Differential-approach tendencies produced by injection of RNA from trained rats

Two groups of rats were trained in a Skinner box to approach the food cup when a discriminative stimulus (click or blinking light) was presented. Ribonucleic acid was extracted from the brains of these two groups of rats and injected into two groups of untrained rats. The untrained two groups then manifested a significant tendency (as compared with one another) to react differently to the two stimuli. On the average, the response appeared to be specific to the stimulus employed during training.     

Extinction following intracranial reward: the effect of delay between acquisition and extinction

Rats trained to press a bar for intracranial reinforcement gave as many responses during extinction as did water-reinforced controls, when extinction came immediately after an acquisition session. However, the experimental animals gave fewer responses in extinction than water-reinforced animals when extinction was delayed for 1 hour after acquisition. The activity level of the experimental animals was high immediately after acquisition but declined markedly over the delay period, which suggests that resistance to extinction after intracranial reinforcement is primarily a function of activity level.     

Localization of amyloid beta protein messenger RNA in brains from patients with Alzheimer's disease

The distribution of cells containing messenger RNA that encodes amyloid beta protein was determined in hippocampi and in various cortical regions from cynomolgus monkeys, normal humans, and patients with Alzheimer's disease by in situ hybridization. Both 35S-labeled RNA antisense and sense probes to amyloid beta protein messenger RNA were used to ensure specific hybridization. Messenger RNA for amyloid beta protein was expressed in a subset of neurons in the prefrontal cortex from monkeys, normal humans, and patients with Alzheimer's disease. This messenger RNA was also present in the neurons of all the hippocampal fields from monkeys, normal humans and, although to a lesser extent in cornu ammonis 1, patients with Alzheimer's disease. The distribution of amyloid beta protein messenger RNA was similar to that of the neurofibrillary tangles of Alzheimer's disease in some regions, but the messenger RNA was also expressed in other neurons that are not usually involved in the pathology of Alzheimer's disease.     

Structural basis of transcription: separation of RNA from DNA by RNA polymerase II

The structure of an RNA polymerase II-transcribing complex has been determined in the posttranslocation state, with a vacancy at the growing end of the RNA-DNA hybrid helix. At the opposite end of the hybrid helix, the RNA separates from the template DNA. This separation of nucleic acid strands is brought about by interaction with a set of proteins loops in a strand/loop network. Formation of the network must occur in the transition from abortive initiation to promoter escape.     

Serengeti migratory wildebeest: facilitation of energy flow by grazing

Dense concentrations of migratory wildebeest leaving the Serengeti Plains in late May 1974 reduced green plant biomass by almost 400 grams per square meter, 85 percent of the initial standing crop. However, this grazing prevented senescence and stimulated net primary productivity of the grasslands. Thomson's gazelles leaving the plains a month later were significantly associated with areas previously grazed by wildebeest, and this association was still evident at the end of the dry season, 6 months later.     

Striated muscle fibers: facilitation of contraction at short lengths by caffeine

One of the factors evidently responsible for decreasing the force of muscle contraction with shortening is inactivation of the myofibrils in the core of a muscle fiber. Caffeine antagonizes this inactivation and, correspondingly, changes the length-force relationship at short muscle lengths.     

Cell-free circularization of viroid progeny RNA by an RNA ligase from wheat germ

Linear, potato spindle tuber viroid RNA has been used as a substrate for an RNA ligase purified from wheat germ. Linear viroid molecules are efficiently converted to circular molecules (circles) which are indistinguishable by electrophoretic mobility and two-dimensional oligonucleotide pattern from viroid circles extracted from infected plants. In light of recent evidence for multimeric viroid replication intermediates, cleavage followed by RNA ligation by a cellular enzyme may (i) be a normal step in the viroid life cycle and (ii) may also reflect cellular events.     

Collagen synthesis in Xenopus oocytes after injection of nuclear RNA of frog embryos

A messenger RNA fraction from polysomes of frog larvae or RNA preparations from isolated nuclei of developing frog embryos were injected into growing Xenopus laevis oocytes that were incubated with labeled proline. Column chromatography of protein hydrolyzates revealed labeled hydroxyproline after injection of the messenger RNA fraction and neurula nuclear RNA, indicating that the injected material had promoted collagen synthesis.     

Homologous viral interference: induction by RNA from defective particles of vesicular stomatitis virus

The viral RNA isolated from the defective particles of vesicular stomatitis virus was capable of interfering with the replication of this virus in chick embryo cells. The data indicate that the interfering ability of the defective particles of this virus is due to their nucleic acid component.     

Nucleoside triphosphate termini from RNA synthesized in vivo by Escherichia coli

Alkaline hydrolyzates of RNA made in vivo by Escherichia coli contain ribonucleoside-3'-monophosphate-5'-triphosphates. These probably arise by hydrolysis of the initial nucleoside triphosphate from the 5' terminus of the nascent RNA chains. Logarithmically growing cultures, labeled for 45 seconds with (32)P-labeled phosphate, yield about 2000 molecules of labeled tetraphosphate per cell, this yield increasing only slightly with continued labeling. Only the tetraphosphates of adenosine and guanosine have been found in Escherichia coli, and these two are present in approximately equal amounts.     

