优良庭院绿化和观赏树种鸡蛋花

\t\t\t\t\t目的\t\t\t\t\t开展鸡蛋花微体快繁技术研究,为实现优良品种(系)的无性快繁提供技术保障。\t\t\t\t\t\t\t\t\t\t\t\t\t方法\t\t\t\t\t以鸡蛋花无菌苗的顶芽为外植体,以1/2 MS为基本培养基,研究不同质量浓度的细胞分裂素和生长素及其配比对鸡蛋花不定芽诱导、伸长和生根的影响。\t\t\t\t\t\t\t\t\t\t\t\t\t结果\t\t\t\t\t不定芽诱导培养基为1/2 MS+6-BA 1.0 mg/L+NAA 0.1 mg/L,增殖系数为4.2;试管苗伸长培养基为1/2 MS+NAA 0.05 mg/L;试管苗不定根诱导培养基为：1/2 MS+3.0 mg/L IBA,生根率为93.3%;试管苗在V(珍珠岩): V(草炭土)=1: 2的基质中的移栽成活率达到86%。\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t结论\t\t\t\t\t获得了鸡蛋花不定芽诱导、伸长、生根的最佳培养基和适宜的移栽基质,建立了微体快繁技术体系。\t\t\t\t     

Absence of cystathionase in human fetal liver: is cystine essential?

Cystathionase activity is not measurable in the livers of 24 human fetuses and 3 premature infants, and the concentration of cystathionine in the liver is higher than that of the brain. The placenta does not subserve the trans-sulfuration function. Cystine (or cysteine) thus may be an essential amino acid in the immature human.     

Functional delivery of a cytosolic tRNA into mutant mitochondria of human cells

Many maternally inherited and incurable neuromyopathies are caused by mutations in mitochondrial (mt) transfer RNA (tRNA) genes. Kinetoplastid protozoa, including Leishmania, have evolved specialized systems for importing nucleus-encoded tRNAs into mitochondria. We found that the Leishmania RNA import complex (RIC) could enter human cells by a caveolin-1-dependent pathway, where it induced import of endogenous cytosolic tRNAs, including tRNA(Lys), and restored mitochondrial function in a cybrid harboring a mutant mt tRNA(Lys) (MT-TK) gene. The use of protein complexes to modulate mitochondrial function may help in the management of such genetic disorders.     

An RNA ligase essential for RNA editing and survival of the bloodstream form of Trypanosoma brucei

RNA editing in trypanosomes occurs by a series of enzymatic steps that are catalyzed by a macromolecular complex. The TbMP52 protein is shown to be a component of this complex, to have RNA ligase activity, and to be one of two adenylatable proteins in the complex. Regulated repression of TbMP52 blocks editing, which shows that it is a functional component of the editing complex. This repression is lethal in bloodforms of the parasite, indicating that editing is essential in the mammalian stage of the life cycle. The editing complex, which is present in all kinetoplastid parasites, may thus be a chemotherapeutic target.     

Messenger RNA splicing in yeast: clues to why the spliceosome is a ribonucleoprotein

The removal of introns from eukaryotic messenger RNA precursors shares mechanistic characteristics with the self-splicing of certain introns, prompting speculation that the catalytic reactions of nuclear pre-messenger RNA splicing are fundamentally RNA-based. The participation of five small nuclear RNAs (snRNAs) in splicing is now well documented. Genetic analysis in yeast has revealed the requirement, in addition, for several dozen proteins. Some of these are tightly bound to snRNAs to form small nuclear ribonucleoproteins (snRNPs); such proteins may promote interactions between snRNAs or between an snRNA and the intron. Other, non-snRNP proteins appear to associate transiently with the spliceosome. Some of these factors, which include RNA-dependent adenosine triphosphatases, may promote the accurate recognition of introns.     

Crystal structure of the GpIbalpha-thrombin complex essential for platelet aggregation

Direct interaction between platelet receptor glycoprotein Ibalpha (GpIbalpha) and thrombin is required for platelet aggregation and activation at sites of vascular injury. Abnormal GpIbalpha-thrombin binding is associated with many pathological conditions,including occlusive arterial thrombosis and bleeding disorders. The crystal structure of the GpIbalpha-thrombin complex at 2.6 angstrom resolution reveals simultaneous interactions of GpIbalpha with exosite I of one thrombin molecule,and with exosite II of a second thrombin molecule. In the crystal lattice,the periodic arrangement of GpIbalpha-thrombin complexes mirrors a scaffold that could serve as a driving force for tight platelet adhesion. The details of these interactions reconcile GpIbalpha-thrombin binding modes that are presently controversial,highlighting two distinct interfaces that are potential targets for development of novel antithrombotic drugs.     

