Zeitlinger J Jennings EG Murray HL Gordon DB Ren B Wyrick JJ Tagne JB Volkert TL Fraenkel E Gifford DK Young RA 《Science (New York, N.Y.)》2002,298(5594):799-804
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Gene regulation by transcription factors and microRNAs 总被引：1，自引：0，他引：1
Hobert O 《Science (New York, N.Y.)》2008,319(5871):1785-1786
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HBx小鼠肿瘤细胞株的建立及初步鉴定 总被引：2，自引：0，他引：2
目的建立稳定、高效的HBxAg体外表达细胞株,以便进一步研究HBX基因和HBxAg的致癌作用及机理。方法用RT-PCR技术扩增出了HBX的cDNA,并克隆到真核表达载体pcDNA3.1中,通过脂质体介导将pcD-NA3.1-HBX转染到小鼠肿瘤细胞株(EL4)中。结果RT-PCR及蛋白质印迹的实验结果表明,HBX基因在小鼠肿瘤细胞EL4细胞中得到了表达。结论本研究成功构建了表达HBx的小鼠肿瘤细胞株,为进一步研究HBX基因和HBx的致癌作用及机制奠定了实验基础。 相似文献
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An unusual property of the circadian timekeeping systems of animals is rhythm "splitting," in which a single daily period of physical activity (usually measured as wheel running) dissociates into two stably coupled components about 12 hours apart; this behavior has been ascribed to a clock composed of two circadian oscillators cycling in antiphase. We analyzed gene expression in the hypothalamic circadian clock, the suprachiasmatic nucleus (SCN), of behaviorally "split" hamsters housed in constant light. The results show that the two oscillators underlying the split condition correspond to the left and right sides of the bilaterally paired SCN. 相似文献
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Balsalobre A Brown SA Marcacci L Tronche F Kellendonk C Reichardt HM Schütz G Schibler U 《Science (New York, N.Y.)》2000,289(5488):2344-2347
In mammals, circadian oscillators reside not only in the suprachiasmatic nucleus of the brain, which harbors the central pacemaker, but also in most peripheral tissues. Here, we show that the glucocorticoid hormone analog dexamethasone induces circadian gene expression in cultured rat-1 fibroblasts and transiently changes the phase of circadian gene expression in liver, kidney, and heart. However, dexamethasone does not affect cyclic gene expression in neurons of the suprachiasmatic nucleus. This enabled us to establish an apparent phase-shift response curve specifically for peripheral clocks in intact animals. In contrast to the central clock, circadian oscillators in peripheral tissues appear to remain responsive to phase resetting throughout the day. 相似文献
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Transcription of class III genes: formation of preinitiation complexes 总被引：125，自引：0，他引：125
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The primary circadian pacemaker, in the suprachiasmatic nucleus (SCN) of the mammalian brain, is photoentrained by light signals from the eyes through the retinohypothalamic tract. Retinal rod and cone cells are not required for photoentrainment. Recent evidence suggests that the entraining photoreceptors are retinal ganglion cells (RGCs) that project to the SCN. The visual pigment for this photoreceptor may be melanopsin, an opsin-like protein whose coding messenger RNA is found in a subset of mammalian RGCs. By cloning rat melanopsin and generating specific antibodies, we show that melanopsin is present in cell bodies, dendrites, and proximal axonal segments of a subset of rat RGCs. In mice heterozygous for tau-lacZ targeted to the melanopsin gene locus, beta-galactosidase-positive RGC axons projected to the SCN and other brain nuclei involved in circadian photoentrainment or the pupillary light reflex. Rat RGCs that exhibited intrinsic photosensitivity invariably expressed melanopsin. Hence, melanopsin is most likely the visual pigment of phototransducing RGCs that set the circadian clock and initiate other non-image-forming visual functions. 相似文献
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A key goal of biology is to relate the expression of specific genes to a particular cellular phenotype. However, current assays for gene expression destroy the structural context. By combining advances in computational fluorescence microscopy with multiplex probe design, we devised technology in which the expression of many genes can be visualized simultaneously inside single cells with high spatial and temporal resolution. Analysis of 11 genes in serum-stimulated cultured cells revealed unique patterns of gene expression within individual cells. Using the nucleus as the substrate for parallel gene analysis, we provide a platform for the fusion of genomics and cell biology: "cellular genomics." 相似文献