松材线虫病疫木除害技术综述

阐述了松材线虫病疫木的除害处理技术措施,包括疫木异地集中除害、安全利用措施及林内就地现砍现烧和就地套袋覆盖熏蒸等传统措施,以及铁纱网罩就地隔离、疫木种植茯苓等除害新技术,并提出了一些针对性的除害处理建议。     

RNA as an RNA polymerase: net elongation of an RNA primer catalyzed by the Tetrahymena ribozyme

A catalytic RNA (ribozyme) derived from an intervening sequence (IVS) RNA of Tetrahymena thermophila will catalyze an RNA polymerization reaction in which pentacytidylic acid (C5) is extended by the successive addition of mononucleotides derived from a guanylyl-(3',5')-nucleotide (GpN). Cytidines or uridines are added to C5 to generate chain lengths of 10 to 11 nucleotides, with longer products being generated at greatly reduced efficiency. The reaction is analogous to that catalyzed by a replicase with C5 acting as the primer, GpNs as the nucleoside triphosphates, and a sequence in the ribozyme providing a template. The demonstration that an RNA enzyme can catalyze net elongation of an RNA primer supports theories of prebiotic RNA self-replication.     

DNA polymerases from RNA tumor viruses and human cells: inhibition by polyuridylic acid

Polyuridylic acid inhibited DNA polymerases purified from three species of oncornaviruses as well as three out of seven DNA polymerases purified from cells. Viral and cellular DNA polymerases could not be distinguished by polyuridylic acid inhibition, but were easily distinguished by their template preferences in the presence of magnesium.     

牛大力总RNA提取的CTAB法改进及优化

采用改良CTAB法提取牛大力总RNA,采用琼脂糖凝胶电泳、核酸蛋白分析仪和RT-PCR检测所提取总RNA样品的质量.结果表明,改良CTAB法提取的牛大力不同组织或器官的RNA纯度和完整性良好,可满足RT-PCR反应等后续试验的要求.     

北京鸭腹部脂肪组织的转录组特征分析

鸭的基因组序列虽已释放,但其基因组信息,尤其是转录组信息仍需进一步开发。文章利用转录组测序分析了鸭的腹部脂肪组织转录组特征。共获得203 200 984个高质量测序数据,鉴定出18 464个基因表达（RPKM≥1）,其中96.9%的基因RPKM值小于1 000。15 070个基因发生了可变剪切,剪切次数为35 913次。统计可变剪切类型发现,内含子保留所占比例最低,占所有可变剪切类型的1.17%,而第一外显子可变剪切、末端外显子可变剪切、外显子跳跃依次是3种比例最高的可变剪切类型,比例分别为45.92%, 43.67%和6.23%。此外,利用这批转录组数据共检测出229 276个SNPs,其中转换是最主要的突变类型,占所有SNPs的73.28%。对SNP所在基因进行功能注释(GO)发现,这些基因涉及细胞组分、分子功能、生物学过程3大功能类别中广泛的生物功能,表明该研究开发的SNPs较为全面;通路分析（KEGG）发现,SNPs所在基因除了富集于脂类、能量代谢相关通路,更多的基因则富集于癌症、免疫以及内分泌系统相关的通路上,表明脂肪组织除了是能量储备组织,同时也是重要的免疫、内分泌组织。这些数据拓展了鸭的遗传信息,建立的SNPs数据库将有助于鸭分子标记辅助育种及功能基因定位。与癌症、免疫相关的SNPs可为癌症及免疫学研究提供候选遗传标记。     

用小RNA深度测序鉴定广西冬种马铃薯病毒

【目的】对广西冬种马铃薯病毒进行鉴定,为无病毒种薯选择和大田防治提供依据。【方法】2012年在马铃薯主要产区采集具有明显病毒病症状的样品,在血清学ELISA检测的基础上,进一步用小RNA深度测序对按症状分类的样品进行混合样本的病毒种类鉴定,再用RT-PCR方法对分组混合样本进行验证。【结果】在109个样本中检测到马铃薯卷叶病毒（Potato leafroll virus,PLRV）、马铃薯A病毒（Potato virus A,PVA）、马铃薯H病毒（Potato virus H,PVH）、马铃薯M病毒（Potato virus M,PVM）、马铃薯S病毒（Potato virus S,PVS）、马铃薯Y病毒（Potato virus Y,PVY）和马铃薯纺锤块茎类病毒（Potato spindle tuber viroid,PSTVd）,同时发现PVS有丰富的株系分化。【结论】近年广西冬种马铃薯病毒种类增多,病症多样,亟需加强种薯管理,培育无毒健康种薯。     

Trizol法提取厚皮甜瓜果实RNA条件的筛选

采用改良的Trizol法提取厚皮甜瓜‘银帝’果实中的RNA.利用琼脂糖凝胶电泳、紫外分光光度法和RT-PCR法进行纯度、浓度和RNA完整性检测.结果表明:1 mL Trizol用于提取200 mg甜瓜果实量时,得到的RNA产量最大,氯仿抽提2次时提取到的RNA的A260/A280在1.9~2.0之间,所提取的RNA无蛋白质和DNA污染,室温沉淀和低温沉淀对RNA的产量无明显影响.将提取的RNA反转录后扩增β-actin基因片段,扩增的条带与设计大小一致,验证了该方法提取的RNA可用于RT-PCR.     

Enzyme from calf thymus degrading the RNA moiety of DNA-RNA Hybrids: effect on DNA-dependent RNA polymerase

An enzyme present in extracts from calf thymus degrades specifically the RNA moiety of DNA-RNA hybrids. Other nucleic acids, such as single- or double-stranded DNA and single- or double-stranded RNA, are not affected to a comparable degree. If prepared free of the hybrid-degrading enzyme, RNA polymerase from calf thymus shows a fivefold increase in activity on denatured DNA as compared to native DNA.