The human gene for the beta subunit of nerve growth factor is located on the proximal short arm of chromosome 1

Fragments of the recently cloned human gene for the beta subunit of nerve growth factor (beta-NGF) were used as hybridization probes in analyzing two sets of rodent-human somatic cell hybrids for the presence of human beta-NGF sequences. Results from the first set of hybrids assigned the human beta-NGF gene to chromosome 1 and ruled out the presence of sequences of comparable homology on any other chromosome. With the second set of hybrids, which contained seven different, but overlapping, regions of chromosome 1, the NGF locus was mapped to band 1p22.     

Predictive identification of exonic splicing enhancers in human genes

Specific short oligonucleotide sequences that enhance pre-mRNA splicing when present in exons, termed exonic splicing enhancers (ESEs), play important roles in constitutive and alternative splicing. A computational method, RESCUE-ESE, was developed that predicts which sequences have ESE activity by statistical analysis of exon-intron and splice site composition. When large data sets of human gene sequences were used, this method identified 10 predicted ESE motifs. Representatives of all 10 motifs were found to display enhancer activity in vivo, whereas point mutants of these sequences exhibited sharply reduced activity. The motifs identified enable prediction of the splicing phenotypes of exonic mutations in human genes.     

混合芳香精油对于改善人类认知能力的作用

探讨吸入天然复方芳香精油对于健康人群认知功能的影响及其可能的神经机制。通过选择健康大学生被试,随机分为有精油吸入组和无精油吸入组,被试需完成注意力、短时记忆与计算能力3个认知任务,采用64通道脑电设备记录被试任务过程中事件相关电位的变化。结果表明,精油吸入条件下,被试在完成注意任务时,注意力水平有所提升,P3、Oz、C4等通道P300波幅出现显著差异,但短时记忆与计算能力则没有出现显著差异。     

Protein splicing converts the yeast TFP1 gene product to the 69-kD subunit of the vacuolar H(+)-adenosine triphosphatase

The TFP1 gene of the yeast Saccharomyces cerevisiae encodes two proteins: the 69-kilodalton (kD) catalytic subunit of the vacuolar proton-translocating adenosine triphosphatase (H(+)-ATPase) and a 50-kD protein. The 69-kD subunit is encoded by the 5' and 3' thirds of the TFP1 coding region, whereas the 50-kD protein is encoded by the central third. Evidence is presented that both the 69-kD and 50-kD proteins are obtained from a single translation product that is cleaved to release the 50-kD protein and spliced to form the 69-kD subunit.     

How old is the genetic code? Statistical geometry of tRNA provides an answer

The age of the molecular organization of life as expressed in the genetic code can be estimated from experimental data. Comparative sequence analysis of transfer RNA by the method of statistical geometry in sequence space suggests that about one-third of the present transfer RNA sequence divergence was present at the urkingdom level about the time when archaebacteria separated from eubacteria. It is concluded that the genetic code is not older than, but almost as old as our planet. While this result may not be unexpected, it was not clear until now that interpretable data exist that permit inferences about such early stages of life as the establishment of the genetic code.     

水稻中介体亚基OsMed6的表达及进化分析

中介体复合物是真核生物RNA聚合酶Ⅱ(PolⅡ)通用转录装置的重要组成部分,是基因特异性转录因子与启动子信息传递的桥梁.本研究对水稻(Oryza sativa)中一个假定的中介体亚基OsMed6的表达和进化进行了分析.通过整合分析不同来源的基因芯片数据,发现OsMed6在各个组织(器官)里都有表达.构建了OsMed6与...     

RIM-binding protein, a central part of the active zone, is essential for neurotransmitter release

The molecular machinery mediating the fusion of synaptic vesicles (SVs) at presynaptic active zone (AZ) membranes has been studied in detail, and several essential components have been identified. AZ-associated protein scaffolds are viewed as only modulatory for transmission. We discovered that Drosophila Rab3-interacting molecule (RIM)-binding protein (DRBP) is essential not only for the integrity of the AZ scaffold but also for exocytotic neurotransmitter release. Two-color stimulated emission depletion microscopy showed that DRBP surrounds the central Ca(2+) channel field. In drbp mutants, Ca(2+) channel clustering and Ca(2+) influx were impaired, and synaptic release probability was drastically reduced. Our data identify RBP family proteins as prime effectors of the AZ scaffold that are essential for the coupling of SVs, Ca(2+) channels, and the SV fusion machinery.     

Genome-wide survey of human alternative pre-mRNA splicing with exon junction microarrays

Alternative pre-messenger RNA (pre-mRNA) splicing plays important roles in development, physiology, and disease, and more than half of human genes are alternatively spliced. To understand the biological roles and regulation of alternative splicing across different tissues and stages of development, systematic methods are needed. Here, we demonstrate the use of microarrays to monitor splicing at every exon-exon junction in more than 10,000 multi-exon human genes in 52 tissues and cell lines. These genome-wide data provide experimental evidence and tissue distributions for thousands of known and novel alternative splicing events. Adding to previous studies, the results indicate that at least 74% of human multi-exon genes are alternatively spliced.