Nucleotide sequence of the "denaturable" leucine transfer RNA from yeast

The nucleotide sequence of " denaturable"leucine acceptor transfer RNA (tRNA(Leu)(3)) from baker's yeast was determined on (32)P-labeled material. The molecule is 85 nucleotides long and can be folded into the "cloverleaf" model for secondary structure. The basis on which the sequence was deduced from the products of complete enzymatic digestion, prior to its unambiguous determination, is presented.     

Protein displacement by DExH/D "RNA helicases" without duplex unwinding

Members of the DExH/D superfamily of nucleic acid-activated nucleotide triphosphatases are essential for virtually all aspects of RNA metabolism, including pre-messenger RNA splicing, RNA interference, translation, and nucleocytoplasmic trafficking. Physiological substrates for these enzymes are thought to be regions of double-stranded RNA, because several DExH/D proteins catalyze strand separation in vitro. These "RNA helicases" can also disrupt RNA-protein interactions, but it is unclear whether this activity is coupled to duplex unwinding. Here we demonstrate that two unrelated DExH/D proteins catalyze protein displacement independently of duplex unwinding. Therefore, the essential functions of DExH/D proteins are not confined to RNA duplexes but can be exerted on a wide range of ribonucleoprotein substrates.     

An examination of "transfer of learning" by nucleic Acid

Nucleic acid extracted from brains of trained animals and injected intraperitoneally into naive animals produced no "transfer of learning" effect on several tasks under many conditions. P(325)-Labeled RNA was not found in the brain after intraperitoneal administration. Even intraventricular injections of nucleic acid produced no "transfer" effect.     

甜菜坏死黄脉病毒不同分离物三联基因区及RNA3的序列分析

以来自于我国内蒙古、黑龙江和宁夏的3个甜菜坏死黄脉病毒（BNYVV）分离物为材料,采用反转录－PCR方法扩增不同RNA组分的基因片段,经cDNA克隆和序列测定后,与国外报道的BNYVV不同株系和来自于我国不同地区的BNYVV分离物之间进行比较分析。结果表明,BNYVV内蒙呼和浩特分离物（HU）RNA2中的42kD至3'端蛋白编码区长度为2435个核苷酸（nt),与法国F2分离物、德国G1分离物、日本S分离物的一致性分别为97．7％,94．9％;而黑龙江（HEI）、宁夏（NIN）和内蒙古包头分离物（BAO）RNA3的25kD蛋白编码区则与以往报道的内蒙呼和浩特分离物（HU）相应片段分别具有95．4％,93．4％和94．0％4的一致性,这些差异进一步证明了在BNYVV分离物之间广泛存在的分子变异,并可能与它们的致病能力相关。     

Changing the acceptor identity of a transfer RNA by altering nucleotides in a "variable pocket"

The specificity of tRNA(Arg) (arginine transfer RNA) for aminoacylation (its acceptor identity) were first identified by computer analysis and then examined with amber suppressor tRNAs in Escherichia coli. On replacing two nucleotides in tRNA(Phe) (phenylalanine transfer RNA) with the corresponding nucleotides from tRNA(Arg), the acceptor identity of the resulting tRNA was changed to that of tRNA(Arg). The nucleotides used in the identity transformation occupy a "variable pocket" structure on the surface of the tRNA molecule where two single-stranded loop segments interact. The middle nucleotide in the anticodon also probably contributes to the interaction, since an amber suppressor of tRNA(Arg) had an acceptor identity for lysine as well as arginine.     

The "spliceosome": yeast pre-messenger RNA associates with a 40S complex in a splicing-dependent reaction

The in vitro splicing reactions of pre-messenger RNA (pre-mRNA) in a yeast extract were analyzed by glycerol gradient centrifugation. Labeled pre-mRNA appears in a 40S peak only if the pre-mRNA undergoes the first of the two partial splicing reactions. RNA analysis after extraction of glycerol gradient fractions shows that lariat-form intermediates, molecules that occur only in mRNA splicing, are found almost exclusively in this 40S complex. Another reaction intermediate, cut 5' exon RNA, can also be found concentrated in this complex. The complex is stable even in 400 mM KCl, although at this salt concentration, it sediments at 35S and is clearly distinguishable from 40S ribosomal subunits. This complex, termed a "spliceosome," is thought to contain components necessary for mRNA splicing; its existence can explain how separated exons on pre-mRNA are brought into contact.     

