共查询到20条相似文献,搜索用时 15 毫秒
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Shibata Y Kumar P Layer R Willcox S Gagan JR Griffith JD Dutta A 《Science (New York, N.Y.)》2012,336(6077):82-86
We have identified tens of thousands of short extrachromosomal circular DNAs (microDNA) in mouse tissues as well as mouse and human cell lines. These microDNAs are 200 to 400 base pairs long, are derived from unique nonrepetitive sequence, and are enriched in the 5'-untranslated regions of genes, exons, and CpG islands. Chromosomal loci that are enriched sources of microDNA in the adult brain are somatically mosaic for microdeletions that appear to arise from the excision of microDNAs. Germline microdeletions identified by the "Thousand Genomes" project may also arise from the excision of microDNAs in the germline lineage. We have thus identified a previously unknown DNA entity in mammalian cells and provide evidence that their generation leaves behind deletions in different genomic loci. 相似文献
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Fragments of embryonic spinal cord (human, rat, and chick) can regenerate and differentiate in tissue culture. Complex bioelectric activity evoked by electric stimuli indicates that nerve cells in cultures may maintain, for months in vitro, not only the capacity to propagate impulses along their neurites but also a remarkable degree of functional organization resembling the activity of synaptic networks of the central nervous system. 相似文献
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Cultured tobacco tissue possesses proplastids capable of differentiating into mature chloroplasts. Kinetin (6-furfurylaminopurine) is a specific requirement for this differentiation; the absence of this compound results in a blockage of the formation of grana. The possibility that kinetin exerts a direct effect upon chloroplast differentiation is considered. 相似文献
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Main JH 《Science (New York, N.Y.)》1966,152(3723):778-780
When tooth germs derived from 14-day mouse embryos were cultured on gelatin sponges in vitro for 37 days, they lost their characteristic morphology, appearing as a layer of undifferentiated epithelium on the sponge surface, with the mesenchymal cells scattered throughout the interstices. These cultures were then transplanted subcutaneously into isologous, newborn recipients and, over a period of 56 days, developed into incisor teeth that were almost perfect in shape and structure. 相似文献
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Gibberellins are a specific growth requirement of tissue cultures derived from the staminate cones of Cupressus funebris. The tissue originally required coconut milk for growth. However, a mixture of acid-hydrolyzed casein hydrolyzate and gibberellins replaces the coconut milk entirely and permits even better growth. It is tentatively suggested that coconut milk contains gibberellins or related substances and that these substances are involved in the nitrogen metabolism of the tissue. 相似文献
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对小水榕组织培养过程中的污染细菌进行分离鉴定,结果表明:分离到的13株污染细菌分别属于4个类群(Alphaproteobacteria、Betaproteobacteria、Gammaproteobacteria、Actinobacteria)的11个属(Paracoccus、Sphingomonas、Agrobacterium、Delftia、Roseateles、Cupriavidus、Herbaspirillum、Stenotrophomonas、Acinetobacter、Microbacterium、Mycobacterium),其中Betaproteobacteria为优势种群,占总数的38.5%;所有菌株和其同源菌株的相似性均在98%以上。 相似文献
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杨树湿地松组织培养愈伤组织耐盐性 总被引:4,自引:1,他引:4
对杨树无性系NL-80105,NL-80106,NL-80117和湿地松组织培养愈伤组织的耐盐性进行了研究。结果表明:以MS为基本培养基,添加2,4-D2.0mg·kg-1和KT0.5mg·kg-1,诱导这些树种愈伤组织效果好;在含氯化钠的培养基上,杨树不同器官外植体的愈伤组织诱导能力和耐盐程度有差异,外植体茎、叶比根强;杨树继代愈伤组织的耐盐能力显著高于湿地松,这与植株水平的耐盐性相一致,表明用愈伤组织鉴别这些植物耐盐性的方法是可行的 相似文献
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黄花白芨组培快繁技术 总被引:5,自引:0,他引:5
用不同的基本培养基,不同的植物生长调节剂及其配比,不同的原球茎切割方式系统地研究了黄花白芨组织培养技术,试验结果表明:1/2MS+1.0mg.L^-1BA+0.1mg.L^-1NAA培养基有利于原球茎增殖,培养60d增殖到4.21倍; 相似文献
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Cerebroside antibody inhibits sulfatide synthesis and myelination and demyelinates in cord tissue cultures 总被引:7,自引:0,他引:7
Antiserum to cerebroside was prepared in rabbits by injection of cerebroside together with bovine serum albumin in complete Freund's adjuvant. When applied to cultures of embryo mouse spinal cord at explantation, this antiserum inhibited sulfatide synthesis and myelination; when applied to myelinated cultures it inhibited sulfatide synthesis and produced demyelination. Complement fixation assays also show antibody to cerebroside in serums from rabbits with experimental allergic encephalomyelitis induced by injection of whole white matter. Absorption of such serum with cerebroside abolishes the inhibiting and demyelinating activities. 相似文献
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定位试验20年黄潮土速效磷养分的变化特征 总被引:1,自引:0,他引:1
利用黄潮土20年长期定位试验,研究了不同施肥条件下土壤速效磷含量的变化特征。结果表明,长期施用磷肥可以基本维持耕层土壤速效磷的水平;不施肥或单施氮肥以及配施厩肥,土壤速效磷含量随年代的变化,分别呈指数函数负相关和正相关。长期施用磷肥或厩肥可不同程度提高土壤剖面各层次速效磷含量,且磷肥与厩肥配施的效果较其单施更明显。在小麦-玉米轮作周期内,长期不同施肥处理可影响作物各生长期的土壤速效磷含量,但它们受外界环境条件影响而随季节变化的趋势基本一致。 相似文献