Preparation of highly labeled (32P)nucleic acids from yeasts; isolation of "denaturable" leucine acceptor transfer RNA

Culture conditions were developed that permit efficient incorporation of [(32)P]phosphate into nucleic acids of baker's yeast. RNA sufficiently labeled for sequence determination was obtained in this way. Pure "denaturable" leucine acceptor transfer RNA (tRNA(Leu)(3)) was isolated for this purpose.     

Sensitive and rapid diagnosis of potato spindle tuber viroid disease by nucleic Acid hybridization

A sensitive and reliable new method for the detection of potato spindle tuber viroid in potato tubers has been developed. The method is based on hybridization of highly radioactive recombinant DNA to viroid RNA that has been attached to a solid support. The method can be automated and permits the rapid testing of large numbers of tubers.     

One-trial interhemispheric transfer of a learning engram

By using spreading depression to decorticate temporarily one hemisphere in rats, a learning trace was established in the opposite functional hemisphere. Spontaneous transfer of the engram from the trained hemisphere to the untrained hemisphere does not occur when both hemispheres are functional. If, however, the animal was allowed to make one reinforced response, complete transfer of the engram to the untrained hemisphere occurred.     

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。     

盘点2006年度郑单958

当夏玉米播种季节结束时,标志着2006年度郑单958销售终结。总体上说,拥有郑单958的授权公司赚了个盆满罐流,大大小小经销商都分得了一杯羹,只有少数批发商和经销户“该出手时没出手”。用两句话来形容这两年郑单958市场价格走势:2005年是“前低后涨还难买”,2006年则是“前平再     

浅叙上海水产大学《计算机应用基础》的考试系统

《计算机应用基础》考核一直是困惑我校教学部门的问题。经历了从最原始的笔试形式,到上机操作考试后由人工阅卷等过程,耗时费力,效果又不理想,为此,组织开发完成了该课程的计算机自动考试系统。该系统经1500人次的新生入学免修考的实践,效果良好。系统包括了考生报名子系统、题库子系统、自动阅卷子系统、考试管理子系统等。1　考试系统的功能模块1.1　考生报名子系统基于Web的考生报名子系统,运用了有关的ASP技术[1],建立考试报名主页。功能有:考生通过网上申请报名考试,在确认考生资格、身份验证后,即时编排,返回考试的场次号、考…     

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.     

Adaptive recognition by nucleic acid aptamers

Nucleic acid molecules play crucial roles in diverse biological processes including the storage, transport, processing, and expression of the genetic information. Nucleic acid aptamers are selected in vitro from libraries containing random sequences of up to a few hundred nucleotides. Selection is based on the ability to bind ligand molecules with high affinity and specificity. Three-dimensional structures have been determined at high resolution for a number of aptamers in complex with their cognate ligands. Structures of aptamer complexes reveal the key molecular interactions conferring specificity to the aptamer-ligand association, including the precise stacking of flat moieties, specific hydrogen bonding, and molecular shape complementarity. These basic principles of discriminatory molecular interactions in aptamer complexes parallel recognition events central to many cellular processes involving nucleic acids.     

中国传统"乐学"思想今探

我国是一个有着悠久历史和灿烂文化的文明古国.自古至今,在绵延数千年的历史发展中,前人为我们留下了丰富的教育思想.其中,"乐学"思想可谓源远流长.它接近于我们现在所说的"快乐教学"的思想.古代一些教育家、思想家,对它有许多精辟论述,儒家在这一领域更是有过许多宝贵建树,提出许多重要思想.于今,对"乐学"思想进行历史性考察,并辩证分析其利弊得失,对我们实施快乐教学,提高教学水平,无疑是有益的.     

证券市场"异象"的行为金融学解释及评介

通过对行为金融学领域有关过度反应和反应不足的四大理论模型,即BSV,DHS,HS和BHS的分析和评介,从投资者的认知偏差和投资行为的非理性角度诠释了证券市场异常行为产生的原因,并从投资者的角度提出基于上述异象的投资策略和建议。     

Comment on "Genetically determined differences in learning from errors"

Klein et al. (Reports, 7 December 2007, p. 1642) used individuals with a polymorphism adjacent to the dopamine receptor 2 gene as naturally occurring models for reduced brain dopamine receptor density in a probabilistic learning task. We raise the concern that this polymorphism resides in the gene for the kinase ANKK1, where it causes a nonconservative amino acid exchange.