The product of the mos proto-oncogene as a candidate "initiator" for oocyte maturation

The endogenous c-mos product, pp39mos, is required for progesterone-induced meiotic maturation in Xenopus oocytes. Treatment of oocytes with progesterone induced a rapid increase in pp39mos that preceded both the activation of maturation promoting factor (MPF) and germinal vesicle breakdown (GVBD). Microinjection of synthetic mos RNA into oocytes activated MPF and induced GVBD in the absence of progesterone. Thus, the mos proto-oncogene product may qualify as a candidate "initiator" protein of MPF and is at least one of the "triggers" for G2 to M transition.     

Antibody formation: initiation in "nonresponder" mice by macrophage synthetic polypeptide RNA

The RNA extracted from normal peritoneal macrophages exposed to a linear, random synthetic polypeptide, Glu(60)Ala(30)Tyr(10), initiated an immune response in C57B1/6J mice, although this strain responds very poorly to the antigen itself. From 10 to 150 micrograms of RNA obtained from mouse, rat, or rabbit macrophages was injected intraperitoneally into recipient mice, and specific antibody was detectable by passive hemagglutination 3 to 4 weeks later. Treatment of the RNA with ribonuclease destroyed its ability to initiate a specific immune response. The RNA contained by weight 0.02 percent of the (specific) antigen. The RNA obtained from cells incubated with a second polypeptide, Glu(36)Lys(24)Ala(40), initiated a response specific for this polymer. This RNA even when incubated in vitro with Glu(60)Ala(30)Tyr(10) failed to initiate antibody formation specific for Glu(60)Ala(30)Tyr(10).     

Comment on "Widespread RNA and DNA sequence differences in the human transcriptome"

Li et al. (Research Articles, 1 July 2011, p. 53; published online 19 May 2011) reported large numbers of differences between DNA and messenger RNA in human cells, indicating unprecedented levels of RNA editing, and including sequence changes not produced by any of the known RNA editing mechanisms. However, common sources of systematic errors in high-throughput sequencing technology, which were not properly accounted for in this study, explain most of the claimed differences.     

一种适用于地黄不同组织器官的RNA提取方法

在药用植物中开展分子生物学研究时的常见困难是RNA提取困难,提取的RNA质量不能满足下一步试验要求。探索了一种适用于地黄不同组织器官的RNA提取方法并对提取的RNA质量在随后的分子生物学中进行了检验。结果证实通过该方法提取的RNA纯度和完整性较好,完全可以满足后续的分子生物学实验要求,也可以作为其它药用植物RNA提取的参考方法。     

农业信息化“最后一公里”和“最初一公里”问题研究

通过翻阅大量与农业信息化“最后一公里”和“最初一公里”问题相关的文献资料,整理了该问题的由来、对该问题的已有观点,最后给出了笔者对于该问题的看法:该问题是对农业信息化没能达到预期效果的一种表述,而这种表述以及对表述的解读却能够影响看待该问题的视角及解决该问题的思路.     

Messenger RNA in early sea-urchin embryos: cytoplasmic particles

Three structures containing messenger RNA can be demonstrated in the cytoplasm of early sea-urchin embryos: (i) particles that sediment more slowly than ribosomes and contain newly synthesized DNA-like RNA, (ii) light polyribosomes, which also contain this newly synthesized RNA, and (iii) heavy polyribosomes, which seemingly contain only already existing or "maternal" messenger RNA and account for the bulk of the synthesis of protein.     

“三避”技术在永福县罗汉果栽培中的应用

阐述了"三避"(避雨、避寒、避晒)技术在罗汉果种植中的应用发展及意义,并提出了目前"三避技术"存在的问题及改进建议。经多年的栽培种植试验证明,采用"三避"技术种植罗汉果,其苗的成活率、产量、质量及商品性状都有明显地提高,近几年,"三避"技术在广西永福县广泛推广,罗汉果农户取得了良好的经济效益,给广西珍贵特产罗汉果种植业的发展增加了活力。     

大红甜橙和冰糖橙果实发育过程中有机酸和氨基酸含量变化研究

以冰糖橙和大红甜橙为材料,研究两个品种果实发育过程中有机酸和氨基酸含量的变化。结果表明,果实发育过程中大红甜橙果实柠檬酸含量、总氨基酸含量均显著高于冰糖橙;大红甜橙和冰糖橙成熟果实中氨基酸总量分别为5.06 g/100g DW和3.46 g/100g DW,以天冬氨酸、谷氨酸和半胱氨酸含量较高。果实发育过程中,谷氨酸族氨基酸在大红甜橙果实中无明显变化,而在冰糖橙果实中逐渐降低;果实发育前期天冬氨酸族氨基酸含量在大红甜橙果实中高于冰糖橙,而果实成熟期两品种无明显差异;鲜味和甜味氨基酸在大红甜橙果实中含量均高于冰糖橙,且均伴随果实成熟而降低。     

戴东原"群""欲"观念的思想史回溯

本文从戴东原"群"欲"概念上溯先秦儒家礼义起源于饮食男女。饮食之道可以引喻个人与众人生命的安稳与否,男女婚配则可匹配天地五行之义,故所谓饮食男女,实又不仅仅止于饱食与性欲。儒家以血缘为基础,以两性生命之结合为开端,开展各种社群关系的价值,究其实则俱不离形体生命的繁衍;而价值观念的形成,也都不离血气心知合一的身体。自"欲"至"群",人类社会始简终大、始寡终众,儒家伦理价值观念由此而生。戴东原群、欲之论,与先秦儒典旧义有承继发展之关系。先秦儒者重视饮食男女之身体活动的道德价值提升与开展,东原则特别勾勒出一个     

"Transdifferentiation" of C6 glial cells in culture

The activities of cyclic nucleotide phosphohydrolase, an enzyme marker for oligodendrocytes, and glutamine synthetase, an enzyme marker for astrocytes, were studied at early (21 to 26) and late (82 to 88) cell passages. The activity of cyclic nucleotide phosphohydrolase was markedly high and that of glutamine synthetase was low in the early passages, but this relation was reversed in the late passages. These findings suggest a "transdifferentiation" of C6 glial cells with passage in culture.     

"4S"技术在精确农业中的应用

"4S"技术是遥感技术RS、地理信息系统GIS、全球定位系统GPS、专家系统ES的总称。介绍了"4S"技术和精确农业的基本概念和特点以及"4S"综合技术在精确农业中的应用情况,指出"4S"技术在精细农业应用中面临的问题,提出了解决问题的建议与对策。     

"Where" and "what" in vision

The mixture of a few horizontal and vertical line segments embedded in an aggregate of diagonal line segments can be rapidly counted and their positions rapidly determined by a parallel (preattentive) process. However, the discrimination between horizontal and vertical orientation (that is, discrimination of a single conspicuous feature) requires serial search by focal attention. Under recent theories of attention, focal attention has been assumed to be required for the recognition of different combinations of features. According to the findings of this experiment, knowing "what" even a single feature is requires time-consuming search by focal attention. Only knowing "where" a target it is mediated by a parallel process.     

Autocatalytic synthesis of a viral RNA in vitro

Experiments with an RNA-dependent RNA polymerase ("replicase") purified from Escherichia coli infected with an RNA bacteriophage (Qbeta) demonstrate that the enzyme generates a polynucleotide of the same molecular weight as viral RNA; the "replicase" cannot distinguish the polynucleotide from its own RNA genome. By starting reactions at input ratios below the saturation levels of template to enzyme, autocatalytic kinetics of RNA increase are observed. The data are consistent with the conclusion that self-propagation of complete viral genomes is occurring in this simple system.